Merge pull request #372 from fosrl/dev

1.13.0

Former-commit-id: 0beee679ca

.env.example

@@ -0,0 +1,5 @@
+# Copy this file to .env and fill in your values
+# Required for connecting to Pangolin service
+PANGOLIN_ENDPOINT=https://app.pangolin.net
+NEWT_ID=changeme-id
+NEWT_SECRET=changeme-secret

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @oschwartz10612 @miloschwartz

.github/DISCUSSION_TEMPLATE/feature-requests.yml

@@ -0,0 +1,47 @@
+body:
+    - type: textarea
+      attributes:
+          label: Summary
+          description: A clear and concise summary of the requested feature.
+      validations:
+          required: true
+
+    - type: textarea
+      attributes:
+          label: Motivation
+          description: |
+              Why is this feature important?
+              Explain the problem this feature would solve or what use case it would enable.
+      validations:
+          required: true
+
+    - type: textarea
+      attributes:
+          label: Proposed Solution
+          description: |
+              How would you like to see this feature implemented?
+              Provide as much detail as possible about the desired behavior, configuration, or changes.
+      validations:
+          required: true
+
+    - type: textarea
+      attributes:
+          label: Alternatives Considered
+          description: Describe any alternative solutions or workarounds you've thought about.
+      validations:
+          required: false
+
+    - type: textarea
+      attributes:
+          label: Additional Context
+          description: Add any other context, mockups, or screenshots about the feature request here.
+      validations:
+          required: false
+
+    - type: markdown
+      attributes:
+          value: |
+              Before submitting, please:
+              - Check if there is an existing issue for this feature.
+              - Clearly explain the benefit and use case.
+              - Be as specific as possible to help contributors evaluate and implement.

.github/ISSUE_TEMPLATE/1.bug_report.yml

@@ -0,0 +1,52 @@
+name: Bug Report
+description: Create a bug report
+labels: []
+body:
+    - type: textarea
+      attributes:
+          label: Describe the Bug
+          description: A clear and concise description of what the bug is.
+      validations:
+          required: true
+
+    - type: textarea
+      attributes:
+          label: Environment
+          description: Please fill out the relevant details below for your environment.
+          value: |
+              - OS Type & Version:
+              - Pangolin Version:
+              - Edition (Community or Enterprise):
+              - Gerbil Version:
+              - Traefik Version:
+              - Newt Version:
+              - Client Version:
+      validations:
+          required: true
+
+    - type: textarea
+      attributes:
+          label: To Reproduce
+          description: |
+              Steps to reproduce the behavior, please provide a clear description of how to reproduce the issue, based on the linked minimal reproduction. Screenshots can be provided in the issue body below.
+
+              If using code blocks, make sure syntax highlighting is correct and double-check that the rendered preview is not broken.
+      validations:
+          required: true
+
+    - type: textarea
+      attributes:
+          label: Expected Behavior
+          description: A clear and concise description of what you expected to happen.
+      validations:
+          required: true
+
+    - type: markdown
+      attributes:
+          value: |
+              Before posting the issue go through the steps you've written down to make sure the steps provided are detailed and clear.
+
+    - type: markdown
+      attributes:
+          value: |
+              Contributors should be able to follow the steps provided in order to reproduce the bug.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+    - name: Need help or have questions?
+      url: https://github.com/orgs/fosrl/discussions
+      about: Ask questions, get help, and discuss with other community members
+    - name: Request a Feature
+      url: https://github.com/orgs/fosrl/discussions/new?category=feature-requests
+      about: Feature requests should be opened as discussions so others can upvote and comment

.github/dependabot.yml

@@ -33,3 +33,8 @@ updates:
       minor-updates:
         update-types:
           - "minor"
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/mirror.yaml

@@ -0,0 +1,132 @@
+name: Mirror & Sign (Docker Hub to GHCR)
+
+on:
+  workflow_dispatch: {}
+
+permissions:
+  contents: read
+  packages: write
+  id-token: write   # for keyless OIDC
+
+env:
+  SOURCE_IMAGE: docker.io/fosrl/newt
+  DEST_IMAGE: ghcr.io/${{ github.repository_owner }}/${{ github.event.repository.name }}
+
+jobs:
+  mirror-and-dual-sign:
+    runs-on: amd64-runner
+    steps:
+      - name: Install skopeo + jq
+        run: |
+          sudo apt-get update -y
+          sudo apt-get install -y skopeo jq
+          skopeo --version
+
+      - name: Install cosign
+        uses: sigstore/cosign-installer@6f9f17788090df1f26f669e9d70d6ae9567deba6 # v4.1.2
+
+      - name: Input check
+        run: |
+          test -n "${SOURCE_IMAGE}" || (echo "SOURCE_IMAGE is empty" && exit 1)
+          echo "Source : ${SOURCE_IMAGE}"
+          echo "Target : ${DEST_IMAGE}"
+
+      # Auth for skopeo (containers-auth)
+      - name: Skopeo login to GHCR
+        run: |
+          skopeo login ghcr.io -u "${{ github.actor }}" -p "${{ secrets.GITHUB_TOKEN }}"
+
+      # Auth for cosign (docker-config)
+      - name: Docker login to GHCR (for cosign)
+        run: |
+          echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u "${{ github.actor }}" --password-stdin
+
+      - name: List source tags
+        run: |
+          set -euo pipefail
+          skopeo list-tags --retry-times 3 docker://"${SOURCE_IMAGE}" \
+            | jq -r '.Tags[]' | sort -u > src-tags.txt
+          echo "Found source tags: $(wc -l < src-tags.txt)"
+          head -n 20 src-tags.txt || true
+
+      - name: List destination tags (skip existing)
+        run: |
+          set -euo pipefail
+          if skopeo list-tags --retry-times 3 docker://"${DEST_IMAGE}" >/tmp/dst.json 2>/dev/null; then
+            jq -r '.Tags[]' /tmp/dst.json | sort -u > dst-tags.txt
+          else
+            : > dst-tags.txt
+          fi
+          echo "Existing destination tags: $(wc -l < dst-tags.txt)"
+
+      - name: Mirror, dual-sign, and verify
+        env:
+          # keyless
+          COSIGN_YES: "true"
+          # key-based
+          COSIGN_PRIVATE_KEY: ${{ secrets.COSIGN_PRIVATE_KEY }}
+          COSIGN_PASSWORD:    ${{ secrets.COSIGN_PASSWORD }}
+          # verify
+          COSIGN_PUBLIC_KEY:  ${{ secrets.COSIGN_PUBLIC_KEY }}
+        run: |
+          set -euo pipefail
+          copied=0; skipped=0; v_ok=0; errs=0
+
+          issuer="https://token.actions.githubusercontent.com"
+          id_regex="^https://github.com/${{ github.repository }}/.+"
+
+          while read -r tag; do
+            [ -z "$tag" ] && continue
+
+            if grep -Fxq "$tag" dst-tags.txt; then
+              echo "::notice ::Skip (exists) ${DEST_IMAGE}:${tag}"
+              skipped=$((skipped+1))
+              continue
+            fi
+
+            echo "==> Copy ${SOURCE_IMAGE}:${tag} → ${DEST_IMAGE}:${tag}"
+            if ! skopeo copy --all --retry-times 3 \
+                 docker://"${SOURCE_IMAGE}:${tag}" docker://"${DEST_IMAGE}:${tag}"; then
+              echo "::warning title=Copy failed::${SOURCE_IMAGE}:${tag}"
+              errs=$((errs+1)); continue
+            fi
+            copied=$((copied+1))
+
+            digest="$(skopeo inspect --retry-times 3 docker://"${DEST_IMAGE}:${tag}" | jq -r '.Digest')"
+            ref="${DEST_IMAGE}@${digest}"
+
+            echo "==> cosign sign (keyless) --recursive ${ref}"
+            if ! cosign sign --recursive "${ref}"; then
+              echo "::warning title=Keyless sign failed::${ref}"
+              errs=$((errs+1))
+            fi
+
+            echo "==> cosign sign (key) --recursive ${ref}"
+            if ! cosign sign --key env://COSIGN_PRIVATE_KEY --recursive "${ref}"; then
+              echo "::warning title=Key sign failed::${ref}"
+              errs=$((errs+1))
+            fi
+
+            echo "==> cosign verify (public key) ${ref}"
+            if ! cosign verify --key env://COSIGN_PUBLIC_KEY "${ref}" -o text; then
+              echo "::warning title=Verify(pubkey) failed::${ref}"
+              errs=$((errs+1))
+            fi
+
+            echo "==> cosign verify (keyless policy) ${ref}"
+            if ! cosign verify \
+                 --certificate-oidc-issuer "${issuer}" \
+                 --certificate-identity-regexp "${id_regex}" \
+                 "${ref}" -o text; then
+              echo "::warning title=Verify(keyless) failed::${ref}"
+              errs=$((errs+1))
+            else
+              v_ok=$((v_ok+1))
+            fi
+          done < src-tags.txt
+
+          echo "---- Summary ----"
+          echo "Copied        : $copied"
+          echo "Skipped       : $skipped"
+          echo "Verified OK   : $v_ok"
+          echo "Errors        : $errs"

.github/workflows/nix-build.yml

@@ -0,0 +1,23 @@
+name: Build Nix package
+
+on:
+  workflow_dispatch:
+  pull_request:
+    paths:
+      - go.mod
+      - go.sum
+
+jobs:
+  nix-build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+
+      - name: Build flake package
+        run: |
+          nix build .#pangolin-newt -L

.github/workflows/nix-dependabot-update-hash.yml

@@ -0,0 +1,48 @@
+name: Update Nix Package Hash On Dependabot PRs
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+    branches:
+      - main
+
+jobs:
+  nix-update:
+    if: github.actor == 'dependabot[bot]'
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+        with:
+          ref: ${{ github.head_ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+
+      - name: Run nix-update
+        run: |
+          nix run nixpkgs#nix-update -- --flake pangolin-newt --no-src --version skip
+
+      - name: Check for changes
+        id: changes
+        run: |
+          if git diff --quiet; then
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Commit and push changes
+        if: steps.changes.outputs.changed == 'true'
+        run: |
+          git config user.name "dependabot[bot]"
+          git config user.email "dependabot[bot]@users.noreply.github.com"
+
+          git add .
+          git commit -m "chore(nix): fix hash for updated go dependencies"
+          git push

.github/workflows/stale-bot.yml

@@ -0,0 +1,37 @@
+name: Mark and Close Stale Issues
+
+on:
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch: # Allow manual trigger
+
+permissions:
+  contents: write # only for delete-branch option
+  issues: write
+  pull-requests: write
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@eb5cf3af3ac0a1aa4c9c45633dd1ae542a27a899 # v10.3.0
+        with:
+          days-before-stale: 14
+          days-before-close: 14
+          stale-issue-message: 'This issue has been automatically marked as stale due to 14 days of inactivity. It will be closed in 14 days if no further activity occurs.'
+          close-issue-message: 'This issue has been automatically closed due to inactivity. If you believe this is still relevant, please open a new issue with up-to-date information.'
+          stale-issue-label: 'stale'
+          
+          exempt-issue-labels: 'needs investigating, networking, new feature, reverse proxy, bug, api, authentication, documentation, enhancement, help wanted, good first issue, question'
+          
+          exempt-all-issue-assignees: true
+          
+          only-labels: ''
+          exempt-pr-labels: ''
+          days-before-pr-stale: -1
+          days-before-pr-close: -1
+          
+          operations-per-run: 100
+          remove-stale-when-updated: true
+          delete-branch: false
+          enable-statistics: true

.github/workflows/test.yml

@@ -1,5 +1,8 @@
 name: Run Tests
 
+permissions:
+  contents: read
+
 on:
   pull_request:
     branches:
@@ -9,20 +12,42 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
-
     steps:
-      - uses: actions/checkout@v4
+      - name: Checkout repository
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
 
       - name: Set up Go
-        uses: actions/setup-go@v4
+        uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
         with:
-          go-version: '1.23'
+          go-version-file: go.mod
 
-      - name: Build go
-        run: go build
+      - name: Run Go tests
+        run: make test
 
-      - name: Build Docker image
-        run: make build
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - local
+          - docker-build
+          - go-build-release-darwin-amd64
+          - go-build-release-darwin-arm64
+          - go-build-release-freebsd-amd64
+          - go-build-release-freebsd-arm64
+          - go-build-release-linux-amd64
+          - go-build-release-linux-arm32-v6
+          - go-build-release-linux-arm32-v7
+          - go-build-release-linux-riscv64
+          - go-build-release-windows-amd64
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
 
-      - name: Build binaries
-        run: make go-build-release
+      - name: Set up Go
+        uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
+        with:
+          go-version-file: go.mod
+
+      - name: Build targets via `make`
+        run: make ${{ matrix.target }}

.gitignore

@@ -1,4 +1,3 @@
-newt
 .DS_Store
 bin/
 nohup.out
@@ -6,3 +5,6 @@ nohup.out
 *.iml
 certs/
 newt_arm64
+key
+/.direnv/
+/result*

.go-version

@@ -1 +1 @@
-1.23.2
+1.25

CONTRIBUTING.md

@@ -4,11 +4,7 @@ Contributions are welcome!
 
 Please see the contribution and local development guide on the docs page before getting started:
 
-https://docs.fossorial.io/development
-
-For ideas about what features to work on and our future plans, please see the roadmap:
-
-https://docs.fossorial.io/roadmap
+https://docs.pangolin.net/development/contributing
 
 ### Licensing Considerations
 
@@ -21,4 +17,4 @@ By creating this pull request, I grant the project maintainers an unlimited,
 perpetual license to use, modify, and redistribute these contributions under any terms they
 choose, including both the AGPLv3 and the Fossorial Commercial license terms. I
 represent that I have the right to grant this license for all contributed content.
-```
+```

Dockerfile

@@ -1,4 +1,8 @@
-FROM golang:1.24.5-alpine AS builder
+# FROM golang:1.25-alpine AS builder
+FROM public.ecr.aws/docker/library/golang:1.25-alpine AS builder
+
+# Install git and ca-certificates
+RUN apk --no-cache add ca-certificates git tzdata
 
 # Set the working directory inside the container
 WORKDIR /app
@@ -13,15 +17,23 @@ RUN go mod download
 COPY . .
 
 # Build the application
-RUN CGO_ENABLED=0 GOOS=linux go build -o /newt
+ARG VERSION=dev
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w -X main.newtVersion=${VERSION}" -o /newt
 
-FROM alpine:3.22 AS runner
+FROM public.ecr.aws/docker/library/alpine:3.23 AS runner
 
-RUN apk --no-cache add ca-certificates tzdata
+RUN apk --no-cache add ca-certificates tzdata iputils
 
 COPY --from=builder /newt /usr/local/bin/
 COPY entrypoint.sh /
 
+# Marks this as an official Fossorial container image.
+# Auto-update is disabled in official images — update by pulling a new image tag.
+ENV NEWT_SYSTEM_SUBSTRATE="CONTAINER"
+
+# Admin/metrics endpoint (Prometheus scrape)
+EXPOSE 2112
+
 RUN chmod +x /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]
-CMD ["newt"]
+CMD ["newt"]

Makefile

@@ -1,37 +1,76 @@
+.PHONY: all local test docker-build docker-build-release
 
-all: build push
+all: local
+
+VERSION ?= dev
+LDFLAGS = -X main.newtVersion=$(VERSION)
+
+local:
+	CGO_ENABLED=0 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=$(shell go env GOOS)_$(shell go env GOARCH)" -o ./bin/newt
+
+test:
+	go test ./...
+
+docker-build:
+	docker build -t fosrl/newt:latest .
 
 docker-build-release:
 	@if [ -z "$(tag)" ]; then \
 		echo "Error: tag is required. Usage: make docker-build-release tag=<tag>"; \
 		exit 1; \
 	fi
-	docker buildx build --platform linux/arm/v7,linux/arm64,linux/amd64 -t fosrl/newt:latest -f Dockerfile --push .
-	docker buildx build --platform linux/arm/v7,linux/arm64,linux/amd64 -t fosrl/newt:$(tag) -f Dockerfile --push .
+	docker buildx build . \
+		--platform linux/arm/v7,linux/arm64,linux/amd64 \
+		-t fosrl/newt:latest \
+		-t fosrl/newt:$(tag) \
+		-f Dockerfile \
+		--push
 
-build:
-	docker build -t fosrl/newt:latest .
+.PHONY: go-build-release \
+        go-build-release-linux-arm64 go-build-release-linux-arm32-v7 \
+        go-build-release-linux-arm32-v6 go-build-release-linux-amd64 \
+        go-build-release-linux-riscv64 go-build-release-darwin-arm64 \
+        go-build-release-darwin-amd64 go-build-release-windows-amd64 \
+        go-build-release-freebsd-amd64 go-build-release-freebsd-arm64
 
-push:
-	docker push fosrl/newt:latest
+go-build-release: \
+    go-build-release-linux-arm64 \
+    go-build-release-linux-arm32-v7 \
+    go-build-release-linux-arm32-v6 \
+    go-build-release-linux-amd64 \
+    go-build-release-linux-riscv64 \
+    go-build-release-darwin-arm64 \
+    go-build-release-darwin-amd64 \
+    go-build-release-windows-amd64 \
+    go-build-release-freebsd-amd64 \
+    go-build-release-freebsd-arm64
 
-test:
-	docker run fosrl/newt:latest
+go-build-release-linux-arm64:
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=linux_arm64" -o bin/newt_linux_arm64
 
-local: 
-	CGO_ENABLED=0 go build -o newt
+go-build-release-linux-arm32-v7:
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=7 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=linux_arm32" -o bin/newt_linux_arm32
 
-go-build-release:
-	CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -o bin/newt_linux_arm64
-	CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=7 go build -o bin/newt_linux_arm32
-	CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=6 go build -o bin/newt_linux_arm32v6
-	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o bin/newt_linux_amd64
-	CGO_ENABLED=0 GOOS=linux GOARCH=riscv64 go build -o bin/newt_linux_riscv64
-	CGO_ENABLED=0 GOOS=darwin GOARCH=arm64 go build -o bin/newt_darwin_arm64
-	CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go build -o bin/newt_darwin_amd64
-	CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -o bin/newt_windows_amd64.exe
-	CGO_ENABLED=0 GOOS=freebsd GOARCH=amd64 go build -o bin/newt_freebsd_amd64
-	CGO_ENABLED=0 GOOS=freebsd GOARCH=arm64 go build -o bin/newt_freebsd_arm64
+go-build-release-linux-arm32-v6:
+	CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=6 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=linux_arm32v6" -o bin/newt_linux_arm32v6
 
-clean:
-	rm newt
+go-build-release-linux-amd64:
+	CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=linux_amd64" -o bin/newt_linux_amd64
+
+go-build-release-linux-riscv64:
+	CGO_ENABLED=0 GOOS=linux GOARCH=riscv64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=linux_riscv64" -o bin/newt_linux_riscv64
+
+go-build-release-darwin-arm64:
+	CGO_ENABLED=0 GOOS=darwin GOARCH=arm64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=darwin_arm64" -o bin/newt_darwin_arm64
+
+go-build-release-darwin-amd64:
+	CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=darwin_amd64" -o bin/newt_darwin_amd64
+
+go-build-release-windows-amd64:
+	CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=windows_amd64" -o bin/newt_windows_amd64.exe
+
+go-build-release-freebsd-amd64:
+	CGO_ENABLED=0 GOOS=freebsd GOARCH=amd64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=freebsd_amd64" -o bin/newt_freebsd_amd64
+
+go-build-release-freebsd-arm64:
+	CGO_ENABLED=0 GOOS=freebsd GOARCH=arm64 go build -ldflags "$(LDFLAGS) -X main.newtPlatform=freebsd_arm64" -o bin/newt_freebsd_arm64

README.md

@@ -1,4 +1,7 @@
 # Newt
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/fosrl/newt)](https://pkg.go.dev/github.com/fosrl/newt)
+[![GitHub License](https://img.shields.io/github/license/fosrl/newt)](https://github.com/fosrl/newt/blob/main/LICENSE)
+[![Go Report Card](https://goreportcard.com/badge/github.com/fosrl/newt)](https://goreportcard.com/report/github.com/fosrl/newt)
 
 Newt is a fully user space [WireGuard](https://www.wireguard.com/) tunnel client and TCP/UDP proxy, designed to securely expose private resources controlled by Pangolin. By using Newt, you don't need to manage complex WireGuard tunnels and NATing.
 
@@ -6,13 +9,7 @@ Newt is a fully user space [WireGuard](https://www.wireguard.com/) tunnel client
 
 Newt is used with Pangolin and Gerbil as part of the larger system. See documentation below:
 
--   [Full Documentation](https://docs.fossorial.io)
-
-## Preview
-
-<img src="public/screenshots/preview.png" alt="Preview"/>
-
-_Sample output of a Newt container connected to Pangolin and hosting various resource target proxies._
+-   [Full Documentation](https://docs.pangolin.net/manage/sites/understanding-sites)
 
 ## Key Functions
 
@@ -22,170 +19,20 @@ Using the Newt ID and a secret, the client will make HTTP requests to Pangolin t
 
 ### Receives WireGuard Control Messages
 
-When Newt receives WireGuard control messages, it will use the information encoded (endpoint, public key) to bring up a WireGuard tunnel using [netstack](https://github.com/WireGuard/wireguard-go/blob/master/tun/netstack/examples/http_server.go) fully in user space. It will ping over the tunnel to ensure the peer on the Gerbil side is brought up. 
+When Newt receives WireGuard control messages, it will use the information encoded (endpoint, public key) to bring up a WireGuard tunnel using [netstack](https://github.com/WireGuard/wireguard-go/blob/master/tun/netstack/examples/http_server.go) fully in user space. It will ping over the tunnel to ensure the peer on the Gerbil side is brought up.
 
 ### Receives Proxy Control Messages
 
 When Newt receives WireGuard control messages, it will use the information encoded to create a local low level TCP and UDP proxies attached to the virtual tunnel in order to relay traffic to programmed targets.
 
-## CLI Args
-
-- `endpoint`: The endpoint where both Gerbil and Pangolin reside in order to connect to the websocket.
-- `id`: Newt ID generated by Pangolin to identify the client.
-- `secret`: A unique secret (not shared and kept private) used to authenticate the client ID with the websocket in order to receive commands. 
-- `mtu`: MTU for the internal WG interface. Default: 1280
-- `dns`: DNS server to use to resolve the endpoint
-- `log-level` (optional): The log level to use. Default: INFO
-- `updown` (optional): A script to be called when targets are added or removed.
-- `tls-client-cert` (optional): Client certificate (p12 or pfx) for mTLS. See [mTLS](#mtls)
-- `docker-socket` (optional): Set the Docker socket to use the container discovery integration
-- `docker-enforce-network-validation` (optional): Validate the container target is on the same network as the newt process
-- `health-file` (optional): Check if connection to WG server (pangolin) is ok. creates a file if ok, removes it if not ok. Can be used with docker healtcheck to restart newt 
-
-- Example:
-
-```bash
-./newt \
---id 31frd0uzbjvp721 \
---secret h51mmlknrvrwv8s4r1i210azhumt6isgbpyavxodibx1k2d6 \
---endpoint https://example.com
-```
-
-You can also run it with Docker compose. For example, a service in your `docker-compose.yml` might look like this using environment vars (recommended):
-
-```yaml
-services:
-  newt:
-    image: fosrl/newt
-    container_name: newt
-    restart: unless-stopped
-    environment:
-      - PANGOLIN_ENDPOINT=https://example.com
-      - NEWT_ID=2ix2t8xk22ubpfy 
-      - NEWT_SECRET=nnisrfsdfc7prqsp9ewo1dvtvci50j5uiqotez00dgap0ii2
-      - HEALTH_FILE=/tmp/healthy 
-```
-
-You can also pass the CLI args to the container:
-
-```yaml
-services:
-  newt:
-    image: fosrl/newt
-    container_name: newt
-    restart: unless-stopped
-    command:
-        - --id 31frd0uzbjvp721
-        - --secret h51mmlknrvrwv8s4r1i210azhumt6isgbpyavxodibx1k2d6
-        - --endpoint https://example.com
-        - --health-file /tmp/healthy
-```
-
-### Docker Socket Integration
-
-Newt can integrate with the Docker socket to provide remote inspection of Docker containers. This allows Pangolin to query and retrieve detailed information about containers running on the Newt client, including metadata, network configuration, port mappings, and more.
-
-**Configuration:**
-
-You can specify the Docker socket path using the `--docker-socket` CLI argument or by setting the `DOCKER_SOCKET` environment variable. On most linux systems the socket is `/var/run/docker.sock`. When deploying newt as a container, you need to mount the host socket as a volume for the newt container to access it. If the Docker socket is not available or accessible, Newt will gracefully disable Docker integration and continue normal operation.
-
-```yaml
-services:
-  newt:
-    image: fosrl/newt
-    container_name: newt
-    restart: unless-stopped
-    volumes:
-      - /var/run/docker.sock:/var/run/docker.sock:ro
-    environment:
-      - PANGOLIN_ENDPOINT=https://example.com
-      - NEWT_ID=2ix2t8xk22ubpfy 
-      - NEWT_SECRET=nnisrfsdfc7prqsp9ewo1dvtvci50j5uiqotez00dgap0ii2
-      - DOCKER_SOCKET=/var/run/docker.sock
-```
-
-#### Hostnames vs IPs
-
-When the Docker Socket Integration is used, depending on the network which Newt is run with, either the hostname (generally considered the container name) or the IP address of the container will be sent to Pangolin. Here are some of the scenarios where IPs or hostname of the container will be utilised:
-- **Running in Network Mode 'host'**: IP addresses will be used
-- **Running in Network Mode 'bridge'**: IP addresses will be used
-- **Running in docker-compose without a network specification**: Docker compose creates a network for the compose by default, hostnames will be used
-- **Running on docker-compose with defined network**: Hostnames will be used
-
-### Docker Enforce Network Validation
-
-When run as a Docker container, Newt can validate that the target being provided is on the same network as the Newt container and only return containers directly accessible by Newt. Validation will be carried out against either the hostname/IP Address and the Port number to ensure the running container is exposing the ports to Newt.
-
-It is important to note that if the Newt container is run with a network mode of `host` that this feature will not work. Running in `host` mode causes the container to share its resources with the host machine, therefore making it so the specific host container information for Newt cannot be retrieved to be able to carry out network validation.
-
-**Configuration:**
-
-Validation is `false` by default. It can be enabled via setting the `--docker-enforce-network-validation` CLI argument or by setting the `DOCKER_ENFORCE_NETWORK_VALIDATION` environment variable.
-
-If validation is enforced and the Docker socket is available, Newt will **not** add the target as it cannot be verified. A warning will be presented in the Newt logs.
-
-### Updown
-
-You can pass in a updown script for Newt to call when it is adding or removing a target:
-
-`--updown "python3 test.py"`
-
-It will get called with args when a target is added: 
-`python3 test.py add tcp localhost:8556`
-`python3 test.py remove tcp localhost:8556`
-
-Returning a string from the script in the format of a target (`ip:dst` so `10.0.0.1:8080`) it will override the target and use this value instead to proxy.
-
-You can look at updown.py as a reference script to get started!
-
-### mTLS
-Newt supports mutual TLS (mTLS) authentication, if the server has been configured to request a client certificate.
-* Only PKCS12 (.p12 or .pfx) file format is accepted
-* The PKCS12 file must contain: 
-  * Private key
-  * Public certificate
-  * CA certificate
-* Encrypted PKCS12 files are currently not supported
-
-Examples:
-
-```bash
-./newt \
---id 31frd0uzbjvp721 \
---secret h51mmlknrvrwv8s4r1i210azhumt6isgbpyavxodibx1k2d6 \
---endpoint https://example.com \
---tls-client-cert ./client.p12
-```
-
-```yaml
-services:
-  newt:
-    image: fosrl/newt
-    container_name: newt
-    restart: unless-stopped
-    environment:
-      - PANGOLIN_ENDPOINT=https://example.com
-      - NEWT_ID=2ix2t8xk22ubpfy 
-      - NEWT_SECRET=nnisrfsdfc7prqsp9ewo1dvtvci50j5uiqotez00dgap0ii2 
-      - TLS_CLIENT_CERT=./client.p12 
-```
-
 ## Build
 
-### Container 
-
-Ensure Docker is installed.
-
-```bash
-make
-```
-
 ### Binary
 
-Make sure to have Go 1.23.1 installed.
+Make sure to have Go 1.25 installed.
 
 ```bash
-make local
+make
 ```
 
 ### Nix Flake

SECURITY.md

@@ -3,7 +3,7 @@
 If you discover a security vulnerability, please follow the steps below to responsibly disclose it to us:
 
 1. **Do not create a public GitHub issue or discussion post.** This could put the security of other users at risk.
-2. Send a detailed report to [security@fossorial.io](mailto:security@fossorial.io) or send a **private** message to a maintainer on [Discord](https://discord.gg/HCJR8Xhme4). Include:
+2. Send a detailed report to [security@pangolin.net](mailto:security@pangolin.net) or send a **private** message to a maintainer on [Discord](https://discord.gg/HCJR8Xhme4). Include:
 
 - Description and location of the vulnerability.
 - Potential impact of the vulnerability.

authdaemon.go

@@ -0,0 +1,150 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"runtime"
+
+	"github.com/fosrl/newt/authdaemon"
+	"github.com/fosrl/newt/logger"
+)
+
+const (
+	defaultPrincipalsPath = "/var/run/auth-daemon/principals"
+	defaultCACertPath     = "/etc/ssh/ca.pem"
+)
+
+var (
+	errPresharedKeyRequired = errors.New("auth-daemon-key is required when --auth-daemon is enabled")
+	errRootRequired         = errors.New("auth-daemon must be run as root (use sudo)")
+	authDaemonServer        *authdaemon.Server // Global auth daemon server instance
+)
+
+// startAuthDaemon initializes and starts the auth daemon in the background.
+// It validates requirements (Linux, root, preshared key) and starts the server
+// in a goroutine so it runs alongside normal newt operation.
+func startAuthDaemon(ctx context.Context) error {
+	// Validation
+	if runtime.GOOS != "linux" {
+		return fmt.Errorf("auth-daemon is only supported on Linux, not %s", runtime.GOOS)
+	}
+	if os.Geteuid() != 0 {
+		return errRootRequired
+	}
+
+	// Use defaults if not set
+	principalsFile := authDaemonPrincipalsFile
+	if principalsFile == "" {
+		principalsFile = defaultPrincipalsPath
+	}
+	caCertPath := authDaemonCACertPath
+	if caCertPath == "" {
+		caCertPath = defaultCACertPath
+	}
+
+	// Create auth daemon server
+	cfg := authdaemon.Config{
+		DisableHTTPS:           true,                   // We run without HTTP server in newt
+		PresharedKey:           "this-key-is-not-used", // Not used in embedded mode, but set to non-empty to satisfy validation
+		PrincipalsFilePath:     principalsFile,
+		CACertPath:             caCertPath,
+		Force:                  true,
+		GenerateRandomPassword: authDaemonGenerateRandomPassword,
+	}
+
+	srv, err := authdaemon.NewServer(cfg)
+	if err != nil {
+		return fmt.Errorf("create auth daemon server: %w", err)
+	}
+
+	authDaemonServer = srv
+
+	// Start the auth daemon in a goroutine so it runs alongside newt
+	go func() {
+		logger.Info("Auth daemon starting (native mode, no HTTP server)")
+		if err := srv.Run(ctx); err != nil {
+			logger.Error("Auth daemon error: %v", err)
+		}
+		logger.Info("Auth daemon stopped")
+	}()
+
+	return nil
+}
+
+// runPrincipalsCmd executes the principals subcommand logic
+func runPrincipalsCmd(args []string) {
+	opts := struct {
+		PrincipalsFile string
+		Username       string
+	}{
+		PrincipalsFile: defaultPrincipalsPath,
+	}
+
+	// Parse flags manually
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--principals-file":
+			if i+1 >= len(args) {
+				fmt.Fprintf(os.Stderr, "Error: --principals-file requires a value\n")
+				os.Exit(1)
+			}
+			opts.PrincipalsFile = args[i+1]
+			i++
+		case "--username":
+			if i+1 >= len(args) {
+				fmt.Fprintf(os.Stderr, "Error: --username requires a value\n")
+				os.Exit(1)
+			}
+			opts.Username = args[i+1]
+			i++
+		case "--help", "-h":
+			printPrincipalsHelp()
+			os.Exit(0)
+		default:
+			fmt.Fprintf(os.Stderr, "Error: unknown flag: %s\n", args[i])
+			printPrincipalsHelp()
+			os.Exit(1)
+		}
+	}
+
+	// Validation
+	if opts.Username == "" {
+		fmt.Fprintf(os.Stderr, "Error: username is required\n")
+		printPrincipalsHelp()
+		os.Exit(1)
+	}
+
+	// Get principals
+	list, err := authdaemon.GetPrincipals(opts.PrincipalsFile, opts.Username)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+	if len(list) == 0 {
+		fmt.Println("")
+		return
+	}
+	for _, principal := range list {
+		fmt.Println(principal)
+	}
+}
+
+func printPrincipalsHelp() {
+	fmt.Fprintf(os.Stderr, `Usage: newt principals [flags]
+
+Output principals for a username (for AuthorizedPrincipalsCommand in sshd_config).
+Read the principals file and print principals that match the given username, one per line.
+Configure in sshd_config with AuthorizedPrincipalsCommand and %%u for the username.
+
+Flags:
+  --principals-file string   Path to the principals file (default "%s")
+  --username string          Username to look up (required)
+  --help, -h                 Show this help message
+
+Example:
+  newt principals --username alice
+
+`, defaultPrincipalsPath)
+}

authdaemon/connection.go

@@ -0,0 +1,27 @@
+package authdaemon
+
+import (
+	"github.com/fosrl/newt/logger"
+)
+
+// ProcessConnection runs the same logic as POST /connection: CA cert, user create/reconcile, principals.
+// Use this when DisableHTTPS is true (e.g. embedded in Newt) instead of calling the API.
+func (s *Server) ProcessConnection(req ConnectionRequest) {
+	logger.Info("connection: niceId=%q username=%q metadata.sudoMode=%q metadata.sudoCommands=%v metadata.homedir=%v metadata.groups=%v",
+		req.NiceId, req.Username, req.Metadata.SudoMode, req.Metadata.SudoCommands, req.Metadata.Homedir, req.Metadata.Groups)
+
+	cfg := &s.cfg
+	if cfg.CACertPath != "" {
+		if err := writeCACertIfNotExists(cfg.CACertPath, req.CaCert, cfg.Force); err != nil {
+			logger.Warn("auth-daemon: write CA cert: %v", err)
+		}
+	}
+	if err := ensureUser(req.Username, req.Metadata, s.cfg.GenerateRandomPassword); err != nil {
+		logger.Warn("auth-daemon: ensure user: %v", err)
+	}
+	if cfg.PrincipalsFilePath != "" && req.NiceId != "" {
+		if err := writePrincipals(cfg.PrincipalsFilePath, req.Username, req.NiceId); err != nil {
+			logger.Warn("auth-daemon: write principals: %v", err)
+		}
+	}
+}

authdaemon/host_linux.go

@@ -0,0 +1,396 @@
+//go:build linux
+
+package authdaemon
+
+import (
+	"bufio"
+	"crypto/rand"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"os/user"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/fosrl/newt/logger"
+)
+
+// writeCACertIfNotExists writes contents to path. If the file already exists: when force is false, skip; when force is true, overwrite only if content differs.
+func writeCACertIfNotExists(path, contents string, force bool) error {
+	contents = strings.TrimSpace(contents)
+	if contents != "" && !strings.HasSuffix(contents, "\n") {
+		contents += "\n"
+	}
+	existing, err := os.ReadFile(path)
+	if err == nil {
+		existingStr := strings.TrimSpace(string(existing))
+		if existingStr != "" && !strings.HasSuffix(existingStr, "\n") {
+			existingStr += "\n"
+		}
+		if existingStr == contents {
+			logger.Debug("auth-daemon: CA cert unchanged at %s, skipping write", path)
+			return nil
+		}
+		if !force {
+			logger.Debug("auth-daemon: CA cert already exists at %s, skipping write (Force disabled)", path)
+			return nil
+		}
+	} else if !os.IsNotExist(err) {
+		return fmt.Errorf("read %s: %w", path, err)
+	}
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("mkdir %s: %w", dir, err)
+	}
+	if err := os.WriteFile(path, []byte(contents), 0644); err != nil {
+		return fmt.Errorf("write CA cert: %w", err)
+	}
+	logger.Info("auth-daemon: wrote CA cert to %s", path)
+	return nil
+}
+
+// writePrincipals updates the principals file at path: JSON object keyed by username, value is array of principals. Adds username and niceId to that user's list (deduped).
+func writePrincipals(path, username, niceId string) error {
+	if path == "" {
+		return nil
+	}
+	username = strings.TrimSpace(username)
+	niceId = strings.TrimSpace(niceId)
+	if username == "" {
+		return nil
+	}
+	data := make(map[string][]string)
+	if raw, err := os.ReadFile(path); err == nil {
+		_ = json.Unmarshal(raw, &data)
+	}
+	list := data[username]
+	seen := make(map[string]struct{}, len(list)+2)
+	for _, p := range list {
+		seen[p] = struct{}{}
+	}
+	for _, p := range []string{username, niceId} {
+		if p == "" {
+			continue
+		}
+		if _, ok := seen[p]; !ok {
+			seen[p] = struct{}{}
+			list = append(list, p)
+		}
+	}
+	data[username] = list
+	body, err := json.Marshal(data)
+	if err != nil {
+		return fmt.Errorf("marshal principals: %w", err)
+	}
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("mkdir %s: %w", dir, err)
+	}
+	if err := os.WriteFile(path, body, 0644); err != nil {
+		return fmt.Errorf("write principals: %w", err)
+	}
+	logger.Debug("auth-daemon: wrote principals to %s", path)
+	return nil
+}
+
+// sudoGroup returns the name of the sudo group (wheel or sudo) that exists on the system. Prefers wheel.
+func sudoGroup() string {
+	f, err := os.Open("/etc/group")
+	if err != nil {
+		return "sudo"
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	hasWheel := false
+	hasSudo := false
+	for sc.Scan() {
+		line := sc.Text()
+		if strings.HasPrefix(line, "wheel:") {
+			hasWheel = true
+		}
+		if strings.HasPrefix(line, "sudo:") {
+			hasSudo = true
+		}
+	}
+	if hasWheel {
+		return "wheel"
+	}
+	if hasSudo {
+		return "sudo"
+	}
+	return "sudo"
+}
+
+// setRandomPassword generates a random password and sets it for username via chpasswd.
+// Used when GenerateRandomPassword is true so SSH with PermitEmptyPasswords no can accept the user.
+func setRandomPassword(username string) error {
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		return fmt.Errorf("generate password: %w", err)
+	}
+	password := hex.EncodeToString(b)
+	cmd := exec.Command("chpasswd")
+	cmd.Stdin = strings.NewReader(username + ":" + password)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		return fmt.Errorf("chpasswd: %w (output: %s)", err, string(out))
+	}
+	return nil
+}
+
+const skelDir = "/etc/skel"
+
+// copySkelInto copies files from srcDir (e.g. /etc/skel) into dstDir (e.g. user's home).
+// Only creates files that don't already exist. All created paths are chowned to uid:gid.
+func copySkelInto(srcDir, dstDir string, uid, gid int) {
+	entries, err := os.ReadDir(srcDir)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			logger.Warn("auth-daemon: read %s: %v", srcDir, err)
+		}
+		return
+	}
+	for _, e := range entries {
+		name := e.Name()
+		src := filepath.Join(srcDir, name)
+		dst := filepath.Join(dstDir, name)
+		if e.IsDir() {
+			if st, err := os.Stat(dst); err == nil && st.IsDir() {
+				copySkelInto(src, dst, uid, gid)
+				continue
+			}
+			if err := os.MkdirAll(dst, 0755); err != nil {
+				logger.Warn("auth-daemon: mkdir %s: %v", dst, err)
+				continue
+			}
+			if err := os.Chown(dst, uid, gid); err != nil {
+				logger.Warn("auth-daemon: chown %s: %v", dst, err)
+			}
+			copySkelInto(src, dst, uid, gid)
+			continue
+		}
+		if _, err := os.Stat(dst); err == nil {
+			continue
+		}
+		data, err := os.ReadFile(src)
+		if err != nil {
+			logger.Warn("auth-daemon: read %s: %v", src, err)
+			continue
+		}
+		if err := os.WriteFile(dst, data, 0644); err != nil {
+			logger.Warn("auth-daemon: write %s: %v", dst, err)
+			continue
+		}
+		if err := os.Chown(dst, uid, gid); err != nil {
+			logger.Warn("auth-daemon: chown %s: %v", dst, err)
+		}
+	}
+}
+
+// ensureUser creates the system user if missing, or reconciles sudo and homedir to match meta.
+func ensureUser(username string, meta ConnectionMetadata, generateRandomPassword bool) error {
+	if username == "" {
+		return nil
+	}
+	u, err := user.Lookup(username)
+	if err != nil {
+		if _, ok := err.(user.UnknownUserError); !ok {
+			return fmt.Errorf("lookup user %s: %w", username, err)
+		}
+		return createUser(username, meta, generateRandomPassword)
+	}
+	return reconcileUser(u, meta)
+}
+
+// desiredGroups returns the exact list of supplementary groups the user should have:
+// meta.Groups plus the sudo group when meta.SudoMode is "full" (deduped).
+func desiredGroups(meta ConnectionMetadata) []string {
+	seen := make(map[string]struct{})
+	var out []string
+	for _, g := range meta.Groups {
+		g = strings.TrimSpace(g)
+		if g == "" {
+			continue
+		}
+		if _, ok := seen[g]; ok {
+			continue
+		}
+		seen[g] = struct{}{}
+		out = append(out, g)
+	}
+	if meta.SudoMode == "full" {
+		sg := sudoGroup()
+		if _, ok := seen[sg]; !ok {
+			out = append(out, sg)
+		}
+	}
+	return out
+}
+
+// setUserGroups sets the user's supplementary groups to exactly groups (local mirrors metadata).
+// When groups is empty, clears all supplementary groups (usermod -G "").
+func setUserGroups(username string, groups []string) {
+	list := strings.Join(groups, ",")
+	cmd := exec.Command("usermod", "-G", list, username)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		logger.Warn("auth-daemon: usermod -G %s: %v (output: %s)", list, err, string(out))
+	} else {
+		logger.Info("auth-daemon: set %s supplementary groups to %s", username, list)
+	}
+}
+
+func createUser(username string, meta ConnectionMetadata, generateRandomPassword bool) error {
+	args := []string{"-s", "/bin/bash"}
+	if meta.Homedir {
+		args = append(args, "-m")
+	} else {
+		args = append(args, "-M")
+	}
+	args = append(args, username)
+	cmd := exec.Command("useradd", args...)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		return fmt.Errorf("useradd %s: %w (output: %s)", username, err, string(out))
+	}
+	logger.Info("auth-daemon: created user %s (homedir=%v)", username, meta.Homedir)
+	if generateRandomPassword {
+		if err := setRandomPassword(username); err != nil {
+			logger.Warn("auth-daemon: set random password for %s: %v", username, err)
+		} else {
+			logger.Info("auth-daemon: set random password for %s (PermitEmptyPasswords no)", username)
+		}
+	}
+	if meta.Homedir {
+		if u, err := user.Lookup(username); err == nil && u.HomeDir != "" {
+			uid, gid := mustAtoi(u.Uid), mustAtoi(u.Gid)
+			copySkelInto(skelDir, u.HomeDir, uid, gid)
+		}
+	}
+	setUserGroups(username, desiredGroups(meta))
+	switch meta.SudoMode {
+	case "full":
+		if err := configurePasswordlessSudo(username); err != nil {
+			logger.Warn("auth-daemon: configure passwordless sudo for %s: %v", username, err)
+		}
+	case "commands":
+		if len(meta.SudoCommands) > 0 {
+			if err := configureSudoCommands(username, meta.SudoCommands); err != nil {
+				logger.Warn("auth-daemon: configure sudo commands for %s: %v", username, err)
+			}
+		}
+	default:
+		removeSudoers(username)
+	}
+	return nil
+}
+
+const sudoersFilePrefix = "90-pangolin-"
+
+func sudoersPath(username string) string {
+	return filepath.Join("/etc/sudoers.d", sudoersFilePrefix+username)
+}
+
+// writeSudoersFile writes content to the user's sudoers.d file and validates with visudo.
+func writeSudoersFile(username, content string) error {
+	sudoersFile := sudoersPath(username)
+	tmpFile := sudoersFile + ".tmp"
+	if err := os.WriteFile(tmpFile, []byte(content), 0440); err != nil {
+		return fmt.Errorf("write temp sudoers file: %w", err)
+	}
+	cmd := exec.Command("visudo", "-c", "-f", tmpFile)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		os.Remove(tmpFile)
+		return fmt.Errorf("visudo validation failed: %w (output: %s)", err, string(out))
+	}
+	if err := os.Rename(tmpFile, sudoersFile); err != nil {
+		os.Remove(tmpFile)
+		return fmt.Errorf("move sudoers file: %w", err)
+	}
+	return nil
+}
+
+// configurePasswordlessSudo creates a sudoers.d file to allow passwordless sudo for the user.
+func configurePasswordlessSudo(username string) error {
+	content := fmt.Sprintf("# Created by Pangolin auth-daemon\n%s ALL=(ALL) NOPASSWD:ALL\n", username)
+	if err := writeSudoersFile(username, content); err != nil {
+		return err
+	}
+	logger.Info("auth-daemon: configured passwordless sudo for %s", username)
+	return nil
+}
+
+// configureSudoCommands creates a sudoers.d file allowing only the listed commands (NOPASSWD).
+// Each command should be a full path (e.g. /usr/bin/systemctl).
+func configureSudoCommands(username string, commands []string) error {
+	var b strings.Builder
+	b.WriteString("# Created by Pangolin auth-daemon (restricted commands)\n")
+	n := 0
+	for _, c := range commands {
+		c = strings.TrimSpace(c)
+		if c == "" {
+			continue
+		}
+		fmt.Fprintf(&b, "%s ALL=(ALL) NOPASSWD: %s\n", username, c)
+		n++
+	}
+	if n == 0 {
+		return fmt.Errorf("no valid sudo commands")
+	}
+	if err := writeSudoersFile(username, b.String()); err != nil {
+		return err
+	}
+	logger.Info("auth-daemon: configured restricted sudo for %s (%d commands)", username, len(commands))
+	return nil
+}
+
+// removeSudoers removes the sudoers.d file for the user.
+func removeSudoers(username string) {
+	sudoersFile := sudoersPath(username)
+	if err := os.Remove(sudoersFile); err != nil && !os.IsNotExist(err) {
+		logger.Warn("auth-daemon: remove sudoers for %s: %v", username, err)
+	} else if err == nil {
+		logger.Info("auth-daemon: removed sudoers for %s", username)
+	}
+}
+
+func mustAtoi(s string) int {
+	n, _ := strconv.Atoi(s)
+	return n
+}
+
+func reconcileUser(u *user.User, meta ConnectionMetadata) error {
+	setUserGroups(u.Username, desiredGroups(meta))
+	switch meta.SudoMode {
+	case "full":
+		if err := configurePasswordlessSudo(u.Username); err != nil {
+			logger.Warn("auth-daemon: configure passwordless sudo for %s: %v", u.Username, err)
+		}
+	case "commands":
+		if len(meta.SudoCommands) > 0 {
+			if err := configureSudoCommands(u.Username, meta.SudoCommands); err != nil {
+				logger.Warn("auth-daemon: configure sudo commands for %s: %v", u.Username, err)
+			}
+		} else {
+			removeSudoers(u.Username)
+		}
+	default:
+		removeSudoers(u.Username)
+	}
+	if meta.Homedir && u.HomeDir != "" {
+		uid, gid := mustAtoi(u.Uid), mustAtoi(u.Gid)
+		if st, err := os.Stat(u.HomeDir); err != nil || !st.IsDir() {
+			if err := os.MkdirAll(u.HomeDir, 0755); err != nil {
+				logger.Warn("auth-daemon: mkdir %s: %v", u.HomeDir, err)
+			} else {
+				_ = os.Chown(u.HomeDir, uid, gid)
+				copySkelInto(skelDir, u.HomeDir, uid, gid)
+				logger.Info("auth-daemon: created home %s for %s", u.HomeDir, u.Username)
+			}
+		} else {
+			// Ensure .bashrc etc. exist (e.g. home existed but was empty or skel was minimal)
+			copySkelInto(skelDir, u.HomeDir, uid, gid)
+		}
+	}
+	return nil
+}

authdaemon/host_stub.go

@@ -0,0 +1,22 @@
+//go:build !linux
+
+package authdaemon
+
+import "fmt"
+
+var errLinuxOnly = fmt.Errorf("auth-daemon PAM agent is only supported on Linux")
+
+// writeCACertIfNotExists returns an error on non-Linux.
+func writeCACertIfNotExists(path, contents string, force bool) error {
+	return errLinuxOnly
+}
+
+// ensureUser returns an error on non-Linux.
+func ensureUser(username string, meta ConnectionMetadata, generateRandomPassword bool) error {
+	return errLinuxOnly
+}
+
+// writePrincipals returns an error on non-Linux.
+func writePrincipals(path, username, niceId string) error {
+	return errLinuxOnly
+}

authdaemon/principals.go

@@ -0,0 +1,28 @@
+package authdaemon
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+)
+
+// GetPrincipals reads the principals data file at path, looks up the given user, and returns that user's principals as a string slice.
+// The file format is JSON: object with username keys and array-of-principals values, e.g. {"alice":["alice","usr-123"],"bob":["bob","usr-456"]}.
+// If the user is not found or the file is missing, returns nil and nil.
+func GetPrincipals(path, user string) ([]string, error) {
+	if path == "" {
+		return nil, fmt.Errorf("principals file path is required")
+	}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("read principals file: %w", err)
+	}
+	var m map[string][]string
+	if err := json.Unmarshal(data, &m); err != nil {
+		return nil, fmt.Errorf("parse principals file: %w", err)
+	}
+	return m[user], nil
+}

authdaemon/routes.go

@@ -0,0 +1,58 @@
+package authdaemon
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// registerRoutes registers all API routes. Add new endpoints here.
+func (s *Server) registerRoutes() {
+	s.mux.HandleFunc("/health", s.handleHealth)
+	s.mux.HandleFunc("/connection", s.handleConnection)
+}
+
+// ConnectionMetadata is the metadata object in POST /connection.
+type ConnectionMetadata struct {
+	SudoMode     string   `json:"sudoMode"`     // "none" | "full" | "commands"
+	SudoCommands []string `json:"sudoCommands"` // used when sudoMode is "commands"
+	Homedir      bool     `json:"homedir"`
+	Groups       []string `json:"groups"` // system groups to add the user to
+}
+
+// ConnectionRequest is the JSON body for POST /connection.
+type ConnectionRequest struct {
+	CaCert   string             `json:"caCert"`
+	NiceId   string             `json:"niceId"`
+	Username string             `json:"username"`
+	Metadata ConnectionMetadata `json:"metadata"`
+}
+
+// healthResponse is the JSON body for GET /health.
+type healthResponse struct {
+	Status string `json:"status"`
+}
+
+// handleHealth responds with 200 and {"status":"ok"}.
+func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(healthResponse{Status: "ok"})
+}
+
+// handleConnection accepts POST with connection payload and delegates to ProcessConnection.
+func (s *Server) handleConnection(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	var req ConnectionRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		http.Error(w, "Bad Request", http.StatusBadRequest)
+		return
+	}
+	s.ProcessConnection(req)
+	w.WriteHeader(http.StatusOK)
+}

authdaemon/server.go

@@ -0,0 +1,180 @@
+package authdaemon
+
+import (
+	"context"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/subtle"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"fmt"
+	"math/big"
+	"net/http"
+	"os"
+	"runtime"
+	"strings"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+)
+
+type Config struct {
+	// DisableHTTPS: when true, Run() does not start the HTTPS server (for embedded use inside Newt). Call ProcessConnection directly for connection events.
+	DisableHTTPS       bool
+	Port               int    // Required when DisableHTTPS is false. Listen port for the HTTPS server. No default.
+	PresharedKey       string // Required when DisableHTTPS is false. HTTP auth (Authorization: Bearer <key> or X-Preshared-Key: <key>). No default.
+	CACertPath         string // Required. Where to write the CA cert (e.g. /etc/ssh/ca.pem). No default.
+	Force                   bool   // If true, overwrite existing CA cert (and other items) when content differs. Default false.
+	PrincipalsFilePath      string // Required. Path to the principals data file (JSON: username -> array of principals). No default.
+	GenerateRandomPassword  bool   // If true, set a random password on users when they are provisioned (for SSH PermitEmptyPasswords no).
+}
+
+type Server struct {
+	cfg          Config
+	addr         string
+	presharedKey string
+	mux          *http.ServeMux
+	tlsCert      tls.Certificate
+}
+
+// generateTLSCert creates a self-signed certificate and key in memory (no disk).
+func generateTLSCert() (tls.Certificate, error) {
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return tls.Certificate{}, fmt.Errorf("generate key: %w", err)
+	}
+	serial, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return tls.Certificate{}, fmt.Errorf("serial: %w", err)
+	}
+	tmpl := &x509.Certificate{
+		SerialNumber: serial,
+		Subject: pkix.Name{
+			CommonName: "localhost",
+		},
+		NotBefore:             time.Now(),
+		NotAfter:              time.Now().Add(365 * 24 * time.Hour),
+		KeyUsage:              x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+		DNSNames:              []string{"localhost", "127.0.0.1"},
+	}
+	certDER, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, key.Public(), key)
+	if err != nil {
+		return tls.Certificate{}, fmt.Errorf("create certificate: %w", err)
+	}
+	keyDER, err := x509.MarshalECPrivateKey(key)
+	if err != nil {
+		return tls.Certificate{}, fmt.Errorf("marshal key: %w", err)
+	}
+	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})
+	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: keyDER})
+	cert, err := tls.X509KeyPair(certPEM, keyPEM)
+	if err != nil {
+		return tls.Certificate{}, fmt.Errorf("x509 key pair: %w", err)
+	}
+	return cert, nil
+}
+
+// authMiddleware wraps next and requires a valid preshared key on every request.
+// Accepts Authorization: Bearer <key> or X-Preshared-Key: <key>.
+func (s *Server) authMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		key := ""
+		if v := r.Header.Get("Authorization"); strings.HasPrefix(v, "Bearer ") {
+			key = strings.TrimSpace(strings.TrimPrefix(v, "Bearer "))
+		}
+		if key == "" {
+			key = strings.TrimSpace(r.Header.Get("X-Preshared-Key"))
+		}
+		if key == "" || subtle.ConstantTimeCompare([]byte(key), []byte(s.presharedKey)) != 1 {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// NewServer builds a new auth-daemon server from cfg. Port, PresharedKey, CACertPath, and PrincipalsFilePath are required (no defaults).
+func NewServer(cfg Config) (*Server, error) {
+	if runtime.GOOS != "linux" {
+		return nil, fmt.Errorf("auth-daemon is only supported on Linux, not %s", runtime.GOOS)
+	}
+	if !cfg.DisableHTTPS {
+		if cfg.Port <= 0 {
+			return nil, fmt.Errorf("port is required and must be positive")
+		}
+		if cfg.PresharedKey == "" {
+			return nil, fmt.Errorf("preshared key is required")
+		}
+	}
+	if cfg.CACertPath == "" {
+		return nil, fmt.Errorf("CACertPath is required")
+	}
+	if cfg.PrincipalsFilePath == "" {
+		return nil, fmt.Errorf("PrincipalsFilePath is required")
+	}
+	s := &Server{cfg: cfg}
+	if !cfg.DisableHTTPS {
+		cert, err := generateTLSCert()
+		if err != nil {
+			return nil, err
+		}
+		s.addr = fmt.Sprintf(":%d", cfg.Port)
+		s.presharedKey = cfg.PresharedKey
+		s.mux = http.NewServeMux()
+		s.tlsCert = cert
+		s.registerRoutes()
+	}
+	return s, nil
+}
+
+// Run starts the HTTPS server (unless DisableHTTPS) and blocks until ctx is cancelled or the server errors.
+// When DisableHTTPS is true, Run() blocks on ctx only and does not listen; use ProcessConnection for connection events.
+func (s *Server) Run(ctx context.Context) error {
+	if s.cfg.DisableHTTPS {
+		logger.Info("auth-daemon running (HTTPS disabled)")
+		<-ctx.Done()
+		s.cleanupPrincipalsFile()
+		return nil
+	}
+	tcfg := &tls.Config{
+		Certificates: []tls.Certificate{s.tlsCert},
+		MinVersion:   tls.VersionTLS12,
+	}
+	handler := s.authMiddleware(s.mux)
+	srv := &http.Server{
+		Addr:              s.addr,
+		Handler:           handler,
+		TLSConfig:         tcfg,
+		ReadTimeout:       10 * time.Second,
+		WriteTimeout:      10 * time.Second,
+		ReadHeaderTimeout: 5 * time.Second,
+		IdleTimeout:       60 * time.Second,
+	}
+	go func() {
+		<-ctx.Done()
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		if err := srv.Shutdown(shutdownCtx); err != nil {
+			logger.Warn("auth-daemon shutdown: %v", err)
+		}
+	}()
+	logger.Info("auth-daemon listening on https://127.0.0.1%s", s.addr)
+	if err := srv.ListenAndServeTLS("", ""); err != nil && err != http.ErrServerClosed {
+		return err
+	}
+	s.cleanupPrincipalsFile()
+	return nil
+}
+
+func (s *Server) cleanupPrincipalsFile() {
+	if s.cfg.PrincipalsFilePath != "" {
+		if err := os.Remove(s.cfg.PrincipalsFilePath); err != nil && !os.IsNotExist(err) {
+			logger.Warn("auth-daemon: remove principals file: %v", err)
+		}
+	}
+}

bind/shared_bind.go

@@ -0,0 +1,840 @@
+//go:build !js
+
+package bind
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"net/netip"
+	"runtime"
+	"sync"
+	"sync/atomic"
+
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
+
+// Magic packet constants for connection testing
+// These packets are intercepted by SharedBind and responded to directly,
+// without being passed to the WireGuard device.
+var (
+	// MagicTestRequest is the prefix for a test request packet
+	// Format: PANGOLIN_TEST_REQ + 8 bytes of random data (for echo)
+	MagicTestRequest = []byte("PANGOLIN_TEST_REQ")
+
+	// MagicTestResponse is the prefix for a test response packet
+	// Format: PANGOLIN_TEST_RSP + 8 bytes echoed from request
+	MagicTestResponse = []byte("PANGOLIN_TEST_RSP")
+)
+
+const (
+	// MagicPacketDataLen is the length of random data included in test packets
+	MagicPacketDataLen = 8
+
+	// MagicTestRequestLen is the total length of a test request packet
+	MagicTestRequestLen = 17 + MagicPacketDataLen // len("PANGOLIN_TEST_REQ") + 8
+
+	// MagicTestResponseLen is the total length of a test response packet
+	MagicTestResponseLen = 17 + MagicPacketDataLen // len("PANGOLIN_TEST_RSP") + 8
+)
+
+// PacketSource identifies where a packet came from
+type PacketSource uint8
+
+const (
+	SourceSocket   PacketSource = iota // From physical UDP socket (hole-punched clients)
+	SourceNetstack                     // From netstack (relay through main tunnel)
+)
+
+// SourceAwareEndpoint wraps an endpoint with source information
+type SourceAwareEndpoint struct {
+	wgConn.Endpoint
+	source PacketSource
+}
+
+// GetSource returns the source of this endpoint
+func (e *SourceAwareEndpoint) GetSource() PacketSource {
+	return e.source
+}
+
+// injectedPacket represents a packet injected into the SharedBind from an internal source
+type injectedPacket struct {
+	data     []byte
+	endpoint wgConn.Endpoint
+}
+
+// Endpoint represents a network endpoint for the SharedBind
+type Endpoint struct {
+	AddrPort netip.AddrPort
+}
+
+// ClearSrc implements the wgConn.Endpoint interface
+func (e *Endpoint) ClearSrc() {}
+
+// DstIP implements the wgConn.Endpoint interface
+func (e *Endpoint) DstIP() netip.Addr {
+	return e.AddrPort.Addr()
+}
+
+// SrcIP implements the wgConn.Endpoint interface
+func (e *Endpoint) SrcIP() netip.Addr {
+	return netip.Addr{}
+}
+
+// DstToBytes implements the wgConn.Endpoint interface
+func (e *Endpoint) DstToBytes() []byte {
+	b, _ := e.AddrPort.MarshalBinary()
+	return b
+}
+
+// DstToString implements the wgConn.Endpoint interface
+func (e *Endpoint) DstToString() string {
+	return e.AddrPort.String()
+}
+
+// SrcToString implements the wgConn.Endpoint interface
+func (e *Endpoint) SrcToString() string {
+	return ""
+}
+
+// SharedBind is a thread-safe UDP bind that can be shared between WireGuard
+// and hole punch senders. It wraps a single UDP connection and implements
+// reference counting to prevent premature closure.
+// It also supports receiving packets from a netstack and routing responses
+// back through the appropriate source.
+type SharedBind struct {
+	mu sync.RWMutex
+
+	// The underlying UDP connection (for hole-punched clients)
+	udpConn *net.UDPConn
+
+	// IPv4 and IPv6 packet connections for advanced features
+	ipv4PC *ipv4.PacketConn
+	ipv6PC *ipv6.PacketConn
+
+	// Reference counting to prevent closing while in use
+	refCount atomic.Int32
+	closed   atomic.Bool
+
+	// Channels for receiving data
+	recvFuncs []wgConn.ReceiveFunc
+
+	// Port binding information
+	port uint16
+
+	// Channel for packets from netstack (from direct relay) - larger buffer for throughput
+	netstackPackets chan injectedPacket
+
+	// Netstack connection for sending responses back through the tunnel
+	// Using atomic.Pointer for lock-free access in hot path
+	netstackConn atomic.Pointer[net.PacketConn]
+
+	// Track which endpoints came from netstack (key: netip.AddrPort, value: struct{})
+	// Using netip.AddrPort directly as key is more efficient than string
+	netstackEndpoints sync.Map
+
+	// Pre-allocated message buffers for batch operations (Linux only)
+	ipv4Msgs []ipv4.Message
+
+	// Shutdown signal for receive goroutines
+	closeChan chan struct{}
+
+	// Callback for magic test responses (used for holepunch testing)
+	magicResponseCallback atomic.Pointer[func(addr netip.AddrPort, echoData []byte)]
+
+	// Rebinding state - used to keep receive goroutines alive during socket transition
+	rebinding     bool       // true when socket is being replaced
+	rebindingCond *sync.Cond // signaled when rebind completes
+}
+
+// MagicResponseCallback is the function signature for magic packet response callbacks
+type MagicResponseCallback func(addr netip.AddrPort, echoData []byte)
+
+// New creates a new SharedBind from an existing UDP connection.
+// The SharedBind takes ownership of the connection and will close it
+// when all references are released.
+func New(udpConn *net.UDPConn) (*SharedBind, error) {
+	if udpConn == nil {
+		return nil, fmt.Errorf("udpConn cannot be nil")
+	}
+
+	bind := &SharedBind{
+		udpConn:         udpConn,
+		netstackPackets: make(chan injectedPacket, 1024), // Larger buffer for better throughput
+		closeChan:       make(chan struct{}),
+	}
+
+	// Initialize the rebinding condition variable
+	bind.rebindingCond = sync.NewCond(&bind.mu)
+
+	// Initialize reference count to 1 (the creator holds the first reference)
+	bind.refCount.Store(1)
+
+	// Get the local port
+	if addr, ok := udpConn.LocalAddr().(*net.UDPAddr); ok {
+		bind.port = uint16(addr.Port)
+	}
+
+	return bind, nil
+}
+
+// SetNetstackConn sets the netstack connection for receiving/sending packets through the tunnel.
+// This connection is used for relay traffic that should go back through the main tunnel.
+func (b *SharedBind) SetNetstackConn(conn net.PacketConn) {
+	b.netstackConn.Store(&conn)
+}
+
+// GetNetstackConn returns the netstack connection if set
+func (b *SharedBind) GetNetstackConn() net.PacketConn {
+	ptr := b.netstackConn.Load()
+	if ptr == nil {
+		return nil
+	}
+	return *ptr
+}
+
+// InjectPacket allows injecting a packet directly into the SharedBind's receive path.
+// This is used for direct relay from netstack without going through the host network.
+// The fromAddr should be the address the packet appears to come from.
+func (b *SharedBind) InjectPacket(data []byte, fromAddr netip.AddrPort) error {
+	if b.closed.Load() {
+		return net.ErrClosed
+	}
+
+	// Unmap IPv4-in-IPv6 addresses to ensure consistency with parsed endpoints
+	if fromAddr.Addr().Is4In6() {
+		fromAddr = netip.AddrPortFrom(fromAddr.Addr().Unmap(), fromAddr.Port())
+	}
+
+	// Track this endpoint as coming from netstack so responses go back the same way
+	// Use AddrPort directly as key (more efficient than string)
+	b.netstackEndpoints.Store(fromAddr, struct{}{})
+
+	// Make a copy of the data to avoid issues with buffer reuse
+	dataCopy := make([]byte, len(data))
+	copy(dataCopy, data)
+
+	select {
+	case b.netstackPackets <- injectedPacket{
+		data:     dataCopy,
+		endpoint: &wgConn.StdNetEndpoint{AddrPort: fromAddr},
+	}:
+		return nil
+	case <-b.closeChan:
+		return net.ErrClosed
+	default:
+		// Channel full, drop the packet
+		return fmt.Errorf("netstack packet buffer full")
+	}
+}
+
+// AddRef increments the reference count. Call this when sharing
+// the bind with another component.
+func (b *SharedBind) AddRef() {
+	newCount := b.refCount.Add(1)
+	// Optional: Add logging for debugging
+	_ = newCount // Placeholder for potential logging
+}
+
+// Release decrements the reference count. When it reaches zero,
+// the underlying UDP connection is closed.
+func (b *SharedBind) Release() error {
+	newCount := b.refCount.Add(-1)
+	// Optional: Add logging for debugging
+	_ = newCount // Placeholder for potential logging
+
+	if newCount < 0 {
+		// This should never happen with proper usage
+		b.refCount.Store(0)
+		return fmt.Errorf("SharedBind reference count went negative")
+	}
+
+	if newCount == 0 {
+		return b.closeConnection()
+	}
+
+	return nil
+}
+
+// closeConnection actually closes the UDP connection
+func (b *SharedBind) closeConnection() error {
+	if !b.closed.CompareAndSwap(false, true) {
+		// Already closed
+		return nil
+	}
+
+	// Signal all goroutines to stop
+	close(b.closeChan)
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	var err error
+	if b.udpConn != nil {
+		err = b.udpConn.Close()
+		b.udpConn = nil
+	}
+
+	b.ipv4PC = nil
+	b.ipv6PC = nil
+
+	// Clear netstack connection (but don't close it - it's managed externally)
+	b.netstackConn.Store(nil)
+
+	// Clear tracked netstack endpoints
+	b.netstackEndpoints = sync.Map{}
+
+	return err
+}
+
+// ClearNetstackConn clears the netstack connection and tracked endpoints.
+// Call this when stopping the relay.
+func (b *SharedBind) ClearNetstackConn() {
+	b.netstackConn.Store(nil)
+
+	// Clear tracked netstack endpoints
+	b.netstackEndpoints = sync.Map{}
+}
+
+// GetUDPConn returns the underlying UDP connection.
+// The caller must not close this connection directly.
+func (b *SharedBind) GetUDPConn() *net.UDPConn {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	return b.udpConn
+}
+
+// GetRefCount returns the current reference count (for debugging)
+func (b *SharedBind) GetRefCount() int32 {
+	return b.refCount.Load()
+}
+
+// IsClosed returns whether the bind is closed
+func (b *SharedBind) IsClosed() bool {
+	return b.closed.Load()
+}
+
+// GetPort returns the current UDP port the bind is using.
+// This is useful when rebinding to try to reuse the same port.
+func (b *SharedBind) GetPort() uint16 {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	return b.port
+}
+
+// CloseSocket closes the underlying UDP connection to release the port,
+// but keeps the SharedBind in a state where it can accept a new connection via Rebind.
+// This allows the caller to close the old socket first, then bind a new socket
+// to the same port before calling Rebind.
+//
+// Returns the port that was being used, so the caller can attempt to rebind to it.
+// Sets the rebinding flag so receive goroutines will wait for the new socket
+// instead of exiting.
+func (b *SharedBind) CloseSocket() (uint16, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.closed.Load() {
+		return 0, fmt.Errorf("bind is closed")
+	}
+
+	port := b.port
+
+	// Set rebinding flag BEFORE closing the socket so receive goroutines
+	// know to wait instead of exit
+	b.rebinding = true
+
+	// Close the old connection to release the port
+	if b.udpConn != nil {
+		logger.Debug("Closing UDP connection to release port %d (rebinding)", port)
+		b.udpConn.Close()
+		b.udpConn = nil
+	}
+
+	return port, nil
+}
+
+// Rebind replaces the underlying UDP connection with a new one.
+// This is necessary when network connectivity changes (e.g., WiFi to cellular
+// transition on macOS/iOS) and the old socket becomes stale.
+//
+// The caller is responsible for creating the new UDP connection and passing it here.
+// After rebind, the caller should trigger a hole punch to re-establish NAT mappings.
+//
+// Note: Call CloseSocket() first if you need to rebind to the same port, as the
+// old socket must be closed before a new socket can bind to the same port.
+func (b *SharedBind) Rebind(newConn *net.UDPConn) error {
+	if newConn == nil {
+		return fmt.Errorf("newConn cannot be nil")
+	}
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.closed.Load() {
+		return fmt.Errorf("bind is closed")
+	}
+
+	// Close the old connection if it's still open
+	// (it may have already been closed via CloseSocket)
+	if b.udpConn != nil {
+		logger.Debug("Closing old UDP connection during rebind")
+		b.udpConn.Close()
+	}
+
+	// Set up the new connection
+	b.udpConn = newConn
+
+	// Update packet connections for the new socket
+	if runtime.GOOS == "linux" || runtime.GOOS == "android" {
+		b.ipv4PC = ipv4.NewPacketConn(newConn)
+		b.ipv6PC = ipv6.NewPacketConn(newConn)
+
+		// Re-initialize message buffers for batch operations
+		batchSize := wgConn.IdealBatchSize
+		b.ipv4Msgs = make([]ipv4.Message, batchSize)
+		for i := range b.ipv4Msgs {
+			b.ipv4Msgs[i].OOB = make([]byte, 0)
+		}
+	} else {
+		// For non-Linux platforms, still set up ipv4PC for consistency
+		b.ipv4PC = ipv4.NewPacketConn(newConn)
+		b.ipv6PC = ipv6.NewPacketConn(newConn)
+	}
+
+	// Update the port
+	if addr, ok := newConn.LocalAddr().(*net.UDPAddr); ok {
+		b.port = uint16(addr.Port)
+		logger.Info("Rebound UDP socket to port %d", b.port)
+	}
+
+	// Clear the rebinding flag and wake up any waiting receive goroutines
+	b.rebinding = false
+	b.rebindingCond.Broadcast()
+
+	logger.Debug("Rebind complete, signaled waiting receive goroutines")
+
+	return nil
+}
+
+// SetMagicResponseCallback sets a callback function that will be called when
+// a magic test response packet is received. This is used for holepunch testing.
+// Pass nil to clear the callback.
+func (b *SharedBind) SetMagicResponseCallback(callback MagicResponseCallback) {
+	if callback == nil {
+		b.magicResponseCallback.Store(nil)
+	} else {
+		// Convert to the function type the atomic.Pointer expects
+		fn := func(addr netip.AddrPort, echoData []byte) {
+			callback(addr, echoData)
+		}
+		b.magicResponseCallback.Store(&fn)
+	}
+}
+
+// WriteToUDP writes data to a specific UDP address.
+// This is thread-safe and can be used by hole punch senders.
+func (b *SharedBind) WriteToUDP(data []byte, addr *net.UDPAddr) (int, error) {
+	if b.closed.Load() {
+		return 0, net.ErrClosed
+	}
+
+	b.mu.RLock()
+	conn := b.udpConn
+	b.mu.RUnlock()
+
+	if conn == nil {
+		return 0, net.ErrClosed
+	}
+
+	return conn.WriteToUDP(data, addr)
+}
+
+// Close implements the WireGuard Bind interface.
+// It decrements the reference count and closes the connection if no references remain.
+func (b *SharedBind) Close() error {
+	return b.Release()
+}
+
+// Open implements the WireGuard Bind interface.
+// Since the connection is already open, this just sets up the receive functions.
+func (b *SharedBind) Open(uport uint16) ([]wgConn.ReceiveFunc, uint16, error) {
+	if b.closed.Load() {
+		return nil, 0, net.ErrClosed
+	}
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.udpConn == nil {
+		return nil, 0, net.ErrClosed
+	}
+
+	// Set up IPv4 and IPv6 packet connections for advanced features
+	if runtime.GOOS == "linux" || runtime.GOOS == "android" {
+		b.ipv4PC = ipv4.NewPacketConn(b.udpConn)
+		b.ipv6PC = ipv6.NewPacketConn(b.udpConn)
+
+		// Pre-allocate message buffers for batch operations
+		batchSize := wgConn.IdealBatchSize
+		b.ipv4Msgs = make([]ipv4.Message, batchSize)
+		for i := range b.ipv4Msgs {
+			b.ipv4Msgs[i].OOB = make([]byte, 0)
+		}
+	}
+
+	// Create receive functions - one for socket, one for netstack
+	recvFuncs := make([]wgConn.ReceiveFunc, 0, 2)
+
+	// Add socket receive function (reads from physical UDP socket)
+	recvFuncs = append(recvFuncs, b.makeReceiveSocket())
+
+	// Add netstack receive function (reads from injected packets channel)
+	recvFuncs = append(recvFuncs, b.makeReceiveNetstack())
+
+	b.recvFuncs = recvFuncs
+	return recvFuncs, b.port, nil
+}
+
+// makeReceiveSocket creates a receive function for physical UDP socket packets
+func (b *SharedBind) makeReceiveSocket() wgConn.ReceiveFunc {
+	return func(bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (n int, err error) {
+		for {
+			if b.closed.Load() {
+				return 0, net.ErrClosed
+			}
+
+			b.mu.RLock()
+			conn := b.udpConn
+			pc := b.ipv4PC
+			b.mu.RUnlock()
+
+			if conn == nil {
+				// Socket is nil - check if we're rebinding or truly closed
+				if b.closed.Load() {
+					return 0, net.ErrClosed
+				}
+
+				// Wait for rebind to complete
+				b.mu.Lock()
+				for b.rebinding && !b.closed.Load() {
+					logger.Debug("Receive goroutine waiting for socket rebind to complete")
+					b.rebindingCond.Wait()
+				}
+				b.mu.Unlock()
+
+				// Check again after waking up
+				if b.closed.Load() {
+					return 0, net.ErrClosed
+				}
+
+				// Loop back to retry with new socket
+				continue
+			}
+
+			// Use batch reading on Linux for performance
+			var n int
+			var err error
+			if pc != nil && (runtime.GOOS == "linux" || runtime.GOOS == "android") {
+				n, err = b.receiveIPv4Batch(pc, bufs, sizes, eps)
+			} else {
+				n, err = b.receiveIPv4Simple(conn, bufs, sizes, eps)
+			}
+
+			if err != nil {
+				// Check if this error is due to rebinding
+				b.mu.RLock()
+				rebinding := b.rebinding
+				b.mu.RUnlock()
+
+				if rebinding {
+					logger.Debug("Receive got error during rebind, waiting for new socket: %v", err)
+					// Wait for rebind to complete and retry
+					b.mu.Lock()
+					for b.rebinding && !b.closed.Load() {
+						b.rebindingCond.Wait()
+					}
+					b.mu.Unlock()
+
+					if b.closed.Load() {
+						return 0, net.ErrClosed
+					}
+
+					// Retry with new socket
+					continue
+				}
+
+				// Not rebinding, return the error
+				return 0, err
+			}
+
+			return n, nil
+		}
+	}
+}
+
+// makeReceiveNetstack creates a receive function for netstack-injected packets
+func (b *SharedBind) makeReceiveNetstack() wgConn.ReceiveFunc {
+	return func(bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (n int, err error) {
+		select {
+		case <-b.closeChan:
+			return 0, net.ErrClosed
+		case pkt := <-b.netstackPackets:
+			if len(pkt.data) <= len(bufs[0]) {
+				copy(bufs[0], pkt.data)
+				sizes[0] = len(pkt.data)
+				eps[0] = pkt.endpoint
+				return 1, nil
+			}
+			// Packet too large for buffer, skip it
+			return 0, nil
+		}
+	}
+}
+
+// receiveIPv4Batch uses batch reading for better performance on Linux
+func (b *SharedBind) receiveIPv4Batch(pc *ipv4.PacketConn, bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (int, error) {
+	// Use pre-allocated messages, just update buffer pointers
+	numBufs := len(bufs)
+	if numBufs > len(b.ipv4Msgs) {
+		numBufs = len(b.ipv4Msgs)
+	}
+
+	for i := 0; i < numBufs; i++ {
+		b.ipv4Msgs[i].Buffers = [][]byte{bufs[i]}
+	}
+
+	numMsgs, err := pc.ReadBatch(b.ipv4Msgs[:numBufs], 0)
+	if err != nil {
+		return 0, err
+	}
+
+	// Process messages and filter out magic packets
+	writeIdx := 0
+	for i := 0; i < numMsgs; i++ {
+		if b.ipv4Msgs[i].N == 0 {
+			continue
+		}
+
+		// Check for magic packet
+		if b.ipv4Msgs[i].Addr != nil {
+			if udpAddr, ok := b.ipv4Msgs[i].Addr.(*net.UDPAddr); ok {
+				data := bufs[i][:b.ipv4Msgs[i].N]
+				if b.handleMagicPacket(data, udpAddr) {
+					// Magic packet handled, skip this message
+					continue
+				}
+			}
+		}
+
+		// Not a magic packet, include in output
+		if writeIdx != i {
+			// Need to copy data to the correct position
+			copy(bufs[writeIdx], bufs[i][:b.ipv4Msgs[i].N])
+		}
+		sizes[writeIdx] = b.ipv4Msgs[i].N
+
+		if b.ipv4Msgs[i].Addr != nil {
+			if udpAddr, ok := b.ipv4Msgs[i].Addr.(*net.UDPAddr); ok {
+				addrPort := udpAddr.AddrPort()
+				// Unmap IPv4-in-IPv6 addresses to ensure consistency with parsed endpoints
+				if addrPort.Addr().Is4In6() {
+					addrPort = netip.AddrPortFrom(addrPort.Addr().Unmap(), addrPort.Port())
+				}
+				eps[writeIdx] = &wgConn.StdNetEndpoint{AddrPort: addrPort}
+			}
+		}
+		writeIdx++
+	}
+
+	return writeIdx, nil
+}
+
+// receiveIPv4Simple uses simple ReadFromUDP for non-Linux platforms
+func (b *SharedBind) receiveIPv4Simple(conn *net.UDPConn, bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (int, error) {
+	// No read deadline - we rely on socket close to unblock during rebind.
+	// The caller (makeReceiveSocket) handles rebind state when errors occur.
+	for {
+		n, addr, err := conn.ReadFromUDP(bufs[0])
+		if err != nil {
+			return 0, err
+		}
+
+		// Check for magic test packet and handle it directly
+		if b.handleMagicPacket(bufs[0][:n], addr) {
+			// Magic packet was handled, read another packet
+			continue
+		}
+
+		sizes[0] = n
+		if addr != nil {
+			addrPort := addr.AddrPort()
+			// Unmap IPv4-in-IPv6 addresses to ensure consistency with parsed endpoints
+			if addrPort.Addr().Is4In6() {
+				addrPort = netip.AddrPortFrom(addrPort.Addr().Unmap(), addrPort.Port())
+			}
+			eps[0] = &wgConn.StdNetEndpoint{AddrPort: addrPort}
+		}
+
+		return 1, nil
+	}
+}
+
+// handleMagicPacket checks if the packet is a magic test packet and responds if so.
+// Returns true if the packet was a magic packet and was handled (should not be passed to WireGuard).
+func (b *SharedBind) handleMagicPacket(data []byte, addr *net.UDPAddr) bool {
+	// Check if this is a test request packet
+	if len(data) >= MagicTestRequestLen && bytes.HasPrefix(data, MagicTestRequest) {
+		// logger.Debug("Received magic test REQUEST from %s, sending response", addr.String())
+		// Extract the random data portion to echo back
+		echoData := data[len(MagicTestRequest) : len(MagicTestRequest)+MagicPacketDataLen]
+
+		// Build response packet
+		response := make([]byte, MagicTestResponseLen)
+		copy(response, MagicTestResponse)
+		copy(response[len(MagicTestResponse):], echoData)
+
+		// Send response back to sender
+		b.mu.RLock()
+		conn := b.udpConn
+		b.mu.RUnlock()
+
+		if conn != nil {
+			_, _ = conn.WriteToUDP(response, addr)
+		}
+
+		return true
+	}
+
+	// Check if this is a test response packet
+	if len(data) >= MagicTestResponseLen && bytes.HasPrefix(data, MagicTestResponse) {
+		// logger.Debug("Received magic test RESPONSE from %s", addr.String())
+		// Extract the echoed data
+		echoData := data[len(MagicTestResponse) : len(MagicTestResponse)+MagicPacketDataLen]
+
+		// Call the callback if set
+		callbackPtr := b.magicResponseCallback.Load()
+		if callbackPtr != nil {
+			callback := *callbackPtr
+			addrPort := addr.AddrPort()
+			// Unmap IPv4-in-IPv6 addresses to ensure consistency
+			if addrPort.Addr().Is4In6() {
+				addrPort = netip.AddrPortFrom(addrPort.Addr().Unmap(), addrPort.Port())
+			}
+			callback(addrPort, echoData)
+		} else {
+			logger.Debug("Magic response received but no callback registered")
+		}
+
+		return true
+	}
+
+	return false
+}
+
+// Send implements the WireGuard Bind interface.
+// It sends packets to the specified endpoint, routing through the appropriate
+// source (netstack or physical socket) based on where the endpoint's packets came from.
+func (b *SharedBind) Send(bufs [][]byte, ep wgConn.Endpoint) error {
+	if b.closed.Load() {
+		return net.ErrClosed
+	}
+
+	// Extract the destination address from the endpoint
+	var destAddrPort netip.AddrPort
+
+	// Try to cast to StdNetEndpoint first (most common case, avoid allocations)
+	if stdEp, ok := ep.(*wgConn.StdNetEndpoint); ok {
+		destAddrPort = stdEp.AddrPort
+	} else {
+		// Fallback: construct from DstIP and DstToBytes
+		dstBytes := ep.DstToBytes()
+		if len(dstBytes) >= 6 { // Minimum for IPv4 (4 bytes) + port (2 bytes)
+			var addr netip.Addr
+			var port uint16
+
+			if len(dstBytes) >= 18 { // IPv6 (16 bytes) + port (2 bytes)
+				addr, _ = netip.AddrFromSlice(dstBytes[:16])
+				port = uint16(dstBytes[16]) | uint16(dstBytes[17])<<8
+			} else { // IPv4
+				addr, _ = netip.AddrFromSlice(dstBytes[:4])
+				port = uint16(dstBytes[4]) | uint16(dstBytes[5])<<8
+			}
+
+			if addr.IsValid() {
+				destAddrPort = netip.AddrPortFrom(addr, port)
+			}
+		}
+	}
+
+	if !destAddrPort.IsValid() {
+		return fmt.Errorf("could not extract destination address from endpoint")
+	}
+
+	// Check if this endpoint came from netstack - if so, send through netstack
+	// Use AddrPort directly as key (more efficient than string conversion)
+	if _, isNetstackEndpoint := b.netstackEndpoints.Load(destAddrPort); isNetstackEndpoint {
+		connPtr := b.netstackConn.Load()
+		if connPtr != nil && *connPtr != nil {
+			netstackConn := *connPtr
+			destAddr := net.UDPAddrFromAddrPort(destAddrPort)
+			// Send all buffers through netstack
+			for _, buf := range bufs {
+				_, err := netstackConn.WriteTo(buf, destAddr)
+				if err != nil {
+					return err
+				}
+			}
+			return nil
+		}
+		// Fall through to socket if netstack conn not available
+	}
+
+	// Send through the physical UDP socket (for hole-punched clients)
+	b.mu.RLock()
+	conn := b.udpConn
+	b.mu.RUnlock()
+
+	if conn == nil {
+		return net.ErrClosed
+	}
+
+	destAddr := net.UDPAddrFromAddrPort(destAddrPort)
+
+	// Send all buffers to the destination
+	for _, buf := range bufs {
+		_, err := conn.WriteToUDP(buf, destAddr)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// SetMark implements the WireGuard Bind interface.
+// It's a no-op for this implementation.
+func (b *SharedBind) SetMark(mark uint32) error {
+	// Not implemented for this use case
+	return nil
+}
+
+// BatchSize returns the preferred batch size for sending packets.
+func (b *SharedBind) BatchSize() int {
+	if runtime.GOOS == "linux" || runtime.GOOS == "android" {
+		return wgConn.IdealBatchSize
+	}
+	return 1
+}
+
+// ParseEndpoint creates a new endpoint from a string address.
+func (b *SharedBind) ParseEndpoint(s string) (wgConn.Endpoint, error) {
+	addrPort, err := netip.ParseAddrPort(s)
+	if err != nil {
+		return nil, err
+	}
+	return &wgConn.StdNetEndpoint{AddrPort: addrPort}, nil
+}

bind/shared_bind_test.go

@@ -0,0 +1,555 @@
+//go:build !js
+
+package bind
+
+import (
+	"net"
+	"net/netip"
+	"sync"
+	"testing"
+	"time"
+
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
+
+// TestSharedBindCreation tests basic creation and initialization
+func TestSharedBindCreation(t *testing.T) {
+	// Create a UDP connection
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+	defer udpConn.Close()
+
+	// Create SharedBind
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+
+	if bind == nil {
+		t.Fatal("SharedBind is nil")
+	}
+
+	// Verify initial reference count
+	if bind.refCount.Load() != 1 {
+		t.Errorf("Expected initial refCount to be 1, got %d", bind.refCount.Load())
+	}
+
+	// Clean up
+	if err := bind.Close(); err != nil {
+		t.Errorf("Failed to close SharedBind: %v", err)
+	}
+}
+
+// TestSharedBindReferenceCount tests reference counting
+func TestSharedBindReferenceCount(t *testing.T) {
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+
+	// Add references
+	bind.AddRef()
+	if bind.refCount.Load() != 2 {
+		t.Errorf("Expected refCount to be 2, got %d", bind.refCount.Load())
+	}
+
+	bind.AddRef()
+	if bind.refCount.Load() != 3 {
+		t.Errorf("Expected refCount to be 3, got %d", bind.refCount.Load())
+	}
+
+	// Release references
+	bind.Release()
+	if bind.refCount.Load() != 2 {
+		t.Errorf("Expected refCount to be 2 after release, got %d", bind.refCount.Load())
+	}
+
+	bind.Release()
+	bind.Release() // This should close the connection
+
+	if !bind.closed.Load() {
+		t.Error("Expected bind to be closed after all references released")
+	}
+}
+
+// TestSharedBindWriteToUDP tests the WriteToUDP functionality
+func TestSharedBindWriteToUDP(t *testing.T) {
+	// Create sender
+	senderConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create sender UDP connection: %v", err)
+	}
+
+	senderBind, err := New(senderConn)
+	if err != nil {
+		t.Fatalf("Failed to create sender SharedBind: %v", err)
+	}
+	defer senderBind.Close()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	// Send data
+	testData := []byte("Hello, SharedBind!")
+	n, err := senderBind.WriteToUDP(testData, receiverAddr)
+	if err != nil {
+		t.Fatalf("WriteToUDP failed: %v", err)
+	}
+
+	if n != len(testData) {
+		t.Errorf("Expected to send %d bytes, sent %d", len(testData), n)
+	}
+
+	// Receive data
+	buf := make([]byte, 1024)
+	receiverConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, _, err = receiverConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive data: %v", err)
+	}
+
+	if string(buf[:n]) != string(testData) {
+		t.Errorf("Expected to receive %q, got %q", testData, buf[:n])
+	}
+}
+
+// TestSharedBindConcurrentWrites tests thread-safety
+func TestSharedBindConcurrentWrites(t *testing.T) {
+	// Create sender
+	senderConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create sender UDP connection: %v", err)
+	}
+
+	senderBind, err := New(senderConn)
+	if err != nil {
+		t.Fatalf("Failed to create sender SharedBind: %v", err)
+	}
+	defer senderBind.Close()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	// Launch concurrent writes
+	numGoroutines := 100
+	var wg sync.WaitGroup
+	wg.Add(numGoroutines)
+
+	for i := 0; i < numGoroutines; i++ {
+		go func(id int) {
+			defer wg.Done()
+			data := []byte{byte(id)}
+			_, err := senderBind.WriteToUDP(data, receiverAddr)
+			if err != nil {
+				t.Errorf("WriteToUDP failed in goroutine %d: %v", id, err)
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}
+
+// TestSharedBindWireGuardInterface tests WireGuard Bind interface implementation
+func TestSharedBindWireGuardInterface(t *testing.T) {
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer bind.Close()
+
+	// Test Open
+	recvFuncs, port, err := bind.Open(0)
+	if err != nil {
+		t.Fatalf("Open failed: %v", err)
+	}
+
+	if len(recvFuncs) == 0 {
+		t.Error("Expected at least one receive function")
+	}
+
+	if port == 0 {
+		t.Error("Expected non-zero port")
+	}
+
+	// Test SetMark (should be a no-op)
+	if err := bind.SetMark(0); err != nil {
+		t.Errorf("SetMark failed: %v", err)
+	}
+
+	// Test BatchSize
+	batchSize := bind.BatchSize()
+	if batchSize <= 0 {
+		t.Error("Expected positive batch size")
+	}
+}
+
+// TestSharedBindSend tests the Send method with WireGuard endpoints
+func TestSharedBindSend(t *testing.T) {
+	// Create sender
+	senderConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create sender UDP connection: %v", err)
+	}
+
+	senderBind, err := New(senderConn)
+	if err != nil {
+		t.Fatalf("Failed to create sender SharedBind: %v", err)
+	}
+	defer senderBind.Close()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	// Create an endpoint
+	addrPort := receiverAddr.AddrPort()
+	endpoint := &wgConn.StdNetEndpoint{AddrPort: addrPort}
+
+	// Send data
+	testData := []byte("WireGuard packet")
+	bufs := [][]byte{testData}
+	err = senderBind.Send(bufs, endpoint)
+	if err != nil {
+		t.Fatalf("Send failed: %v", err)
+	}
+
+	// Receive data
+	buf := make([]byte, 1024)
+	receiverConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, _, err := receiverConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive data: %v", err)
+	}
+
+	if string(buf[:n]) != string(testData) {
+		t.Errorf("Expected to receive %q, got %q", testData, buf[:n])
+	}
+}
+
+// TestSharedBindMultipleUsers simulates WireGuard and hole punch using the same bind
+func TestSharedBindMultipleUsers(t *testing.T) {
+	// Create shared bind
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+
+	// Add reference for hole punch sender
+	sharedBind.AddRef()
+
+	// Create receiver
+	receiverConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create receiver UDP connection: %v", err)
+	}
+	defer receiverConn.Close()
+
+	receiverAddr := receiverConn.LocalAddr().(*net.UDPAddr)
+
+	var wg sync.WaitGroup
+
+	// Simulate WireGuard using the bind
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		addrPort := receiverAddr.AddrPort()
+		endpoint := &wgConn.StdNetEndpoint{AddrPort: addrPort}
+
+		for i := 0; i < 10; i++ {
+			data := []byte("WireGuard packet")
+			bufs := [][]byte{data}
+			if err := sharedBind.Send(bufs, endpoint); err != nil {
+				t.Errorf("WireGuard Send failed: %v", err)
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	}()
+
+	// Simulate hole punch sender using the bind
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < 10; i++ {
+			data := []byte("Hole punch packet")
+			if _, err := sharedBind.WriteToUDP(data, receiverAddr); err != nil {
+				t.Errorf("Hole punch WriteToUDP failed: %v", err)
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	}()
+
+	wg.Wait()
+
+	// Release the hole punch reference
+	sharedBind.Release()
+
+	// Close WireGuard's reference (should close the connection)
+	sharedBind.Close()
+
+	if !sharedBind.closed.Load() {
+		t.Error("Expected bind to be closed after all users released it")
+	}
+}
+
+// TestEndpoint tests the Endpoint implementation
+func TestEndpoint(t *testing.T) {
+	addr := netip.MustParseAddr("192.168.1.1")
+	addrPort := netip.AddrPortFrom(addr, 51820)
+
+	ep := &Endpoint{AddrPort: addrPort}
+
+	// Test DstIP
+	if ep.DstIP() != addr {
+		t.Errorf("Expected DstIP to be %v, got %v", addr, ep.DstIP())
+	}
+
+	// Test DstToString
+	expected := "192.168.1.1:51820"
+	if ep.DstToString() != expected {
+		t.Errorf("Expected DstToString to be %q, got %q", expected, ep.DstToString())
+	}
+
+	// Test DstToBytes
+	bytes := ep.DstToBytes()
+	if len(bytes) == 0 {
+		t.Error("Expected DstToBytes to return non-empty slice")
+	}
+
+	// Test SrcIP (should be zero)
+	if ep.SrcIP().IsValid() {
+		t.Error("Expected SrcIP to be invalid")
+	}
+
+	// Test ClearSrc (should not panic)
+	ep.ClearSrc()
+}
+
+// TestParseEndpoint tests the ParseEndpoint method
+func TestParseEndpoint(t *testing.T) {
+	udpConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create UDP connection: %v", err)
+	}
+
+	bind, err := New(udpConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer bind.Close()
+
+	tests := []struct {
+		name      string
+		input     string
+		wantErr   bool
+		checkAddr func(*testing.T, wgConn.Endpoint)
+	}{
+		{
+			name:    "valid IPv4",
+			input:   "192.168.1.1:51820",
+			wantErr: false,
+			checkAddr: func(t *testing.T, ep wgConn.Endpoint) {
+				if ep.DstToString() != "192.168.1.1:51820" {
+					t.Errorf("Expected 192.168.1.1:51820, got %s", ep.DstToString())
+				}
+			},
+		},
+		{
+			name:    "valid IPv6",
+			input:   "[::1]:51820",
+			wantErr: false,
+			checkAddr: func(t *testing.T, ep wgConn.Endpoint) {
+				if ep.DstToString() != "[::1]:51820" {
+					t.Errorf("Expected [::1]:51820, got %s", ep.DstToString())
+				}
+			},
+		},
+		{
+			name:    "invalid - missing port",
+			input:   "192.168.1.1",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - bad format",
+			input:   "not-an-address",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ep, err := bind.ParseEndpoint(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseEndpoint() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr && tt.checkAddr != nil {
+				tt.checkAddr(t, ep)
+			}
+		})
+	}
+}
+
+// TestNetstackRouting tests that packets from netstack endpoints are routed back through netstack
+func TestNetstackRouting(t *testing.T) {
+	// Create the SharedBind with a physical UDP socket
+	physicalConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create physical UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(physicalConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer sharedBind.Close()
+
+	// Create a mock "netstack" connection (just another UDP socket for testing)
+	netstackConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create netstack UDP connection: %v", err)
+	}
+	defer netstackConn.Close()
+
+	// Set the netstack connection
+	sharedBind.SetNetstackConn(netstackConn)
+
+	// Create a "client" that would receive packets
+	clientConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create client UDP connection: %v", err)
+	}
+	defer clientConn.Close()
+
+	clientAddr := clientConn.LocalAddr().(*net.UDPAddr)
+	clientAddrPort := clientAddr.AddrPort()
+
+	// Inject a packet from the "netstack" source - this should track the endpoint
+	testData := []byte("test packet from netstack")
+	err = sharedBind.InjectPacket(testData, clientAddrPort)
+	if err != nil {
+		t.Fatalf("InjectPacket failed: %v", err)
+	}
+
+	// Now when we send a response to this endpoint, it should go through netstack
+	endpoint := &wgConn.StdNetEndpoint{AddrPort: clientAddrPort}
+	responseData := []byte("response packet")
+	err = sharedBind.Send([][]byte{responseData}, endpoint)
+	if err != nil {
+		t.Fatalf("Send failed: %v", err)
+	}
+
+	// The packet should be received by the client from the netstack connection
+	buf := make([]byte, 1024)
+	clientConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, fromAddr, err := clientConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive response: %v", err)
+	}
+
+	if string(buf[:n]) != string(responseData) {
+		t.Errorf("Expected to receive %q, got %q", responseData, buf[:n])
+	}
+
+	// Verify the response came from the netstack connection, not the physical one
+	netstackAddr := netstackConn.LocalAddr().(*net.UDPAddr)
+	if fromAddr.Port != netstackAddr.Port {
+		t.Errorf("Expected response from netstack port %d, got %d", netstackAddr.Port, fromAddr.Port)
+	}
+}
+
+// TestSocketRouting tests that packets from socket endpoints are routed through socket
+func TestSocketRouting(t *testing.T) {
+	// Create the SharedBind with a physical UDP socket
+	physicalConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create physical UDP connection: %v", err)
+	}
+
+	sharedBind, err := New(physicalConn)
+	if err != nil {
+		t.Fatalf("Failed to create SharedBind: %v", err)
+	}
+	defer sharedBind.Close()
+
+	// Create a mock "netstack" connection
+	netstackConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create netstack UDP connection: %v", err)
+	}
+	defer netstackConn.Close()
+
+	// Set the netstack connection
+	sharedBind.SetNetstackConn(netstackConn)
+
+	// Create a "client" that would receive packets (this simulates a hole-punched client)
+	clientConn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4zero, Port: 0})
+	if err != nil {
+		t.Fatalf("Failed to create client UDP connection: %v", err)
+	}
+	defer clientConn.Close()
+
+	clientAddr := clientConn.LocalAddr().(*net.UDPAddr)
+	clientAddrPort := clientAddr.AddrPort()
+
+	// Don't inject from netstack - this endpoint is NOT tracked as netstack-sourced
+	// So Send should use the physical socket
+
+	endpoint := &wgConn.StdNetEndpoint{AddrPort: clientAddrPort}
+	responseData := []byte("response packet via socket")
+	err = sharedBind.Send([][]byte{responseData}, endpoint)
+	if err != nil {
+		t.Fatalf("Send failed: %v", err)
+	}
+
+	// The packet should be received by the client from the physical connection
+	buf := make([]byte, 1024)
+	clientConn.SetReadDeadline(time.Now().Add(2 * time.Second))
+	n, fromAddr, err := clientConn.ReadFromUDP(buf)
+	if err != nil {
+		t.Fatalf("Failed to receive response: %v", err)
+	}
+
+	if string(buf[:n]) != string(responseData) {
+		t.Errorf("Expected to receive %q, got %q", responseData, buf[:n])
+	}
+
+	// Verify the response came from the physical connection, not the netstack one
+	physicalAddr := physicalConn.LocalAddr().(*net.UDPAddr)
+	if fromAddr.Port != physicalAddr.Port {
+		t.Errorf("Expected response from physical port %d, got %d", physicalAddr.Port, fromAddr.Port)
+	}
+}

browsergateway/browsergateway.go

@@ -0,0 +1,144 @@
+package browsergateway
+
+import (
+	"crypto/subtle"
+	"errors"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+
+	"github.com/fosrl/newt/nativessh"
+)
+
+// Forwarding buffer size. RDP graphics traffic is bursty and TLS records cap
+// at ~16 KiB, so 64 KiB lets a couple of records pile up per syscall/frame
+// without wasting memory per session.
+const forwardBufSize = 64 * 1024
+
+// ListenPort is the port the browser gateway HTTP server listens on inside the
+// WireGuard netstack. This is a fixed value shared between newt and pangolin.
+// Targets do not overlap with this port because they start at 40000.
+const ListenPort = 39999
+
+// Target represents an allowed proxy destination for the browser gateway.
+// Only connections whose (Type, Destination, DestinationPort, AuthToken) match a
+// registered Target will be forwarded; all others are rejected.
+type Target struct {
+	ID              int
+	Type            string // "rdp" | "ssh" | "vnc"
+	Destination     string
+	DestinationPort int
+	AuthToken       string // per-target secret; must match the token supplied by the client
+}
+
+// Config holds the configuration for a Gateway.
+type Config struct {
+	// AuthToken is used only for NativeSSH mode (which has no external target
+	// to match against). For all proxy targets (RDP/SSH/VNC), auth tokens are
+	// stored per-Target and validated by isAllowed.
+	AuthToken string
+	// SSHCredentials are used by native SSH browser sessions for certificate
+	// validation against the in-memory CA/principal store.
+	SSHCredentials *nativessh.CredentialStore
+}
+
+// Gateway is a browser-based RDP/SSH/VNC WebSocket proxy.
+// Create one with New and mount it via RegisterHandlers or the individual
+// HandleRDP / HandleSSH / HandleVNC http.HandlerFunc methods.
+type Gateway struct {
+	authToken string
+	sshCreds  *nativessh.CredentialStore
+
+	mu      sync.RWMutex
+	targets map[int]Target // keyed by Target.ID
+
+	server *http.Server
+}
+
+// New creates a new Gateway from the provided Config.
+func New(cfg Config) *Gateway {
+	return &Gateway{
+		authToken: cfg.AuthToken,
+		sshCreds:  cfg.SSHCredentials,
+		targets:   make(map[int]Target),
+	}
+}
+
+// SetTargets replaces the entire allowed-destination list atomically.
+func (g *Gateway) SetTargets(targets []Target) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.targets = make(map[int]Target, len(targets))
+	for _, t := range targets {
+		g.targets[t.ID] = t
+	}
+}
+
+// AddTarget adds or updates a single allowed destination.
+func (g *Gateway) AddTarget(t Target) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	g.targets[t.ID] = t
+}
+
+// RemoveTarget removes an allowed destination by its ID.
+func (g *Gateway) RemoveTarget(id int) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	delete(g.targets, id)
+}
+
+// isAllowed reports whether a connection to (targetType, host, port) with the
+// given authToken is permitted. The token is compared against the per-target
+// AuthToken using constant-time comparison to prevent timing attacks.
+func (g *Gateway) isAllowed(targetType, host string, port int, authToken string) bool {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+	for _, t := range g.targets {
+		if t.Type == targetType && t.Destination == host && t.DestinationPort == port {
+			return subtle.ConstantTimeCompare([]byte(authToken), []byte(t.AuthToken)) == 1
+		}
+	}
+	return false
+}
+
+// isTokenValid reports whether the given authToken matches any registered
+// target of the specified type. Used for native SSH mode where there is no
+// external destination to match against.
+func (g *Gateway) isTokenValid(targetType, authToken string) bool {
+	g.mu.RLock()
+	defer g.mu.RUnlock()
+	for _, t := range g.targets {
+		if t.Type == targetType {
+			if subtle.ConstantTimeCompare([]byte(authToken), []byte(t.AuthToken)) == 1 {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// Start serves the browser gateway HTTP server on the provided listener.
+// It returns nil when the listener is closed (normal shutdown).
+func (g *Gateway) Start(ln net.Listener) error {
+	mux := http.NewServeMux()
+	g.RegisterHandlers(mux)
+	g.server = &http.Server{Handler: mux}
+	err := g.server.Serve(ln)
+	if err == nil ||
+		errors.Is(err, net.ErrClosed) ||
+		errors.Is(err, http.ErrServerClosed) ||
+		strings.Contains(err.Error(), "use of closed") ||
+		strings.Contains(err.Error(), "invalid state") {
+		return nil
+	}
+	return err
+}
+
+// RegisterHandlers registers the /rdp, /ssh, and /vnc routes on mux.
+func (g *Gateway) RegisterHandlers(mux *http.ServeMux) {
+	mux.HandleFunc("/gateway/rdp", g.HandleRDP)
+	mux.HandleFunc("/gateway/ssh", g.HandleSSH)
+	mux.HandleFunc("/gateway/vnc", g.handleVNC)
+}

browsergateway/rdcleanpath.go

@@ -0,0 +1,88 @@
+package browsergateway
+
+import (
+	"encoding/asn1"
+	"fmt"
+)
+
+// RDCleanPath PDU version (BASE_VERSION + 1 = 3389 + 1).
+const rdCleanPathVersion = int64(3390)
+
+// rdCleanPathPdu is a Go translation of the ASN.1 SEQUENCE defined in the
+// ironrdp-rdcleanpath crate. All optional fields use EXPLICIT context-specific
+// tagging, matching the Rust `der::Sequence` derivation with
+// `tag_mode = "EXPLICIT"`.
+//
+// We only need a subset of fields for the basic proxy flow, but the struct
+// declares every tag we may encounter so that decoding does not fail on an
+// unexpected element.
+type rdCleanPathPdu struct {
+	Version           int64    `asn1:"explicit,tag:0"`
+	Destination       string   `asn1:"explicit,tag:2,optional,utf8"`
+	ProxyAuth         string   `asn1:"explicit,tag:3,optional,utf8"`
+	ServerAuth        string   `asn1:"explicit,tag:4,optional,utf8"`
+	PreconnectionBlob string   `asn1:"explicit,tag:5,optional,utf8"`
+	X224              []byte   `asn1:"explicit,tag:6,optional"`
+	ServerCertChain   [][]byte `asn1:"explicit,tag:7,optional"`
+	ServerAddr        string   `asn1:"explicit,tag:9,optional,utf8"`
+}
+
+// decodeRDCleanPathRequest parses a client-to-proxy RDCleanPath PDU.
+func decodeRDCleanPathRequest(buf []byte) (*rdCleanPathPdu, error) {
+	var pdu rdCleanPathPdu
+	rest, err := asn1.Unmarshal(buf, &pdu)
+	if err != nil {
+		return nil, fmt.Errorf("asn1 unmarshal: %w", err)
+	}
+	if len(rest) != 0 {
+		return nil, fmt.Errorf("trailing data after RDCleanPath PDU: %d bytes", len(rest))
+	}
+	if pdu.Version != rdCleanPathVersion {
+		return nil, fmt.Errorf("unexpected RDCleanPath version: %d", pdu.Version)
+	}
+	return &pdu, nil
+}
+
+// encodeRDCleanPathResponse builds a proxy-to-client RDCleanPath response PDU
+// containing the server address, X.224 connection confirm and server TLS chain.
+func encodeRDCleanPathResponse(serverAddr string, x224Rsp []byte, certChain [][]byte) ([]byte, error) {
+	pdu := rdCleanPathPdu{
+		Version:         rdCleanPathVersion,
+		X224:            x224Rsp,
+		ServerCertChain: certChain,
+		ServerAddr:      serverAddr,
+	}
+	return asn1.Marshal(pdu)
+}
+
+// detectRDCleanPathLength returns the total DER length of an RDCleanPath PDU
+// if enough bytes are available, otherwise -1.
+//
+// The PDU is a DER SEQUENCE, which begins with the universal SEQUENCE tag
+// (0x30) followed by a length octet/octets. We parse just enough to know the
+// total length so we can buffer accordingly.
+func detectRDCleanPathLength(buf []byte) int {
+	if len(buf) < 2 {
+		return -1
+	}
+	if buf[0] != 0x30 {
+		// Not a SEQUENCE: cannot be RDCleanPath.
+		return -2
+	}
+	l := buf[1]
+	if l < 0x80 {
+		return 2 + int(l)
+	}
+	n := int(l & 0x7f)
+	if n == 0 || n > 4 {
+		return -2
+	}
+	if len(buf) < 2+n {
+		return -1
+	}
+	total := 0
+	for i := 0; i < n; i++ {
+		total = (total << 8) | int(buf[2+i])
+	}
+	return 2 + n + total
+}

browsergateway/rdp.go

@@ -0,0 +1,271 @@
+package browsergateway
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/coder/websocket"
+)
+
+// HandleRDP is an http.HandlerFunc for RDP-over-WebSocket connections.
+func (g *Gateway) HandleRDP(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	ws, err := websocket.Accept(w, r, &websocket.AcceptOptions{
+		InsecureSkipVerify: true, // any-origin: minimal dev proxy with no auth
+		Subprotocols:       []string{"binary"},
+	})
+	if err != nil {
+		log.Printf("websocket upgrade failed: %v", err)
+		return
+	}
+	// Disable per-message read size cap (default is 32 KiB which would break
+	// large RDP graphics messages).
+	ws.SetReadLimit(-1)
+	defer ws.CloseNow() //nolint:errcheck
+
+	if err := g.serveSession(ctx, ws); err != nil {
+		log.Printf("session error: %v", err)
+	}
+}
+
+func (g *Gateway) serveSession(ctx context.Context, ws *websocket.Conn) error {
+	// Expose the WebSocket as a streaming net.Conn. Binary messages are
+	// concatenated into a byte stream and writes become single binary frames.
+	// This is a thin wrapper with no per-message goroutine, unlike Gorilla.
+	stream := websocket.NetConn(ctx, ws, websocket.MessageBinary)
+	defer stream.Close() //nolint:errcheck
+
+	// -- Read the initial RDCleanPath request from the client --
+	pdu, err := readCleanPath(stream)
+	if err != nil {
+		return fmt.Errorf("read RDCleanPath: %w", err)
+	}
+
+	if pdu.Destination == "" {
+		return errors.New("RDCleanPath missing destination")
+	}
+	if len(pdu.X224) == 0 {
+		return errors.New("RDCleanPath missing X224 connection PDU")
+	}
+
+	target := pdu.Destination
+	// Default port for RDP if not specified.
+	if _, _, splitErr := net.SplitHostPort(target); splitErr != nil {
+		target = net.JoinHostPort(target, "3389")
+	}
+
+	// Validate destination against the registered target allowlist,
+	// including per-target auth token.
+	rdpHost, rdpPortStr, _ := net.SplitHostPort(target)
+	rdpPort, _ := strconv.Atoi(rdpPortStr)
+	if !g.isAllowed("rdp", rdpHost, rdpPort, pdu.ProxyAuth) {
+		return fmt.Errorf("RDP destination %s is not in the allowed target list or auth token mismatch", target)
+	}
+
+	log.Printf("Connecting to RDP server %s", target)
+
+	// -- Open TCP connection to the destination RDP server --
+	serverTCP, err := net.DialTimeout("tcp", target, 15*time.Second)
+	if err != nil {
+		return fmt.Errorf("dial %s: %w", target, err)
+	}
+	defer serverTCP.Close()
+	if tcp, ok := serverTCP.(*net.TCPConn); ok {
+		// NoDelay is Go's default; set explicitly. RDP wants low latency for
+		// input echo, and the bulk path is naturally chunked by TLS records.
+		_ = tcp.SetNoDelay(true)
+		_ = tcp.SetKeepAlive(true)
+		_ = tcp.SetKeepAlivePeriod(30 * time.Second)
+		_ = tcp.SetReadBuffer(forwardBufSize)
+		_ = tcp.SetWriteBuffer(forwardBufSize)
+	}
+	serverAddr := serverTCP.RemoteAddr().String()
+
+	// Forward the optional pre-connection blob, then the X.224 connection request.
+	if pdu.PreconnectionBlob != "" {
+		if _, err := serverTCP.Write([]byte(pdu.PreconnectionBlob)); err != nil {
+			return fmt.Errorf("send PCB: %w", err)
+		}
+	}
+	if _, err := serverTCP.Write(pdu.X224); err != nil {
+		return fmt.Errorf("send X224: %w", err)
+	}
+
+	// -- Read the X.224 connection confirm from the server --
+	x224Rsp, err := readX224(serverTCP)
+	if err != nil {
+		return fmt.Errorf("read X224 response: %w", err)
+	}
+	logX224Negotiation(x224Rsp)
+
+	// -- Upgrade the server connection to TLS (skip verification) --
+	//
+	// Windows RDP hosts are picky: only set SNI when the target is a hostname
+	// (Go would skip SNI for IP literals anyway, but be explicit), and accept
+	// the full range of TLS versions / ciphers since some servers only
+	// negotiate TLS 1.0 or legacy suites.
+	host, _, _ := net.SplitHostPort(target)
+	tlsCfg := &tls.Config{
+		InsecureSkipVerify: true, //nolint:gosec // proxy intentionally skips verification
+		MinVersion:         tls.VersionTLS10,
+		// Cap at TLS 1.2: Windows RDP servers commonly send a TLS "internal_error"
+		// alert when CredSSP/NLA is layered on top of a TLS 1.3 session.
+		MaxVersion: tls.VersionTLS12,
+	}
+	if net.ParseIP(host) == nil {
+		tlsCfg.ServerName = host
+	}
+	tlsConn := tls.Client(serverTCP, tlsCfg)
+	if err := tlsConn.Handshake(); err != nil {
+		return fmt.Errorf("TLS handshake with server: %w", err)
+	}
+	log.Printf("Server TLS handshake OK (version=0x%04x cipher=0x%04x)",
+		tlsConn.ConnectionState().Version, tlsConn.ConnectionState().CipherSuite)
+
+	// Collect the raw DER server certificate chain to return to the client.
+	state := tlsConn.ConnectionState()
+	if len(state.PeerCertificates) == 0 {
+		return errors.New("server did not present any certificates")
+	}
+	chain := make([][]byte, 0, len(state.PeerCertificates))
+	for _, c := range state.PeerCertificates {
+		chain = append(chain, c.Raw)
+	}
+
+	// -- Send the RDCleanPath response back to the client --
+	rsp, err := encodeRDCleanPathResponse(serverAddr, x224Rsp, chain)
+	if err != nil {
+		return fmt.Errorf("encode RDCleanPath response: %w", err)
+	}
+	if _, err := stream.Write(rsp); err != nil {
+		return fmt.Errorf("write RDCleanPath response: %w", err)
+	}
+
+	log.Printf("RDCleanPath handshake complete, forwarding traffic to %s", serverAddr)
+
+	// -- Two-way blind forwarding of the (now TLS-encrypted) RDP stream --
+	return forward(stream, tlsConn)
+}
+
+// readCleanPath buffers bytes from the stream until a full RDCleanPath PDU has
+// been received, then decodes it.
+func readCleanPath(r io.Reader) (*rdCleanPathPdu, error) {
+	buf := make([]byte, 0, 1024)
+	tmp := make([]byte, 1024)
+	for {
+		total := detectRDCleanPathLength(buf)
+		switch {
+		case total == -2:
+			return nil, errors.New("invalid RDCleanPath PDU")
+		case total > 0 && len(buf) >= total:
+			return decodeRDCleanPathRequest(buf[:total])
+		}
+		n, err := r.Read(tmp)
+		if n > 0 {
+			buf = append(buf, tmp[:n]...)
+		}
+		if err != nil {
+			return nil, err
+		}
+	}
+}
+
+// readX224 reads exactly one TPKT-framed X.224 PDU from the server.
+//
+// The TPKT header is 4 bytes: version (0x03), reserved (0x00), and a u16
+// big-endian total length that includes the header itself.
+func readX224(r io.Reader) ([]byte, error) {
+	hdr := make([]byte, 4)
+	if _, err := io.ReadFull(r, hdr); err != nil {
+		return nil, err
+	}
+	if hdr[0] != 0x03 {
+		return nil, fmt.Errorf("unexpected TPKT version 0x%02x", hdr[0])
+	}
+	total := int(binary.BigEndian.Uint16(hdr[2:4]))
+	if total < 4 || total > 4096 {
+		return nil, fmt.Errorf("unreasonable TPKT length %d", total)
+	}
+	out := make([]byte, total)
+	copy(out, hdr)
+	if _, err := io.ReadFull(r, out[4:]); err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// logX224Negotiation prints which RDP security protocol the server selected
+// (or the failure code), to help diagnose handshake issues such as the server
+// requiring NLA/CredSSP.
+//
+// X.224 Connection Confirm layout (RFC 1006 / [MS-RDPBCGR]):
+//
+//	bytes 0..3   TPKT header (03 00 LL LL)
+//	byte  4      X.224 length indicator
+//	byte  5      X.224 code (0xD0 = CC)
+//	bytes 6..10  DST-REF, SRC-REF, class
+//	byte  11     optional RDP Negotiation type (0x02 = response, 0x03 = failure)
+//	byte  12     flags
+//	bytes 13..14 length (little-endian, =8)
+//	bytes 15..18 selected protocol / failure code (u32 little-endian)
+func logX224Negotiation(pdu []byte) {
+	if len(pdu) < 19 {
+		log.Printf("X.224 response too short (%d bytes) to contain RDP negotiation", len(pdu))
+		return
+	}
+	switch pdu[11] {
+	case 0x02:
+		proto := uint32(pdu[15]) | uint32(pdu[16])<<8 | uint32(pdu[17])<<16 | uint32(pdu[18])<<24
+		name := "unknown"
+		switch proto {
+		case 0:
+			name = "RDP (standard)"
+		case 1:
+			name = "SSL/TLS"
+		case 2:
+			name = "HYBRID (CredSSP/NLA)"
+		case 8:
+			name = "HYBRID_EX"
+		}
+		log.Printf("Server selected RDP protocol 0x%x (%s)", proto, name)
+	case 0x03:
+		code := uint32(pdu[15]) | uint32(pdu[16])<<8 | uint32(pdu[17])<<16 | uint32(pdu[18])<<24
+		log.Printf("Server returned RDP negotiation failure code 0x%x", code)
+	default:
+		log.Printf("X.224 response has no RDP negotiation block (type=0x%02x)", pdu[11])
+	}
+}
+
+// forward shuttles bytes between the two streams until either side closes.
+func forward(a, b io.ReadWriteCloser) error {
+	errc := make(chan error, 2)
+	go func() {
+		buf := make([]byte, forwardBufSize)
+		_, err := io.CopyBuffer(a, b, buf)
+		_ = a.Close()
+		_ = b.Close()
+		errc <- err
+	}()
+	go func() {
+		buf := make([]byte, forwardBufSize)
+		_, err := io.CopyBuffer(b, a, buf)
+		_ = a.Close()
+		_ = b.Close()
+		errc <- err
+	}()
+	// Wait for one side to finish, then return.
+	err := <-errc
+	if errors.Is(err, io.EOF) || err == nil {
+		return nil
+	}
+	return err
+}

browsergateway/ssh.go

@@ -0,0 +1,259 @@
+package browsergateway
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/coder/websocket"
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/crypto/ssh"
+)
+
+// sshClientMsg is a JSON message sent from the browser to the proxy.
+type sshClientMsg struct {
+	// type: "auth" | "data" | "resize"
+	Type       string `json:"type"`
+	Password   string `json:"password,omitempty"`   // used when type="auth"
+	PrivateKey string `json:"privateKey,omitempty"` // used when type="auth"
+	Certificate string `json:"certificate,omitempty"` // used when type="auth"
+	Data       string `json:"data,omitempty"`       // used when type="data"
+	Cols       uint32 `json:"cols,omitempty"`       // used when type="resize"
+	Rows       uint32 `json:"rows,omitempty"`       // used when type="resize"
+}
+
+// sshServerMsg is a JSON message sent from the proxy back to the browser.
+type sshServerMsg struct {
+	// type: "data" | "error"
+	Type  string `json:"type"`
+	Data  string `json:"data,omitempty"`
+	Error string `json:"error,omitempty"`
+}
+
+// HandleSSH is an http.HandlerFunc for SSH-over-WebSocket connections.
+func (g *Gateway) HandleSSH(w http.ResponseWriter, r *http.Request) {
+	logger.Debug("SSH connection request from %s", r.RemoteAddr)
+	ctx := r.Context()
+
+	token := r.URL.Query().Get("authToken")
+
+	// "mode=native" (default) connects to the local SSH daemon on this host.
+	// "mode=proxy" connects to an arbitrary host+port supplied in query params.
+	nativeSSH := r.URL.Query().Get("mode") != "proxy"
+
+	// In proxy mode we also need host + username from query params.
+	var target, username string
+	if !nativeSSH {
+		host := r.URL.Query().Get("host")
+		port := r.URL.Query().Get("port")
+		username = r.URL.Query().Get("username")
+		if host == "" || username == "" {
+			http.Error(w, "missing host or username", http.StatusBadRequest)
+			return
+		}
+		if port == "" {
+			port = "22"
+		}
+		sshPort, _ := strconv.Atoi(port)
+		if !g.isAllowed("ssh", host, sshPort, token) {
+			http.Error(w, "destination not allowed or auth token mismatch", http.StatusForbidden)
+			return
+		}
+		target = net.JoinHostPort(host, port)
+	} else {
+		// Native SSH mode: validate the token against any registered ssh target.
+		if !g.isTokenValid("ssh", token) {
+			http.Error(w, "unauthorized", http.StatusUnauthorized)
+			return
+		}
+		username = r.URL.Query().Get("username")
+		if username == "" {
+			http.Error(w, "missing username", http.StatusBadRequest)
+			return
+		}
+	}
+
+	ws, err := websocket.Accept(w, r, &websocket.AcceptOptions{
+		InsecureSkipVerify: true,
+		Subprotocols:       []string{"ssh"},
+	})
+	if err != nil {
+		log.Printf("SSH websocket upgrade failed: %v", err)
+		return
+	}
+	ws.SetReadLimit(-1)
+	defer ws.CloseNow() //nolint:errcheck
+
+	if nativeSSH {
+		if err := serveNativeSSHSession(ctx, ws, username, g.sshCreds); err != nil {
+			log.Printf("SSH native session error: %v", err)
+		}
+	} else {
+		if err := serveSSHSession(ctx, ws, target, username, g.authToken); err != nil {
+			log.Printf("SSH session error: %v", err)
+		}
+	}
+}
+
+func serveSSHSession(ctx context.Context, ws *websocket.Conn, target, username, _ string) error {
+	// -- Wait for the auth message from the client to get the password --
+	_, authBytes, err := ws.Read(ctx)
+	if err != nil {
+		return fmt.Errorf("read auth message: %w", err)
+	}
+	var authMsg sshClientMsg
+	if err := json.Unmarshal(authBytes, &authMsg); err != nil || authMsg.Type != "auth" {
+		return fmt.Errorf("expected auth message, got: %s", authBytes)
+	}
+	password := authMsg.Password
+	privateKey := authMsg.PrivateKey
+
+	// Build the list of auth methods. Private key takes priority when provided.
+	var authMethods []ssh.AuthMethod
+	if privateKey != "" {
+		signer, err := ssh.ParsePrivateKey([]byte(privateKey))
+		if err != nil {
+			sendSSHError(ctx, ws, fmt.Sprintf("Failed to parse private key: %v", err))
+			return fmt.Errorf("parse private key: %w", err)
+		}
+		authMethods = append(authMethods, ssh.PublicKeys(signer))
+	}
+	if password != "" {
+		authMethods = append(authMethods, ssh.Password(password))
+	}
+	if len(authMethods) == 0 {
+		sendSSHError(ctx, ws, "No authentication credentials provided")
+		return fmt.Errorf("no auth credentials")
+	}
+	log.Printf("SSH: connecting to %s as %s", target, username)
+	sshCfg := &ssh.ClientConfig{
+		User: username,
+		Auth: authMethods,
+		// HostKeyCallback is intentionally InsecureIgnoreHostKey for this dev
+		// proxy. In production, verify against a known-hosts store.
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(), //nolint:gosec
+		Timeout:         15 * time.Second,
+	}
+
+	sshClient, err := ssh.Dial("tcp", target, sshCfg)
+	if err != nil {
+		sendSSHError(ctx, ws, fmt.Sprintf("SSH dial failed: %v", err))
+		return fmt.Errorf("ssh dial %s: %w", target, err)
+	}
+	defer sshClient.Close()
+
+	// -- Open an interactive session --
+	sess, err := sshClient.NewSession()
+	if err != nil {
+		sendSSHError(ctx, ws, fmt.Sprintf("Failed to open SSH session: %v", err))
+		return fmt.Errorf("ssh new session: %w", err)
+	}
+	defer sess.Close()
+
+	// Request a PTY.
+	if err := sess.RequestPty("xterm-256color", 24, 80, ssh.TerminalModes{
+		ssh.ECHO:          1,
+		ssh.TTY_OP_ISPEED: 38400,
+		ssh.TTY_OP_OSPEED: 38400,
+	}); err != nil {
+		sendSSHError(ctx, ws, fmt.Sprintf("Failed to request PTY: %v", err))
+		return fmt.Errorf("ssh request pty: %w", err)
+	}
+
+	stdinPipe, err := sess.StdinPipe()
+	if err != nil {
+		return fmt.Errorf("ssh stdin pipe: %w", err)
+	}
+	stdoutPipe, err := sess.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("ssh stdout pipe: %w", err)
+	}
+	stderrPipe, err := sess.StderrPipe()
+	if err != nil {
+		return fmt.Errorf("ssh stderr pipe: %w", err)
+	}
+
+	if err := sess.Shell(); err != nil {
+		sendSSHError(ctx, ws, fmt.Sprintf("Failed to start shell: %v", err))
+		return fmt.Errorf("ssh shell: %w", err)
+	}
+
+	log.Printf("SSH: session established with %s", target)
+
+	// -- Pump SSH stdout/stderr → WebSocket --
+	sessCtx, cancelSess := context.WithCancel(ctx)
+	defer cancelSess()
+
+	go func() {
+		buf := make([]byte, 4096)
+		for {
+			n, readErr := stdoutPipe.Read(buf)
+			if n > 0 {
+				msg := sshServerMsg{Type: "data", Data: string(buf[:n])}
+				b, _ := json.Marshal(msg)
+				if writeErr := ws.Write(sessCtx, websocket.MessageText, b); writeErr != nil {
+					return
+				}
+			}
+			if readErr != nil {
+				cancelSess()
+				return
+			}
+		}
+	}()
+
+	go func() {
+		buf := make([]byte, 4096)
+		for {
+			n, readErr := stderrPipe.Read(buf)
+			if n > 0 {
+				msg := sshServerMsg{Type: "data", Data: string(buf[:n])}
+				b, _ := json.Marshal(msg)
+				if writeErr := ws.Write(sessCtx, websocket.MessageText, b); writeErr != nil {
+					return
+				}
+			}
+			if readErr != nil {
+				return
+			}
+		}
+	}()
+
+	// -- Pump WebSocket input → SSH stdin / resize --
+	for {
+		_, msgBytes, readErr := ws.Read(sessCtx)
+		if readErr != nil {
+			break
+		}
+
+		var msg sshClientMsg
+		if err := json.Unmarshal(msgBytes, &msg); err != nil {
+			continue
+		}
+
+		switch msg.Type {
+		case "data":
+			if _, err := stdinPipe.Write([]byte(msg.Data)); err != nil {
+				return fmt.Errorf("write ssh stdin: %w", err)
+			}
+		case "resize":
+			if msg.Cols > 0 && msg.Rows > 0 {
+				_ = sess.WindowChange(int(msg.Rows), int(msg.Cols))
+			}
+		}
+	}
+
+	return nil
+}
+
+// sendSSHError sends an error message to the browser and logs it.
+func sendSSHError(ctx context.Context, ws *websocket.Conn, msg string) {
+	log.Printf("SSH error: %s", msg)
+	b, _ := json.Marshal(sshServerMsg{Type: "error", Error: msg})
+	_ = ws.Write(ctx, websocket.MessageText, b)
+}

browsergateway/ssh_native.go

@@ -0,0 +1,94 @@
+//go:build !windows
+
+package browsergateway
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+
+	"github.com/coder/websocket"
+	"github.com/fosrl/newt/nativessh"
+)
+
+// serveNativeSSHSession handles a WebSocket SSH session by authenticating the
+// user against the host OS (authorized_keys then PAM password) and then
+// spawning a PTY+shell running as that user.
+//
+// The auth frame from the browser must be a JSON sshClientMsg with type="auth"
+// carrying the same password/privateKey fields used by the proxy SSH path.
+// The target username is passed in from the HTTP layer (query param).
+func serveNativeSSHSession(ctx context.Context, ws *websocket.Conn, username string, creds *nativessh.CredentialStore) error {
+	// Read the auth frame.
+	_, authBytes, err := ws.Read(ctx)
+	if err != nil {
+		return fmt.Errorf("read auth message: %w", err)
+	}
+	var authMsg sshClientMsg
+	if err := json.Unmarshal(authBytes, &authMsg); err != nil || authMsg.Type != "auth" {
+		return fmt.Errorf("expected auth message, got: %s", authBytes)
+	}
+
+	// Authenticate using host authorized_keys or PAM password.
+	if err := nativessh.AuthenticateWithCertificate(creds, username, authMsg.Password, authMsg.PrivateKey, authMsg.Certificate); err != nil {
+		sendSSHError(ctx, ws, "Authentication failed")
+		return fmt.Errorf("auth for user %q: %w", username, err)
+	}
+
+	log.Printf("SSH native: spawning shell as user %q", username)
+
+	sess, err := nativessh.NewPTYSessionAs(username)
+	if err != nil {
+		sendSSHError(ctx, ws, fmt.Sprintf("Failed to spawn shell: %v", err))
+		return fmt.Errorf("pty session as %q: %w", username, err)
+	}
+	defer sess.Close()
+
+	// Cancel context to unblock the WebSocket read loop when the shell exits.
+	sessCtx, cancelSess := context.WithCancel(ctx)
+	defer cancelSess()
+
+	// Pump PTY output → WebSocket.
+	go func() {
+		defer cancelSess()
+		buf := make([]byte, 4096)
+		for {
+			n, readErr := sess.Read(buf)
+			if n > 0 {
+				msg := sshServerMsg{Type: "data", Data: string(buf[:n])}
+				b, _ := json.Marshal(msg)
+				if writeErr := ws.Write(sessCtx, websocket.MessageText, b); writeErr != nil {
+					return
+				}
+			}
+			if readErr != nil {
+				return
+			}
+		}
+	}()
+
+	// Pump WebSocket input → PTY stdin / resize.
+	for {
+		_, msgBytes, readErr := ws.Read(sessCtx)
+		if readErr != nil {
+			break
+		}
+		var msg sshClientMsg
+		if err := json.Unmarshal(msgBytes, &msg); err != nil {
+			continue
+		}
+		switch msg.Type {
+		case "data":
+			if _, writeErr := sess.Write([]byte(msg.Data)); writeErr != nil {
+				return fmt.Errorf("write pty: %w", writeErr)
+			}
+		case "resize":
+			if msg.Cols > 0 && msg.Rows > 0 {
+				_ = sess.Resize(uint16(msg.Cols), uint16(msg.Rows))
+			}
+		}
+	}
+
+	return nil
+}

browsergateway/ssh_native_windows.go

@@ -0,0 +1,16 @@
+//go:build windows
+
+package browsergateway
+
+import (
+	"context"
+	"errors"
+
+	"github.com/coder/websocket"
+	"github.com/fosrl/newt/nativessh"
+)
+
+// serveNativeSSHSession is not supported on Windows.
+func serveNativeSSHSession(_ context.Context, _ *websocket.Conn, _ string, _ *nativessh.CredentialStore) error {
+	return errors.New("native SSH is not supported on Windows")
+}

browsergateway/vnc.go

@@ -0,0 +1,98 @@
+package browsergateway
+
+import (
+	"context"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"strconv"
+	"time"
+
+	"github.com/coder/websocket"
+)
+
+const (
+	vncDialTimeout    = 10 * time.Second
+	vncKeepAlive      = 30 * time.Second
+	vncForwardBufSize = 32 * 1024
+)
+
+// handleVNC proxies a noVNC WebSocket connection to a raw TCP VNC backend.
+// It follows the same auth-token-in-query-param pattern as handleSSH.
+//
+// Query parameters:
+//
+//	authToken – shared secret matching the -auth-token flag
+//	host      – VNC backend hostname or IP
+//	port      – VNC backend port (default: 5900)
+func (g *Gateway) handleVNC(w http.ResponseWriter, r *http.Request) {
+	host := r.URL.Query().Get("host")
+	port := r.URL.Query().Get("port")
+	if host == "" {
+		http.Error(w, "missing host", http.StatusBadRequest)
+		return
+	}
+	if port == "" {
+		port = "5900"
+	}
+	vncPort, _ := strconv.Atoi(port)
+	authToken := r.URL.Query().Get("authToken")
+	if !g.isAllowed("vnc", host, vncPort, authToken) {
+		http.Error(w, "destination not allowed or auth token mismatch", http.StatusForbidden)
+		return
+	}
+	target := net.JoinHostPort(host, port)
+
+	// Accept the WebSocket. noVNC negotiates the "binary" subprotocol;
+	// fall back gracefully when the client sends "base64" as well.
+	ws, err := websocket.Accept(w, r, &websocket.AcceptOptions{
+		InsecureSkipVerify: true,
+		Subprotocols:       []string{"binary", "base64"},
+	})
+	if err != nil {
+		log.Printf("vnc: websocket upgrade failed: %v", err)
+		return
+	}
+	ws.SetReadLimit(-1)
+	defer ws.CloseNow() //nolint:errcheck
+
+	ctx := r.Context()
+	if err := serveVNC(ctx, ws, target); err != nil {
+		log.Printf("vnc: session error (%s): %v", target, err)
+	}
+}
+
+func serveVNC(ctx context.Context, ws *websocket.Conn, target string) error {
+	// Dial the VNC backend TCP server.
+	dialer := &net.Dialer{
+		Timeout:   vncDialTimeout,
+		KeepAlive: vncKeepAlive,
+	}
+	conn, err := dialer.DialContext(ctx, "tcp", target)
+	if err != nil {
+		return err
+	}
+	defer conn.Close() //nolint:errcheck
+
+	// Expose the WebSocket as a plain net.Conn byte stream (binary frames).
+	stream := websocket.NetConn(ctx, ws, websocket.MessageBinary)
+	defer stream.Close() //nolint:errcheck
+
+	// Proxy bidirectionally: VNC backend <-> browser.
+	errc := make(chan error, 2)
+	go func() {
+		buf := make([]byte, vncForwardBufSize)
+		_, err := io.CopyBuffer(conn, stream, buf)
+		errc <- err
+	}()
+	go func() {
+		buf := make([]byte, vncForwardBufSize)
+		_, err := io.CopyBuffer(stream, conn, buf)
+		errc <- err
+	}()
+
+	// Return when either direction closes.
+	err = <-errc
+	return err
+}

clients.go

@@ -0,0 +1,114 @@
+package main
+
+import (
+	"strings"
+
+	"github.com/fosrl/newt/clients"
+	wgnetstack "github.com/fosrl/newt/clients"
+	"github.com/fosrl/newt/clients/permissions"
+	"github.com/fosrl/newt/logger"
+	"github.com/fosrl/newt/nativessh"
+	"github.com/fosrl/newt/websocket"
+	"golang.zx2c4.com/wireguard/tun/netstack"
+)
+
+var wgService *clients.WireGuardService
+var ready bool
+
+func setupClients(client *websocket.Client, credStore *nativessh.CredentialStore) {
+	var host = endpoint
+	if strings.HasPrefix(host, "http://") {
+		host = strings.TrimPrefix(host, "http://")
+	} else if strings.HasPrefix(host, "https://") {
+		host = strings.TrimPrefix(host, "https://")
+	}
+
+	host = strings.TrimSuffix(host, "/")
+
+	logger.Debug("Setting up clients with netstack2...")
+
+	// if useNativeInterface is true make sure we have permission to use native interface
+	if useNativeInterface {
+		logger.Debug("Checking permissions for native interface")
+		err := permissions.CheckNativeInterfacePermissions()
+		if err != nil {
+			logger.Fatal("Insufficient permissions to create native TUN interface: %v", err)
+			return
+		}
+	}
+
+	// Create WireGuard service
+	wgService, err = wgnetstack.NewWireGuardService(interfaceName, port, mtuInt, host, id, client, dns, useNativeInterface)
+	if err != nil {
+		logger.Fatal("Failed to create WireGuard service: %v", err)
+	}
+
+	wgService.SetCredentialStore(credStore)
+
+	client.OnTokenUpdate(func(token string) {
+		wgService.SetToken(token)
+	})
+
+	ready = true
+}
+
+func setDownstreamTNetstack(tnet *netstack.Net) {
+	if wgService != nil {
+		wgService.SetOthertnet(tnet)
+	}
+}
+
+func closeClients() {
+	logger.Info("Closing clients...")
+	if wgService != nil {
+		wgService.Close()
+		wgService = nil
+	}
+}
+
+// setClientsBlocked enables or disables connection blocking on the WireGuard service.
+func setClientsBlocked(v bool) {
+	if wgService != nil {
+		wgService.SetBlocked(v)
+	}
+}
+
+func clientsHandleNewtConnection(publicKey string, endpoint string, relayPort uint16) {
+	if !ready {
+		return
+	}
+
+	// split off the port from the endpoint
+	parts := strings.Split(endpoint, ":")
+	if len(parts) < 2 {
+		logger.Error("Invalid endpoint format: %s", endpoint)
+		return
+	}
+	endpoint = strings.Join(parts[:len(parts)-1], ":")
+
+	if wgService != nil {
+		wgService.StartHolepunch(publicKey, endpoint, relayPort)
+	}
+}
+
+func clientsOnConnect() {
+	if !ready {
+		return
+	}
+	if wgService != nil {
+		wgService.LoadRemoteConfig()
+	}
+}
+
+// clientsStartDirectRelay starts a direct UDP relay from the main tunnel netstack
+// to the clients' WireGuard, bypassing the proxy for better performance.
+func clientsStartDirectRelay(tunnelIP string) {
+	if !ready {
+		return
+	}
+	if wgService != nil {
+		if err := wgService.StartDirectUDPRelay(tunnelIP); err != nil {
+			logger.Error("Failed to start direct UDP relay: %v", err)
+		}
+	}
+}

clients/permissions/permissions_android.go

@@ -0,0 +1,8 @@
+//go:build android
+
+package permissions
+
+// CheckNativeInterfacePermissions always allows permission on Android.
+func CheckNativeInterfacePermissions() error {
+	return nil
+}

clients/permissions/permissions_darwin.go

@@ -0,0 +1,18 @@
+//go:build darwin && !ios
+
+package permissions
+
+import (
+	"fmt"
+	"os"
+)
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on macOS.
+// This typically requires root privileges.
+func CheckNativeInterfacePermissions() error {
+	if os.Geteuid() == 0 {
+		return nil
+	}
+	return fmt.Errorf("insufficient permissions: need root to create TUN interface on macOS")
+}

clients/permissions/permissions_freebsd.go

@@ -0,0 +1,57 @@
+//go:build freebsd
+
+package permissions
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/fosrl/newt/logger"
+)
+
+const (
+	// TUN device on FreeBSD
+	tunDevice = "/dev/tun"
+	ifnamsiz  = 16
+	iffTun    = 0x0001
+	iffNoPi   = 0x1000
+)
+
+// ifReq is the structure for TUN interface configuration
+type ifReq struct {
+	Name  [ifnamsiz]byte
+	Flags uint16
+	_     [22]byte // padding to match kernel structure
+}
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on FreeBSD.
+// This requires root privileges (UID 0).
+func CheckNativeInterfacePermissions() error {
+	logger.Debug("Checking native interface permissions on FreeBSD")
+
+	// Check if running as root
+	if os.Geteuid() == 0 {
+		logger.Debug("Running as root, sufficient permissions for native TUN interface")
+		return nil
+	}
+
+	// On FreeBSD, only root can create TUN interfaces
+	// Try to open the TUN device to verify
+	return tryOpenTunDevice()
+}
+
+// tryOpenTunDevice attempts to open the TUN device to verify permissions.
+// On FreeBSD, /dev/tun is a cloning device that creates a new interface
+// when opened.
+func tryOpenTunDevice() error {
+	// Try opening /dev/tun (cloning device)
+	f, err := os.OpenFile(tunDevice, os.O_RDWR, 0)
+	if err != nil {
+		return fmt.Errorf("cannot open %s: %v (need root privileges)", tunDevice, err)
+	}
+	defer f.Close()
+
+	logger.Debug("Successfully opened TUN device, sufficient permissions for native TUN interface")
+	return nil
+}

clients/permissions/permissions_ios.go

@@ -0,0 +1,8 @@
+//go:build ios
+
+package permissions
+
+// CheckNativeInterfacePermissions always allows permission on iOS.
+func CheckNativeInterfacePermissions() error {
+	return nil
+}

clients/permissions/permissions_linux.go

@@ -0,0 +1,96 @@
+//go:build linux && !android
+
+package permissions
+
+import (
+	"fmt"
+	"os"
+	"unsafe"
+
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	// TUN device constants
+	tunDevice = "/dev/net/tun"
+	ifnamsiz  = 16
+	iffTun    = 0x0001
+	iffNoPi   = 0x1000
+	tunSetIff = 0x400454ca
+)
+
+// ifReq is the structure for TUNSETIFF ioctl
+type ifReq struct {
+	Name  [ifnamsiz]byte
+	Flags uint16
+	_     [22]byte // padding to match kernel structure
+}
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on Linux.
+// This requires either root privileges (UID 0) or CAP_NET_ADMIN capability.
+func CheckNativeInterfacePermissions() error {
+	logger.Debug("Checking native interface permissions on Linux")
+
+	// Check if running as root
+	if os.Geteuid() == 0 {
+		logger.Debug("Running as root, sufficient permissions for native TUN interface")
+		return nil
+	}
+
+	// Check for CAP_NET_ADMIN capability
+	caps := unix.CapUserHeader{
+		Version: unix.LINUX_CAPABILITY_VERSION_3,
+		Pid:     0, // 0 means current process
+	}
+
+	var data [2]unix.CapUserData
+	if err := unix.Capget(&caps, &data[0]); err != nil {
+		logger.Debug("Failed to get capabilities: %v, will try creating test TUN", err)
+	} else {
+		// CAP_NET_ADMIN is capability bit 12
+		const CAP_NET_ADMIN = 12
+		if data[0].Effective&(1<<CAP_NET_ADMIN) != 0 {
+			logger.Debug("Process has CAP_NET_ADMIN capability, sufficient permissions for native TUN interface")
+			return nil
+		}
+		logger.Debug("Process does not have CAP_NET_ADMIN capability in effective set")
+	}
+
+	// Actually try to create a TUN interface to verify permissions
+	// This is the most reliable check as it tests the actual operation
+	return tryCreateTestTun()
+}
+
+// tryCreateTestTun attempts to create a temporary TUN interface to verify
+// we have the necessary permissions. This tests the actual ioctl call that
+// will be used when creating the real interface.
+func tryCreateTestTun() error {
+	f, err := os.OpenFile(tunDevice, os.O_RDWR, 0)
+	if err != nil {
+		return fmt.Errorf("cannot open %s: %v (need root or CAP_NET_ADMIN capability)", tunDevice, err)
+	}
+	defer f.Close()
+
+	// Try to create a TUN interface with a test name
+	// Using a random-ish name to avoid conflicts
+	var req ifReq
+	copy(req.Name[:], "tuntest0")
+	req.Flags = iffTun | iffNoPi
+
+	_, _, errno := unix.Syscall(
+		unix.SYS_IOCTL,
+		f.Fd(),
+		uintptr(tunSetIff),
+		uintptr(unsafe.Pointer(&req)),
+	)
+
+	if errno != 0 {
+		return fmt.Errorf("cannot create TUN interface (ioctl TUNSETIFF failed): %v (need root or CAP_NET_ADMIN capability)", errno)
+	}
+
+	// Success - the interface will be automatically destroyed when we close the fd
+	logger.Debug("Successfully created test TUN interface, sufficient permissions for native TUN interface")
+	return nil
+}

clients/permissions/permissions_windows.go

@@ -0,0 +1,48 @@
+//go:build windows
+
+package permissions
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/svc"
+)
+
+// CheckNativeInterfacePermissions checks if the process has sufficient
+// permissions to create a native TUN interface on Windows.
+// This requires Administrator privileges and must be running as a Windows service.
+func CheckNativeInterfacePermissions() error {
+	// Check if running as a Windows service
+	isService, err := svc.IsWindowsService()
+	if err != nil {
+		return fmt.Errorf("failed to check if running as Windows service: %v", err)
+	}
+	if !isService {
+		return fmt.Errorf("native TUN interface requires running as a Windows service")
+	}
+
+	var sid *windows.SID
+	err = windows.AllocateAndInitializeSid(
+		&windows.SECURITY_NT_AUTHORITY,
+		2,
+		windows.SECURITY_BUILTIN_DOMAIN_RID,
+		windows.DOMAIN_ALIAS_RID_ADMINS,
+		0, 0, 0, 0, 0, 0,
+		&sid)
+	if err != nil {
+		return fmt.Errorf("failed to initialize SID: %v", err)
+	}
+	defer windows.FreeSid(sid)
+
+	token := windows.Token(0)
+	member, err := token.IsMember(sid)
+	if err != nil {
+		return fmt.Errorf("failed to check admin group membership: %v", err)
+	}
+
+	if !member {
+		return fmt.Errorf("insufficient permissions: need Administrator to create TUN interface on Windows")
+	}
+	return nil
+}

common.go

@@ -2,43 +2,32 @@ package main
 
 import (
 	"bytes"
-	"encoding/base64"
-	"encoding/hex"
+	"context"
 	"encoding/json"
 	"fmt"
 	"net"
 	"os"
 	"os/exec"
+	"regexp"
 	"strings"
 	"time"
 
 	"math/rand"
 
+	"github.com/fosrl/newt/internal/telemetry"
 	"github.com/fosrl/newt/logger"
 	"github.com/fosrl/newt/proxy"
 	"github.com/fosrl/newt/websocket"
 	"golang.org/x/net/icmp"
 	"golang.org/x/net/ipv4"
-	"golang.zx2c4.com/wireguard/device"
 	"golang.zx2c4.com/wireguard/tun/netstack"
+	"gopkg.in/yaml.v3"
 )
 
-func fixKey(key string) string {
-	// Remove any whitespace
-	key = strings.TrimSpace(key)
-
-	// Decode from base64
-	decoded, err := base64.StdEncoding.DecodeString(key)
-	if err != nil {
-		logger.Fatal("Error decoding base64: %v", err)
-	}
-
-	// Convert to hex
-	return hex.EncodeToString(decoded)
-}
+const msgHealthFileWriteFailed = "Failed to write health file: %v"
 
 func ping(tnet *netstack.Net, dst string, timeout time.Duration) (time.Duration, error) {
-	logger.Debug("Pinging %s", dst)
+	// logger.Debug("Pinging %s", dst)
 	socket, err := tnet.Dial("ping4", dst)
 	if err != nil {
 		return 0, fmt.Errorf("failed to create ICMP socket: %w", err)
@@ -97,7 +86,7 @@ func ping(tnet *netstack.Net, dst string, timeout time.Duration) (time.Duration,
 
 	latency := time.Since(start)
 
-	logger.Debug("Ping to %s successful, latency: %v", dst, latency)
+	// logger.Debug("Ping to %s successful, latency: %v", dst, latency)
 
 	return latency, nil
 }
@@ -132,19 +121,11 @@ func reliablePing(tnet *netstack.Net, dst string, baseTimeout time.Duration, max
 		totalLatency += latency
 		successCount++
 
-		// If we get at least one success, we can return early for health checks
-		if successCount > 0 {
-			avgLatency := totalLatency / time.Duration(successCount)
-			logger.Debug("Reliable ping succeeded after %d attempts, avg latency: %v", attempt, avgLatency)
-			return avgLatency, nil
-		}
+		// Return on first success
+		return totalLatency / time.Duration(successCount), nil
 	}
 
-	if successCount == 0 {
-		return 0, fmt.Errorf("all %d ping attempts failed, last error: %v", maxAttempts, lastErr)
-	}
-
-	return totalLatency / time.Duration(successCount), nil
+	return 0, fmt.Errorf("all %d ping attempts failed, last error: %v", maxAttempts, lastErr)
 }
 
 func pingWithRetry(tnet *netstack.Net, dst string, timeout time.Duration) (stopChan chan struct{}, err error) {
@@ -175,7 +156,7 @@ func pingWithRetry(tnet *netstack.Net, dst string, timeout time.Duration) (stopC
 		if healthFile != "" {
 			err := os.WriteFile(healthFile, []byte("ok"), 0644)
 			if err != nil {
-				logger.Warn("Failed to write health file: %v", err)
+				logger.Warn(msgHealthFileWriteFailed, err)
 			}
 		}
 		return stopChan, nil
@@ -216,11 +197,14 @@ func pingWithRetry(tnet *netstack.Net, dst string, timeout time.Duration) (stopC
 					if healthFile != "" {
 						err := os.WriteFile(healthFile, []byte("ok"), 0644)
 						if err != nil {
-							logger.Warn("Failed to write health file: %v", err)
+							logger.Warn(msgHealthFileWriteFailed, err)
 						}
 					}
 					return
 				}
+			case <-pingStopChan:
+				// Stop the goroutine when signaled
+				return
 			}
 		}
 	}()
@@ -229,7 +213,26 @@ func pingWithRetry(tnet *netstack.Net, dst string, timeout time.Duration) (stopC
 	return stopChan, fmt.Errorf("initial ping attempts failed, continuing in background")
 }
 
-func startPingCheck(tnet *netstack.Net, serverIP string, client *websocket.Client) chan struct{} {
+// shouldFireRecovery decides whether the data-plane recovery flow in
+// startPingCheck should run on this tick. Recovery fires once when the
+// consecutive-failure counter first crosses the threshold; the connectionLost
+// flag prevents re-firing until a successful ping resets the state.
+//
+// This condition was previously inlined into startPingCheck and AND-ed with
+// `currentInterval < maxInterval`, which silently broke recovery once
+// pingInterval's default was bumped to 15s while maxInterval stayed at 6s
+// (commit 8161fa6, March 2026): the gate became permanently false on default
+// settings, so the recovery code never executed and ping failures climbed
+// forever — the proximate cause of fosrl/newt#284, #310 and pangolin#1004.
+//
+// Recovery and backoff are independent concerns; the backoff ramp is now
+// computed separately in the caller. Do not re-introduce currentInterval
+// here.
+func shouldFireRecovery(consecutiveFailures, failureThreshold int, connectionLost bool) bool {
+	return consecutiveFailures >= failureThreshold && !connectionLost
+}
+
+func startPingCheck(tnet *netstack.Net, serverIP string, client *websocket.Client, tunnelID string) chan struct{} {
 	maxInterval := 6 * time.Second
 	currentInterval := pingInterval
 	consecutiveFailures := 0
@@ -288,36 +291,52 @@ func startPingCheck(tnet *netstack.Net, serverIP string, client *websocket.Clien
 
 					// More lenient threshold for declaring connection lost under load
 					failureThreshold := 4
-					if consecutiveFailures >= failureThreshold && currentInterval < maxInterval {
-						if !connectionLost {
-							connectionLost = true
-							logger.Warn("Connection to server lost after %d failures. Continuous reconnection attempts will be made.", consecutiveFailures)
-							stopFunc = client.SendMessageInterval("newt/ping/request", map[string]interface{}{}, 3*time.Second)
-							// Send registration message to the server for backward compatibility
-							err := client.SendMessage("newt/wg/register", map[string]interface{}{
-								"publicKey":           publicKey.String(),
-								"backwardsCompatible": true,
-							})
+					if shouldFireRecovery(consecutiveFailures, failureThreshold, connectionLost) {
+						connectionLost = true
+						logger.Warn("Connection to server lost after %d failures. Continuous reconnection attempts will be made.", consecutiveFailures)
+						if tunnelID != "" {
+							telemetry.IncReconnect(context.Background(), tunnelID, "client", telemetry.ReasonTimeout)
+						}
+						pingChainId := generateChainId()
+						pendingPingChainId = pingChainId
+						stopFunc = client.SendMessageInterval("newt/ping/request", map[string]interface{}{
+							"chainId": pingChainId,
+						}, 3*time.Second)
+						// Send registration message to the server for backward compatibility
+						bcChainId := generateChainId()
+						pendingRegisterChainId = bcChainId
+						err := client.SendMessage("newt/wg/register", map[string]interface{}{
+							"publicKey":           publicKey.String(),
+							"backwardsCompatible": true,
+							"chainId":             bcChainId,
+						})
+						if err != nil {
+							logger.Error("Failed to send registration message: %v", err)
+						}
+						if healthFile != "" {
+							err = os.Remove(healthFile)
 							if err != nil {
-								logger.Error("Failed to send registration message: %v", err)
-							}
-							if healthFile != "" {
-								err = os.Remove(healthFile)
-								if err != nil {
-									logger.Error("Failed to remove health file: %v", err)
-								}
+								logger.Error("Failed to remove health file: %v", err)
 							}
 						}
-						currentInterval = time.Duration(float64(currentInterval) * 1.3) // Slower increase
+					}
+					// Backoff: ramp the periodic-ping interval up while we are
+					// past the failure threshold, capped at maxInterval. Kept
+					// independent of the recovery trigger above so the trigger
+					// fires on every outage regardless of pingInterval.
+					if consecutiveFailures >= failureThreshold && currentInterval < maxInterval {
+						currentInterval = time.Duration(float64(currentInterval) * 1.3)
 						if currentInterval > maxInterval {
 							currentInterval = maxInterval
 						}
-						ticker.Reset(currentInterval)
-						logger.Debug("Increased ping check interval to %v due to consecutive failures", currentInterval)
 					}
 				} else {
 					// Track recent latencies
 					recentLatencies = append(recentLatencies, latency)
+					// Record tunnel latency (limit sampling to this periodic check)
+					if tunnelID != "" {
+						telemetry.ObserveTunnelLatency(context.Background(), tunnelID, "wireguard", latency.Seconds())
+					}
 					if len(recentLatencies) > 10 {
 						recentLatencies = recentLatencies[1:]
 					}
@@ -352,89 +371,6 @@ func startPingCheck(tnet *netstack.Net, serverIP string, client *websocket.Clien
 	return pingStopChan
 }
 
-func parseLogLevel(level string) logger.LogLevel {
-	switch strings.ToUpper(level) {
-	case "DEBUG":
-		return logger.DEBUG
-	case "INFO":
-		return logger.INFO
-	case "WARN":
-		return logger.WARN
-	case "ERROR":
-		return logger.ERROR
-	case "FATAL":
-		return logger.FATAL
-	default:
-		return logger.INFO // default to INFO if invalid level provided
-	}
-}
-
-func mapToWireGuardLogLevel(level logger.LogLevel) int {
-	switch level {
-	case logger.DEBUG:
-		return device.LogLevelVerbose
-	// case logger.INFO:
-	// return device.LogLevel
-	case logger.WARN:
-		return device.LogLevelError
-	case logger.ERROR, logger.FATAL:
-		return device.LogLevelSilent
-	default:
-		return device.LogLevelSilent
-	}
-}
-
-func resolveDomain(domain string) (string, error) {
-	// Check if there's a port in the domain
-	host, port, err := net.SplitHostPort(domain)
-	if err != nil {
-		// No port found, use the domain as is
-		host = domain
-		port = ""
-	}
-
-	// Remove any protocol prefix if present
-	if strings.HasPrefix(host, "http://") {
-		host = strings.TrimPrefix(host, "http://")
-	} else if strings.HasPrefix(host, "https://") {
-		host = strings.TrimPrefix(host, "https://")
-	}
-
-	// if there are any trailing slashes, remove them
-	host = strings.TrimSuffix(host, "/")
-
-	// Lookup IP addresses
-	ips, err := net.LookupIP(host)
-	if err != nil {
-		return "", fmt.Errorf("DNS lookup failed: %v", err)
-	}
-
-	if len(ips) == 0 {
-		return "", fmt.Errorf("no IP addresses found for domain %s", host)
-	}
-
-	// Get the first IPv4 address if available
-	var ipAddr string
-	for _, ip := range ips {
-		if ipv4 := ip.To4(); ipv4 != nil {
-			ipAddr = ipv4.String()
-			break
-		}
-	}
-
-	// If no IPv4 found, use the first IP (might be IPv6)
-	if ipAddr == "" {
-		ipAddr = ips[0].String()
-	}
-
-	// Add port back if it existed
-	if port != "" {
-		ipAddr = net.JoinHostPort(ipAddr, port)
-	}
-
-	return ipAddr, nil
-}
-
 func parseTargetData(data interface{}) (TargetData, error) {
 	var targetData TargetData
 	jsonData, err := json.Marshal(data)
@@ -450,26 +386,62 @@ func parseTargetData(data interface{}) (TargetData, error) {
 	return targetData, nil
 }
 
+// parseTargetString parses a target string in the format "listenPort:host:targetPort"
+// It properly handles IPv6 addresses which must be in brackets: "listenPort:[ipv6]:targetPort"
+// Examples:
+//   - IPv4: "3001:192.168.1.1:80"
+//   - IPv6: "3001:[::1]:8080" or "3001:[fd70:1452:b736:4dd5:caca:7db9:c588:f5b3]:80"
+//
+// Returns listenPort, targetAddress (in host:port format suitable for net.Dial), and error
+func parseTargetString(target string) (int, string, error) {
+	// Find the first colon to extract the listen port
+	firstColon := strings.Index(target, ":")
+	if firstColon == -1 {
+		return 0, "", fmt.Errorf("invalid target format, no colon found: %s", target)
+	}
+
+	listenPortStr := target[:firstColon]
+	var listenPort int
+	_, err := fmt.Sscanf(listenPortStr, "%d", &listenPort)
+	if err != nil {
+		return 0, "", fmt.Errorf("invalid listen port: %s", listenPortStr)
+	}
+	if listenPort <= 0 || listenPort > 65535 {
+		return 0, "", fmt.Errorf("listen port out of range: %d", listenPort)
+	}
+
+	// The remainder is host:targetPort - use net.SplitHostPort which handles IPv6 brackets
+	remainder := target[firstColon+1:]
+	host, targetPort, err := net.SplitHostPort(remainder)
+	if err != nil {
+		return 0, "", fmt.Errorf("invalid host:port format '%s': %w", remainder, err)
+	}
+
+	// Reject empty host or target port
+	if host == "" {
+		return 0, "", fmt.Errorf("empty host in target: %s", target)
+	}
+	if targetPort == "" {
+		return 0, "", fmt.Errorf("empty target port in target: %s", target)
+	}
+
+	// Reconstruct the target address using JoinHostPort (handles IPv6 properly)
+	targetAddr := net.JoinHostPort(host, targetPort)
+
+	return listenPort, targetAddr, nil
+}
+
 func updateTargets(pm *proxy.ProxyManager, action string, tunnelIP string, proto string, targetData TargetData) error {
 	for _, t := range targetData.Targets {
-		// Split the first number off of the target with : separator and use as the port
-		parts := strings.Split(t, ":")
-		if len(parts) != 3 {
-			logger.Info("Invalid target format: %s", t)
-			continue
-		}
-
-		// Get the port as an int
-		port := 0
-		_, err := fmt.Sscanf(parts[0], "%d", &port)
+		// Parse the target string, handling both IPv4 and IPv6 addresses
+		port, target, err := parseTargetString(t)
 		if err != nil {
-			logger.Info("Invalid port: %s", parts[0])
+			logger.Info("Invalid target format: %s (%v)", t, err)
 			continue
 		}
 
-		if action == "add" {
-			target := parts[1] + ":" + parts[2]
-
+		switch action {
+		case "add":
 			// Call updown script if provided
 			processedTarget := target
 			if updownScript != "" {
@@ -493,11 +465,9 @@ func updateTargets(pm *proxy.ProxyManager, action string, tunnelIP string, proto
 			// Add the new target
 			pm.AddTarget(proto, tunnelIP, port, processedTarget)
 
-		} else if action == "remove" {
+		case "remove":
 			logger.Info("Removing target with port %d", port)
 
-			target := parts[1] + ":" + parts[2]
-
 			// Call updown script if provided
 			if updownScript != "" {
 				_, err := executeUpdownScript(action, proto, target)
@@ -506,11 +476,13 @@ func updateTargets(pm *proxy.ProxyManager, action string, tunnelIP string, proto
 				}
 			}
 
-			err := pm.RemoveTarget(proto, tunnelIP, port)
+			err = pm.RemoveTarget(proto, tunnelIP, port)
 			if err != nil {
 				logger.Error("Failed to remove target: %v", err)
 				return err
 			}
+		default:
+			logger.Info("Unknown action: %s", action)
 		}
 	}
 
@@ -558,3 +530,73 @@ func executeUpdownScript(action, proto, target string) (string, error) {
 
 	return target, nil
 }
+
+// interpolateBlueprint finds all {{...}} tokens in the raw blueprint bytes and
+// replaces recognised schemes with their resolved values. Currently supported:
+//
+//   - env.<VAR>  – replaced with the value of the named environment variable
+//
+// Any token that does not match a supported scheme is left as-is so that
+// future schemes (e.g. tag., api.) are preserved rather than silently dropped.
+func interpolateBlueprint(data []byte) []byte {
+	re := regexp.MustCompile(`\{\{([^}]+)\}\}`)
+	return re.ReplaceAllFunc(data, func(match []byte) []byte {
+		// strip the surrounding {{ }}
+		inner := strings.TrimSpace(string(match[2 : len(match)-2]))
+
+		if strings.HasPrefix(inner, "env.") {
+			varName := strings.TrimPrefix(inner, "env.")
+			return []byte(os.Getenv(varName))
+		}
+
+		// unrecognised scheme – leave the token untouched
+		return match
+	})
+}
+
+func sendBlueprint(client *websocket.Client, file string) error {
+	if file == "" {
+		return nil
+	}
+	// try to read the blueprint file
+	blueprintData, err := os.ReadFile(file)
+	if err != nil {
+		logger.Error("Failed to read blueprint file: %v", err)
+	} else {
+		// interpolate {{env.VAR}} (and any future schemes) before parsing
+		blueprintData = interpolateBlueprint(blueprintData)
+
+		// first we should convert the yaml to json and error if the yaml is bad
+		var yamlObj interface{}
+		var blueprintJsonData string
+
+		err = yaml.Unmarshal(blueprintData, &yamlObj)
+		if err != nil {
+			logger.Error("Failed to parse blueprint YAML: %v", err)
+		} else {
+			// convert to json
+			jsonBytes, err := json.Marshal(yamlObj)
+			if err != nil {
+				logger.Error("Failed to convert blueprint to JSON: %v", err)
+			} else {
+				blueprintJsonData = string(jsonBytes)
+				logger.Debug("Converted blueprint to JSON: %s", blueprintJsonData)
+			}
+		}
+
+		// if we have valid json data, we can send it to the server
+		if blueprintJsonData == "" {
+			logger.Error("No valid blueprint JSON data to send to server")
+			return nil
+		}
+
+		logger.Info("Sending blueprint to server for application")
+
+		// send the blueprint data to the server
+		err = client.SendMessage("newt/blueprint/apply", map[string]interface{}{
+			"blueprint": blueprintJsonData,
+		})
+	}
+
+	return nil
+}

common_test.go

@@ -0,0 +1,251 @@
+package main
+
+import (
+	"net"
+	"testing"
+)
+
+func TestParseTargetString(t *testing.T) {
+	tests := []struct {
+		name           string
+		input          string
+		wantListenPort int
+		wantTargetAddr string
+		wantErr        bool
+	}{
+		// IPv4 test cases
+		{
+			name:           "valid IPv4 basic",
+			input:          "3001:192.168.1.1:80",
+			wantListenPort: 3001,
+			wantTargetAddr: "192.168.1.1:80",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv4 localhost",
+			input:          "8080:127.0.0.1:3000",
+			wantListenPort: 8080,
+			wantTargetAddr: "127.0.0.1:3000",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv4 same ports",
+			input:          "443:10.0.0.1:443",
+			wantListenPort: 443,
+			wantTargetAddr: "10.0.0.1:443",
+			wantErr:        false,
+		},
+
+		// IPv6 test cases
+		{
+			name:           "valid IPv6 loopback",
+			input:          "3001:[::1]:8080",
+			wantListenPort: 3001,
+			wantTargetAddr: "[::1]:8080",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 full address",
+			input:          "80:[fd70:1452:b736:4dd5:caca:7db9:c588:f5b3]:8080",
+			wantListenPort: 80,
+			wantTargetAddr: "[fd70:1452:b736:4dd5:caca:7db9:c588:f5b3]:8080",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 link-local",
+			input:          "443:[fe80::1]:443",
+			wantListenPort: 443,
+			wantTargetAddr: "[fe80::1]:443",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 all zeros compressed",
+			input:          "8000:[::]:9000",
+			wantListenPort: 8000,
+			wantTargetAddr: "[::]:9000",
+			wantErr:        false,
+		},
+		{
+			name:           "valid IPv6 mixed notation",
+			input:          "5000:[::ffff:192.168.1.1]:6000",
+			wantListenPort: 5000,
+			wantTargetAddr: "[::ffff:192.168.1.1]:6000",
+			wantErr:        false,
+		},
+
+		// Hostname test cases
+		{
+			name:           "valid hostname",
+			input:          "8080:example.com:80",
+			wantListenPort: 8080,
+			wantTargetAddr: "example.com:80",
+			wantErr:        false,
+		},
+		{
+			name:           "valid hostname with subdomain",
+			input:          "443:api.example.com:8443",
+			wantListenPort: 443,
+			wantTargetAddr: "api.example.com:8443",
+			wantErr:        false,
+		},
+		{
+			name:           "valid localhost hostname",
+			input:          "3000:localhost:3000",
+			wantListenPort: 3000,
+			wantTargetAddr: "localhost:3000",
+			wantErr:        false,
+		},
+
+		// Error cases
+		{
+			name:    "invalid - no colons",
+			input:   "invalid",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - empty string",
+			input:   "",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - non-numeric listen port",
+			input:   "abc:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - missing target port",
+			input:   "3001:192.168.1.1",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - IPv6 without brackets",
+			input:   "3001:fd70:1452:b736:4dd5:caca:7db9:c588:f5b3:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - only listen port",
+			input:   "3001:",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - missing host",
+			input:   "3001::80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - IPv6 unclosed bracket",
+			input:   "3001:[::1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - listen port zero",
+			input:   "0:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - listen port negative",
+			input:   "-1:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - listen port out of range",
+			input:   "70000:192.168.1.1:80",
+			wantErr: true,
+		},
+		{
+			name:    "invalid - empty target port",
+			input:   "3001:192.168.1.1:",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			listenPort, targetAddr, err := parseTargetString(tt.input)
+
+			if (err != nil) != tt.wantErr {
+				t.Errorf("parseTargetString(%q) error = %v, wantErr %v", tt.input, err, tt.wantErr)
+				return
+			}
+
+			if tt.wantErr {
+				return // Don't check other values if we expected an error
+			}
+
+			if listenPort != tt.wantListenPort {
+				t.Errorf("parseTargetString(%q) listenPort = %d, want %d", tt.input, listenPort, tt.wantListenPort)
+			}
+
+			if targetAddr != tt.wantTargetAddr {
+				t.Errorf("parseTargetString(%q) targetAddr = %q, want %q", tt.input, targetAddr, tt.wantTargetAddr)
+			}
+		})
+	}
+}
+
+// TestParseTargetStringNetDialCompatibility verifies that the output is compatible with net.Dial
+func TestParseTargetStringNetDialCompatibility(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+	}{
+		{"IPv4", "8080:127.0.0.1:80"},
+		{"IPv6 loopback", "8080:[::1]:80"},
+		{"IPv6 full", "8080:[2001:db8::1]:80"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, targetAddr, err := parseTargetString(tt.input)
+			if err != nil {
+				t.Fatalf("parseTargetString(%q) unexpected error: %v", tt.input, err)
+			}
+
+			// Verify the format is valid for net.Dial by checking it can be split back
+			// This doesn't actually dial, just validates the format
+			_, _, err = net.SplitHostPort(targetAddr)
+			if err != nil {
+				t.Errorf("parseTargetString(%q) produced invalid net.Dial format %q: %v", tt.input, targetAddr, err)
+			}
+		})
+	}
+}
+
+// TestShouldFireRecovery is the regression guard for the broken trigger gate
+// that prevented data-plane recovery from ever firing under default settings
+// (fosrl/newt#284, #310, pangolin#1004). The pre-fix condition was
+//
+//	consecutiveFailures >= failureThreshold && currentInterval < maxInterval
+//
+// which became permanently false once pingInterval's default was bumped from
+// 3s to 15s in commit 8161fa6 — currentInterval starts at pingInterval=15s,
+// maxInterval stayed at 6s, so 15<6 is false and the recovery branch never
+// executed.
+//
+// The fix is to drop currentInterval from the trigger condition entirely;
+// backoff is a separate concern computed in the caller. The cases below
+// exercise the documented contract.
+func TestShouldFireRecovery(t *testing.T) {
+	const threshold = 4
+	cases := []struct {
+		name           string
+		failures       int
+		connectionLost bool
+		want           bool
+	}{
+		{"below threshold, fresh", 3, false, false},
+		{"below threshold, already lost", 3, true, false},
+		{"at threshold, fresh — recovery must fire", threshold, false, true},
+		{"at threshold, already lost — gate prevents re-fire", threshold, true, false},
+		{"far above threshold, fresh", 100, false, true},
+		{"far above threshold, already lost", 100, true, false},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			if got := shouldFireRecovery(c.failures, threshold, c.connectionLost); got != c.want {
+				t.Errorf("shouldFireRecovery(failures=%d, threshold=%d, lost=%v) = %v, want %v",
+					c.failures, threshold, c.connectionLost, got, c.want)
+			}
+		})
+	}
+}

device/tun_unix.go

@@ -0,0 +1,44 @@
+//go:build !windows
+
+package device
+
+import (
+	"net"
+	"os"
+
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/sys/unix"
+	"golang.zx2c4.com/wireguard/ipc"
+	"golang.zx2c4.com/wireguard/tun"
+)
+
+func CreateTUNFromFD(tunFd uint32, mtuInt int) (tun.Device, error) {
+	dupTunFd, err := unix.Dup(int(tunFd))
+	if err != nil {
+		logger.Error("Unable to dup tun fd: %v", err)
+		return nil, err
+	}
+
+	err = unix.SetNonblock(dupTunFd, true)
+	if err != nil {
+		unix.Close(dupTunFd)
+		return nil, err
+	}
+
+	file := os.NewFile(uintptr(dupTunFd), "/dev/tun")
+	device, err := tun.CreateTUNFromFile(file, mtuInt)
+	if err != nil {
+		file.Close()
+		return nil, err
+	}
+
+	return device, nil
+}
+
+func UapiOpen(interfaceName string) (*os.File, error) {
+	return ipc.UAPIOpen(interfaceName)
+}
+
+func UapiListen(interfaceName string, fileUAPI *os.File) (net.Listener, error) {
+	return ipc.UAPIListen(interfaceName, fileUAPI)
+}

device/tun_windows.go

@@ -0,0 +1,25 @@
+//go:build windows
+
+package device
+
+import (
+	"errors"
+	"net"
+	"os"
+
+	"golang.zx2c4.com/wireguard/ipc"
+	"golang.zx2c4.com/wireguard/tun"
+)
+
+func CreateTUNFromFD(tunFd uint32, mtuInt int) (tun.Device, error) {
+	return nil, errors.New("CreateTUNFromFile not supported on Windows")
+}
+
+func UapiOpen(interfaceName string) (*os.File, error) {
+	return nil, nil
+}
+
+func UapiListen(interfaceName string, fileUAPI *os.File) (net.Listener, error) {
+	// On Windows, UAPIListen only takes one parameter
+	return ipc.UAPIListen(interfaceName)
+}

docker-compose.metrics.collector.yml

@@ -0,0 +1,41 @@
+services:
+  newt:
+    build: .
+    image: newt:dev
+    env_file:
+      - .env
+    environment:
+      - NEWT_METRICS_PROMETHEUS_ENABLED=false   # important: disable direct /metrics scraping
+      - NEWT_METRICS_OTLP_ENABLED=true          # OTLP to the Collector
+      # optional:
+      # - NEWT_METRICS_INCLUDE_TUNNEL_ID=false
+  # When using the Collector pattern, do NOT map the Newt admin/metrics port
+  # (2112) on the application service. Mapping 2112 here can cause port
+  # conflicts and may result in duplicated Prometheus scraping (app AND
+  # collector being scraped for the same metrics). Instead either:
+  #  - leave ports unset on the app service (recommended), or
+  #  - map 2112 only on a dedicated metrics/collector service that is
+  #    responsible for exposing metrics to Prometheus.
+  # Example: do NOT map here
+  # ports: []
+  # Example: map 2112 only on a collector service
+  # collector:
+  #   ports:
+  #     - "2112:2112"  # collector's prometheus exporter (scraped by Prometheus)
+
+  otel-collector:
+    image: otel/opentelemetry-collector-contrib:latest
+    command: ["--config=/etc/otelcol/config.yaml"]
+    volumes:
+      - ./examples/otel-collector.yaml:/etc/otelcol/config.yaml:ro
+    ports:
+      - "4317:4317"   # OTLP gRPC
+      - "8889:8889"   # Prometheus Exporter (scraped by Prometheus)
+
+  prometheus:
+    image: prom/prometheus:latest
+    volumes:
+      - ./examples/prometheus.with-collector.yml:/etc/prometheus/prometheus.yml:ro
+    ports:
+      - "9090:9090"
+

docker-compose.metrics.yml

@@ -0,0 +1,56 @@
+name: Newt-Metrics
+services:
+  # Recommended Variant A: Direct Prometheus scrape of Newt (/metrics)
+  # Optional: You may add the Collector service and enable OTLP export, but do NOT
+  # scrape both Newt and the Collector for the same process.
+
+  newt:
+    build: .
+    image: newt:dev
+    env_file:
+      - .env
+    environment:
+      OTEL_SERVICE_NAME: newt
+      NEWT_METRICS_PROMETHEUS_ENABLED: "true"
+      NEWT_METRICS_OTLP_ENABLED: "false"   # avoid double-scrape by default
+      NEWT_ADMIN_ADDR: ":2112"
+      # Base NEWT configuration
+      PANGOLIN_ENDPOINT: ${PANGOLIN_ENDPOINT}
+      NEWT_ID: ${NEWT_ID}
+      NEWT_SECRET: ${NEWT_SECRET}
+      LOG_LEVEL: "DEBUG"
+    ports:
+      - "2112:2112"
+
+  # Optional Variant B: Enable the Collector and switch Prometheus scrape to it.
+  # collector:
+  #   image: otel/opentelemetry-collector-contrib:0.136.0
+  #   command: ["--config=/etc/otelcol/config.yaml"]
+  #   volumes:
+  #     - ./examples/otel-collector.yaml:/etc/otelcol/config.yaml:ro
+  #   ports:
+  #     - "4317:4317"   # OTLP gRPC in
+  #     - "8889:8889"   # Prometheus scrape out
+
+  prometheus:
+    image: prom/prometheus:v3.6.0
+    volumes:
+      - ./examples/prometheus.yml:/etc/prometheus/prometheus.yml:ro
+    ports:
+      - "9090:9090"
+
+  grafana:
+    image: grafana/grafana:12.2.0
+    container_name: newt-metrics-grafana
+    restart: unless-stopped
+    environment:
+      - GF_SECURITY_ADMIN_USER=admin
+      - GF_SECURITY_ADMIN_PASSWORD=admin
+    ports:
+      - "3005:3000"
+    depends_on:
+      - prometheus
+    volumes:
+      - ./examples/grafana/provisioning/datasources:/etc/grafana/provisioning/datasources:ro
+      - ./examples/grafana/provisioning/dashboards:/etc/grafana/provisioning/dashboards:ro
+      - ./examples/grafana/dashboards:/var/lib/grafana/dashboards:ro

docker-compose.yml

@@ -4,7 +4,7 @@ services:
     container_name: newt
     restart: unless-stopped
     environment:
-      - PANGOLIN_ENDPOINT=https://example.com
+      - PANGOLIN_ENDPOINT=https://app.pangolin.net
       - NEWT_ID=2ix2t8xk22ubpfy 
       - NEWT_SECRET=nnisrfsdfc7prqsp9ewo1dvtvci50j5uiqotez00dgap0ii2 
       - LOG_LEVEL=DEBUG

docker/docker.go

@@ -9,9 +9,9 @@ import (
 	"strings"
 	"time"
 
-	"github.com/docker/docker/api/types/container"
-	"github.com/docker/docker/api/types/filters"
-	"github.com/docker/docker/client"
+	"github.com/moby/moby/api/types/container"
+	"github.com/moby/moby/api/types/events"
+	"github.com/moby/moby/client"
 	"github.com/fosrl/newt/logger"
 )
 
@@ -53,22 +53,65 @@ type Network struct {
 	DNSNames            []string `json:"dnsNames,omitempty"`
 }
 
+// Strcuture parts of docker api endpoint
+type dockerHost struct {
+	protocol string // e.g. unix, http, tcp, ssh
+	address  string // e.g. "/var/run/docker.sock" or "host:port"
+}
+
+// Parse the docker api endpoint into its parts
+func parseDockerHost(raw string) (dockerHost, error) {
+	switch {
+	case strings.HasPrefix(raw, "unix://"):
+		return dockerHost{"unix", strings.TrimPrefix(raw, "unix://")}, nil
+	case strings.HasPrefix(raw, "ssh://"):
+		// SSH is treated as TCP-like transport by the docker client
+		return dockerHost{"ssh", strings.TrimPrefix(raw, "ssh://")}, nil
+	case strings.HasPrefix(raw, "tcp://"), strings.HasPrefix(raw, "http://"), strings.HasPrefix(raw, "https://"):
+		s := raw
+		s = strings.TrimPrefix(s, "tcp://")
+		s = strings.TrimPrefix(s, "http://")
+		s = strings.TrimPrefix(s, "https://")
+		return dockerHost{"tcp", s}, nil
+	case strings.HasPrefix(raw, "/"):
+		// Absolute path without scheme - treat as unix socket
+		return dockerHost{"unix", raw}, nil
+	default:
+		// For relative paths or other formats, also default to unix
+		return dockerHost{"unix", raw}, nil
+	}
+}
+
 // CheckSocket checks if Docker socket is available
 func CheckSocket(socketPath string) bool {
 	// Use the provided socket path or default to standard location
 	if socketPath == "" {
-		socketPath = "/var/run/docker.sock"
+		socketPath = "unix:///var/run/docker.sock"
 	}
 
-	// Try to create a connection to the Docker socket
-	conn, err := net.Dial("unix", socketPath)
+	// Ensure the socket path is properly formatted
+	if !strings.Contains(socketPath, "://") {
+		// If no scheme provided, assume unix socket
+		socketPath = "unix://" + socketPath
+	}
+
+	host, err := parseDockerHost(socketPath)
 	if err != nil {
-		logger.Debug("Docker socket not available at %s: %v", socketPath, err)
+		logger.Debug("Invalid Docker socket path '%s': %v", socketPath, err)
+		return false
+	}
+	protocol := host.protocol
+	addr := host.address
+
+	// ssh might need different verification, but tcp works for basic reachability
+	conn, err := net.DialTimeout(protocol, addr, 2*time.Second)
+	if err != nil {
+		logger.Debug("Docker not reachable via %s at %s: %v", protocol, addr, err)
 		return false
 	}
 	defer conn.Close()
 
-	logger.Debug("Docker socket is available at %s", socketPath)
+	logger.Debug("Docker reachable via %s at %s", protocol, addr)
 	return true
 }
 
@@ -116,11 +159,17 @@ func IsWithinHostNetwork(socketPath string, targetAddress string, targetPort int
 func ListContainers(socketPath string, enforceNetworkValidation bool) ([]Container, error) {
 	// Use the provided socket path or default to standard location
 	if socketPath == "" {
-		socketPath = "/var/run/docker.sock"
+		socketPath = "unix:///var/run/docker.sock"
+	}
+
+	// Ensure the socket path is properly formatted for the Docker client
+	if !strings.Contains(socketPath, "://") {
+		// If no scheme provided, assume unix socket
+		socketPath = "unix://" + socketPath
 	}
 
 	// Used to filter down containers returned to Pangolin
-	containerFilters := filters.NewArgs()
+	containerFilters := make(client.Filters)
 
 	// Used to determine if we will send IP addresses or hostnames to Pangolin
 	useContainerIpAddresses := true
@@ -132,7 +181,7 @@ func ListContainers(socketPath string, enforceNetworkValidation bool) ([]Contain
 
 	// Create client with custom socket path
 	cli, err := client.NewClientWithOpts(
-		client.WithHost("unix://"+socketPath),
+		client.WithHost(socketPath),
 		client.WithAPIVersionNegotiation(),
 	)
 	if err != nil {
@@ -165,24 +214,30 @@ func ListContainers(socketPath string, enforceNetworkValidation bool) ([]Contain
 	}
 
 	// List containers
-	containers, err := cli.ContainerList(ctx, container.ListOptions{All: true, Filters: containerFilters})
+	containerListResult, err := cli.ContainerList(ctx, client.ContainerListOptions{All: true, Filters: containerFilters})
 	if err != nil {
 		return nil, fmt.Errorf("failed to list containers: %v", err)
 	}
 
+	addrToString := func(addr interface{ IsValid() bool; String() string }) string {
+		if addr.IsValid() {
+			return addr.String()
+		}
+		return ""
+	}
+
 	var dockerContainers []Container
-	for _, c := range containers {
+	for _, c := range containerListResult.Items {
 		// Short ID like docker ps
 		shortId := c.ID[:12]
 
 		// Inspect container to get hostname
 		hostname := ""
-		containerInfo, err := cli.ContainerInspect(ctx, c.ID)
-		if err == nil && containerInfo.Config != nil {
-			hostname = containerInfo.Config.Hostname
+		containerInfo, err := cli.ContainerInspect(ctx, c.ID, client.ContainerInspectOptions{})
+		if err == nil && containerInfo.Container.Config != nil {
+			hostname = containerInfo.Container.Config.Hostname
 		}
 
-
 		// Skip host container if set
 		if hostContainerId != "" && c.ID == hostContainerId {
 			continue
@@ -204,8 +259,8 @@ func ListContainers(socketPath string, enforceNetworkValidation bool) ([]Contain
 			if port.PublicPort != 0 {
 				dockerPort.PublicPort = int(port.PublicPort)
 			}
-			if port.IP != "" {
-				dockerPort.IP = port.IP
+			if port.IP.IsValid() {
+				dockerPort.IP = port.IP.String()
 			}
 			ports = append(ports, dockerPort)
 		}
@@ -219,19 +274,19 @@ func ListContainers(socketPath string, enforceNetworkValidation bool) ([]Contain
 				dockerNetwork := Network{
 					NetworkID:           endpoint.NetworkID,
 					EndpointID:          endpoint.EndpointID,
-					Gateway:             endpoint.Gateway,
+					Gateway:             addrToString(endpoint.Gateway),
 					IPPrefixLen:         endpoint.IPPrefixLen,
-					IPv6Gateway:         endpoint.IPv6Gateway,
-					GlobalIPv6Address:   endpoint.GlobalIPv6Address,
+					IPv6Gateway:         addrToString(endpoint.IPv6Gateway),
+					GlobalIPv6Address:   addrToString(endpoint.GlobalIPv6Address),
 					GlobalIPv6PrefixLen: endpoint.GlobalIPv6PrefixLen,
-					MacAddress:          endpoint.MacAddress,
+					MacAddress:          endpoint.MacAddress.String(),
 					Aliases:             endpoint.Aliases,
 					DNSNames:            endpoint.DNSNames,
 				}
 
 				// Use IPs over hostnames/containers as we're on the bridge network
 				if useContainerIpAddresses {
-					dockerNetwork.IPAddress = endpoint.IPAddress
+					dockerNetwork.IPAddress = addrToString(endpoint.IPAddress)
 				}
 
 				networks[networkName] = dockerNetwork
@@ -242,7 +297,7 @@ func ListContainers(socketPath string, enforceNetworkValidation bool) ([]Contain
 			ID:       shortId,
 			Name:     name,
 			Image:    c.Image,
-			State:    c.State,
+			State:    string(c.State),
 			Status:   c.Status,
 			Ports:    ports,
 			Labels:   c.Labels,
@@ -266,10 +321,137 @@ func getHostContainer(dockerContext context.Context, dockerClient *client.Client
 	}
 
 	// Get host container from the docker socket
-	hostContainer, err := dockerClient.ContainerInspect(dockerContext, hostContainerName)
+	hostContainer, err := dockerClient.ContainerInspect(dockerContext, hostContainerName, client.ContainerInspectOptions{})
 	if err != nil {
 		return nil, fmt.Errorf("failed to find host container")
 	}
 
-	return &hostContainer, nil
+	return &hostContainer.Container, nil
+}
+
+// EventCallback defines the function signature for handling Docker events
+type EventCallback func(containers []Container)
+
+// EventMonitor handles Docker event monitoring
+type EventMonitor struct {
+	client                   *client.Client
+	ctx                      context.Context
+	cancel                   context.CancelFunc
+	callback                 EventCallback
+	socketPath               string
+	enforceNetworkValidation bool
+}
+
+// NewEventMonitor creates a new Docker event monitor
+func NewEventMonitor(socketPath string, enforceNetworkValidation bool, callback EventCallback) (*EventMonitor, error) {
+	if socketPath == "" {
+		socketPath = "unix:///var/run/docker.sock"
+	}
+
+	if !strings.Contains(socketPath, "://") {
+		socketPath = "unix://" + socketPath
+	}
+
+	cli, err := client.NewClientWithOpts(
+		client.WithHost(socketPath),
+		client.WithAPIVersionNegotiation(),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create Docker client: %v", err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	return &EventMonitor{
+		client:                   cli,
+		ctx:                      ctx,
+		cancel:                   cancel,
+		callback:                 callback,
+		socketPath:               socketPath,
+		enforceNetworkValidation: enforceNetworkValidation,
+	}, nil
+}
+
+// Start begins monitoring Docker events
+func (em *EventMonitor) Start() error {
+	logger.Debug("Starting Docker event monitoring")
+
+	// Filter for container events we care about
+	eventFilters := make(client.Filters)
+	eventFilters.Add("type", "container")
+	// eventFilters.Add("event", "create")
+	eventFilters.Add("event", "start")
+	eventFilters.Add("event", "stop")
+	// eventFilters.Add("event", "destroy")
+	// eventFilters.Add("event", "die")
+	// eventFilters.Add("event", "pause")
+	// eventFilters.Add("event", "unpause")
+
+	// Start listening for events
+	eventsResult := em.client.Events(em.ctx, client.EventsListOptions{
+		Filters: eventFilters,
+	})
+	eventCh, errCh := eventsResult.Messages, eventsResult.Err
+
+	go func() {
+		defer func() {
+			if err := em.client.Close(); err != nil {
+				logger.Error("Error closing Docker client: %v", err)
+			}
+		}()
+
+		for {
+			select {
+			case event := <-eventCh:
+				logger.Debug("Docker event received: %s %s for container %s", event.Action, event.Type, event.Actor.ID[:12])
+
+				// Fetch updated container list and trigger callback
+				go em.handleEvent(event)
+
+			case err := <-errCh:
+				if err != nil && err != context.Canceled {
+					logger.Error("Docker event stream error: %v", err)
+					// Try to reconnect after a brief delay
+					time.Sleep(5 * time.Second)
+					if em.ctx.Err() == nil {
+						logger.Info("Attempting to reconnect to Docker event stream")
+						eventsResult = em.client.Events(em.ctx, client.EventsListOptions{
+							Filters: eventFilters,
+						})
+						eventCh, errCh = eventsResult.Messages, eventsResult.Err
+					}
+				}
+				return
+
+			case <-em.ctx.Done():
+				logger.Info("Docker event monitoring stopped")
+				return
+			}
+		}
+	}()
+
+	return nil
+}
+
+// handleEvent processes a Docker event and triggers the callback with updated container list
+func (em *EventMonitor) handleEvent(event events.Message) {
+	// Add a small delay to ensure Docker has fully processed the event
+	time.Sleep(100 * time.Millisecond)
+
+	containers, err := ListContainers(em.socketPath, em.enforceNetworkValidation)
+	if err != nil {
+		logger.Error("Failed to list containers after Docker event %s: %v", event.Action, err)
+		return
+	}
+
+	logger.Debug("Triggering callback with %d containers after Docker event %s", len(containers), event.Action)
+	em.callback(containers)
+}
+
+// Stop stops the event monitoring
+func (em *EventMonitor) Stop() {
+	logger.Info("Stopping Docker event monitoring")
+	if em.cancel != nil {
+		em.cancel()
+	}
 }

examples/README.md

@@ -0,0 +1,167 @@
+# Extensible Logger
+
+This logger package provides a flexible logging system that can be extended with custom log writers.
+
+## Basic Usage (Current Behavior)
+
+The logger works exactly as before with no changes required:
+
+```go
+package main
+
+import "your-project/logger"
+
+func main() {
+    // Use default logger
+    logger.Info("This works as before")
+    logger.Debug("Debug message")
+    logger.Error("Error message")
+    
+    // Or create a custom instance
+    log := logger.NewLogger()
+    log.SetLevel(logger.INFO)
+    log.Info("Custom logger instance")
+}
+```
+
+## Custom Log Writers
+
+To use a custom log backend, implement the `LogWriter` interface:
+
+```go
+type LogWriter interface {
+    Write(level LogLevel, timestamp time.Time, message string)
+}
+```
+
+### Example: OS Log Writer (macOS/iOS)
+
+```go
+package main
+
+import "your-project/logger"
+
+func main() {
+    // Create an OS log writer
+    osWriter := logger.NewOSLogWriter(
+        "net.pangolin.Pangolin.PacketTunnel",
+        "PangolinGo",
+        "MyApp",
+    )
+    
+    // Create a logger with the OS log writer
+    log := logger.NewLoggerWithWriter(osWriter)
+    log.SetLevel(logger.DEBUG)
+    
+    // Use it just like the standard logger
+    log.Info("This message goes to os_log")
+    log.Error("Error logged to os_log")
+}
+```
+
+### Example: Custom Writer
+
+```go
+package main
+
+import (
+    "fmt"
+    "time"
+    "your-project/logger"
+)
+
+// CustomWriter writes logs to a custom destination
+type CustomWriter struct {
+    // your custom fields
+}
+
+func (w *CustomWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+    // Your custom logging logic
+    fmt.Printf("[CUSTOM] %s [%s] %s\n", timestamp.Format(time.RFC3339), level.String(), message)
+}
+
+func main() {
+    customWriter := &CustomWriter{}
+    log := logger.NewLoggerWithWriter(customWriter)
+    log.Info("Custom logging!")
+}
+```
+
+### Example: Multi-Writer (Log to Multiple Destinations)
+
+```go
+package main
+
+import (
+    "time"
+    "your-project/logger"
+)
+
+// MultiWriter writes to multiple log writers
+type MultiWriter struct {
+    writers []logger.LogWriter
+}
+
+func NewMultiWriter(writers ...logger.LogWriter) *MultiWriter {
+    return &MultiWriter{writers: writers}
+}
+
+func (w *MultiWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+    for _, writer := range w.writers {
+        writer.Write(level, timestamp, message)
+    }
+}
+
+func main() {
+    // Log to both standard output and OS log
+    standardWriter := logger.NewStandardWriter()
+    osWriter := logger.NewOSLogWriter("com.example.app", "Main", "App")
+    
+    multiWriter := NewMultiWriter(standardWriter, osWriter)
+    log := logger.NewLoggerWithWriter(multiWriter)
+    
+    log.Info("This goes to both stdout and os_log!")
+}
+```
+
+## API Reference
+
+### Creating Loggers
+
+- `NewLogger()` - Creates a logger with the default StandardWriter
+- `NewLoggerWithWriter(writer LogWriter)` - Creates a logger with a custom writer
+
+### Built-in Writers
+
+- `NewStandardWriter()` - Standard writer that outputs to stdout (default)
+- `NewOSLogWriter(subsystem, category, prefix string)` - OS log writer for macOS/iOS (example)
+
+### Logger Methods
+
+- `SetLevel(level LogLevel)` - Set minimum log level
+- `SetOutput(output *os.File)` - Set output file (StandardWriter only)
+- `Debug(format string, args ...interface{})` - Log debug message
+- `Info(format string, args ...interface{})` - Log info message
+- `Warn(format string, args ...interface{})` - Log warning message
+- `Error(format string, args ...interface{})` - Log error message
+- `Fatal(format string, args ...interface{})` - Log fatal message and exit
+
+### Global Functions
+
+For convenience, you can use global functions that use the default logger:
+
+- `logger.Debug(format, args...)`
+- `logger.Info(format, args...)`
+- `logger.Warn(format, args...)`
+- `logger.Error(format, args...)`
+- `logger.Fatal(format, args...)`
+- `logger.SetOutput(output *os.File)`
+
+## Migration Guide
+
+No changes needed! The logger maintains 100% backward compatibility. Your existing code will continue to work without modifications.
+
+If you want to switch to a custom writer:
+1. Create your writer implementing `LogWriter`
+2. Use `NewLoggerWithWriter()` instead of `NewLogger()`
+3. That's it!

examples/grafana/dashboards/newt-overview.json

@@ -0,0 +1,898 @@
+{
+  "annotations": {
+    "list": [
+      {
+        "builtIn": 1,
+        "datasource": {
+          "type": "grafana",
+          "uid": "-- Grafana --"
+        },
+        "enable": true,
+        "hide": true,
+        "iconColor": "rgba(0, 211, 255, 1)",
+        "name": "Annotations & Alerts",
+        "type": "dashboard"
+      }
+    ]
+  },
+  "editable": true,
+  "fiscalYearStartMonth": 0,
+  "graphTooltip": 0,
+  "id": null,
+  "links": [],
+  "liveNow": false,
+  "panels": [
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "decimals": 0,
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "red",
+                "value": 500
+              }
+            ]
+          }
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 7,
+        "w": 6,
+        "x": 0,
+        "y": 0
+      },
+      "id": 1,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "horizontal",
+        "reduceOptions": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "value_and_name"
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "go_goroutine_count",
+          "instant": true,
+          "legendFormat": "",
+          "refId": "A"
+        }
+      ],
+      "title": "Goroutines",
+      "transformations": [],
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "decimals": 1,
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "orange",
+                "value": 256
+              },
+              {
+                "color": "red",
+                "value": 512
+              }
+            ]
+          },
+          "unit": "bytes"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 7,
+        "w": 6,
+        "x": 6,
+        "y": 0
+      },
+      "id": 2,
+      "options": {
+        "colorMode": "background",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "horizontal",
+        "reduceOptions": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "value_and_name"
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "go_memory_gc_goal_bytes / 1024 / 1024",
+          "format": "time_series",
+          "instant": true,
+          "legendFormat": "",
+          "refId": "A"
+        }
+      ],
+      "title": "GC Target Heap (MiB)",
+      "transformations": [],
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "decimals": 2,
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "orange",
+                "value": 10
+              },
+              {
+                "color": "red",
+                "value": 25
+              }
+            ]
+          },
+          "unit": "ops"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 7,
+        "w": 6,
+        "x": 12,
+        "y": 0
+      },
+      "id": 3,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "horizontal",
+        "reduceOptions": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "value_and_name"
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(http_server_request_duration_seconds_count[$__rate_interval]))",
+          "instant": false,
+          "legendFormat": "req/s",
+          "refId": "A"
+        }
+      ],
+      "title": "HTTP Requests / s",
+      "transformations": [],
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "color": {
+            "mode": "thresholds"
+          },
+          "decimals": 3,
+          "mappings": [],
+          "thresholds": {
+            "mode": "absolute",
+            "steps": [
+              {
+                "color": "green",
+                "value": null
+              },
+              {
+                "color": "orange",
+                "value": 0.1
+              },
+              {
+                "color": "red",
+                "value": 0.5
+              }
+            ]
+          },
+          "unit": "ops"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 7,
+        "w": 6,
+        "x": 18,
+        "y": 0
+      },
+      "id": 4,
+      "options": {
+        "colorMode": "value",
+        "graphMode": "area",
+        "justifyMode": "auto",
+        "orientation": "horizontal",
+        "reduceOptions": {
+          "calcs": [
+            "lastNotNull"
+          ],
+          "fields": "",
+          "values": false
+        },
+        "textMode": "value_and_name"
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(newt_connection_errors_total{site_id=~\"$site_id\"}[$__rate_interval]))",
+          "instant": false,
+          "legendFormat": "errors/s",
+          "refId": "A"
+        }
+      ],
+      "title": "Connection Errors / s",
+      "transformations": [],
+      "type": "stat"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "mappings": [],
+          "unit": "bytes"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 0,
+        "y": 7
+      },
+      "id": 5,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(go_memory_used_bytes)",
+          "legendFormat": "Used",
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "go_memory_gc_goal_bytes",
+          "legendFormat": "GC Goal",
+          "refId": "B"
+        }
+      ],
+      "title": "Go Heap Usage vs GC Goal",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "decimals": 0,
+          "mappings": [],
+          "unit": "short"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 12,
+        "y": 7
+      },
+      "id": 6,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "rate(go_memory_allocations_total[$__rate_interval])",
+          "legendFormat": "Allocations/s",
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "rate(go_memory_allocated_bytes_total[$__rate_interval])",
+          "legendFormat": "Allocated bytes/s",
+          "refId": "B"
+        }
+      ],
+      "title": "Allocation Activity",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "mappings": [],
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 0,
+        "y": 16
+      },
+      "id": 7,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.5, sum(rate(http_server_request_duration_seconds_bucket[$__rate_interval])) by (le))",
+          "legendFormat": "p50",
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.95, sum(rate(http_server_request_duration_seconds_bucket[$__rate_interval])) by (le))",
+          "legendFormat": "p95",
+          "refId": "B"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.99, sum(rate(http_server_request_duration_seconds_bucket[$__rate_interval])) by (le))",
+          "legendFormat": "p99",
+          "refId": "C"
+        }
+      ],
+      "title": "HTTP Request Duration Quantiles",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "mappings": [],
+          "unit": "ops"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 12,
+        "y": 16
+      },
+      "id": 8,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(http_server_request_duration_seconds_count[$__rate_interval])) by (http_response_status_code)",
+          "legendFormat": "{{http_response_status_code}}",
+          "refId": "A"
+        }
+      ],
+      "title": "HTTP Requests by Status",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "mappings": [],
+          "unit": "ops"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 0,
+        "y": 25
+      },
+      "id": 9,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(newt_connection_attempts_total{site_id=~\"$site_id\"}[$__rate_interval])) by (transport, result)",
+          "legendFormat": "{{transport}} • {{result}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Connection Attempts by Transport/Result",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "mappings": [],
+          "unit": "ops"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 12,
+        "y": 25
+      },
+      "id": 10,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(newt_connection_errors_total{site_id=~\"$site_id\"}[$__rate_interval])) by (transport, error_type)",
+          "legendFormat": "{{transport}} • {{error_type}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Connection Errors by Type",
+      "type": "timeseries"
+    },
+    {
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "decimals": 3,
+          "mappings": [],
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 0,
+        "y": 34
+      },
+      "id": 11,
+      "options": {
+        "legend": {
+          "calcs": [],
+          "displayMode": "table",
+          "placement": "right"
+        },
+        "tooltip": {
+          "mode": "multi",
+          "sort": "desc"
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.5, sum(rate(newt_tunnel_latency_seconds_bucket{site_id=~\"$site_id\", tunnel_id=~\"$tunnel_id\"}[$__rate_interval])) by (le))",
+          "legendFormat": "p50",
+          "refId": "A"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.95, sum(rate(newt_tunnel_latency_seconds_bucket{site_id=~\"$site_id\", tunnel_id=~\"$tunnel_id\"}[$__rate_interval])) by (le))",
+          "legendFormat": "p95",
+          "refId": "B"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "histogram_quantile(0.99, sum(rate(newt_tunnel_latency_seconds_bucket{site_id=~\"$site_id\", tunnel_id=~\"$tunnel_id\"}[$__rate_interval])) by (le))",
+          "legendFormat": "p99",
+          "refId": "C"
+        }
+      ],
+      "title": "Tunnel Latency Quantiles",
+      "type": "timeseries"
+    },
+    {
+      "cards": {},
+      "color": {
+        "cardColor": "#b4ff00",
+        "colorScale": "sqrt",
+        "colorScheme": "interpolateTurbo"
+      },
+      "dataFormat": "tsbuckets",
+      "datasource": {
+        "type": "prometheus",
+        "uid": "prometheus"
+      },
+      "fieldConfig": {
+        "defaults": {
+          "custom": {},
+          "mappings": [],
+          "unit": "s"
+        },
+        "overrides": []
+      },
+      "gridPos": {
+        "h": 9,
+        "w": 12,
+        "x": 12,
+        "y": 34
+      },
+      "heatmap": {},
+      "hideZeroBuckets": true,
+      "id": 12,
+      "legend": {
+        "show": false
+      },
+      "options": {
+        "calculate": true,
+        "cellGap": 2,
+        "cellSize": "auto",
+        "color": {
+          "exponent": 0.5
+        },
+        "exemplars": {
+          "color": "rgba(255,255,255,0.7)"
+        },
+        "filterValues": {
+          "le": 1e-9
+        },
+        "legend": {
+          "show": false
+        },
+        "tooltip": {
+          "mode": "single",
+          "show": true
+        },
+        "xAxis": {
+          "show": true
+        },
+        "yAxis": {
+          "decimals": 3,
+          "show": true
+        }
+      },
+      "pluginVersion": "11.1.0",
+      "targets": [
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "editorMode": "code",
+          "expr": "sum(rate(newt_tunnel_latency_seconds_bucket{site_id=~\"$site_id\", tunnel_id=~\"$tunnel_id\"}[$__rate_interval])) by (le)",
+          "format": "heatmap",
+          "legendFormat": "{{le}}",
+          "refId": "A"
+        }
+      ],
+      "title": "Tunnel Latency Bucket Rate",
+      "type": "heatmap"
+    }
+  ],
+  "refresh": "30s",
+  "schemaVersion": 39,
+  "style": "dark",
+  "tags": [
+    "newt",
+    "otel"
+  ],
+  "templating": {
+    "list": [
+      {
+        "current": {
+          "selected": false,
+          "text": "Prometheus",
+          "value": "prometheus"
+        },
+        "hide": 0,
+        "label": "Datasource",
+        "name": "DS_PROMETHEUS",
+        "options": [],
+        "query": "prometheus",
+        "refresh": 1,
+        "type": "datasource"
+      },
+      {
+        "current": {
+          "selected": false,
+          "text": "All",
+          "value": "$__all"
+        },
+        "datasource": {
+          "type": "prometheus",
+          "uid": "prometheus"
+        },
+        "definition": "label_values(target_info, site_id)",
+        "hide": 0,
+        "includeAll": true,
+        "label": "Site",
+        "multi": true,
+        "name": "site_id",
+        "options": [],
+        "query": {
+          "query": "label_values(target_info, site_id)",
+          "refId": "SiteIdVar"
+        },
+        "refresh": 2,
+        "regex": "",
+        "skipUrlSync": false,
+        "sort": 1,
+        "tagValuesQuery": "",
+        "tags": [],
+      "tagsQuery": "",
+        "type": "query",
+        "useTags": false
+      },
+      {
+        "current": {
+          "selected": false,
+          "text": "All",
+          "value": "$__all"
+        },
+        "datasource": {
+          "type": "prometheus",
+          "uid": "prometheus"
+        },
+        "definition": "label_values(newt_tunnel_latency_seconds_bucket{site_id=~\"$site_id\"}, tunnel_id)",
+        "hide": 0,
+        "includeAll": true,
+        "label": "Tunnel",
+        "multi": true,
+        "name": "tunnel_id",
+        "options": [],
+        "query": {
+          "query": "label_values(newt_tunnel_latency_seconds_bucket{site_id=~\"$site_id\"}, tunnel_id)",
+          "refId": "TunnelVar"
+        },
+        "refresh": 2,
+        "regex": "",
+        "skipUrlSync": false,
+        "sort": 1,
+        "tagValuesQuery": "",
+        "tags": [],
+        "tagsQuery": "",
+        "type": "query",
+        "useTags": false
+      }
+    ]
+  },
+  "time": {
+    "from": "now-6h",
+    "to": "now"
+  },
+  "timepicker": {
+    "refresh_intervals": [
+      "10s",
+      "30s",
+      "1m",
+      "5m",
+      "15m",
+      "30m",
+      "1h",
+      "2h",
+      "1d"
+    ],
+    "time_options": [
+      "5m",
+      "15m",
+      "1h",
+      "6h",
+      "12h",
+      "24h",
+      "2d",
+      "7d",
+      "30d"
+    ]
+  },
+  "timezone": "browser",
+  "title": "Newt Overview",
+  "uid": "newt-overview",
+  "version": 1,
+  "weekStart": ""
+}

examples/grafana/provisioning/dashboards/dashboard.yaml

@@ -0,0 +1,9 @@
+apiVersion: 1
+providers:
+  - name: "newt"
+    folder: "Newt"
+    type: file
+    disableDeletion: false
+    allowUiUpdates: true
+    options:
+      path: /var/lib/grafana/dashboards

examples/grafana/provisioning/datasources/prometheus.yaml

@@ -0,0 +1,9 @@
+apiVersion: 1
+datasources:
+  - name: Prometheus
+    type: prometheus
+    access: proxy
+    url: http://prometheus:9090
+    uid: prometheus
+    isDefault: true
+    editable: true

examples/logger_examples.go

@@ -0,0 +1,161 @@
+// Example usage patterns for the extensible logger
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+)
+
+// Example 1: Using the default logger (works exactly as before)
+func exampleDefaultLogger() {
+	logger.Info("Starting application")
+	logger.Debug("Debug information")
+	logger.Warn("Warning message")
+	logger.Error("Error occurred")
+}
+
+// Example 2: Using a custom logger instance with standard writer
+func exampleCustomInstance() {
+	log := logger.NewLogger()
+	log.SetLevel(logger.INFO)
+	log.Info("This is from a custom instance")
+}
+
+// Example 3: Custom writer that adds JSON formatting
+type JSONWriter struct{}
+
+func (w *JSONWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	fmt.Printf("{\"time\":\"%s\",\"level\":\"%s\",\"message\":\"%s\"}\n",
+		timestamp.Format(time.RFC3339),
+		level.String(),
+		message)
+}
+
+func exampleJSONLogger() {
+	jsonWriter := &JSONWriter{}
+	log := logger.NewLoggerWithWriter(jsonWriter)
+	log.Info("This will be logged as JSON")
+}
+
+// Example 4: File writer
+type FileWriter struct {
+	file *os.File
+}
+
+func NewFileWriter(filename string) (*FileWriter, error) {
+	file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
+	if err != nil {
+		return nil, err
+	}
+	return &FileWriter{file: file}, nil
+}
+
+func (w *FileWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	fmt.Fprintf(w.file, "[%s] %s: %s\n",
+		timestamp.Format("2006-01-02 15:04:05"),
+		level.String(),
+		message)
+}
+
+func (w *FileWriter) Close() error {
+	return w.file.Close()
+}
+
+func exampleFileLogger() {
+	fileWriter, err := NewFileWriter("/tmp/app.log")
+	if err != nil {
+		panic(err)
+	}
+	defer fileWriter.Close()
+
+	log := logger.NewLoggerWithWriter(fileWriter)
+	log.Info("This goes to a file")
+}
+
+// Example 5: Multi-writer to log to multiple destinations
+type MultiWriter struct {
+	writers []logger.LogWriter
+}
+
+func NewMultiWriter(writers ...logger.LogWriter) *MultiWriter {
+	return &MultiWriter{writers: writers}
+}
+
+func (w *MultiWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	for _, writer := range w.writers {
+		writer.Write(level, timestamp, message)
+	}
+}
+
+func exampleMultiWriter() {
+	// Log to both stdout and a file
+	standardWriter := logger.NewStandardWriter()
+	fileWriter, _ := NewFileWriter("/tmp/app.log")
+
+	multiWriter := NewMultiWriter(standardWriter, fileWriter)
+	log := logger.NewLoggerWithWriter(multiWriter)
+
+	log.Info("This goes to both stdout and file!")
+}
+
+// Example 6: Conditional writer (only log errors to a specific destination)
+type ErrorOnlyWriter struct {
+	writer logger.LogWriter
+}
+
+func NewErrorOnlyWriter(writer logger.LogWriter) *ErrorOnlyWriter {
+	return &ErrorOnlyWriter{writer: writer}
+}
+
+func (w *ErrorOnlyWriter) Write(level logger.LogLevel, timestamp time.Time, message string) {
+	if level >= logger.ERROR {
+		w.writer.Write(level, timestamp, message)
+	}
+}
+
+func exampleConditionalWriter() {
+	errorWriter, _ := NewFileWriter("/tmp/errors.log")
+	errorOnlyWriter := NewErrorOnlyWriter(errorWriter)
+
+	log := logger.NewLoggerWithWriter(errorOnlyWriter)
+	log.Info("This won't be logged")
+	log.Error("This will be logged to errors.log")
+}
+
+/* Example 7: OS Log Writer (macOS/iOS only)
+// Uncomment on Darwin platforms
+
+func exampleOSLogWriter() {
+	osWriter := logger.NewOSLogWriter(
+		"net.pangolin.Pangolin.PacketTunnel",
+		"PangolinGo",
+		"MyApp",
+	)
+
+	log := logger.NewLoggerWithWriter(osWriter)
+	log.Info("This goes to os_log and can be viewed with Console.app")
+}
+*/
+
+func main() {
+	fmt.Println("=== Example 1: Default Logger ===")
+	exampleDefaultLogger()
+
+	fmt.Println("\n=== Example 2: Custom Instance ===")
+	exampleCustomInstance()
+
+	fmt.Println("\n=== Example 3: JSON Logger ===")
+	exampleJSONLogger()
+
+	fmt.Println("\n=== Example 4: File Logger ===")
+	exampleFileLogger()
+
+	fmt.Println("\n=== Example 5: Multi-Writer ===")
+	exampleMultiWriter()
+
+	fmt.Println("\n=== Example 6: Conditional Writer ===")
+	exampleConditionalWriter()
+}

examples/oslog_writer_example.go

@@ -0,0 +1,86 @@
+//go:build darwin
+// +build darwin
+
+package main
+
+/*
+#cgo CFLAGS: -I../PacketTunnel
+#include "../PacketTunnel/OSLogBridge.h"
+#include <stdlib.h>
+*/
+import "C"
+import (
+	"fmt"
+	"runtime"
+	"time"
+	"unsafe"
+)
+
+// OSLogWriter is a LogWriter implementation that writes to Apple's os_log
+type OSLogWriter struct {
+	subsystem string
+	category  string
+	prefix    string
+}
+
+// NewOSLogWriter creates a new OSLogWriter
+func NewOSLogWriter(subsystem, category, prefix string) *OSLogWriter {
+	writer := &OSLogWriter{
+		subsystem: subsystem,
+		category:  category,
+		prefix:    prefix,
+	}
+
+	// Initialize the OS log bridge
+	cSubsystem := C.CString(subsystem)
+	cCategory := C.CString(category)
+	defer C.free(unsafe.Pointer(cSubsystem))
+	defer C.free(unsafe.Pointer(cCategory))
+
+	C.initOSLogBridge(cSubsystem, cCategory)
+
+	return writer
+}
+
+// Write implements the LogWriter interface
+func (w *OSLogWriter) Write(level LogLevel, timestamp time.Time, message string) {
+	// Get caller information (skip 3 frames to get to the actual caller)
+	_, file, line, ok := runtime.Caller(3)
+	if !ok {
+		file = "unknown"
+		line = 0
+	} else {
+		// Get just the filename, not the full path
+		for i := len(file) - 1; i > 0; i-- {
+			if file[i] == '/' {
+				file = file[i+1:]
+				break
+			}
+		}
+	}
+
+	formattedTime := timestamp.Format("2006-01-02 15:04:05.000")
+	fullMessage := fmt.Sprintf("[%s] [%s] [%s] %s:%d - %s",
+		formattedTime, level.String(), w.prefix, file, line, message)
+
+	cMessage := C.CString(fullMessage)
+	defer C.free(unsafe.Pointer(cMessage))
+
+	// Map Go log levels to os_log levels:
+	// 0=DEBUG, 1=INFO, 2=DEFAULT (WARN), 3=ERROR
+	var osLogLevel C.int
+	switch level {
+	case DEBUG:
+		osLogLevel = 0 // DEBUG
+	case INFO:
+		osLogLevel = 1 // INFO
+	case WARN:
+		osLogLevel = 2 // DEFAULT
+	case ERROR, FATAL:
+		osLogLevel = 3 // ERROR
+	default:
+		osLogLevel = 2 // DEFAULT
+	}
+
+	C.logToOSLog(osLogLevel, cMessage)
+}

examples/otel-collector.yaml

@@ -0,0 +1,61 @@
+# Variant A: Direct scrape of Newt (/metrics) via Prometheus (no Collector needed)
+# Note: Newt already exposes labels like site_id, protocol, direction. Do not promote
+# resource attributes into labels when scraping Newt directly.
+#
+# Example Prometheus scrape config:
+# global:
+#   scrape_interval: 15s
+# scrape_configs:
+#   - job_name: newt
+#     static_configs:
+#       - targets: ["newt:2112"]
+#
+# Variant B: Use OTEL Collector (Newt -> OTLP -> Collector -> Prometheus)
+# This pipeline scrapes metrics from the Collector's Prometheus exporter.
+# Labels are already on datapoints; promotion from resource is OPTIONAL and typically NOT required.
+# If you enable transform/promote below, ensure you do not duplicate labels.
+
+receivers:
+  otlp:
+    protocols:
+      grpc:
+        endpoint: ":4317"
+
+processors:
+  memory_limiter:
+    check_interval: 5s
+    limit_percentage: 80
+    spike_limit_percentage: 25
+  resourcedetection:
+    detectors: [env, system]
+    timeout: 5s
+  batch: {}
+  # OPTIONAL: Only enable if you need to promote resource attributes to labels.
+  # WARNING: Newt already provides site_id as a label; avoid double-promotion.
+  # transform/promote:
+  #   error_mode: ignore
+  #   metric_statements:
+  #     - context: datapoint
+  #       statements:
+  #         - set(attributes["service_instance_id"], resource.attributes["service.instance.id"]) where resource.attributes["service.instance.id"] != nil
+  #         - set(attributes["site_id"], resource.attributes["site_id"]) where resource.attributes["site_id"] != nil
+
+exporters:
+  prometheus:
+    endpoint: ":8889"
+    send_timestamps: true
+  # prometheusremotewrite:
+  #   endpoint: http://mimir:9009/api/v1/push
+  debug:
+    verbosity: basic
+
+service:
+  pipelines:
+    metrics:
+      receivers: [otlp]
+      processors: [memory_limiter, resourcedetection, batch] # add transform/promote if you really need it
+      exporters: [prometheus]
+    traces:
+      receivers: [otlp]
+      processors: [memory_limiter, resourcedetection, batch]
+      exporters: [debug]

examples/prometheus.with-collector.yml

@@ -0,0 +1,16 @@
+global:
+  scrape_interval: 15s
+
+scrape_configs:
+  # IMPORTANT: Do not scrape Newt directly; scrape only the Collector!
+  - job_name: 'otel-collector'
+    static_configs:
+      - targets: ['otel-collector:8889']
+
+    # optional: limit metric cardinality
+    relabel_configs:
+      - action: labeldrop
+        regex: 'tunnel_id'
+      # - action: keep
+      #   source_labels: [site_id]
+      #   regex: '(site-a|site-b)'

examples/prometheus.yml

@@ -0,0 +1,21 @@
+global:
+  scrape_interval: 15s
+
+scrape_configs:
+  - job_name: 'newt'
+    scrape_interval: 15s
+    static_configs:
+      - targets: ['newt:2112']  # /metrics
+    relabel_configs:
+    # optional: drop tunnel_id
+      - action: labeldrop
+        regex: 'tunnel_id'
+    # optional: allow only specific sites
+      - action: keep
+        source_labels: [site_id]
+        regex: '(site-a|site-b)'
+
+  # WARNING: Do not enable this together with the 'newt' job above or you will double-count.
+  # - job_name: 'otel-collector'
+  #   static_configs:
+  #     - targets: ['otel-collector:8889']

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1752308619,
-        "narHash": "sha256-pzrVLKRQNPrii06Rm09Q0i0dq3wt2t2pciT/GNq5EZQ=",
+        "lastModified": 1763934636,
+        "narHash": "sha256-9glbI7f1uU+yzQCq5LwLgdZqx6svOhZWkd4JRY265fc=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "650e572363c091045cdbc5b36b0f4c1f614d3058",
+        "rev": "ee09932cedcef15aaf476f9343d1dea2cb77e261",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-25.05",
+        "ref": "nixpkgs-unstable",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -2,7 +2,7 @@
   description = "newt - A tunneling client for Pangolin";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
   };
 
   outputs =
@@ -22,22 +22,49 @@
         system:
         let
           pkgs = pkgsFor system;
+          inherit (pkgs) lib;
+
+          # Update version when releasing
+          version = "1.12.5";
         in
         {
           default = self.packages.${system}.pangolin-newt;
+
           pangolin-newt = pkgs.buildGoModule {
             pname = "pangolin-newt";
-            version = "1.3.2";
+            inherit version;
+            src = pkgs.nix-gitignore.gitignoreSource [ ] ./.;
 
-            src = ./.;
+            vendorHash = "sha256-X70emc3uPN2YpsbudtoeEZDHilaTvFMqfRaDmIgRVZE=";
 
-            vendorHash = "sha256-Y/f7GCO7Kf1iQiDR32DIEIGJdcN+PKS0OrhBvXiHvwo=";
+            nativeInstallCheckInputs = [ pkgs.versionCheckHook ];
 
-            meta = with pkgs.lib; {
+            env = {
+              CGO_ENABLED = 0;
+            };
+
+            ldflags = [
+              "-s"
+              "-w"
+              "-X main.newtVersion=${version}"
+            ];
+
+            # Tests are broken due to a lack of Internet.
+            # Disable running `go test`, and instead do
+            # a simple version check instead.
+            doCheck = false;
+            doInstallCheck = true;
+
+            versionCheckProgramArg = [ "-version" ];
+
+            meta = {
               description = "A tunneling client for Pangolin";
               homepage = "https://github.com/fosrl/newt";
-              license = licenses.gpl3;
-              maintainers = [ ];
+              license = lib.licenses.gpl3;
+              maintainers = [
+                lib.maintainers.water-sucks
+              ];
+              mainProgram = "newt";
             };
           };
         }
@@ -46,10 +73,20 @@
         system:
         let
           pkgs = pkgsFor system;
+
+          inherit (pkgs)
+            go
+            gopls
+            gotools
+            go-outline
+            gopkgs
+            godef
+            golint
+            ;
         in
         {
           default = pkgs.mkShell {
-            buildInputs = with pkgs; [
+            buildInputs = [
               go
               gopls
               gotools

get-newt.sh

@@ -1,7 +1,7 @@
-#!/bin/bash
+#!/bin/sh
 
 # Get Newt - Cross-platform installation script
-# Usage: curl -fsSL https://raw.githubusercontent.com/fosrl/newt/refs/heads/main/get-newt.sh | bash
+# Usage: curl -fsSL https://raw.githubusercontent.com/fosrl/newt/refs/heads/main/get-newt.sh | sh
 
 set -e
 
@@ -17,54 +17,51 @@ GITHUB_API_URL="https://api.github.com/repos/${REPO}/releases/latest"
 
 # Function to print colored output
 print_status() {
-    echo -e "${GREEN}[INFO]${NC} $1"
+    printf '%b[INFO]%b %s\n' "${GREEN}" "${NC}" "$1"
 }
 
 print_warning() {
-    echo -e "${YELLOW}[WARN]${NC} $1"
+    printf '%b[WARN]%b %s\n' "${YELLOW}" "${NC}" "$1"
 }
 
 print_error() {
-    echo -e "${RED}[ERROR]${NC} $1"
+    printf '%b[ERROR]%b %s\n' "${RED}" "${NC}" "$1"
 }
 
 # Function to get latest version from GitHub API
 get_latest_version() {
-    local latest_info
-    
+    latest_info=""
+
     if command -v curl >/dev/null 2>&1; then
         latest_info=$(curl -fsSL "$GITHUB_API_URL" 2>/dev/null)
     elif command -v wget >/dev/null 2>&1; then
         latest_info=$(wget -qO- "$GITHUB_API_URL" 2>/dev/null)
     else
-        print_error "Neither curl nor wget is available. Please install one of them." >&2
+        print_error "Neither curl nor wget is available."
         exit 1
     fi
-    
+
     if [ -z "$latest_info" ]; then
-        print_error "Failed to fetch latest version information" >&2
+        print_error "Failed to fetch latest version info"
         exit 1
     fi
-    
-    # Extract version from JSON response (works without jq)
-    local version=$(echo "$latest_info" | grep '"tag_name"' | head -1 | sed 's/.*"tag_name": *"\([^"]*\)".*/\1/')
-    
+
+    version=$(printf '%s' "$latest_info" | grep '"tag_name"' | head -1 | sed 's/.*"tag_name": *"\([^"]*\)".*/\1/')
+
     if [ -z "$version" ]; then
-        print_error "Could not parse version from GitHub API response" >&2
+        print_error "Could not parse version from GitHub API response"
         exit 1
     fi
-    
-    # Remove 'v' prefix if present
-    version=$(echo "$version" | sed 's/^v//')
-    
-    echo "$version"
+
+    version=$(printf '%s' "$version" | sed 's/^v//')
+    printf '%s' "$version"
 }
 
 # Detect OS and architecture
 detect_platform() {
-    local os arch
-    
-    # Detect OS
+    os=""
+    arch=""
+
     case "$(uname -s)" in
         Linux*)     os="linux" ;;
         Darwin*)    os="darwin" ;;
@@ -75,12 +72,11 @@ detect_platform() {
             exit 1
             ;;
     esac
-    
-    # Detect architecture
+
     case "$(uname -m)" in
         x86_64|amd64)   arch="amd64" ;;
         arm64|aarch64)  arch="arm64" ;;
-        armv7l|armv6l)  
+        armv7l|armv6l)
             if [ "$os" = "linux" ]; then
                 if [ "$(uname -m)" = "armv6l" ]; then
                     arch="arm32v6"
@@ -88,10 +84,10 @@ detect_platform() {
                     arch="arm32"
                 fi
             else
-                arch="arm64"  # Default for non-Linux ARM
+                arch="arm64"
             fi
             ;;
-        riscv64)        
+        riscv64)
             if [ "$os" = "linux" ]; then
                 arch="riscv64"
             else
@@ -104,90 +100,166 @@ detect_platform() {
             exit 1
             ;;
     esac
-    
-    echo "${os}_${arch}"
+
+    printf '%s_%s' "$os" "$arch"
 }
 
-# Get installation directory
+# Determine installation directory (default fallback)
 get_install_dir() {
-    if [ "$OS" = "windows" ]; then
-        echo "$HOME/bin"
-    else
-        # Try to use a directory in PATH, fallback to ~/.local/bin
-        if echo "$PATH" | grep -q "/usr/local/bin"; then
-            if [ -w "/usr/local/bin" ] 2>/dev/null; then
-                echo "/usr/local/bin"
-            else
-                echo "$HOME/.local/bin"
-            fi
-        else
-            echo "$HOME/.local/bin"
+    case "$PLATFORM" in
+        *windows*)
+            echo "$HOME/bin"
+            ;;
+        *)
+            echo "/usr/local/bin"
+            ;;
+    esac
+}
+
+# Parse --path argument from args
+# Returns the value after --path, or empty string if not provided
+parse_path_arg() {
+    while [ $# -gt 0 ]; do
+        case "$1" in
+            --path)
+                if [ -n "$2" ]; then
+                    printf '%s' "$2"
+                    return
+                fi
+                ;;
+            --path=*)
+                printf '%s' "${1#--path=}"
+                return
+                ;;
+        esac
+        shift
+    done
+}
+
+# Detect an existing newt binary location.
+# Tries unprivileged which first, then sudo which (for binaries only visible to root).
+# Returns the full path of the binary, or empty string if not found.
+detect_existing_binary() {
+    existing=""
+
+    # Try unprivileged which first
+    existing=$(command -v newt 2>/dev/null || true)
+    if [ -n "$existing" ]; then
+        printf '%s' "$existing"
+        return
+    fi
+
+    # Try sudo which — some installations land in paths only root can see in $PATH
+    if command -v sudo >/dev/null 2>&1; then
+        existing=$(sudo which newt 2>/dev/null || true)
+        if [ -n "$existing" ]; then
+            printf '%s' "$existing"
+            return
         fi
     fi
 }
 
+# Check if we need sudo for installation
+needs_sudo() {
+    install_dir="$1"
+    if [ -w "$install_dir" ] 2>/dev/null; then
+        return 1  # No sudo needed
+    else
+        return 0  # Sudo needed
+    fi
+}
+
+# Get the appropriate command prefix (sudo or empty)
+get_sudo_cmd() {
+    install_dir="$1"
+    if needs_sudo "$install_dir"; then
+        if command -v sudo >/dev/null 2>&1; then
+            echo "sudo"
+        else
+            print_error "Cannot write to ${install_dir} and sudo is not available."
+            print_error "Please run this script as root or install sudo."
+            exit 1
+        fi
+    else
+        echo ""
+    fi
+}
+
 # Download and install newt
 install_newt() {
-    local platform="$1"
-    local install_dir="$2"
-    local binary_name="newt_${platform}"
-    local exe_suffix=""
-    
-    # Add .exe suffix for Windows
-    if [[ "$platform" == *"windows"* ]]; then
-        binary_name="${binary_name}.exe"
-        exe_suffix=".exe"
+    platform="$1"
+    install_dir="$2"
+    sudo_cmd="$3"
+    custom_path="$4"
+    binary_name="newt_${platform}"
+    final_name="newt"
+
+    case "$platform" in
+        *windows*)
+            binary_name="${binary_name}.exe"
+            final_name="newt.exe"
+            ;;
+    esac
+
+    download_url="${BASE_URL}/${binary_name}"
+    temp_file="/tmp/${final_name}"
+
+    # If a custom path is provided, use it directly; otherwise use install_dir/final_name
+    if [ -n "$custom_path" ]; then
+        final_path="$custom_path"
+        install_dir=$(dirname "$final_path")
+    else
+        final_path="${install_dir}/${final_name}"
     fi
-    
-    local download_url="${BASE_URL}/${binary_name}"
-    local temp_file="/tmp/newt${exe_suffix}"
-    local final_path="${install_dir}/newt${exe_suffix}"
-    
+
     print_status "Downloading newt from ${download_url}"
-    
-    # Download the binary
+
     if command -v curl >/dev/null 2>&1; then
         curl -fsSL "$download_url" -o "$temp_file"
     elif command -v wget >/dev/null 2>&1; then
         wget -q "$download_url" -O "$temp_file"
     else
-        print_error "Neither curl nor wget is available. Please install one of them."
+        print_error "Neither curl nor wget is available."
         exit 1
     fi
-    
-    # Create install directory if it doesn't exist
-    mkdir -p "$install_dir"
-    
-    # Move binary to install directory
-    mv "$temp_file" "$final_path"
-    
-    # Make executable (not needed on Windows, but doesn't hurt)
-    chmod +x "$final_path"
-    
+
+    # Make executable before moving
+    chmod +x "$temp_file"
+
+    # Create install directory if it doesn't exist and move binary
+    if [ -n "$sudo_cmd" ]; then
+        $sudo_cmd mkdir -p "$install_dir"
+        print_status "Using sudo to install to ${install_dir}"
+        $sudo_cmd mv "$temp_file" "$final_path"
+    else
+        mkdir -p "$install_dir"
+        mv "$temp_file" "$final_path"
+    fi
+
     print_status "newt installed to ${final_path}"
-    
+
     # Check if install directory is in PATH
     if ! echo "$PATH" | grep -q "$install_dir"; then
         print_warning "Install directory ${install_dir} is not in your PATH."
-        print_warning "Add it to your PATH by adding this line to your shell profile:"
+        print_warning "Add it with:"
         print_warning "  export PATH=\"${install_dir}:\$PATH\""
     fi
 }
 
 # Verify installation
 verify_installation() {
-    local install_dir="$1"
-    local exe_suffix=""
-    
-    if [[ "$PLATFORM" == *"windows"* ]]; then
-        exe_suffix=".exe"
-    fi
-    
-    local newt_path="${install_dir}/newt${exe_suffix}"
-    
-    if [ -f "$newt_path" ] && [ -x "$newt_path" ]; then
+    install_dir="$1"
+    exe_suffix=""
+
+    case "$PLATFORM" in
+        *windows*) exe_suffix=".exe" ;;
+    esac
+
+    newt_path="${install_dir}/newt${exe_suffix}"
+
+    if [ -x "$newt_path" ]; then
         print_status "Installation successful!"
-        print_status "newt version: $("$newt_path" --version 2>/dev/null || echo "unknown")"
+        print_status "newt version: $("$newt_path" --version 2>/dev/null || printf 'unknown')"
         return 0
     else
         print_error "Installation failed. Binary not found or not executable."
@@ -197,39 +269,66 @@ verify_installation() {
 
 # Main installation process
 main() {
-    print_status "Installing latest version of newt..."
-    
-    # Get latest version
-    print_status "Fetching latest version from GitHub..."
+    # --path explicitly overrides everything
+    CUSTOM_PATH=$(parse_path_arg "$@")
+
+    if [ -n "$CUSTOM_PATH" ]; then
+        print_status "Installing latest version of newt to ${CUSTOM_PATH}..."
+    else
+        print_status "Installing latest version of newt..."
+    fi
+
+    print_status "Fetching latest version..."
     VERSION=$(get_latest_version)
     print_status "Latest version: v${VERSION}"
-    
-    # Set base URL with the fetched version
+
     BASE_URL="https://github.com/${REPO}/releases/download/${VERSION}"
-    
-    # Detect platform
+
     PLATFORM=$(detect_platform)
     print_status "Detected platform: ${PLATFORM}"
-    
-    # Get install directory
-    INSTALL_DIR=$(get_install_dir)
-    print_status "Install directory: ${INSTALL_DIR}"
-    
-    # Install newt
-    install_newt "$PLATFORM" "$INSTALL_DIR"
-    
-    # Verify installation
-    if verify_installation "$INSTALL_DIR"; then
-        print_status "newt is ready to use!"
-        if [[ "$PLATFORM" == *"windows"* ]]; then
-            print_status "Run 'newt --help' to get started"
+
+    if [ -n "$CUSTOM_PATH" ]; then
+        # --path wins; derive INSTALL_DIR from it
+        INSTALL_DIR=$(dirname "$CUSTOM_PATH")
+    else
+        # Try to find an existing installation so we update the right place
+        EXISTING_BINARY=$(detect_existing_binary)
+        if [ -n "$EXISTING_BINARY" ]; then
+            print_status "Found existing newt binary at ${EXISTING_BINARY}"
+            CUSTOM_PATH="$EXISTING_BINARY"
+            INSTALL_DIR=$(dirname "$EXISTING_BINARY")
+            print_status "Will update existing installation at ${INSTALL_DIR}"
         else
-            print_status "Run 'newt --help' to get started"
+            INSTALL_DIR=$(get_install_dir)
         fi
+    fi
+
+    print_status "Install directory: ${INSTALL_DIR}"
+
+    # Check if we need sudo
+    SUDO_CMD=$(get_sudo_cmd "$INSTALL_DIR")
+    if [ -n "$SUDO_CMD" ]; then
+        print_status "Root privileges required for installation to ${INSTALL_DIR}"
+    fi
+
+    install_newt "$PLATFORM" "$INSTALL_DIR" "$SUDO_CMD" "$CUSTOM_PATH"
+
+    if [ -n "$CUSTOM_PATH" ]; then
+        if [ -x "$CUSTOM_PATH" ]; then
+            print_status "Installation successful!"
+            print_status "newt version: $("$CUSTOM_PATH" --version 2>/dev/null || printf 'unknown')"
+            print_status "newt is ready to use!"
+        else
+            print_error "Installation failed. Binary not found or not executable at ${CUSTOM_PATH}."
+            exit 1
+        fi
+    elif verify_installation "$INSTALL_DIR"; then
+        print_status "newt is ready to use!"
+        print_status "Run 'newt --help' to get started."
     else
         exit 1
     fi
 }
 
 # Run main function
-main "$@"
+main "$@"

go.mod

@@ -1,58 +1,74 @@
 module github.com/fosrl/newt
 
-go 1.23.1
-
-toolchain go1.23.2
+go 1.25.0
 
 require (
-	github.com/docker/docker v28.3.2+incompatible
-	github.com/google/gopacket v1.1.19
+	github.com/coder/websocket v1.8.14
+	github.com/creack/pty v1.1.24
+	github.com/gaissmai/bart v0.26.1
+	github.com/go-crypt/crypt v0.14.15
+	github.com/go-crypt/x v0.4.16
 	github.com/gorilla/websocket v1.5.3
+	github.com/moby/moby/api v1.54.2
+	github.com/moby/moby/client v0.4.1
+	github.com/prometheus/client_golang v1.23.2
 	github.com/vishvananda/netlink v1.3.1
-	golang.org/x/crypto v0.40.0
-	golang.org/x/exp v0.0.0-20250218142911-aa4b98e5adaa
-	golang.org/x/net v0.42.0
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.68.0
+	go.opentelemetry.io/contrib/instrumentation/runtime v0.68.0
+	go.opentelemetry.io/otel v1.43.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.43.0
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.43.0
+	go.opentelemetry.io/otel/exporters/prometheus v0.65.0
+	go.opentelemetry.io/otel/metric v1.43.0
+	go.opentelemetry.io/otel/sdk v1.43.0
+	go.opentelemetry.io/otel/sdk/metric v1.43.0
+	golang.org/x/crypto v0.52.0
+	golang.org/x/exp v0.0.0-20251113190631-e25ba8c21ef6
+	golang.org/x/net v0.55.0
+	golang.org/x/sys v0.45.0
 	golang.zx2c4.com/wireguard v0.0.0-20250521234502-f333402bd9cb
 	golang.zx2c4.com/wireguard/wgctrl v0.0.0-20241231184526-a9ab2273dd10
+	golang.zx2c4.com/wireguard/windows v1.0.1
+	google.golang.org/grpc v1.81.1
+	gopkg.in/yaml.v3 v3.0.1
 	gvisor.dev/gvisor v0.0.0-20250503011706-39ed1f5ac29c
-	software.sslmate.com/src/go-pkcs12 v0.5.0
+	software.sslmate.com/src/go-pkcs12 v0.7.1
 )
 
 require (
-	github.com/Microsoft/go-winio v0.6.0 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cenkalti/backoff/v5 v5.0.3 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/containerd/errdefs v1.0.0 // indirect
 	github.com/containerd/errdefs/pkg v0.3.0 // indirect
 	github.com/distribution/reference v0.6.0 // indirect
-	github.com/docker/go-connections v0.5.0 // indirect
-	github.com/docker/go-units v0.4.0 // indirect
+	github.com/docker/go-connections v0.7.0 // indirect
+	github.com/docker/go-units v0.5.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
-	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/google/btree v1.1.2 // indirect
-	github.com/google/go-cmp v0.7.0 // indirect
-	github.com/josharian/native v1.1.0 // indirect
-	github.com/mdlayher/genetlink v1.3.2 // indirect
-	github.com/mdlayher/netlink v1.7.2 // indirect
-	github.com/mdlayher/socket v0.5.1 // indirect
+	github.com/google/btree v1.1.3 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0 // indirect
 	github.com/moby/docker-image-spec v1.3.1 // indirect
-	github.com/moby/sys/atomicwriter v0.1.0 // indirect
-	github.com/moby/term v0.5.2 // indirect
-	github.com/morikuni/aec v1.0.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.1.1 // indirect
-	github.com/pkg/errors v0.9.1 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.67.5 // indirect
+	github.com/prometheus/otlptranslator v1.0.0 // indirect
+	github.com/prometheus/procfs v0.20.1 // indirect
 	github.com/vishvananda/netns v0.0.5 // indirect
-	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
-	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0 // indirect
-	go.opentelemetry.io/otel v1.36.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.36.0 // indirect
-	go.opentelemetry.io/otel/metric v1.36.0 // indirect
-	go.opentelemetry.io/otel/trace v1.36.0 // indirect
-	golang.org/x/mod v0.23.0 // indirect
-	golang.org/x/sync v0.11.0 // indirect
-	golang.org/x/sys v0.34.0 // indirect
-	golang.org/x/time v0.7.0 // indirect
-	golang.org/x/tools v0.30.0 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.43.0 // indirect
+	go.opentelemetry.io/otel/trace v1.43.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.10.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.4 // indirect
+	golang.org/x/text v0.37.0 // indirect
+	golang.org/x/time v0.12.0 // indirect
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20260401024825-9d38bb4040a9 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260401024825-9d38bb4040a9 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 )

go.sum

@@ -1,175 +1,166 @@
-github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c h1:udKWzYgxTojEKWjV8V+WSxDXJ4NFATAsZjh8iIbsQIg=
-github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c/go.mod h1:xomTg63KZ2rFqZQzSB4Vz2SUXa1BpHTVz9L5PTmPC4E=
-github.com/Microsoft/go-winio v0.6.0 h1:slsWYD/zyx7lCXoZVlvQrj0hPTM1HI4+v1sIda2yDvg=
-github.com/Microsoft/go-winio v0.6.0/go.mod h1:cTAf44im0RAYeL23bpB+fzCyDH2MJiz2BO69KH/soAE=
-github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
-github.com/cenkalti/backoff/v5 v5.0.2 h1:rIfFVxEf1QsI7E1ZHfp/B4DF/6QBAUhmgkxc0H7Zss8=
-github.com/cenkalti/backoff/v5 v5.0.2/go.mod h1:rkhZdG3JZukswDf7f0cwqPNk4K0sa+F97BxZthm/crw=
+github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
+github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cenkalti/backoff/v5 v5.0.3 h1:ZN+IMa753KfX5hd8vVaMixjnqRZ3y8CuJKRKj1xcsSM=
+github.com/cenkalti/backoff/v5 v5.0.3/go.mod h1:rkhZdG3JZukswDf7f0cwqPNk4K0sa+F97BxZthm/crw=
+github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/coder/websocket v1.8.14 h1:9L0p0iKiNOibykf283eHkKUHHrpG7f65OE3BhhO7v9g=
+github.com/coder/websocket v1.8.14/go.mod h1:NX3SzP+inril6yawo5CQXx8+fk145lPDC6pumgx0mVg=
 github.com/containerd/errdefs v1.0.0 h1:tg5yIfIlQIrxYtu9ajqY42W3lpS19XqdxRQeEwYG8PI=
 github.com/containerd/errdefs v1.0.0/go.mod h1:+YBYIdtsnF4Iw6nWZhJcqGSg/dwvV7tyJ/kCkyJ2k+M=
 github.com/containerd/errdefs/pkg v0.3.0 h1:9IKJ06FvyNlexW690DXuQNx2KA2cUJXx151Xdx3ZPPE=
 github.com/containerd/errdefs/pkg v0.3.0/go.mod h1:NJw6s9HwNuRhnjJhM7pylWwMyAkmCQvQ4GpJHEqRLVk=
-github.com/containerd/log v0.1.0 h1:TCJt7ioM2cr/tfR8GPbGf9/VRAX8D2B4PjzCpfX540I=
-github.com/containerd/log v0.1.0/go.mod h1:VRRf09a7mHDIRezVKTRCrOq78v577GXq3bSa3EhrzVo=
+github.com/creack/pty v1.1.24 h1:bJrF4RRfyJnbTJqzRLHzcGaZK1NeM5kTC9jGgovnR1s=
+github.com/creack/pty v1.1.24/go.mod h1:08sCNb52WyoAwi2QDyzUCTgcvVFhUzewun7wtTfvcwE=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/distribution/reference v0.6.0 h1:0IXCQ5g4/QMHHkarYzh5l+u8T3t73zM5QvfrDyIgxBk=
 github.com/distribution/reference v0.6.0/go.mod h1:BbU0aIcezP1/5jX/8MP0YiH4SdvB5Y4f/wlDRiLyi3E=
-github.com/docker/docker v28.3.2+incompatible h1:wn66NJ6pWB1vBZIilP8G3qQPqHy5XymfYn5vsqeA5oA=
-github.com/docker/docker v28.3.2+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
-github.com/docker/go-connections v0.5.0 h1:USnMq7hx7gwdVZq1L49hLXaFtUdTADjXGp+uj1Br63c=
-github.com/docker/go-connections v0.5.0/go.mod h1:ov60Kzw0kKElRwhNs9UlUHAE/F9Fe6GLaXnqyDdmEXc=
-github.com/docker/go-units v0.4.0 h1:3uh0PgVws3nIA0Q+MwDC8yjEPf9zjRfZZWXZYDct3Tw=
-github.com/docker/go-units v0.4.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
+github.com/docker/go-connections v0.7.0 h1:6SsRfJddP22WMrCkj19x9WKjEDTB+ahsdiGYf0mN39c=
+github.com/docker/go-connections v0.7.0/go.mod h1:no1qkHdjq7kLMGUXYAduOhYPSJxxvgWBh7ogVvptn3Q=
+github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4=
+github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/gaissmai/bart v0.26.1 h1:+w4rnLGNlA2GDVn382Tfe3jOsK5vOr5n4KmigJ9lbTo=
+github.com/gaissmai/bart v0.26.1/go.mod h1:GREWQfTLRWz/c5FTOsIw+KkscuFkIV5t8Rp7Nd1Td5c=
+github.com/go-crypt/crypt v0.14.15 h1:q1i5OMpL05r935IxWmXgpDAVF0nvi4SMoHhGXLBQUEQ=
+github.com/go-crypt/crypt v0.14.15/go.mod h1:0n/to1VqIZPENj2yEUa/sLLYYnmupma6cp+QMX4zfF0=
+github.com/go-crypt/x v0.4.16 h1:WXdY28H/0MsXnH+gwerxuCcvBTJPkBG90u6oS4gIPZI=
+github.com/go-crypt/x v0.4.16/go.mod h1:vmVFA/d/oLrEaCbqsLcjBMlTqF8u8pvH/c4+EJ/ped8=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
-github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
-github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
+github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
-github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
-github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
-github.com/google/btree v1.1.2 h1:xf4v41cLI2Z6FxbKm+8Bu+m8ifhj15JuZ9sa0jZCMUU=
-github.com/google/btree v1.1.2/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
+github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
+github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
+github.com/google/btree v1.1.3 h1:CVpQJjYgC4VbzxeGVHfvZrv1ctoYCAI8vbl07Fcxlyg=
+github.com/google/btree v1.1.3/go.mod h1:qOPhT0dTNdNzV6Z/lhRX0YXUafgPLFUh+gZMl761Gm4=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
-github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
-github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
-github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.3 h1:5ZPtiqj0JL5oKWmcsq4VMaAW5ukBEgSGXEN89zeH1Jo=
-github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.3/go.mod h1:ndYquD05frm2vACXE1nsccT4oJzjhw2arTS2cpUD1PI=
-github.com/josharian/native v1.1.0 h1:uuaP0hAbW7Y4l0ZRQ6C9zfb7Mg1mbFKry/xzDAfmtLA=
-github.com/josharian/native v1.1.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
-github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
-github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
-github.com/mdlayher/genetlink v1.3.2 h1:KdrNKe+CTu+IbZnm/GVUMXSqBBLqcGpRDa0xkQy56gw=
-github.com/mdlayher/genetlink v1.3.2/go.mod h1:tcC3pkCrPUGIKKsCsp0B3AdaaKuHtaxoJRz3cc+528o=
-github.com/mdlayher/netlink v1.7.2 h1:/UtM3ofJap7Vl4QWCPDGXY8d3GIY2UGSDbK+QWmY8/g=
-github.com/mdlayher/netlink v1.7.2/go.mod h1:xraEF7uJbxLhc5fpHL4cPe221LI2bdttWlU+ZGLfQSw=
-github.com/mdlayher/socket v0.5.1 h1:VZaqt6RkGkt2OE9l3GcC6nZkqD3xKeQLyfleW/uBcos=
-github.com/mdlayher/socket v0.5.1/go.mod h1:TjPLHI1UgwEv5J1B5q0zTZq12A/6H7nKmtTanQE37IQ=
-github.com/mikioh/ipaddr v0.0.0-20190404000644-d465c8ab6721 h1:RlZweED6sbSArvlE924+mUcZuXKLBHA35U7LN621Bws=
-github.com/mikioh/ipaddr v0.0.0-20190404000644-d465c8ab6721/go.mod h1:Ickgr2WtCLZ2MDGd4Gr0geeCH5HybhRJbonOgQpvSxc=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0 h1:HWRh5R2+9EifMyIHV7ZV+MIZqgz+PMpZ14Jynv3O2Zs=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0/go.mod h1:JfhWUomR1baixubs02l85lZYYOm7LV6om4ceouMv45c=
+github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
+github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
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healthcheck/healthcheck.go

@@ -0,0 +1,674 @@
+package healthcheck
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"fmt"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+)
+
+// Health represents the health status of a target
+type Health int
+
+const (
+	StatusUnknown Health = iota
+	StatusHealthy
+	StatusUnhealthy
+)
+
+func (s Health) String() string {
+	switch s {
+	case StatusHealthy:
+		return "healthy"
+	case StatusUnhealthy:
+		return "unhealthy"
+	default:
+		return "unknown"
+	}
+}
+
+// Config holds the health check configuration for a target
+type Config struct {
+	ID                 int               `json:"id"`
+	Enabled            bool              `json:"hcEnabled"`
+	Path               string            `json:"hcPath"`
+	Scheme             string            `json:"hcScheme"`
+	Mode               string            `json:"hcMode"`
+	Hostname           string            `json:"hcHostname"`
+	Port               int               `json:"hcPort"`
+	Interval           int               `json:"hcInterval"`          // in seconds
+	UnhealthyInterval  int               `json:"hcUnhealthyInterval"` // in seconds
+	Timeout            int               `json:"hcTimeout"`           // in seconds
+	FollowRedirects    *bool             `json:"hcFollowRedirects"`
+	Headers            map[string]string `json:"hcHeaders"`
+	Method             string            `json:"hcMethod"`
+	Status             int               `json:"hcStatus"` // HTTP status code
+	TLSServerName      string            `json:"hcTlsServerName"`
+	HealthyThreshold   int               `json:"hcHealthyThreshold"`   // consecutive successes required to become healthy
+	UnhealthyThreshold int               `json:"hcUnhealthyThreshold"` // consecutive failures required to become unhealthy
+}
+
+// Target represents a health check target with its current status
+type Target struct {
+	Config               Config    `json:"config"`
+	Status               Health    `json:"status"`
+	LastCheck            time.Time `json:"lastCheck"`
+	LastError            string    `json:"lastError,omitempty"`
+	CheckCount           int       `json:"checkCount"`
+	timer                *time.Timer
+	ctx                  context.Context
+	cancel               context.CancelFunc
+	client               *http.Client
+	consecutiveSuccesses int
+	consecutiveFailures  int
+}
+
+// StatusChangeCallback is called when any target's status changes
+type StatusChangeCallback func(targets map[int]*Target)
+
+// Monitor manages health check targets and their monitoring
+type Monitor struct {
+	targets     map[int]*Target
+	mutex       sync.RWMutex
+	callback    StatusChangeCallback
+	enforceCert bool
+}
+
+// NewMonitor creates a new health check monitor
+func NewMonitor(callback StatusChangeCallback, enforceCert bool) *Monitor {
+	logger.Debug("Creating new health check monitor with certificate enforcement: %t", enforceCert)
+
+	return &Monitor{
+		targets:     make(map[int]*Target),
+		callback:    callback,
+		enforceCert: enforceCert,
+	}
+}
+
+// parseHeaders parses the headers string into a map
+func parseHeaders(headersStr string) map[string]string {
+	headers := make(map[string]string)
+	if headersStr == "" {
+		return headers
+	}
+
+	// Try to parse as JSON first
+	if err := json.Unmarshal([]byte(headersStr), &headers); err == nil {
+		return headers
+	}
+
+	// Fallback to simple key:value parsing
+	pairs := strings.Split(headersStr, ",")
+	for _, pair := range pairs {
+		kv := strings.SplitN(strings.TrimSpace(pair), ":", 2)
+		if len(kv) == 2 {
+			headers[strings.TrimSpace(kv[0])] = strings.TrimSpace(kv[1])
+		}
+	}
+	return headers
+}
+
+// AddTarget adds a new health check target
+func (m *Monitor) AddTarget(config Config) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	logger.Info("Adding health check target: ID=%d, hostname=%s, port=%d, enabled=%t",
+		config.ID, config.Hostname, config.Port, config.Enabled)
+
+	return m.addTargetUnsafe(config)
+}
+
+// AddTargets adds multiple health check targets in bulk
+func (m *Monitor) AddTargets(configs []Config) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	logger.Debug("Adding %d health check targets in bulk", len(configs))
+
+	for _, config := range configs {
+		if err := m.addTargetUnsafe(config); err != nil {
+			logger.Error("Failed to add target %d: %v", config.ID, err)
+			return fmt.Errorf("failed to add target %d: %v", config.ID, err)
+		}
+		logger.Debug("Successfully added target: ID=%d, hostname=%s", config.ID, config.Hostname)
+	}
+
+	// Don't notify callback immediately - let the initial health checks complete first
+	// The callback will be triggered when the first health check results are available
+
+	logger.Debug("Successfully added all %d health check targets", len(configs))
+	return nil
+}
+
+// addTargetUnsafe adds a target without acquiring the mutex (internal method)
+func (m *Monitor) addTargetUnsafe(config Config) error {
+	// Set defaults
+	if config.Scheme == "" {
+		config.Scheme = "http"
+	}
+	if config.Mode == "" {
+		config.Mode = "http"
+	}
+	if config.Method == "" {
+		config.Method = "GET"
+	}
+	if config.Interval == 0 {
+		config.Interval = 30
+	}
+	if config.UnhealthyInterval == 0 {
+		config.UnhealthyInterval = 30
+	}
+	if config.Timeout == 0 {
+		config.Timeout = 5
+	}
+	if config.HealthyThreshold == 0 {
+		config.HealthyThreshold = 1
+	}
+	if config.UnhealthyThreshold == 0 {
+		config.UnhealthyThreshold = 1
+	}
+
+	logger.Debug("Target %d configuration: mode=%s, scheme=%s, method=%s, interval=%ds, timeout=%ds, healthyThreshold=%d, unhealthyThreshold=%d",
+		config.ID, config.Mode, config.Scheme, config.Method, config.Interval, config.Timeout,
+		config.HealthyThreshold, config.UnhealthyThreshold)
+
+	// Parse headers if provided as string
+	if len(config.Headers) == 0 && config.Path != "" {
+		// This is a simplified header parsing - in real use you might want more robust parsing
+		config.Headers = make(map[string]string)
+	}
+
+	// Remove existing target if it exists
+	if existing, exists := m.targets[config.ID]; exists {
+		logger.Info("Replacing existing target with ID %d", config.ID)
+		existing.cancel()
+	}
+
+	// Create new target
+	ctx, cancel := context.WithCancel(context.Background())
+	target := &Target{
+		Config: config,
+		Status: StatusUnknown,
+		ctx:    ctx,
+		cancel: cancel,
+		client: &http.Client{
+			CheckRedirect: func() func(*http.Request, []*http.Request) error {
+				// Default to following redirects if not explicitly configured
+				followRedirects := config.FollowRedirects == nil || *config.FollowRedirects
+				if !followRedirects {
+					return func(req *http.Request, via []*http.Request) error {
+						return http.ErrUseLastResponse
+					}
+				}
+				return nil
+			}(),
+			Transport: &http.Transport{
+				TLSClientConfig: &tls.Config{
+					// Configure TLS settings based on certificate enforcement
+					InsecureSkipVerify: !m.enforceCert,
+					// Use SNI TLS header if present
+					ServerName: config.TLSServerName,
+				},
+			},
+		},
+	}
+
+	m.targets[config.ID] = target
+
+	// Start monitoring if enabled
+	if config.Enabled {
+		logger.Info("Starting monitoring for target %d (%s:%d)", config.ID, config.Hostname, config.Port)
+		go m.monitorTarget(target)
+	} else {
+		logger.Debug("Target %d added but monitoring is disabled", config.ID)
+	}
+
+	return nil
+}
+
+// RemoveTarget removes a health check target
+func (m *Monitor) RemoveTarget(id int) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	target, exists := m.targets[id]
+	if !exists {
+		logger.Warn("Attempted to remove non-existent target with ID %d", id)
+		return fmt.Errorf("target with id %d not found", id)
+	}
+
+	logger.Info("Removing health check target: ID=%d", id)
+	target.cancel()
+	delete(m.targets, id)
+
+	// Notify callback of status change
+	if m.callback != nil {
+		go m.callback(m.getAllTargetsUnsafe())
+	}
+
+	logger.Info("Successfully removed target %d", id)
+	return nil
+}
+
+// RemoveTargets removes multiple health check targets
+func (m *Monitor) RemoveTargets(ids []int) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	logger.Info("Removing %d health check targets", len(ids))
+	var notFound []int
+
+	for _, id := range ids {
+		target, exists := m.targets[id]
+		if !exists {
+			notFound = append(notFound, id)
+			logger.Warn("Target with ID %d not found during bulk removal", id)
+			continue
+		}
+
+		logger.Debug("Removing target %d", id)
+		target.cancel()
+		delete(m.targets, id)
+	}
+
+	removedCount := len(ids) - len(notFound)
+	logger.Info("Successfully removed %d targets", removedCount)
+
+	// Notify callback of status change if any targets were removed
+	if len(notFound) != len(ids) && m.callback != nil {
+		go m.callback(m.getAllTargetsUnsafe())
+	}
+
+	if len(notFound) > 0 {
+		logger.Error("Some targets not found during removal: %v", notFound)
+		return fmt.Errorf("targets not found: %v", notFound)
+	}
+
+	return nil
+}
+
+// RemoveTargetsByID is a convenience method that accepts either a single ID or multiple IDs
+func (m *Monitor) RemoveTargetsByID(ids ...int) error {
+	return m.RemoveTargets(ids)
+}
+
+// GetTargets returns a copy of all targets
+func (m *Monitor) GetTargets() map[int]*Target {
+	m.mutex.RLock()
+	defer m.mutex.RUnlock()
+	return m.getAllTargetsUnsafe()
+}
+
+// getAllTargetsUnsafe returns a copy of all targets without acquiring the mutex (internal method)
+func (m *Monitor) getAllTargetsUnsafe() map[int]*Target {
+	targets := make(map[int]*Target)
+	for id, target := range m.targets {
+		// Create a copy to avoid race conditions
+		targetCopy := *target
+		targets[id] = &targetCopy
+	}
+	return targets
+}
+
+// getAllTargets returns a copy of all targets (deprecated, use GetTargets)
+func (m *Monitor) getAllTargets() map[int]*Target {
+	return m.GetTargets()
+}
+
+// monitorTarget monitors a single target
+func (m *Monitor) monitorTarget(target *Target) {
+	logger.Info("Starting health check monitoring for target %d (%s:%d)",
+		target.Config.ID, target.Config.Hostname, target.Config.Port)
+
+	// Initial check
+	oldStatus := target.Status
+	m.performHealthCheck(target)
+
+	// Notify callback after initial check if status changed or if it's the first check
+	if (oldStatus != target.Status || oldStatus == StatusUnknown) && m.callback != nil {
+		logger.Info("Target %d initial status: %s", target.Config.ID, target.Status.String())
+		go m.callback(m.GetTargets())
+	}
+
+	// Set up timer based on current status
+	interval := time.Duration(target.Config.Interval) * time.Second
+	if target.Status == StatusUnhealthy {
+		interval = time.Duration(target.Config.UnhealthyInterval) * time.Second
+	}
+
+	logger.Debug("Target %d: initial check interval set to %v", target.Config.ID, interval)
+	target.timer = time.NewTimer(interval)
+	defer target.timer.Stop()
+
+	for {
+		select {
+		case <-target.ctx.Done():
+			logger.Info("Stopping health check monitoring for target %d", target.Config.ID)
+			return
+		case <-target.timer.C:
+			oldStatus := target.Status
+			m.performHealthCheck(target)
+
+			// Update timer interval if status changed
+			newInterval := time.Duration(target.Config.Interval) * time.Second
+			if target.Status == StatusUnhealthy {
+				newInterval = time.Duration(target.Config.UnhealthyInterval) * time.Second
+			}
+
+			if newInterval != interval {
+				logger.Debug("Target %d: updating check interval from %v to %v due to status change",
+					target.Config.ID, interval, newInterval)
+				interval = newInterval
+			}
+
+			// Reset timer for next check with current interval
+			target.timer.Reset(interval)
+
+			// Notify callback if status changed
+			if oldStatus != target.Status && m.callback != nil {
+				logger.Info("Target %d status changed: %s -> %s",
+					target.Config.ID, oldStatus.String(), target.Status.String())
+				go m.callback(m.GetTargets())
+			}
+		}
+	}
+}
+
+// performHealthCheck performs a health check on a target and applies threshold logic
+func (m *Monitor) performHealthCheck(target *Target) {
+	target.CheckCount++
+	target.LastCheck = time.Now()
+
+	var passed bool
+	var checkErr string
+
+	switch strings.ToLower(target.Config.Mode) {
+	case "tcp":
+		passed, checkErr = m.performTCPCheck(target)
+	default:
+		// "http", "https", or anything else falls through to HTTP
+		passed, checkErr = m.performHTTPCheck(target)
+	}
+
+	if passed {
+		target.consecutiveFailures = 0
+		target.consecutiveSuccesses++
+
+		logger.Debug("Target %d: check passed (consecutive successes: %d / threshold: %d)",
+			target.Config.ID, target.consecutiveSuccesses, target.Config.HealthyThreshold)
+
+		if target.consecutiveSuccesses >= target.Config.HealthyThreshold {
+			target.Status = StatusHealthy
+			target.LastError = ""
+		}
+	} else {
+		target.consecutiveSuccesses = 0
+		target.consecutiveFailures++
+		target.LastError = checkErr
+
+		logger.Debug("Target %d: check failed (consecutive failures: %d / threshold: %d): %s",
+			target.Config.ID, target.consecutiveFailures, target.Config.UnhealthyThreshold, checkErr)
+
+		if target.consecutiveFailures >= target.Config.UnhealthyThreshold {
+			target.Status = StatusUnhealthy
+		}
+	}
+}
+
+// performTCPCheck dials the target's host:port over TCP and returns whether it succeeded
+func (m *Monitor) performTCPCheck(target *Target) (bool, string) {
+	address := net.JoinHostPort(target.Config.Hostname, strconv.Itoa(target.Config.Port))
+	timeout := time.Duration(target.Config.Timeout) * time.Second
+
+	logger.Debug("Target %d: performing TCP health check to %s (timeout: %v)",
+		target.Config.ID, address, timeout)
+
+	conn, err := net.DialTimeout("tcp", address, timeout)
+	if err != nil {
+		msg := fmt.Sprintf("TCP dial failed: %v", err)
+		logger.Warn("Target %d: %s", target.Config.ID, msg)
+		return false, msg
+	}
+	conn.Close()
+
+	logger.Debug("Target %d: TCP health check passed", target.Config.ID)
+	return true, ""
+}
+
+// performHTTPCheck performs an HTTP/HTTPS health check and returns whether it succeeded
+func (m *Monitor) performHTTPCheck(target *Target) (bool, string) {
+	// Build URL (use net.JoinHostPort to properly handle IPv6 addresses with ports)
+	host := target.Config.Hostname
+	if target.Config.Port > 0 {
+		host = net.JoinHostPort(target.Config.Hostname, strconv.Itoa(target.Config.Port))
+	}
+	url := fmt.Sprintf("%s://%s", target.Config.Scheme, host)
+	if target.Config.Path != "" {
+		if !strings.HasPrefix(target.Config.Path, "/") {
+			url += "/"
+		}
+		url += target.Config.Path
+	}
+
+	logger.Debug("Target %d: performing HTTP health check %d to %s",
+		target.Config.ID, target.CheckCount, url)
+
+	if target.Config.Scheme == "https" {
+		logger.Debug("Target %d: HTTPS health check with certificate enforcement: %t",
+			target.Config.ID, m.enforceCert)
+	}
+
+	// Create request with timeout context
+	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(target.Config.Timeout)*time.Second)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, target.Config.Method, url, nil)
+	if err != nil {
+		msg := fmt.Sprintf("failed to create request: %v", err)
+		logger.Warn("Target %d: %s", target.Config.ID, msg)
+		return false, msg
+	}
+
+	// Add headers
+	for key, value := range target.Config.Headers {
+		// Handle Host header specially - it must be set on req.Host, not in headers
+		if strings.EqualFold(key, "Host") {
+			req.Host = value
+		} else {
+			req.Header.Set(key, value)
+		}
+	}
+
+	// Perform request
+	resp, err := target.client.Do(req)
+	if err != nil {
+		msg := fmt.Sprintf("request failed: %v", err)
+		logger.Warn("Target %d: health check failed: %v", target.Config.ID, err)
+		return false, msg
+	}
+	defer resp.Body.Close()
+
+	// Check response status
+	if target.Config.Status > 0 {
+		// Check for specific status code
+		logger.Debug("Target %d: checking status against expected code %d", target.Config.ID, target.Config.Status)
+		if resp.StatusCode == target.Config.Status {
+			logger.Debug("Target %d: health check passed (status: %d)", target.Config.ID, resp.StatusCode)
+			return true, ""
+		}
+		msg := fmt.Sprintf("unexpected status code: %d (expected: %d)", resp.StatusCode, target.Config.Status)
+		logger.Warn("Target %d: %s", target.Config.ID, msg)
+		return false, msg
+	}
+
+	// Default: check for 2xx range
+	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+		logger.Debug("Target %d: health check passed (status: %d)", target.Config.ID, resp.StatusCode)
+		return true, ""
+	}
+
+	msg := fmt.Sprintf("unhealthy status code: %d", resp.StatusCode)
+	logger.Warn("Target %d: health check failed with status code %d", target.Config.ID, resp.StatusCode)
+	return false, msg
+}
+
+// Stop stops monitoring all targets
+func (m *Monitor) Stop() {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	targetCount := len(m.targets)
+	logger.Info("Stopping health check monitor with %d targets", targetCount)
+
+	for id, target := range m.targets {
+		logger.Debug("Stopping monitoring for target %d", id)
+		target.cancel()
+	}
+	m.targets = make(map[int]*Target)
+
+	logger.Info("Health check monitor stopped")
+}
+
+// EnableTarget enables monitoring for a specific target
+func (m *Monitor) EnableTarget(id int) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	target, exists := m.targets[id]
+	if !exists {
+		logger.Warn("Attempted to enable non-existent target with ID %d", id)
+		return fmt.Errorf("target with id %d not found", id)
+	}
+
+	if !target.Config.Enabled {
+		logger.Info("Enabling health check monitoring for target %d", id)
+		target.Config.Enabled = true
+		target.cancel() // Stop existing monitoring
+
+		ctx, cancel := context.WithCancel(context.Background())
+		target.ctx = ctx
+		target.cancel = cancel
+
+		go m.monitorTarget(target)
+	} else {
+		logger.Debug("Target %d is already enabled", id)
+	}
+
+	return nil
+}
+
+// DisableTarget disables monitoring for a specific target
+func (m *Monitor) DisableTarget(id int) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	target, exists := m.targets[id]
+	if !exists {
+		logger.Warn("Attempted to disable non-existent target with ID %d", id)
+		return fmt.Errorf("target with id %d not found", id)
+	}
+
+	if target.Config.Enabled {
+		logger.Info("Disabling health check monitoring for target %d", id)
+		target.Config.Enabled = false
+		target.cancel()
+		target.Status = StatusUnknown
+
+		// Notify callback of status change
+		if m.callback != nil {
+			go m.callback(m.getAllTargetsUnsafe())
+		}
+	} else {
+		logger.Debug("Target %d is already disabled", id)
+	}
+
+	return nil
+}
+
+// GetTargetIDs returns a slice of all current target IDs
+func (m *Monitor) GetTargetIDs() []int {
+	m.mutex.RLock()
+	defer m.mutex.RUnlock()
+
+	ids := make([]int, 0, len(m.targets))
+	for id := range m.targets {
+		ids = append(ids, id)
+	}
+	return ids
+}
+
+// SyncTargets synchronizes the current targets to match the desired set.
+// It removes targets not in the desired set and adds targets that are missing.
+func (m *Monitor) SyncTargets(desiredConfigs []Config) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+
+	logger.Info("Syncing health check targets: %d desired targets", len(desiredConfigs))
+
+	// Build a set of desired target IDs
+	desiredIDs := make(map[int]Config)
+	for _, config := range desiredConfigs {
+		desiredIDs[config.ID] = config
+	}
+
+	// Find targets to remove (exist but not in desired set)
+	var toRemove []int
+	for id := range m.targets {
+		if _, exists := desiredIDs[id]; !exists {
+			toRemove = append(toRemove, id)
+		}
+	}
+
+	// Remove targets that are not in the desired set
+	for _, id := range toRemove {
+		logger.Info("Sync: removing health check target %d", id)
+		if target, exists := m.targets[id]; exists {
+			target.cancel()
+			delete(m.targets, id)
+		}
+	}
+
+	// Add or update targets from the desired set
+	var addedCount, updatedCount int
+	for id, config := range desiredIDs {
+		if existing, exists := m.targets[id]; exists {
+			// Target exists - check if config changed and update if needed
+			// For now, we'll replace it to ensure config is up to date
+			logger.Debug("Sync: updating health check target %d", id)
+			existing.cancel()
+			delete(m.targets, id)
+			if err := m.addTargetUnsafe(config); err != nil {
+				logger.Error("Sync: failed to update target %d: %v", id, err)
+				return fmt.Errorf("failed to update target %d: %v", id, err)
+			}
+			updatedCount++
+		} else {
+			// Target doesn't exist - add it
+			logger.Debug("Sync: adding health check target %d", id)
+			if err := m.addTargetUnsafe(config); err != nil {
+				logger.Error("Sync: failed to add target %d: %v", id, err)
+				return fmt.Errorf("failed to add target %d: %v", id, err)
+			}
+			addedCount++
+		}
+	}
+
+	logger.Info("Sync complete: removed %d, added %d, updated %d targets",
+		len(toRemove), addedCount, updatedCount)
+
+	// Notify callback if any changes were made
+	if (len(toRemove) > 0 || addedCount > 0 || updatedCount > 0) && m.callback != nil {
+		go m.callback(m.getAllTargetsUnsafe())
+	}
+
+	return nil
+}

holepunch/holepunch.go

@@ -0,0 +1,616 @@
+package holepunch
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"strconv"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/bind"
+	"github.com/fosrl/newt/logger"
+	"github.com/fosrl/newt/util"
+	"golang.org/x/crypto/chacha20poly1305"
+	"golang.org/x/crypto/curve25519"
+	mrand "golang.org/x/exp/rand"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+)
+
+// ExitNode represents a WireGuard exit node for hole punching
+type ExitNode struct {
+	Endpoint  string `json:"endpoint"`
+	RelayPort uint16 `json:"relayPort"`
+	PublicKey string `json:"publicKey"`
+	SiteIds   []int  `json:"siteIds,omitempty"`
+}
+
+// Manager handles UDP hole punching operations
+type Manager struct {
+	mu          sync.Mutex
+	running     bool
+	stopChan    chan struct{}
+	sharedBind  *bind.SharedBind
+	ID          string
+	token       string
+	publicKey   string
+	clientType  string
+	exitNodes   map[string]ExitNode // key is endpoint
+	updateChan  chan struct{}        // signals the goroutine to refresh exit nodes
+	publicDNS []string
+
+	sendHolepunchInterval    time.Duration
+	sendHolepunchIntervalMin time.Duration
+	sendHolepunchIntervalMax time.Duration
+	defaultIntervalMin       time.Duration
+	defaultIntervalMax       time.Duration
+}
+
+const defaultSendHolepunchIntervalMax = 60 * time.Second
+const defaultSendHolepunchIntervalMin = 1 * time.Second
+
+// NewManager creates a new hole punch manager
+func NewManager(sharedBind *bind.SharedBind, ID string, clientType string, publicKey string, publicDNS []string) *Manager {
+	return &Manager{
+		sharedBind:               sharedBind,
+		ID:                       ID,
+		clientType:               clientType,
+		publicKey:                publicKey,
+		publicDNS:              publicDNS,
+		exitNodes:                make(map[string]ExitNode),
+		sendHolepunchInterval:    defaultSendHolepunchIntervalMin,
+		sendHolepunchIntervalMin: defaultSendHolepunchIntervalMin,
+		sendHolepunchIntervalMax: defaultSendHolepunchIntervalMax,
+		defaultIntervalMin:       defaultSendHolepunchIntervalMin,
+		defaultIntervalMax:       defaultSendHolepunchIntervalMax,
+	}
+}
+
+// SetToken updates the authentication token used for hole punching
+func (m *Manager) SetToken(token string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.token = token
+}
+
+// IsRunning returns whether hole punching is currently active
+func (m *Manager) IsRunning() bool {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.running
+}
+
+// Stop stops any ongoing hole punch operations
+func (m *Manager) Stop() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if !m.running {
+		return
+	}
+
+	if m.stopChan != nil {
+		close(m.stopChan)
+		m.stopChan = nil
+	}
+
+	if m.updateChan != nil {
+		close(m.updateChan)
+		m.updateChan = nil
+	}
+
+	m.running = false
+	logger.Info("Hole punch manager stopped")
+}
+
+// AddExitNode adds a new exit node to the rotation if it doesn't already exist
+func (m *Manager) AddExitNode(exitNode ExitNode) bool {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if _, exists := m.exitNodes[exitNode.Endpoint]; exists {
+		logger.Debug("Exit node %s already exists in rotation", exitNode.Endpoint)
+		return false
+	}
+
+	m.exitNodes[exitNode.Endpoint] = exitNode
+	logger.Info("Added exit node %s to hole punch rotation", exitNode.Endpoint)
+
+	// Signal the goroutine to refresh if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+
+	return true
+}
+
+// RemoveExitNode removes an exit node from the rotation
+func (m *Manager) RemoveExitNode(endpoint string) bool {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if _, exists := m.exitNodes[endpoint]; !exists {
+		logger.Debug("Exit node %s not found in rotation", endpoint)
+		return false
+	}
+
+	delete(m.exitNodes, endpoint)
+	logger.Info("Removed exit node %s from hole punch rotation", endpoint)
+
+	// Signal the goroutine to refresh if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+
+	return true
+}
+
+/*
+RemoveExitNodesByPeer removes the peer ID from the SiteIds list in each exit node.
+If the SiteIds list becomes empty after removal, the exit node is removed entirely.
+Returns the number of exit nodes removed.
+*/
+func (m *Manager) RemoveExitNodesByPeer(peerID int) int {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	removed := 0
+	for endpoint, node := range m.exitNodes {
+		// Remove peerID from SiteIds if present
+		newSiteIds := make([]int, 0, len(node.SiteIds))
+		for _, id := range node.SiteIds {
+			if id != peerID {
+				newSiteIds = append(newSiteIds, id)
+			}
+		}
+		if len(newSiteIds) != len(node.SiteIds) {
+			node.SiteIds = newSiteIds
+			if len(node.SiteIds) == 0 {
+				delete(m.exitNodes, endpoint)
+				logger.Info("Removed exit node %s as no more site IDs remain after removing peer %d", endpoint, peerID)
+				removed++
+			} else {
+				m.exitNodes[endpoint] = node
+				logger.Info("Removed peer %d from exit node %s site IDs", peerID, endpoint)
+			}
+		}
+	}
+
+	if removed > 0 {
+		// Signal the goroutine to refresh if running
+		if m.running && m.updateChan != nil {
+			select {
+			case m.updateChan <- struct{}{}:
+			default:
+				// Channel full or closed, skip
+			}
+		}
+	}
+
+	return removed
+}
+
+// GetExitNodes returns a copy of the current exit nodes
+func (m *Manager) GetExitNodes() []ExitNode {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	nodes := make([]ExitNode, 0, len(m.exitNodes))
+	for _, node := range m.exitNodes {
+		nodes = append(nodes, node)
+	}
+	return nodes
+}
+
+// SetServerHolepunchInterval sets custom min and max intervals for hole punching.
+// This is useful for low power mode where longer intervals are desired.
+func (m *Manager) SetServerHolepunchInterval(min, max time.Duration) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	m.sendHolepunchIntervalMin = min
+	m.sendHolepunchIntervalMax = max
+	m.sendHolepunchInterval = min
+
+	logger.Info("Set hole punch intervals: min=%v, max=%v", min, max)
+
+	// Signal the goroutine to apply the new interval if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+}
+
+// GetInterval returns the current min and max intervals
+func (m *Manager) GetServerHolepunchInterval() (min, max time.Duration) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.sendHolepunchIntervalMin, m.sendHolepunchIntervalMax
+}
+
+// ResetServerHolepunchInterval resets the hole punch interval back to the default values.
+// This restores normal operation after low power mode or other custom settings.
+func (m *Manager) ResetServerHolepunchInterval() {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	m.sendHolepunchIntervalMin = m.defaultIntervalMin
+	m.sendHolepunchIntervalMax = m.defaultIntervalMax
+	m.sendHolepunchInterval = m.defaultIntervalMin
+
+	logger.Info("Reset hole punch intervals to defaults: min=%v, max=%v", m.defaultIntervalMin, m.defaultIntervalMax)
+
+	// Signal the goroutine to apply the new interval if running
+	if m.running && m.updateChan != nil {
+		select {
+		case m.updateChan <- struct{}{}:
+		default:
+			// Channel full or closed, skip
+		}
+	}
+}
+
+// TriggerHolePunch sends an immediate hole punch packet to all configured exit nodes
+// This is useful for triggering hole punching on demand without waiting for the interval
+func (m *Manager) TriggerHolePunch() error {
+	m.mu.Lock()
+
+	if len(m.exitNodes) == 0 {
+		m.mu.Unlock()
+		return fmt.Errorf("no exit nodes configured")
+	}
+
+	// Get a copy of exit nodes to work with
+	currentExitNodes := make([]ExitNode, 0, len(m.exitNodes))
+	for _, node := range m.exitNodes {
+		currentExitNodes = append(currentExitNodes, node)
+	}
+	m.mu.Unlock()
+
+	logger.Info("Triggering on-demand hole punch to %d exit nodes", len(currentExitNodes))
+
+	// Send hole punch to all exit nodes
+	successCount := 0
+	for _, exitNode := range currentExitNodes {
+		var host string
+		var err error
+		if len(m.publicDNS) > 0 {
+			host, err = util.ResolveDomainUpstream(exitNode.Endpoint, m.publicDNS)
+		} else {
+			host, err = util.ResolveDomain(exitNode.Endpoint)
+		}
+		if err != nil {
+			logger.Warn("Failed to resolve endpoint %s: %v", exitNode.Endpoint, err)
+			continue
+		}
+
+		serverAddr := net.JoinHostPort(host, strconv.Itoa(int(exitNode.RelayPort)))
+		remoteAddr, err := net.ResolveUDPAddr("udp", serverAddr)
+		if err != nil {
+			logger.Error("Failed to resolve UDP address %s: %v", serverAddr, err)
+			continue
+		}
+
+		if err := m.sendHolePunch(remoteAddr, exitNode.PublicKey); err != nil {
+			logger.Warn("Failed to send on-demand hole punch to %s: %v", exitNode.Endpoint, err)
+			continue
+		}
+
+		logger.Debug("Sent on-demand hole punch to %s", exitNode.Endpoint)
+		successCount++
+	}
+
+	if successCount == 0 {
+		return fmt.Errorf("failed to send hole punch to any exit node")
+	}
+
+	logger.Info("Successfully sent on-demand hole punch to %d/%d exit nodes", successCount, len(currentExitNodes))
+	return nil
+}
+
+// StartMultipleExitNodes starts hole punching to multiple exit nodes
+func (m *Manager) StartMultipleExitNodes(exitNodes []ExitNode) error {
+	m.mu.Lock()
+
+	if m.running {
+		m.mu.Unlock()
+		logger.Debug("UDP hole punch already running, skipping new request")
+		return fmt.Errorf("hole punch already running")
+	}
+
+	// Populate exit nodes map
+	m.exitNodes = make(map[string]ExitNode)
+	for _, node := range exitNodes {
+		m.exitNodes[node.Endpoint] = node
+	}
+
+	m.running = true
+	m.stopChan = make(chan struct{})
+	m.updateChan = make(chan struct{}, 1)
+	m.mu.Unlock()
+
+	logger.Debug("Starting UDP hole punch to %d exit nodes with shared bind", len(exitNodes))
+
+	go m.runMultipleExitNodes()
+
+	return nil
+}
+
+// Start starts hole punching with the current set of exit nodes
+func (m *Manager) Start() error {
+	m.mu.Lock()
+
+	if m.running {
+		m.mu.Unlock()
+		logger.Debug("UDP hole punch already running")
+		return fmt.Errorf("hole punch already running")
+	}
+
+	m.running = true
+	m.stopChan = make(chan struct{})
+	m.updateChan = make(chan struct{}, 1)
+	nodeCount := len(m.exitNodes)
+	m.mu.Unlock()
+
+	if nodeCount == 0 {
+		logger.Info("Starting UDP hole punch manager (waiting for exit nodes to be added)")
+	} else {
+		logger.Info("Starting UDP hole punch with %d exit nodes", nodeCount)
+	}
+
+	go m.runMultipleExitNodes()
+
+	return nil
+}
+
+// runMultipleExitNodes performs hole punching to multiple exit nodes
+func (m *Manager) runMultipleExitNodes() {
+	defer func() {
+		m.mu.Lock()
+		m.running = false
+		m.mu.Unlock()
+		logger.Info("UDP hole punch goroutine ended for all exit nodes")
+	}()
+
+	// Resolve all endpoints upfront
+	type resolvedExitNode struct {
+		remoteAddr   *net.UDPAddr
+		publicKey    string
+		endpointName string
+	}
+
+	resolveNodes := func() []resolvedExitNode {
+		m.mu.Lock()
+		currentExitNodes := make([]ExitNode, 0, len(m.exitNodes))
+		for _, node := range m.exitNodes {
+			currentExitNodes = append(currentExitNodes, node)
+		}
+		m.mu.Unlock()
+
+		var resolvedNodes []resolvedExitNode
+		for _, exitNode := range currentExitNodes {
+			var host string
+			var err error
+			if len(m.publicDNS) > 0 {
+				host, err = util.ResolveDomainUpstream(exitNode.Endpoint, m.publicDNS)
+			} else {
+				host, err = util.ResolveDomain(exitNode.Endpoint)
+			}
+			if err != nil {
+				logger.Warn("Failed to resolve endpoint %s: %v", exitNode.Endpoint, err)
+				continue
+			}
+
+			serverAddr := net.JoinHostPort(host, strconv.Itoa(int(exitNode.RelayPort)))
+			remoteAddr, err := net.ResolveUDPAddr("udp", serverAddr)
+			if err != nil {
+				logger.Error("Failed to resolve UDP address %s: %v", serverAddr, err)
+				continue
+			}
+
+			resolvedNodes = append(resolvedNodes, resolvedExitNode{
+				remoteAddr:   remoteAddr,
+				publicKey:    exitNode.PublicKey,
+				endpointName: exitNode.Endpoint,
+			})
+			logger.Debug("Resolved exit node: %s -> %s", exitNode.Endpoint, remoteAddr.String())
+		}
+		return resolvedNodes
+	}
+
+	resolvedNodes := resolveNodes()
+
+	if len(resolvedNodes) == 0 {
+		logger.Info("No exit nodes available yet, waiting for nodes to be added")
+	} else {
+		// Send initial hole punch to all exit nodes
+		for _, node := range resolvedNodes {
+			if err := m.sendHolePunch(node.remoteAddr, node.publicKey); err != nil {
+				logger.Warn("Failed to send initial hole punch to %s: %v", node.endpointName, err)
+			}
+		}
+	}
+
+	// Start with minimum interval
+	m.mu.Lock()
+	m.sendHolepunchInterval = m.sendHolepunchIntervalMin
+	m.mu.Unlock()
+
+	ticker := time.NewTicker(m.sendHolepunchInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-m.stopChan:
+			logger.Debug("Hole punch stopped by signal")
+			return
+		case <-m.updateChan:
+			// Re-resolve exit nodes when update is signaled
+			logger.Info("Refreshing exit nodes for hole punching")
+			resolvedNodes = resolveNodes()
+			if len(resolvedNodes) == 0 {
+				logger.Warn("No exit nodes available after refresh")
+			} else {
+				logger.Info("Updated resolved nodes count: %d", len(resolvedNodes))
+			}
+			// Reset interval to minimum on update
+			m.mu.Lock()
+			m.sendHolepunchInterval = m.sendHolepunchIntervalMin
+			m.mu.Unlock()
+			ticker.Reset(m.sendHolepunchInterval)
+			// Send immediate hole punch to newly resolved nodes
+			for _, node := range resolvedNodes {
+				if err := m.sendHolePunch(node.remoteAddr, node.publicKey); err != nil {
+					logger.Debug("Failed to send hole punch to %s: %v", node.endpointName, err)
+				}
+			}
+		case <-ticker.C:
+			// Send hole punch to all exit nodes (if any are available)
+			if len(resolvedNodes) > 0 {
+				for _, node := range resolvedNodes {
+					if err := m.sendHolePunch(node.remoteAddr, node.publicKey); err != nil {
+						logger.Debug("Failed to send hole punch to %s: %v", node.endpointName, err)
+					}
+				}
+				// Exponential backoff: double the interval up to max
+				m.mu.Lock()
+				newInterval := m.sendHolepunchInterval * 2
+				if newInterval > m.sendHolepunchIntervalMax {
+					newInterval = m.sendHolepunchIntervalMax
+				}
+				if newInterval != m.sendHolepunchInterval {
+					m.sendHolepunchInterval = newInterval
+					ticker.Reset(m.sendHolepunchInterval)
+					logger.Debug("Increased hole punch interval to %v", m.sendHolepunchInterval)
+				}
+				m.mu.Unlock()
+			}
+		}
+	}
+}
+
+// sendHolePunch sends an encrypted hole punch packet using the shared bind
+func (m *Manager) sendHolePunch(remoteAddr *net.UDPAddr, serverPubKey string) error {
+	m.mu.Lock()
+	token := m.token
+	ID := m.ID
+	m.mu.Unlock()
+
+	if serverPubKey == "" || token == "" {
+		return fmt.Errorf("server public key or OLM token is empty")
+	}
+
+	var payload interface{}
+	if m.clientType == "newt" {
+		payload = struct {
+			ID        string `json:"newtId"`
+			Token     string `json:"token"`
+			PublicKey string `json:"publicKey"`
+		}{
+			ID:        ID,
+			Token:     token,
+			PublicKey: m.publicKey,
+		}
+	} else {
+		payload = struct {
+			ID        string `json:"olmId"`
+			Token     string `json:"token"`
+			PublicKey string `json:"publicKey"`
+		}{
+			ID:        ID,
+			Token:     token,
+			PublicKey: m.publicKey,
+		}
+	}
+
+	// Convert payload to JSON
+	payloadBytes, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("failed to marshal payload: %w", err)
+	}
+
+	// Encrypt the payload using the server's WireGuard public key
+	encryptedPayload, err := encryptPayload(payloadBytes, serverPubKey)
+	if err != nil {
+		return fmt.Errorf("failed to encrypt payload: %w", err)
+	}
+
+	jsonData, err := json.Marshal(encryptedPayload)
+	if err != nil {
+		return fmt.Errorf("failed to marshal encrypted payload: %w", err)
+	}
+
+	_, err = m.sharedBind.WriteToUDP(jsonData, remoteAddr)
+	if err != nil {
+		return fmt.Errorf("failed to write to UDP: %w", err)
+	}
+
+	logger.Debug("Sent UDP hole punch to %s: %s", remoteAddr.String(), string(jsonData))
+
+	return nil
+}
+
+// encryptPayload encrypts the payload using ChaCha20-Poly1305 AEAD with X25519 key exchange
+func encryptPayload(payload []byte, serverPublicKey string) (interface{}, error) {
+	// Generate an ephemeral keypair for this message
+	ephemeralPrivateKey, err := wgtypes.GeneratePrivateKey()
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate ephemeral private key: %v", err)
+	}
+	ephemeralPublicKey := ephemeralPrivateKey.PublicKey()
+
+	// Parse the server's public key
+	serverPubKey, err := wgtypes.ParseKey(serverPublicKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse server public key: %v", err)
+	}
+
+	// Use X25519 for key exchange
+	var ephPrivKeyFixed [32]byte
+	copy(ephPrivKeyFixed[:], ephemeralPrivateKey[:])
+
+	// Perform X25519 key exchange
+	sharedSecret, err := curve25519.X25519(ephPrivKeyFixed[:], serverPubKey[:])
+	if err != nil {
+		return nil, fmt.Errorf("failed to perform X25519 key exchange: %v", err)
+	}
+
+	// Create an AEAD cipher using the shared secret
+	aead, err := chacha20poly1305.New(sharedSecret)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create AEAD cipher: %v", err)
+	}
+
+	// Generate a random nonce
+	nonce := make([]byte, aead.NonceSize())
+	if _, err := mrand.Read(nonce); err != nil {
+		return nil, fmt.Errorf("failed to generate nonce: %v", err)
+	}
+
+	// Encrypt the payload
+	ciphertext := aead.Seal(nil, nonce, payload, nil)
+
+	// Prepare the final encrypted message
+	encryptedMsg := struct {
+		EphemeralPublicKey string `json:"ephemeralPublicKey"`
+		Nonce              []byte `json:"nonce"`
+		Ciphertext         []byte `json:"ciphertext"`
+	}{
+		EphemeralPublicKey: ephemeralPublicKey.String(),
+		Nonce:              nonce,
+		Ciphertext:         ciphertext,
+	}
+
+	return encryptedMsg, nil
+}

holepunch/tester.go

@@ -0,0 +1,412 @@
+package holepunch
+
+import (
+	"crypto/rand"
+	"fmt"
+	"net"
+	"net/netip"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/bind"
+	"github.com/fosrl/newt/logger"
+	"github.com/fosrl/newt/util"
+)
+
+// TestResult represents the result of a connection test
+type TestResult struct {
+	// Success indicates whether the test was successful
+	Success bool
+	// RTT is the round-trip time of the test packet
+	RTT time.Duration
+	// Endpoint is the endpoint that was tested
+	Endpoint string
+	// Error contains any error that occurred during the test
+	Error error
+}
+
+// TestConnectionOptions configures the connection test
+type TestConnectionOptions struct {
+	// Timeout is how long to wait for a response (default: 5 seconds)
+	Timeout time.Duration
+	// Retries is the number of times to retry on failure (default: 0)
+	Retries int
+}
+
+// DefaultTestOptions returns the default test options
+func DefaultTestOptions() TestConnectionOptions {
+	return TestConnectionOptions{
+		Timeout: 5 * time.Second,
+		Retries: 0,
+	}
+}
+
+// cachedAddr holds a cached resolved UDP address
+type cachedAddr struct {
+	addr      *net.UDPAddr
+	resolvedAt time.Time
+}
+
+// HolepunchTester monitors holepunch connectivity using magic packets
+type HolepunchTester struct {
+	sharedBind  *bind.SharedBind
+	publicDNS []string
+	mu          sync.RWMutex
+	running     bool
+	stopChan    chan struct{}
+
+	// Pending requests waiting for responses (key: echo data as string)
+	pendingRequests sync.Map // map[string]*pendingRequest
+
+	// Callback when connection status changes
+	callback HolepunchStatusCallback
+
+	// Address cache to avoid repeated DNS/UDP resolution
+	addrCache    map[string]*cachedAddr
+	addrCacheMu  sync.RWMutex
+	addrCacheTTL time.Duration // How long cached addresses are valid
+}
+
+// HolepunchStatus represents the status of a holepunch connection
+type HolepunchStatus struct {
+	Endpoint  string
+	Connected bool
+	RTT       time.Duration
+}
+
+// HolepunchStatusCallback is called when holepunch status changes
+type HolepunchStatusCallback func(status HolepunchStatus)
+
+// pendingRequest tracks a pending test request
+type pendingRequest struct {
+	endpoint  string
+	sentAt    time.Time
+	replyChan chan time.Duration
+}
+
+// NewHolepunchTester creates a new holepunch tester using the given SharedBind
+func NewHolepunchTester(sharedBind *bind.SharedBind, publicDNS []string) *HolepunchTester {
+	return &HolepunchTester{
+		sharedBind:   sharedBind,
+		publicDNS:  publicDNS,
+		addrCache:    make(map[string]*cachedAddr),
+		addrCacheTTL: 5 * time.Minute, // Cache addresses for 5 minutes
+	}
+}
+
+// SetCallback sets the callback for connection status changes
+func (t *HolepunchTester) SetCallback(callback HolepunchStatusCallback) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.callback = callback
+}
+
+// Start begins listening for magic packet responses
+func (t *HolepunchTester) Start() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if t.running {
+		return fmt.Errorf("tester already running")
+	}
+
+	if t.sharedBind == nil {
+		return fmt.Errorf("sharedBind is nil")
+	}
+
+	t.running = true
+	t.stopChan = make(chan struct{})
+
+	// Register our callback with the SharedBind to receive magic responses
+	t.sharedBind.SetMagicResponseCallback(t.handleResponse)
+
+	logger.Debug("HolepunchTester started")
+	return nil
+}
+
+// Stop stops the tester
+func (t *HolepunchTester) Stop() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if !t.running {
+		return
+	}
+
+	t.running = false
+	close(t.stopChan)
+
+	// Clear the callback
+	if t.sharedBind != nil {
+		t.sharedBind.SetMagicResponseCallback(nil)
+	}
+
+	// Cancel all pending requests
+	t.pendingRequests.Range(func(key, value interface{}) bool {
+		if req, ok := value.(*pendingRequest); ok {
+			close(req.replyChan)
+		}
+		t.pendingRequests.Delete(key)
+		return true
+	})
+
+	// Clear address cache
+	t.addrCacheMu.Lock()
+	t.addrCache = make(map[string]*cachedAddr)
+	t.addrCacheMu.Unlock()
+
+	logger.Debug("HolepunchTester stopped")
+}
+
+// resolveEndpoint resolves an endpoint to a UDP address, using cache when possible
+func (t *HolepunchTester) resolveEndpoint(endpoint string) (*net.UDPAddr, error) {
+	// Check cache first
+	t.addrCacheMu.RLock()
+	cached, ok := t.addrCache[endpoint]
+	ttl := t.addrCacheTTL
+	t.addrCacheMu.RUnlock()
+
+	if ok && time.Since(cached.resolvedAt) < ttl {
+		return cached.addr, nil
+	}
+
+	// Resolve the endpoint
+	var host string
+	var err error
+	if len(t.publicDNS) > 0 {
+		host, err = util.ResolveDomainUpstream(endpoint, t.publicDNS)
+	} else {
+		host, err = util.ResolveDomain(endpoint)
+	}
+	if err != nil {
+		host = endpoint
+	}
+
+	_, _, err = net.SplitHostPort(host)
+	if err != nil {
+		host = net.JoinHostPort(host, "21820")
+	}
+
+	remoteAddr, err := net.ResolveUDPAddr("udp", host)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve UDP address %s: %w", host, err)
+	}
+
+	// Cache the result
+	t.addrCacheMu.Lock()
+	t.addrCache[endpoint] = &cachedAddr{
+		addr:       remoteAddr,
+		resolvedAt: time.Now(),
+	}
+	t.addrCacheMu.Unlock()
+
+	return remoteAddr, nil
+}
+
+// InvalidateCache removes a specific endpoint from the address cache
+func (t *HolepunchTester) InvalidateCache(endpoint string) {
+	t.addrCacheMu.Lock()
+	delete(t.addrCache, endpoint)
+	t.addrCacheMu.Unlock()
+}
+
+// ClearCache clears all cached addresses
+func (t *HolepunchTester) ClearCache() {
+	t.addrCacheMu.Lock()
+	t.addrCache = make(map[string]*cachedAddr)
+	t.addrCacheMu.Unlock()
+}
+
+// handleResponse is called by SharedBind when a magic response is received
+func (t *HolepunchTester) handleResponse(addr netip.AddrPort, echoData []byte) {
+	// logger.Debug("Received magic response from %s", addr.String())
+	key := string(echoData)
+
+	value, ok := t.pendingRequests.LoadAndDelete(key)
+	if !ok {
+		// No matching request found
+		logger.Debug("No pending request found for magic response from %s", addr.String())
+		return
+	}
+
+	req := value.(*pendingRequest)
+	rtt := time.Since(req.sentAt)
+	// logger.Debug("Magic response matched pending request for %s (RTT: %v)", req.endpoint, rtt)
+
+	// Send RTT to the waiting goroutine (non-blocking)
+	select {
+	case req.replyChan <- rtt:
+	default:
+	}
+}
+
+// TestEndpoint sends a magic test packet to the endpoint and waits for a response.
+// This uses the SharedBind so packets come from the same source port as WireGuard.
+func (t *HolepunchTester) TestEndpoint(endpoint string, timeout time.Duration) TestResult {
+	result := TestResult{
+		Endpoint: endpoint,
+	}
+
+	t.mu.RLock()
+	running := t.running
+	sharedBind := t.sharedBind
+	t.mu.RUnlock()
+
+	if !running {
+		result.Error = fmt.Errorf("tester not running")
+		return result
+	}
+
+	if sharedBind == nil || sharedBind.IsClosed() {
+		result.Error = fmt.Errorf("sharedBind is nil or closed")
+		return result
+	}
+
+	// Resolve the endpoint (using cache)
+	remoteAddr, err := t.resolveEndpoint(endpoint)
+	if err != nil {
+		result.Error = err
+		return result
+	}
+
+	// Generate random data for the test packet
+	randomData := make([]byte, bind.MagicPacketDataLen)
+	if _, err := rand.Read(randomData); err != nil {
+		result.Error = fmt.Errorf("failed to generate random data: %w", err)
+		return result
+	}
+
+	// Create a pending request
+	req := &pendingRequest{
+		endpoint:  endpoint,
+		sentAt:    time.Now(),
+		replyChan: make(chan time.Duration, 1),
+	}
+
+	key := string(randomData)
+	t.pendingRequests.Store(key, req)
+
+	// Build the test request packet
+	request := make([]byte, bind.MagicTestRequestLen)
+	copy(request, bind.MagicTestRequest)
+	copy(request[len(bind.MagicTestRequest):], randomData)
+
+	// Send the test packet
+	_, err = sharedBind.WriteToUDP(request, remoteAddr)
+	if err != nil {
+		t.pendingRequests.Delete(key)
+		result.Error = fmt.Errorf("failed to send test packet: %w", err)
+		return result
+	}
+
+	// Wait for response with timeout
+	select {
+	case rtt, ok := <-req.replyChan:
+		if ok {
+			result.Success = true
+			result.RTT = rtt
+		} else {
+			result.Error = fmt.Errorf("request cancelled")
+		}
+	case <-time.After(timeout):
+		t.pendingRequests.Delete(key)
+		result.Error = fmt.Errorf("timeout waiting for response")
+	}
+
+	return result
+}
+
+// TestConnectionWithBind sends a magic test packet using an existing SharedBind.
+// This is useful when you want to test the connection through the same socket
+// that WireGuard is using, which tests the actual hole-punched path.
+func TestConnectionWithBind(sharedBind *bind.SharedBind, endpoint string, opts *TestConnectionOptions) TestResult {
+	if opts == nil {
+		defaultOpts := DefaultTestOptions()
+		opts = &defaultOpts
+	}
+
+	result := TestResult{
+		Endpoint: endpoint,
+	}
+
+	if sharedBind == nil {
+		result.Error = fmt.Errorf("sharedBind is nil")
+		return result
+	}
+
+	if sharedBind.IsClosed() {
+		result.Error = fmt.Errorf("sharedBind is closed")
+		return result
+	}
+
+	// Resolve the endpoint
+	host, err := util.ResolveDomain(endpoint)
+	if err != nil {
+		host = endpoint
+	}
+
+	_, _, err = net.SplitHostPort(host)
+	if err != nil {
+		host = net.JoinHostPort(host, "21820")
+	}
+
+	remoteAddr, err := net.ResolveUDPAddr("udp", host)
+	if err != nil {
+		result.Error = fmt.Errorf("failed to resolve UDP address %s: %w", host, err)
+		return result
+	}
+
+	// Generate random data for the test packet
+	randomData := make([]byte, bind.MagicPacketDataLen)
+	if _, err := rand.Read(randomData); err != nil {
+		result.Error = fmt.Errorf("failed to generate random data: %w", err)
+		return result
+	}
+
+	// Build the test request packet
+	request := make([]byte, bind.MagicTestRequestLen)
+	copy(request, bind.MagicTestRequest)
+	copy(request[len(bind.MagicTestRequest):], randomData)
+
+	// Get the underlying UDP connection to set read deadline and read response
+	udpConn := sharedBind.GetUDPConn()
+	if udpConn == nil {
+		result.Error = fmt.Errorf("could not get UDP connection from SharedBind")
+		return result
+	}
+
+	attempts := opts.Retries + 1
+	for attempt := 0; attempt < attempts; attempt++ {
+		if attempt > 0 {
+			logger.Debug("Retrying connection test to %s (attempt %d/%d)", endpoint, attempt+1, attempts)
+		}
+
+		// Note: We can't easily set a read deadline on the shared connection
+		// without affecting WireGuard, so we use a goroutine with timeout instead
+		startTime := time.Now()
+
+		// Send the test packet through the shared bind
+		_, err = sharedBind.WriteToUDP(request, remoteAddr)
+		if err != nil {
+			result.Error = fmt.Errorf("failed to send test packet: %w", err)
+			if attempt < attempts-1 {
+				continue
+			}
+			return result
+		}
+
+		// For shared bind test, we send the packet but can't easily wait for
+		// response without interfering with WireGuard's receive loop.
+		// The response will be handled by SharedBind automatically.
+		// We consider the test successful if the send succeeded.
+		// For a full round-trip test, use TestConnection() with a separate socket.
+
+		result.RTT = time.Since(startTime)
+		result.Success = true
+		result.Error = nil
+		logger.Debug("Test packet sent to %s via SharedBind", endpoint)
+		return result
+	}
+
+	return result
+}

internal/state/telemetry_view.go

@@ -0,0 +1,80 @@
+package state
+
+import (
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/fosrl/newt/internal/telemetry"
+)
+
+// TelemetryView is a minimal, thread-safe implementation to feed observables.
+// Since one Newt process represents one site, we expose a single logical site.
+// site_id is a resource attribute, so we do not emit per-site labels here.
+type TelemetryView struct {
+	online     atomic.Bool
+	lastHBUnix atomic.Int64 // unix seconds
+	// per-tunnel sessions
+	sessMu   sync.RWMutex
+	sessions map[string]*atomic.Int64
+}
+
+var (
+	globalView atomic.Pointer[TelemetryView]
+)
+
+// Global returns a singleton TelemetryView.
+func Global() *TelemetryView {
+	if v := globalView.Load(); v != nil { return v }
+	v := &TelemetryView{ sessions: make(map[string]*atomic.Int64) }
+	globalView.Store(v)
+	telemetry.RegisterStateView(v)
+	return v
+}
+
+// Instrumentation helpers
+func (v *TelemetryView) IncSessions(tunnelID string) {
+	v.sessMu.Lock(); defer v.sessMu.Unlock()
+	c := v.sessions[tunnelID]
+	if c == nil { c = &atomic.Int64{}; v.sessions[tunnelID] = c }
+	c.Add(1)
+}
+func (v *TelemetryView) DecSessions(tunnelID string) {
+	v.sessMu.Lock(); defer v.sessMu.Unlock()
+	if c := v.sessions[tunnelID]; c != nil {
+		c.Add(-1)
+		if c.Load() <= 0 { delete(v.sessions, tunnelID) }
+	}
+}
+func (v *TelemetryView) ClearTunnel(tunnelID string) {
+	v.sessMu.Lock(); defer v.sessMu.Unlock()
+	delete(v.sessions, tunnelID)
+}
+func (v *TelemetryView) SetOnline(b bool) { v.online.Store(b) }
+func (v *TelemetryView) TouchHeartbeat() { v.lastHBUnix.Store(time.Now().Unix()) }
+
+// --- telemetry.StateView interface ---
+
+func (v *TelemetryView) ListSites() []string { return []string{"self"} }
+func (v *TelemetryView) Online(_ string) (bool, bool) { return v.online.Load(), true }
+func (v *TelemetryView) LastHeartbeat(_ string) (time.Time, bool) {
+	sec := v.lastHBUnix.Load()
+	if sec == 0 { return time.Time{}, false }
+	return time.Unix(sec, 0), true
+}
+func (v *TelemetryView) ActiveSessions(_ string) (int64, bool) {
+	// aggregated sessions (not used for per-tunnel gauge)
+	v.sessMu.RLock(); defer v.sessMu.RUnlock()
+	var sum int64
+	for _, c := range v.sessions { if c != nil { sum += c.Load() } }
+	return sum, true
+}
+
+// Extended accessor used by telemetry callback to publish per-tunnel samples.
+func (v *TelemetryView) SessionsByTunnel() map[string]int64 {
+	v.sessMu.RLock(); defer v.sessMu.RUnlock()
+	out := make(map[string]int64, len(v.sessions))
+	for id, c := range v.sessions { if c != nil && c.Load() > 0 { out[id] = c.Load() } }
+	return out
+}
+

internal/telemetry/constants.go

@@ -0,0 +1,19 @@
+package telemetry
+
+// Protocol labels (low-cardinality)
+const (
+	ProtocolTCP = "tcp"
+	ProtocolUDP = "udp"
+)
+
+// Reconnect reason bins (fixed, low-cardinality)
+const (
+	ReasonServerRequest  = "server_request"
+	ReasonTimeout        = "timeout"
+	ReasonPeerClose      = "peer_close"
+	ReasonNetworkChange  = "network_change"
+	ReasonAuthError      = "auth_error"
+	ReasonHandshakeError = "handshake_error"
+	ReasonConfigChange   = "config_change"
+	ReasonError          = "error"
+)

internal/telemetry/constants_test.go

@@ -0,0 +1,32 @@
+package telemetry
+
+import "testing"
+
+func TestAllowedConstants(t *testing.T) {
+	allowedReasons := map[string]struct{}{
+		ReasonServerRequest:  {},
+		ReasonTimeout:        {},
+		ReasonPeerClose:      {},
+		ReasonNetworkChange:  {},
+		ReasonAuthError:      {},
+		ReasonHandshakeError: {},
+		ReasonConfigChange:   {},
+		ReasonError:          {},
+	}
+	for k := range allowedReasons {
+		if k == "" {
+			t.Fatalf("empty reason constant")
+		}
+	}
+
+	allowedProtocols := map[string]struct{}{
+		ProtocolTCP: {},
+		ProtocolUDP: {},
+	}
+	for k := range allowedProtocols {
+		if k == "" {
+			t.Fatalf("empty protocol constant")
+		}
+	}
+}
+

internal/telemetry/metrics.go

@@ -0,0 +1,542 @@
+package telemetry
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+)
+
+// Instruments and helpers for Newt metrics following the naming, units, and
+// low-cardinality label guidance from the issue description.
+//
+// Counters end with _total, durations are in seconds, sizes in bytes.
+// Only low-cardinality stable labels are supported: tunnel_id,
+// transport, direction, result, reason, error_type.
+var (
+	initOnce sync.Once
+
+	meter metric.Meter
+
+	// Site / Registration
+	mSiteRegistrations metric.Int64Counter
+	mSiteOnline        metric.Int64ObservableGauge
+	mSiteLastHeartbeat metric.Float64ObservableGauge
+
+	// Tunnel / Sessions
+	mTunnelSessions metric.Int64ObservableGauge
+	mTunnelBytes    metric.Int64Counter
+	mTunnelLatency  metric.Float64Histogram
+	mReconnects     metric.Int64Counter
+
+	// Connection / NAT
+	mConnAttempts metric.Int64Counter
+	mConnErrors   metric.Int64Counter
+
+	// Config/Restart
+	mConfigReloads     metric.Int64Counter
+	mConfigApply       metric.Float64Histogram
+	mCertRotationTotal metric.Int64Counter
+	mProcessStartTime  metric.Float64ObservableGauge
+
+	// Build info
+	mBuildInfo metric.Int64ObservableGauge
+
+	// WebSocket
+	mWSConnectLatency   metric.Float64Histogram
+	mWSMessages         metric.Int64Counter
+	mWSDisconnects      metric.Int64Counter
+	mWSKeepaliveFailure metric.Int64Counter
+	mWSSessionDuration  metric.Float64Histogram
+	mWSConnected        metric.Int64ObservableGauge
+	mWSReconnects       metric.Int64Counter
+
+	// Proxy
+	mProxyActiveConns      metric.Int64ObservableGauge
+	mProxyBufferBytes      metric.Int64ObservableGauge
+	mProxyAsyncBacklogByte metric.Int64ObservableGauge
+	mProxyDropsTotal       metric.Int64Counter
+	mProxyAcceptsTotal     metric.Int64Counter
+	mProxyConnDuration     metric.Float64Histogram
+	mProxyConnectionsTotal metric.Int64Counter
+
+	buildVersion     string
+	buildCommit      string
+	processStartUnix = float64(time.Now().UnixNano()) / 1e9
+	wsConnectedState atomic.Int64
+)
+
+// Proxy connection lifecycle events.
+const (
+	ProxyConnectionOpened = "opened"
+	ProxyConnectionClosed = "closed"
+)
+
+// attrsWithSite appends site/region labels only when explicitly enabled to keep
+// label cardinality low by default.
+func attrsWithSite(extra ...attribute.KeyValue) []attribute.KeyValue {
+	attrs := make([]attribute.KeyValue, len(extra))
+	copy(attrs, extra)
+	if ShouldIncludeSiteLabels() {
+		attrs = append(attrs, siteAttrs()...)
+	}
+	return attrs
+}
+
+func registerInstruments() error {
+	var err error
+	initOnce.Do(func() {
+		meter = otel.Meter("newt")
+		if e := registerSiteInstruments(); e != nil {
+			err = e
+			return
+		}
+		if e := registerTunnelInstruments(); e != nil {
+			err = e
+			return
+		}
+		if e := registerConnInstruments(); e != nil {
+			err = e
+			return
+		}
+		if e := registerConfigInstruments(); e != nil {
+			err = e
+			return
+		}
+		if e := registerBuildWSProxyInstruments(); e != nil {
+			err = e
+			return
+		}
+	})
+	return err
+}
+
+func registerSiteInstruments() error {
+	var err error
+	mSiteRegistrations, err = meter.Int64Counter("newt_site_registrations_total",
+		metric.WithDescription("Total site registration attempts"))
+	if err != nil {
+		return err
+	}
+	mSiteOnline, err = meter.Int64ObservableGauge("newt_site_online",
+		metric.WithDescription("Site online (0/1)"))
+	if err != nil {
+		return err
+	}
+	mSiteLastHeartbeat, err = meter.Float64ObservableGauge("newt_site_last_heartbeat_timestamp_seconds",
+		metric.WithDescription("Unix timestamp of the last site heartbeat"),
+		metric.WithUnit("s"))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func registerTunnelInstruments() error {
+	var err error
+	mTunnelSessions, err = meter.Int64ObservableGauge("newt_tunnel_sessions",
+		metric.WithDescription("Active tunnel sessions"))
+	if err != nil {
+		return err
+	}
+	mTunnelBytes, err = meter.Int64Counter("newt_tunnel_bytes_total",
+		metric.WithDescription("Tunnel bytes ingress/egress"),
+		metric.WithUnit("By"))
+	if err != nil {
+		return err
+	}
+	mTunnelLatency, err = meter.Float64Histogram("newt_tunnel_latency_seconds",
+		metric.WithDescription("Per-tunnel latency in seconds"),
+		metric.WithUnit("s"))
+	if err != nil {
+		return err
+	}
+	mReconnects, err = meter.Int64Counter("newt_tunnel_reconnects_total",
+		metric.WithDescription("Tunnel reconnect events"))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func registerConnInstruments() error {
+	var err error
+	mConnAttempts, err = meter.Int64Counter("newt_connection_attempts_total",
+		metric.WithDescription("Connection attempts"))
+	if err != nil {
+		return err
+	}
+	mConnErrors, err = meter.Int64Counter("newt_connection_errors_total",
+		metric.WithDescription("Connection errors by type"))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func registerConfigInstruments() error {
+	mConfigReloads, _ = meter.Int64Counter("newt_config_reloads_total",
+		metric.WithDescription("Configuration reloads"))
+	mConfigApply, _ = meter.Float64Histogram("newt_config_apply_seconds",
+		metric.WithDescription("Configuration apply duration in seconds"),
+		metric.WithUnit("s"))
+	mCertRotationTotal, _ = meter.Int64Counter("newt_cert_rotation_total",
+		metric.WithDescription("Certificate rotation events (success/failure)"))
+	mProcessStartTime, _ = meter.Float64ObservableGauge("process_start_time_seconds",
+		metric.WithDescription("Unix timestamp of the process start time"),
+		metric.WithUnit("s"))
+	if mProcessStartTime != nil {
+		if _, err := meter.RegisterCallback(func(ctx context.Context, o metric.Observer) error {
+			o.ObserveFloat64(mProcessStartTime, processStartUnix)
+			return nil
+		}, mProcessStartTime); err != nil {
+			otel.Handle(err)
+		}
+	}
+	return nil
+}
+
+func registerBuildWSProxyInstruments() error {
+	// Build info gauge (value 1 with version/commit attributes)
+	mBuildInfo, _ = meter.Int64ObservableGauge("newt_build_info",
+		metric.WithDescription("Newt build information (value is always 1)"))
+	// WebSocket
+	mWSConnectLatency, _ = meter.Float64Histogram("newt_websocket_connect_latency_seconds",
+		metric.WithDescription("WebSocket connect latency in seconds"),
+		metric.WithUnit("s"))
+	mWSMessages, _ = meter.Int64Counter("newt_websocket_messages_total",
+		metric.WithDescription("WebSocket messages by direction and type"))
+	mWSDisconnects, _ = meter.Int64Counter("newt_websocket_disconnects_total",
+		metric.WithDescription("WebSocket disconnects by reason/result"))
+	mWSKeepaliveFailure, _ = meter.Int64Counter("newt_websocket_keepalive_failures_total",
+		metric.WithDescription("WebSocket keepalive (ping/pong) failures"))
+	mWSSessionDuration, _ = meter.Float64Histogram("newt_websocket_session_duration_seconds",
+		metric.WithDescription("Duration of established WebSocket sessions"),
+		metric.WithUnit("s"))
+	mWSConnected, _ = meter.Int64ObservableGauge("newt_websocket_connected",
+		metric.WithDescription("WebSocket connection state (1=connected, 0=disconnected)"))
+	mWSReconnects, _ = meter.Int64Counter("newt_websocket_reconnects_total",
+		metric.WithDescription("WebSocket reconnect attempts by reason"))
+	// Proxy
+	mProxyActiveConns, _ = meter.Int64ObservableGauge("newt_proxy_active_connections",
+		metric.WithDescription("Proxy active connections per tunnel and protocol"))
+	mProxyBufferBytes, _ = meter.Int64ObservableGauge("newt_proxy_buffer_bytes",
+		metric.WithDescription("Proxy buffer bytes (may approximate async backlog)"),
+		metric.WithUnit("By"))
+	mProxyAsyncBacklogByte, _ = meter.Int64ObservableGauge("newt_proxy_async_backlog_bytes",
+		metric.WithDescription("Unflushed async byte backlog per tunnel and protocol"),
+		metric.WithUnit("By"))
+	mProxyDropsTotal, _ = meter.Int64Counter("newt_proxy_drops_total",
+		metric.WithDescription("Proxy drops due to write errors"))
+	mProxyAcceptsTotal, _ = meter.Int64Counter("newt_proxy_accept_total",
+		metric.WithDescription("Proxy connection accepts by protocol and result"))
+	mProxyConnDuration, _ = meter.Float64Histogram("newt_proxy_connection_duration_seconds",
+		metric.WithDescription("Duration of completed proxy connections"),
+		metric.WithUnit("s"))
+	mProxyConnectionsTotal, _ = meter.Int64Counter("newt_proxy_connections_total",
+		metric.WithDescription("Proxy connection lifecycle events by protocol"))
+	// Register a default callback for build info if version/commit set
+	reg, e := meter.RegisterCallback(func(ctx context.Context, o metric.Observer) error {
+		if buildVersion == "" && buildCommit == "" {
+			return nil
+		}
+		attrs := []attribute.KeyValue{}
+		if buildVersion != "" {
+			attrs = append(attrs, attribute.String("version", buildVersion))
+		}
+		if buildCommit != "" {
+			attrs = append(attrs, attribute.String("commit", buildCommit))
+		}
+		if ShouldIncludeSiteLabels() {
+			attrs = append(attrs, siteAttrs()...)
+		}
+		o.ObserveInt64(mBuildInfo, 1, metric.WithAttributes(attrs...))
+		return nil
+	}, mBuildInfo)
+	if e != nil {
+		otel.Handle(e)
+	} else {
+		// Provide a functional stopper that unregisters the callback
+		obsStopper = func() { _ = reg.Unregister() }
+	}
+	if mWSConnected != nil {
+		if regConn, err := meter.RegisterCallback(func(ctx context.Context, o metric.Observer) error {
+			val := wsConnectedState.Load()
+			o.ObserveInt64(mWSConnected, val, metric.WithAttributes(attrsWithSite()...))
+			return nil
+		}, mWSConnected); err != nil {
+			otel.Handle(err)
+		} else {
+			wsConnStopper = func() { _ = regConn.Unregister() }
+		}
+	}
+	return nil
+}
+
+// Observable registration: Newt can register a callback to report gauges.
+// Call SetObservableCallback once to start observing online status, last
+// heartbeat seconds, and active sessions.
+
+var (
+	obsOnce       sync.Once
+	obsStopper    func()
+	proxyObsOnce  sync.Once
+	proxyStopper  func()
+	wsConnStopper func()
+)
+
+// SetObservableCallback registers a single callback that will be invoked
+// on collection. Use the provided observer to emit values for the observable
+// gauges defined here.
+//
+// Example inside your code (where you have access to current state):
+//
+//	telemetry.SetObservableCallback(func(ctx context.Context, o metric.Observer) error {
+//	    o.ObserveInt64(mSiteOnline, 1)
+//	    o.ObserveFloat64(mSiteLastHeartbeat, float64(lastHB.Unix()))
+//	    o.ObserveInt64(mTunnelSessions, int64(len(activeSessions)))
+//	    return nil
+//	})
+func SetObservableCallback(cb func(context.Context, metric.Observer) error) {
+	obsOnce.Do(func() {
+		reg, e := meter.RegisterCallback(cb, mSiteOnline, mSiteLastHeartbeat, mTunnelSessions)
+		if e != nil {
+			otel.Handle(e)
+			obsStopper = func() {
+				// no-op: registration failed; keep stopper callable
+			}
+			return
+		}
+		// Provide a functional stopper mirroring proxy/build-info behavior
+		obsStopper = func() { _ = reg.Unregister() }
+	})
+}
+
+// SetProxyObservableCallback registers a callback to observe proxy gauges.
+func SetProxyObservableCallback(cb func(context.Context, metric.Observer) error) {
+	proxyObsOnce.Do(func() {
+		reg, e := meter.RegisterCallback(cb, mProxyActiveConns, mProxyBufferBytes, mProxyAsyncBacklogByte)
+		if e != nil {
+			otel.Handle(e)
+			proxyStopper = func() {
+				// no-op: registration failed; keep stopper callable
+			}
+			return
+		}
+		// Provide a functional stopper to unregister later if needed
+		proxyStopper = func() { _ = reg.Unregister() }
+	})
+}
+
+// Build info registration
+func RegisterBuildInfo(version, commit string) {
+	buildVersion = version
+	buildCommit = commit
+}
+
+// Config reloads
+func IncConfigReload(ctx context.Context, result string) {
+	mConfigReloads.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("result", result),
+	)...))
+}
+
+// Helpers for counters/histograms
+
+func IncSiteRegistration(ctx context.Context, result string) {
+	attrs := []attribute.KeyValue{
+		attribute.String("result", result),
+	}
+	mSiteRegistrations.Add(ctx, 1, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+func AddTunnelBytes(ctx context.Context, tunnelID, direction string, n int64) {
+	attrs := []attribute.KeyValue{
+		attribute.String("direction", direction),
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mTunnelBytes.Add(ctx, n, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+// AddTunnelBytesSet adds bytes using a pre-built attribute.Set to avoid per-call allocations.
+func AddTunnelBytesSet(ctx context.Context, n int64, attrs attribute.Set) {
+	mTunnelBytes.Add(ctx, n, metric.WithAttributeSet(attrs))
+}
+
+// --- WebSocket helpers ---
+
+func ObserveWSConnectLatency(ctx context.Context, seconds float64, result, errorType string) {
+	attrs := []attribute.KeyValue{
+		attribute.String("transport", "websocket"),
+		attribute.String("result", result),
+	}
+	if errorType != "" {
+		attrs = append(attrs, attribute.String("error_type", errorType))
+	}
+	mWSConnectLatency.Record(ctx, seconds, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+func IncWSMessage(ctx context.Context, direction, msgType string) {
+	mWSMessages.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("direction", direction),
+		attribute.String("msg_type", msgType),
+	)...))
+}
+
+func IncWSDisconnect(ctx context.Context, reason, result string) {
+	mWSDisconnects.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("reason", reason),
+		attribute.String("result", result),
+	)...))
+}
+
+func IncWSKeepaliveFailure(ctx context.Context, reason string) {
+	mWSKeepaliveFailure.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("reason", reason),
+	)...))
+}
+
+// SetWSConnectionState updates the backing gauge for the WebSocket connected state.
+func SetWSConnectionState(connected bool) {
+	if connected {
+		wsConnectedState.Store(1)
+	} else {
+		wsConnectedState.Store(0)
+	}
+}
+
+// IncWSReconnect increments the WebSocket reconnect counter with a bounded reason label.
+func IncWSReconnect(ctx context.Context, reason string) {
+	if reason == "" {
+		reason = "unknown"
+	}
+	mWSReconnects.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("reason", reason),
+	)...))
+}
+
+func ObserveWSSessionDuration(ctx context.Context, seconds float64, result string) {
+	mWSSessionDuration.Record(ctx, seconds, metric.WithAttributes(attrsWithSite(
+		attribute.String("result", result),
+	)...))
+}
+
+// --- Proxy helpers ---
+
+func ObserveProxyActiveConnsObs(o metric.Observer, value int64, attrs []attribute.KeyValue) {
+	o.ObserveInt64(mProxyActiveConns, value, metric.WithAttributes(attrs...))
+}
+
+func ObserveProxyBufferBytesObs(o metric.Observer, value int64, attrs []attribute.KeyValue) {
+	o.ObserveInt64(mProxyBufferBytes, value, metric.WithAttributes(attrs...))
+}
+
+func ObserveProxyAsyncBacklogObs(o metric.Observer, value int64, attrs []attribute.KeyValue) {
+	o.ObserveInt64(mProxyAsyncBacklogByte, value, metric.WithAttributes(attrs...))
+}
+
+func IncProxyDrops(ctx context.Context, tunnelID, protocol string) {
+	attrs := []attribute.KeyValue{
+		attribute.String("protocol", protocol),
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mProxyDropsTotal.Add(ctx, 1, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+func IncProxyAccept(ctx context.Context, tunnelID, protocol, result, reason string) {
+	attrs := []attribute.KeyValue{
+		attribute.String("protocol", protocol),
+		attribute.String("result", result),
+	}
+	if reason != "" {
+		attrs = append(attrs, attribute.String("reason", reason))
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mProxyAcceptsTotal.Add(ctx, 1, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+func ObserveProxyConnectionDuration(ctx context.Context, tunnelID, protocol, result string, seconds float64) {
+	attrs := []attribute.KeyValue{
+		attribute.String("protocol", protocol),
+		attribute.String("result", result),
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mProxyConnDuration.Record(ctx, seconds, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+// IncProxyConnectionEvent records proxy connection lifecycle events (opened/closed).
+func IncProxyConnectionEvent(ctx context.Context, tunnelID, protocol, event string) {
+	if event == "" {
+		event = "unknown"
+	}
+	attrs := []attribute.KeyValue{
+		attribute.String("protocol", protocol),
+		attribute.String("event", event),
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mProxyConnectionsTotal.Add(ctx, 1, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+// --- Config/PKI helpers ---
+
+func ObserveConfigApply(ctx context.Context, phase, result string, seconds float64) {
+	mConfigApply.Record(ctx, seconds, metric.WithAttributes(attrsWithSite(
+		attribute.String("phase", phase),
+		attribute.String("result", result),
+	)...))
+}
+
+func IncCertRotation(ctx context.Context, result string) {
+	mCertRotationTotal.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("result", result),
+	)...))
+}
+
+func ObserveTunnelLatency(ctx context.Context, tunnelID, transport string, seconds float64) {
+	attrs := []attribute.KeyValue{
+		attribute.String("transport", transport),
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mTunnelLatency.Record(ctx, seconds, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+func IncReconnect(ctx context.Context, tunnelID, initiator, reason string) {
+	attrs := []attribute.KeyValue{
+		attribute.String("initiator", initiator),
+		attribute.String("reason", reason),
+	}
+	if ShouldIncludeTunnelID() && tunnelID != "" {
+		attrs = append(attrs, attribute.String("tunnel_id", tunnelID))
+	}
+	mReconnects.Add(ctx, 1, metric.WithAttributes(attrsWithSite(attrs...)...))
+}
+
+func IncConnAttempt(ctx context.Context, transport, result string) {
+	mConnAttempts.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("transport", transport),
+		attribute.String("result", result),
+	)...))
+}
+
+func IncConnError(ctx context.Context, transport, typ string) {
+	mConnErrors.Add(ctx, 1, metric.WithAttributes(attrsWithSite(
+		attribute.String("transport", transport),
+		attribute.String("error_type", typ),
+	)...))
+}

internal/telemetry/metrics_test_helper.go

@@ -0,0 +1,59 @@
+package telemetry
+
+import (
+	"sync"
+	"time"
+)
+
+func resetMetricsForTest() {
+	initOnce = sync.Once{}
+	obsOnce = sync.Once{}
+	proxyObsOnce = sync.Once{}
+	obsStopper = nil
+	proxyStopper = nil
+	if wsConnStopper != nil {
+		wsConnStopper()
+	}
+	wsConnStopper = nil
+	meter = nil
+
+	mSiteRegistrations = nil
+	mSiteOnline = nil
+	mSiteLastHeartbeat = nil
+
+	mTunnelSessions = nil
+	mTunnelBytes = nil
+	mTunnelLatency = nil
+	mReconnects = nil
+
+	mConnAttempts = nil
+	mConnErrors = nil
+
+	mConfigReloads = nil
+	mConfigApply = nil
+	mCertRotationTotal = nil
+	mProcessStartTime = nil
+
+	mBuildInfo = nil
+
+	mWSConnectLatency = nil
+	mWSMessages = nil
+	mWSDisconnects = nil
+	mWSKeepaliveFailure = nil
+	mWSSessionDuration = nil
+	mWSConnected = nil
+	mWSReconnects = nil
+
+	mProxyActiveConns = nil
+	mProxyBufferBytes = nil
+	mProxyAsyncBacklogByte = nil
+	mProxyDropsTotal = nil
+	mProxyAcceptsTotal = nil
+	mProxyConnDuration = nil
+	mProxyConnectionsTotal = nil
+
+	processStartUnix = float64(time.Now().UnixNano()) / 1e9
+	wsConnectedState.Store(0)
+	includeTunnelIDVal.Store(false)
+	includeSiteLabelVal.Store(false)
+}

internal/telemetry/state_view.go

@@ -0,0 +1,106 @@
+package telemetry
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+)
+
+// StateView provides a read-only view for observable gauges.
+// Implementations must be concurrency-safe and avoid blocking operations.
+// All methods should be fast and use RLocks where applicable.
+type StateView interface {
+	// ListSites returns a stable, low-cardinality list of site IDs to expose.
+	ListSites() []string
+	// Online returns whether the site is online.
+	Online(siteID string) (online bool, ok bool)
+	// LastHeartbeat returns the last heartbeat time for a site.
+	LastHeartbeat(siteID string) (t time.Time, ok bool)
+	// ActiveSessions returns the current number of active sessions for a site (across tunnels),
+	// or scoped to site if your model is site-scoped.
+	ActiveSessions(siteID string) (n int64, ok bool)
+}
+
+var (
+	stateView atomic.Value // of type StateView
+)
+
+// RegisterStateView sets the global StateView used by the default observable callback.
+func RegisterStateView(v StateView) {
+	stateView.Store(v)
+	// If instruments are registered, ensure a callback exists.
+	if v != nil {
+		SetObservableCallback(func(ctx context.Context, o metric.Observer) error {
+			if any := stateView.Load(); any != nil {
+				if sv, ok := any.(StateView); ok {
+					for _, siteID := range sv.ListSites() {
+						observeSiteOnlineFor(o, sv, siteID)
+						observeLastHeartbeatFor(o, sv, siteID)
+						observeSessionsFor(o, siteID, sv)
+					}
+				}
+			}
+			return nil
+		})
+	}
+}
+
+func observeSiteOnlineFor(o metric.Observer, sv StateView, siteID string) {
+	if online, ok := sv.Online(siteID); ok {
+		val := int64(0)
+		if online {
+			val = 1
+		}
+		o.ObserveInt64(mSiteOnline, val, metric.WithAttributes(
+			attribute.String("site_id", siteID),
+		))
+	}
+}
+
+func observeLastHeartbeatFor(o metric.Observer, sv StateView, siteID string) {
+	if t, ok := sv.LastHeartbeat(siteID); ok {
+		ts := float64(t.UnixNano()) / 1e9
+		o.ObserveFloat64(mSiteLastHeartbeat, ts, metric.WithAttributes(
+			attribute.String("site_id", siteID),
+		))
+	}
+}
+
+func observeSessionsFor(o metric.Observer, siteID string, any interface{}) {
+	if tm, ok := any.(interface{ SessionsByTunnel() map[string]int64 }); ok {
+		sessions := tm.SessionsByTunnel()
+		// If tunnel_id labels are enabled, preserve existing per-tunnel observations
+		if ShouldIncludeTunnelID() {
+			for tid, n := range sessions {
+				attrs := []attribute.KeyValue{
+					attribute.String("site_id", siteID),
+				}
+				if tid != "" {
+					attrs = append(attrs, attribute.String("tunnel_id", tid))
+				}
+				o.ObserveInt64(mTunnelSessions, n, metric.WithAttributes(attrs...))
+			}
+			return
+		}
+		// When tunnel_id is disabled, collapse per-tunnel counts into a single site-level value
+		var total int64
+		for _, n := range sessions {
+			total += n
+		}
+		// If there are no per-tunnel entries, fall back to ActiveSessions() if available
+		if total == 0 {
+			if svAny := stateView.Load(); svAny != nil {
+				if sv, ok := svAny.(StateView); ok {
+					if n, ok2 := sv.ActiveSessions(siteID); ok2 {
+						total = n
+					}
+				}
+			}
+		}
+		o.ObserveInt64(mTunnelSessions, total, metric.WithAttributes(attribute.String("site_id", siteID)))
+		return
+	}
+}

internal/telemetry/telemetry.go

@@ -0,0 +1,384 @@
+package telemetry
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"os"
+	"strings"
+	"sync/atomic"
+	"time"
+
+	promclient "github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.opentelemetry.io/contrib/instrumentation/runtime"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/exporters/prometheus"
+	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/resource"
+	"go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
+	"google.golang.org/grpc/credentials"
+)
+
+// Config controls telemetry initialization via env flags.
+//
+// Defaults align with the issue requirements:
+//   - Prometheus exporter enabled by default (/metrics)
+//   - OTLP exporter disabled by default
+//   - Durations in seconds, bytes in raw bytes
+//   - Admin HTTP server address configurable (for mounting /metrics)
+type Config struct {
+	ServiceName    string
+	ServiceVersion string
+
+	// Optional resource attributes
+	SiteID string
+	Region string
+
+	PromEnabled bool
+	OTLPEnabled bool
+
+	OTLPEndpoint string // host:port
+	OTLPInsecure bool
+
+	MetricExportInterval time.Duration
+	AdminAddr            string // e.g.: ":2112"
+
+	// Optional build info for newt_build_info metric
+	BuildVersion string
+	BuildCommit  string
+}
+
+// FromEnv reads configuration from environment variables.
+//
+//	NEWT_METRICS_PROMETHEUS_ENABLED (default: true)
+//	NEWT_METRICS_OTLP_ENABLED       (default: false)
+//	OTEL_EXPORTER_OTLP_ENDPOINT     (default: "localhost:4317")
+//	OTEL_EXPORTER_OTLP_INSECURE     (default: true)
+//	OTEL_METRIC_EXPORT_INTERVAL     (default: 15s)
+//	OTEL_SERVICE_NAME               (default: "newt")
+//	OTEL_SERVICE_VERSION            (default: "")
+//	NEWT_ADMIN_ADDR                 (default: ":2112")
+func FromEnv() Config {
+	// Prefer explicit NEWT_* env vars, then fall back to OTEL_RESOURCE_ATTRIBUTES
+	site := getenv("NEWT_SITE_ID", "")
+	if site == "" {
+		site = getenv("NEWT_ID", "")
+	}
+	region := os.Getenv("NEWT_REGION")
+	if site == "" || region == "" {
+		if ra := os.Getenv("OTEL_RESOURCE_ATTRIBUTES"); ra != "" {
+			m := parseResourceAttributes(ra)
+			if site == "" {
+				site = m["site_id"]
+			}
+			if region == "" {
+				region = m["region"]
+			}
+		}
+	}
+	return Config{
+		ServiceName:          getenv("OTEL_SERVICE_NAME", "newt"),
+		ServiceVersion:       os.Getenv("OTEL_SERVICE_VERSION"),
+		SiteID:               site,
+		Region:               region,
+		PromEnabled:          getenv("NEWT_METRICS_PROMETHEUS_ENABLED", "true") == "true",
+		OTLPEnabled:          getenv("NEWT_METRICS_OTLP_ENABLED", "false") == "true",
+		OTLPEndpoint:         getenv("OTEL_EXPORTER_OTLP_ENDPOINT", "localhost:4317"),
+		OTLPInsecure:         getenv("OTEL_EXPORTER_OTLP_INSECURE", "true") == "true",
+		MetricExportInterval: getdur("OTEL_METRIC_EXPORT_INTERVAL", 15*time.Second),
+		AdminAddr:            getenv("NEWT_ADMIN_ADDR", ":2112"),
+	}
+}
+
+// Setup holds initialized telemetry providers and (optionally) a /metrics handler.
+// Call Shutdown when the process terminates to flush exporters.
+type Setup struct {
+	MeterProvider  *metric.MeterProvider
+	TracerProvider *trace.TracerProvider
+
+	PrometheusHandler http.Handler // nil if Prometheus exporter disabled
+
+	shutdowns []func(context.Context) error
+}
+
+// Init configures OpenTelemetry metrics and (optionally) tracing.
+//
+// It sets a global MeterProvider and TracerProvider, registers runtime instrumentation,
+// installs recommended histogram views for *_latency_seconds, and returns a Setup with
+// a Shutdown method to flush exporters.
+func Init(ctx context.Context, cfg Config) (*Setup, error) {
+	// Configure tunnel_id label inclusion from env (default true)
+	if getenv("NEWT_METRICS_INCLUDE_TUNNEL_ID", "true") == "true" {
+		includeTunnelIDVal.Store(true)
+	} else {
+		includeTunnelIDVal.Store(false)
+	}
+        if getenv("NEWT_METRICS_INCLUDE_SITE_LABELS", "true") == "true" {
+                includeSiteLabelVal.Store(true)
+        } else {
+                includeSiteLabelVal.Store(false)
+        }
+	res := buildResource(ctx, cfg)
+	UpdateSiteInfo(cfg.SiteID, cfg.Region)
+
+	s := &Setup{}
+	readers, promHandler, shutdowns, err := setupMetricExport(ctx, cfg, res)
+	if err != nil {
+		return nil, err
+	}
+	s.PrometheusHandler = promHandler
+	// Build provider
+	mp := buildMeterProvider(res, readers)
+	otel.SetMeterProvider(mp)
+	s.MeterProvider = mp
+	s.shutdowns = append(s.shutdowns, mp.Shutdown)
+	// Optional tracing
+	if cfg.OTLPEnabled {
+		if tp, shutdown := setupTracing(ctx, cfg, res); tp != nil {
+			otel.SetTracerProvider(tp)
+			s.TracerProvider = tp
+			s.shutdowns = append(s.shutdowns, func(c context.Context) error {
+				return errors.Join(shutdown(c), tp.Shutdown(c))
+			})
+		}
+	}
+	// Add metric exporter shutdowns
+	s.shutdowns = append(s.shutdowns, shutdowns...)
+	// Runtime metrics
+	_ = runtime.Start(runtime.WithMeterProvider(mp))
+	// Instruments
+	if err := registerInstruments(); err != nil {
+		return nil, err
+	}
+	if cfg.BuildVersion != "" || cfg.BuildCommit != "" {
+		RegisterBuildInfo(cfg.BuildVersion, cfg.BuildCommit)
+	}
+	return s, nil
+}
+
+func buildResource(ctx context.Context, cfg Config) *resource.Resource {
+	attrs := []attribute.KeyValue{
+		semconv.ServiceName(cfg.ServiceName),
+		semconv.ServiceVersion(cfg.ServiceVersion),
+	}
+	if cfg.SiteID != "" {
+		attrs = append(attrs, attribute.String("site_id", cfg.SiteID))
+	}
+	if cfg.Region != "" {
+		attrs = append(attrs, attribute.String("region", cfg.Region))
+	}
+	res, _ := resource.New(ctx, resource.WithFromEnv(), resource.WithHost(), resource.WithAttributes(attrs...))
+	return res
+}
+
+func setupMetricExport(ctx context.Context, cfg Config, _ *resource.Resource) ([]metric.Reader, http.Handler, []func(context.Context) error, error) {
+	var readers []metric.Reader
+	var shutdowns []func(context.Context) error
+	var promHandler http.Handler
+	if cfg.PromEnabled {
+		reg := promclient.NewRegistry()
+		exp, err := prometheus.New(prometheus.WithRegisterer(reg))
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		readers = append(readers, exp)
+		promHandler = promhttp.HandlerFor(reg, promhttp.HandlerOpts{})
+	}
+	if cfg.OTLPEnabled {
+		mopts := []otlpmetricgrpc.Option{otlpmetricgrpc.WithEndpoint(cfg.OTLPEndpoint)}
+		if hdrs := parseOTLPHeaders(os.Getenv("OTEL_EXPORTER_OTLP_HEADERS")); len(hdrs) > 0 {
+			mopts = append(mopts, otlpmetricgrpc.WithHeaders(hdrs))
+		}
+		if cfg.OTLPInsecure {
+			mopts = append(mopts, otlpmetricgrpc.WithInsecure())
+		} else if certFile := os.Getenv("OTEL_EXPORTER_OTLP_CERTIFICATE"); certFile != "" {
+			if creds, cerr := credentials.NewClientTLSFromFile(certFile, ""); cerr == nil {
+				mopts = append(mopts, otlpmetricgrpc.WithTLSCredentials(creds))
+			}
+		}
+		mexp, err := otlpmetricgrpc.New(ctx, mopts...)
+		if err != nil {
+			return nil, nil, nil, err
+		}
+		readers = append(readers, metric.NewPeriodicReader(mexp, metric.WithInterval(cfg.MetricExportInterval)))
+		shutdowns = append(shutdowns, mexp.Shutdown)
+	}
+	return readers, promHandler, shutdowns, nil
+}
+
+func buildMeterProvider(res *resource.Resource, readers []metric.Reader) *metric.MeterProvider {
+	var mpOpts []metric.Option
+	mpOpts = append(mpOpts, metric.WithResource(res))
+	for _, r := range readers {
+		mpOpts = append(mpOpts, metric.WithReader(r))
+	}
+	mpOpts = append(mpOpts, metric.WithView(metric.NewView(
+		metric.Instrument{Name: "newt_*_latency_seconds"},
+		metric.Stream{Aggregation: metric.AggregationExplicitBucketHistogram{Boundaries: []float64{0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10, 30}}},
+	)))
+	mpOpts = append(mpOpts, metric.WithView(metric.NewView(
+		metric.Instrument{Name: "newt_*"},
+		metric.Stream{AttributeFilter: func(kv attribute.KeyValue) bool {
+			k := string(kv.Key)
+			switch k {
+			case "tunnel_id", "transport", "direction", "protocol", "result", "reason", "initiator", "error_type", "msg_type", "phase", "version", "commit", "site_id", "region":
+				return true
+			default:
+				return false
+			}
+		}},
+	)))
+	return metric.NewMeterProvider(mpOpts...)
+}
+
+func setupTracing(ctx context.Context, cfg Config, res *resource.Resource) (*trace.TracerProvider, func(context.Context) error) {
+	topts := []otlptracegrpc.Option{otlptracegrpc.WithEndpoint(cfg.OTLPEndpoint)}
+	if hdrs := parseOTLPHeaders(os.Getenv("OTEL_EXPORTER_OTLP_HEADERS")); len(hdrs) > 0 {
+		topts = append(topts, otlptracegrpc.WithHeaders(hdrs))
+	}
+	if cfg.OTLPInsecure {
+		topts = append(topts, otlptracegrpc.WithInsecure())
+	} else if certFile := os.Getenv("OTEL_EXPORTER_OTLP_CERTIFICATE"); certFile != "" {
+		if creds, cerr := credentials.NewClientTLSFromFile(certFile, ""); cerr == nil {
+			topts = append(topts, otlptracegrpc.WithTLSCredentials(creds))
+		}
+	}
+	exp, err := otlptracegrpc.New(ctx, topts...)
+	if err != nil {
+		return nil, nil
+	}
+	tp := trace.NewTracerProvider(trace.WithBatcher(exp), trace.WithResource(res))
+	return tp, exp.Shutdown
+}
+
+// Shutdown flushes exporters and providers in reverse init order.
+func (s *Setup) Shutdown(ctx context.Context) error {
+	var err error
+	for i := len(s.shutdowns) - 1; i >= 0; i-- {
+		err = errors.Join(err, s.shutdowns[i](ctx))
+	}
+	return err
+}
+
+func parseOTLPHeaders(h string) map[string]string {
+	m := map[string]string{}
+	if h == "" {
+		return m
+	}
+	pairs := strings.Split(h, ",")
+	for _, p := range pairs {
+		kv := strings.SplitN(strings.TrimSpace(p), "=", 2)
+		if len(kv) == 2 {
+			m[strings.TrimSpace(kv[0])] = strings.TrimSpace(kv[1])
+		}
+	}
+	return m
+}
+
+// parseResourceAttributes parses OTEL_RESOURCE_ATTRIBUTES formatted as k=v,k2=v2
+func parseResourceAttributes(s string) map[string]string {
+	m := map[string]string{}
+	if s == "" {
+		return m
+	}
+	parts := strings.Split(s, ",")
+	for _, p := range parts {
+		kv := strings.SplitN(strings.TrimSpace(p), "=", 2)
+		if len(kv) == 2 {
+			m[strings.TrimSpace(kv[0])] = strings.TrimSpace(kv[1])
+		}
+	}
+	return m
+}
+
+// Global site/region used to enrich metric labels.
+var siteIDVal atomic.Value
+var regionVal atomic.Value
+var (
+	includeTunnelIDVal  atomic.Value // bool; default true
+	includeSiteLabelVal atomic.Value // bool; default false
+)
+
+// UpdateSiteInfo updates the global site_id and region used for metric labels.
+// Thread-safe via atomic.Value: subsequent metric emissions will include
+// the new labels, prior emissions remain unchanged.
+func UpdateSiteInfo(siteID, region string) {
+	if siteID != "" {
+		siteIDVal.Store(siteID)
+	}
+	if region != "" {
+		regionVal.Store(region)
+	}
+}
+
+func getSiteID() string {
+	if v, ok := siteIDVal.Load().(string); ok {
+		return v
+	}
+	return ""
+}
+
+func getRegion() string {
+	if v, ok := regionVal.Load().(string); ok {
+		return v
+	}
+	return ""
+}
+
+// siteAttrs returns label KVs for site_id and region (if set).
+func siteAttrs() []attribute.KeyValue {
+	var out []attribute.KeyValue
+	if s := getSiteID(); s != "" {
+		out = append(out, attribute.String("site_id", s))
+	}
+	if r := getRegion(); r != "" {
+		out = append(out, attribute.String("region", r))
+	}
+	return out
+}
+
+// SiteLabelKVs exposes site label KVs for other packages (e.g., proxy manager).
+func SiteLabelKVs() []attribute.KeyValue {
+	if !ShouldIncludeSiteLabels() {
+		return nil
+	}
+	return siteAttrs()
+}
+
+// ShouldIncludeTunnelID returns whether tunnel_id labels should be emitted.
+func ShouldIncludeTunnelID() bool {
+	if v, ok := includeTunnelIDVal.Load().(bool); ok {
+		return v
+	}
+	return true
+}
+
+// ShouldIncludeSiteLabels returns whether site_id/region should be emitted as
+// metric labels in addition to resource attributes.
+func ShouldIncludeSiteLabels() bool {
+	if v, ok := includeSiteLabelVal.Load().(bool); ok {
+		return v
+	}
+	return false
+}
+
+func getenv(k, d string) string {
+	if v := os.Getenv(k); v != "" {
+		return v
+	}
+	return d
+}
+
+func getdur(k string, d time.Duration) time.Duration {
+	if v := os.Getenv(k); v != "" {
+		if p, e := time.ParseDuration(v); e == nil {
+			return p
+		}
+	}
+	return d
+}

internal/telemetry/telemetry_attrfilter_test.go

@@ -0,0 +1,53 @@
+package telemetry
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Test that disallowed attributes are filtered from the exposition.
+func TestAttributeFilterDropsUnknownKeys(t *testing.T) {
+        ctx := context.Background()
+        resetMetricsForTest()
+        t.Setenv("NEWT_METRICS_INCLUDE_SITE_LABELS", "true")
+        cfg := Config{ServiceName: "newt", PromEnabled: true, AdminAddr: "127.0.0.1:0"}
+	tel, err := Init(ctx, cfg)
+	if err != nil {
+		t.Fatalf("init: %v", err)
+	}
+	defer func() { _ = tel.Shutdown(context.Background()) }()
+
+	if tel.PrometheusHandler == nil {
+		t.Fatalf("prom handler nil")
+	}
+	ts := httptest.NewServer(tel.PrometheusHandler)
+	defer ts.Close()
+
+	// Add samples with disallowed attribute keys
+	for _, k := range []string{"forbidden", "site_id", "host"} {
+		set := attribute.NewSet(attribute.String(k, "x"))
+		AddTunnelBytesSet(ctx, 123, set)
+	}
+	time.Sleep(50 * time.Millisecond)
+
+	resp, err := http.Get(ts.URL)
+	if err != nil {
+		t.Fatalf("GET: %v", err)
+	}
+	defer resp.Body.Close()
+	b, _ := io.ReadAll(resp.Body)
+	body := string(b)
+	if strings.Contains(body, "forbidden=") {
+		t.Fatalf("unexpected forbidden attribute leaked into metrics: %s", body)
+	}
+	if !strings.Contains(body, "site_id=\"x\"") {
+		t.Fatalf("expected allowed attribute site_id to be present in metrics, got: %s", body)
+	}
+}

internal/telemetry/telemetry_golden_test.go

@@ -0,0 +1,76 @@
+package telemetry
+
+import (
+	"bufio"
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+// Golden test that /metrics contains expected metric names.
+func TestMetricsGoldenContains(t *testing.T) {
+	ctx := context.Background()
+	resetMetricsForTest()
+	t.Setenv("NEWT_METRICS_INCLUDE_SITE_LABELS", "true")
+	cfg := Config{ServiceName: "newt", PromEnabled: true, AdminAddr: "127.0.0.1:0", BuildVersion: "test"}
+	tel, err := Init(ctx, cfg)
+	if err != nil {
+		t.Fatalf("telemetry init error: %v", err)
+	}
+	defer func() { _ = tel.Shutdown(context.Background()) }()
+
+	if tel.PrometheusHandler == nil {
+		t.Fatalf("prom handler nil")
+	}
+	ts := httptest.NewServer(tel.PrometheusHandler)
+	defer ts.Close()
+
+	// Trigger counters to ensure they appear in the scrape
+	IncConnAttempt(ctx, "websocket", "success")
+	IncWSReconnect(ctx, "io_error")
+	IncProxyConnectionEvent(ctx, "", "tcp", ProxyConnectionOpened)
+	if tel.MeterProvider != nil {
+		_ = tel.MeterProvider.ForceFlush(ctx)
+	}
+	time.Sleep(100 * time.Millisecond)
+
+	var body string
+	for i := 0; i < 5; i++ {
+		resp, err := http.Get(ts.URL)
+		if err != nil {
+			t.Fatalf("GET metrics failed: %v", err)
+		}
+		b, _ := io.ReadAll(resp.Body)
+		_ = resp.Body.Close()
+		body = string(b)
+		if strings.Contains(body, "newt_connection_attempts_total") {
+			break
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+
+	f, err := os.Open(filepath.Join("testdata", "expected_contains.golden"))
+	if err != nil {
+		t.Fatalf("read golden: %v", err)
+	}
+	defer f.Close()
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		needle := strings.TrimSpace(s.Text())
+		if needle == "" {
+			continue
+		}
+		if !strings.Contains(body, needle) {
+			t.Fatalf("expected metrics body to contain %q. body=\n%s", needle, body)
+		}
+	}
+	if err := s.Err(); err != nil {
+		t.Fatalf("scan golden: %v", err)
+	}
+}

internal/telemetry/telemetry_smoke_test.go

@@ -0,0 +1,65 @@
+package telemetry
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+)
+
+// Smoke test that /metrics contains at least one newt_* metric when Prom exporter is enabled.
+func TestMetricsSmoke(t *testing.T) {
+	ctx := context.Background()
+	resetMetricsForTest()
+	t.Setenv("NEWT_METRICS_INCLUDE_SITE_LABELS", "true")
+	cfg := Config{
+		ServiceName:          "newt",
+		PromEnabled:          true,
+		OTLPEnabled:          false,
+		AdminAddr:            "127.0.0.1:0",
+		BuildVersion:         "test",
+		BuildCommit:          "deadbeef",
+		MetricExportInterval: 5 * time.Second,
+	}
+	tel, err := Init(ctx, cfg)
+	if err != nil {
+		t.Fatalf("telemetry init error: %v", err)
+	}
+	defer func() { _ = tel.Shutdown(context.Background()) }()
+
+	// Serve the Prom handler on a test server
+	if tel.PrometheusHandler == nil {
+		t.Fatalf("Prometheus handler nil; PromEnabled should enable it")
+	}
+	ts := httptest.NewServer(tel.PrometheusHandler)
+	defer ts.Close()
+
+	// Record a simple metric and then fetch /metrics
+	IncConnAttempt(ctx, "websocket", "success")
+	if tel.MeterProvider != nil {
+		_ = tel.MeterProvider.ForceFlush(ctx)
+	}
+	// Give the exporter a tick to collect
+	time.Sleep(100 * time.Millisecond)
+
+	var body string
+	for i := 0; i < 5; i++ {
+		resp, err := http.Get(ts.URL)
+		if err != nil {
+			t.Fatalf("GET /metrics failed: %v", err)
+		}
+		b, _ := io.ReadAll(resp.Body)
+		_ = resp.Body.Close()
+		body = string(b)
+		if strings.Contains(body, "newt_connection_attempts_total") {
+			break
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	if !strings.Contains(body, "newt_connection_attempts_total") {
+		t.Fatalf("expected newt_connection_attempts_total in metrics, got:\n%s", body)
+	}
+}

internal/telemetry/testdata/expected_contains.golden

@@ -0,0 +1,3 @@
+newt_connection_attempts_total
+newt_websocket_reconnects_total
+newt_proxy_connections_total

linux.go

@@ -1,83 +0,0 @@
-//go:build linux
-
-package main
-
-import (
-	"fmt"
-	"strings"
-
-	"github.com/fosrl/newt/logger"
-	"github.com/fosrl/newt/proxy"
-	"github.com/fosrl/newt/websocket"
-	"github.com/fosrl/newt/wg"
-	"github.com/fosrl/newt/wgtester"
-)
-
-var wgService *wg.WireGuardService
-var wgTesterServer *wgtester.Server
-
-func setupClients(client *websocket.Client) {
-	var host = endpoint
-	if strings.HasPrefix(host, "http://") {
-		host = strings.TrimPrefix(host, "http://")
-	} else if strings.HasPrefix(host, "https://") {
-		host = strings.TrimPrefix(host, "https://")
-	}
-
-	host = strings.TrimSuffix(host, "/")
-
-	// Create WireGuard service
-	wgService, err = wg.NewWireGuardService(interfaceName, mtuInt, generateAndSaveKeyTo, host, id, client)
-	if err != nil {
-		logger.Fatal("Failed to create WireGuard service: %v", err)
-	}
-	defer wgService.Close(rm)
-
-	wgTesterServer = wgtester.NewServer("0.0.0.0", wgService.Port, id) // TODO: maybe make this the same ip of the wg server?
-	err := wgTesterServer.Start()
-	if err != nil {
-		logger.Error("Failed to start WireGuard tester server: %v", err)
-	} else {
-		// Make sure to stop the server on exit
-		defer wgTesterServer.Stop()
-	}
-
-	client.OnTokenUpdate(func(token string) {
-		wgService.SetToken(token)
-	})
-}
-
-func closeClients() {
-	if wgService != nil {
-		wgService.Close(rm)
-		wgService = nil
-	}
-
-	if wgTesterServer != nil {
-		wgTesterServer.Stop()
-		wgTesterServer = nil
-	}
-}
-
-func clientsHandleNewtConnection(publicKey string) {
-	if wgService == nil {
-		return
-	}
-	wgService.SetServerPubKey(publicKey)
-}
-
-func clientsOnConnect() {
-	if wgService == nil {
-		return
-	}
-	wgService.LoadRemoteConfig()
-}
-
-func clientsAddProxyTarget(pm *proxy.ProxyManager, tunnelIp string) {
-	if wgService == nil {
-		return
-	}
-	// add a udp proxy for localost and the wgService port
-	// TODO: make sure this port is not used in a target
-	pm.AddTarget("udp", tunnelIp, int(wgService.Port), fmt.Sprintf("127.0.0.1:%d", wgService.Port))
-}

logger/logger.go

@@ -2,15 +2,15 @@ package logger
 
 import (
 	"fmt"
-	"log"
 	"os"
+	"strings"
 	"sync"
 	"time"
 )
 
 // Logger struct holds the logger instance
 type Logger struct {
-	logger *log.Logger
+	writer LogWriter
 	level  LogLevel
 }
 
@@ -19,17 +19,29 @@ var (
 	once          sync.Once
 )
 
-// NewLogger creates a new logger instance
+// NewLogger creates a new logger instance with the default StandardWriter
 func NewLogger() *Logger {
 	return &Logger{
-		logger: log.New(os.Stdout, "", 0),
+		writer: NewStandardWriter(),
+		level:  DEBUG,
+	}
+}
+
+// NewLoggerWithWriter creates a new logger instance with a custom LogWriter
+func NewLoggerWithWriter(writer LogWriter) *Logger {
+	return &Logger{
+		writer: writer,
 		level:  DEBUG,
 	}
 }
 
 // Init initializes the default logger
-func Init() *Logger {
+func Init(logger *Logger) *Logger {
 	once.Do(func() {
+		if logger != nil {
+			defaultLogger = logger
+			return
+		}
 		defaultLogger = NewLogger()
 	})
 	return defaultLogger
@@ -38,7 +50,7 @@ func Init() *Logger {
 // GetLogger returns the default logger instance
 func GetLogger() *Logger {
 	if defaultLogger == nil {
-		Init()
+		Init(nil)
 	}
 	return defaultLogger
 }
@@ -48,30 +60,21 @@ func (l *Logger) SetLevel(level LogLevel) {
 	l.level = level
 }
 
+// SetOutput sets the output destination for the logger (only works with StandardWriter)
+func (l *Logger) SetOutput(output *os.File) {
+	if sw, ok := l.writer.(*StandardWriter); ok {
+		sw.SetOutput(output)
+	}
+}
+
 // log handles the actual logging
 func (l *Logger) log(level LogLevel, format string, args ...interface{}) {
 	if level < l.level {
 		return
 	}
 
-	// Get timezone from environment variable or use local timezone
-	timezone := os.Getenv("LOGGER_TIMEZONE")
-	var location *time.Location
-	var err error
-
-	if timezone != "" {
-		location, err = time.LoadLocation(timezone)
-		if err != nil {
-			// If invalid timezone, fall back to local
-			location = time.Local
-		}
-	} else {
-		location = time.Local
-	}
-
-	timestamp := time.Now().In(location).Format("2006/01/02 15:04:05")
 	message := fmt.Sprintf(format, args...)
-	l.logger.Printf("%s: %s %s", level.String(), timestamp, message)
+	l.writer.Write(level, time.Now(), message)
 }
 
 // Debug logs debug level messages
@@ -120,3 +123,31 @@ func Error(format string, args ...interface{}) {
 func Fatal(format string, args ...interface{}) {
 	GetLogger().Fatal(format, args...)
 }
+
+// SetOutput sets the output destination for the default logger
+func SetOutput(output *os.File) {
+	GetLogger().SetOutput(output)
+}
+
+// WireGuardLogger is a wrapper type that matches WireGuard's Logger interface
+type WireGuardLogger struct {
+	Verbosef func(format string, args ...any)
+	Errorf   func(format string, args ...any)
+}
+
+// GetWireGuardLogger returns a WireGuard-compatible logger that writes to the newt logger
+// The prepend string is added as a prefix to all log messages
+func (l *Logger) GetWireGuardLogger(prepend string) *WireGuardLogger {
+	return &WireGuardLogger{
+		Verbosef: func(format string, args ...any) {
+			// if the format string contains "Sending keepalive packet", skip debug logging to reduce noise
+			if strings.Contains(format, "Sending keepalive packet") {
+				return
+			}
+			l.Debug(prepend+format, args...)
+		},
+		Errorf: func(format string, args ...any) {
+			l.Error(prepend+format, args...)
+		},
+	}
+}

logger/writer.go

@@ -0,0 +1,54 @@
+package logger
+
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+// LogWriter is an interface for writing log messages
+// Implement this interface to create custom log backends (OS log, syslog, etc.)
+type LogWriter interface {
+	// Write writes a log message with the given level, timestamp, and formatted message
+	Write(level LogLevel, timestamp time.Time, message string)
+}
+
+// StandardWriter is the default log writer that writes to an io.Writer
+type StandardWriter struct {
+	output   *os.File
+	timezone *time.Location
+}
+
+// NewStandardWriter creates a new standard writer with the default configuration
+func NewStandardWriter() *StandardWriter {
+	// Get timezone from environment variable or use local timezone
+	timezone := os.Getenv("LOGGER_TIMEZONE")
+	var location *time.Location
+	var err error
+
+	if timezone != "" {
+		location, err = time.LoadLocation(timezone)
+		if err != nil {
+			// If invalid timezone, fall back to local
+			location = time.Local
+		}
+	} else {
+		location = time.Local
+	}
+
+	return &StandardWriter{
+		output:   os.Stdout,
+		timezone: location,
+	}
+}
+
+// SetOutput sets the output destination
+func (w *StandardWriter) SetOutput(output *os.File) {
+	w.output = output
+}
+
+// Write implements the LogWriter interface
+func (w *StandardWriter) Write(level LogLevel, timestamp time.Time, message string) {
+	formattedTime := timestamp.In(w.timezone).Format("2006/01/02 15:04:05")
+	fmt.Fprintf(w.output, "%s: %s %s\n", level.String(), formattedTime, message)
+}

nativessh/auth.go

@@ -0,0 +1,158 @@
+package nativessh
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"os/user"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/crypto/ssh"
+)
+
+type staticConnMeta struct {
+	user string
+}
+
+func (m staticConnMeta) User() string              { return m.user }
+func (m staticConnMeta) SessionID() []byte         { return nil }
+func (m staticConnMeta) ClientVersion() []byte     { return nil }
+func (m staticConnMeta) ServerVersion() []byte     { return nil }
+func (m staticConnMeta) RemoteAddr() net.Addr      { return nil }
+func (m staticConnMeta) LocalAddr() net.Addr       { return nil }
+
+// CheckAuthorizedKeys reports whether key matches any entry in the system
+// user's ~/.ssh/authorized_keys file.  Returns false (not an error) when the
+// user or file does not exist.
+func CheckAuthorizedKeys(username string, key ssh.PublicKey) bool {
+	u, err := user.Lookup(username)
+	if err != nil {
+		return false
+	}
+	f, err := os.Open(filepath.Join(u.HomeDir, ".ssh", "authorized_keys"))
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	want := ssh.FingerprintSHA256(key)
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+		parsed, _, _, _, err := ssh.ParseAuthorizedKey([]byte(line))
+		if err != nil {
+			continue
+		}
+		if ssh.FingerprintSHA256(parsed) == want {
+			return true
+		}
+	}
+	return false
+}
+
+// SystemUserExists reports whether a user account with the given name exists
+// on the host OS.
+func SystemUserExists(username string) bool {
+	_, err := user.Lookup(username)
+	return err == nil
+}
+
+// Authenticate authenticates a user for a browser-based native SSH session.
+// It tries, in order:
+//  1. Private key — parses privateKeyPEM and checks it against the user's
+//     ~/.ssh/authorized_keys.
+//  2. Password — verifies password via the host OS PAM stack (Linux only).
+//
+// Returns nil on the first method that succeeds, or an error if all fail.
+func Authenticate(username, password, privateKeyPEM string) error {
+	return AuthenticateWithCertificate(nil, username, password, privateKeyPEM, "")
+}
+
+// AuthenticateWithCertificate authenticates a user for a browser-based native
+// SSH session using the same method ordering as the native SSH server:
+//  1. Private key in host ~/.ssh/authorized_keys.
+//  2. SSH certificate signed by the configured CA (when provided).
+//  3. Password via host PAM stack.
+func AuthenticateWithCertificate(store *CredentialStore, username, password, privateKeyPEM, certificate string) error {
+	log.Printf("nativessh: authenticating user %q (hasPassword=%v, hasPrivateKey=%v)", username, password != "", privateKeyPEM != "")
+	if !SystemUserExists(username) {
+		log.Printf("nativessh: user %q not found on system", username)
+		return fmt.Errorf("user %q does not exist", username)
+	}
+
+	var signer ssh.Signer
+	if privateKeyPEM != "" {
+		parsedSigner, err := ssh.ParsePrivateKey([]byte(privateKeyPEM))
+		if err != nil {
+			log.Printf("nativessh: failed to parse private key for %q: %v", username, err)
+		} else if CheckAuthorizedKeys(username, parsedSigner.PublicKey()) {
+			log.Printf("nativessh: private key auth succeeded for %q", username)
+			return nil
+		} else {
+			signer = parsedSigner
+			log.Printf("nativessh: private key not in authorized_keys for %q", username)
+		}
+	}
+
+	if store != nil && certificate != "" {
+		if signer == nil {
+			log.Printf("nativessh: certificate provided for %q but no matching private key was provided", username)
+		} else {
+			pub, _, _, _, err := ssh.ParseAuthorizedKey([]byte(certificate))
+			if err != nil {
+				log.Printf("nativessh: failed to parse certificate for %q: %v", username, err)
+			} else {
+				cert, ok := pub.(*ssh.Certificate)
+				if !ok {
+					log.Printf("nativessh: provided cert data for %q is not an SSH certificate", username)
+				} else if ssh.FingerprintSHA256(cert.Key) != ssh.FingerprintSHA256(signer.PublicKey()) {
+					log.Printf("nativessh: certificate key mismatch for %q", username)
+				} else {
+					caKey, userPrincipals := store.get(username)
+					if caKey == nil {
+						log.Printf("nativessh: CA key is not set for certificate auth user %q", username)
+					} else if len(userPrincipals) == 0 {
+						log.Printf("nativessh: no allowed principals found for certificate auth user %q", username)
+					} else {
+						checker := &ssh.CertChecker{
+							IsUserAuthority: func(auth ssh.PublicKey) bool {
+								return ssh.FingerprintSHA256(auth) == ssh.FingerprintSHA256(caKey)
+							},
+						}
+
+						var lastErr error
+						for principal := range userPrincipals {
+							_, authErr := checker.Authenticate(staticConnMeta{user: principal}, cert)
+							if authErr == nil {
+								log.Printf("nativessh: certificate auth succeeded for %q (principal=%q)", username, principal)
+								return nil
+							}
+							lastErr = authErr
+						}
+						if lastErr != nil {
+							log.Printf("nativessh: certificate auth failed for %q: %v", username, lastErr)
+						}
+					}
+				}
+			}
+		}
+	}
+
+	if password != "" {
+		if err := VerifySystemPassword(username, password); err != nil {
+			log.Printf("nativessh: password auth failed for %q: %v", username, err)
+		} else {
+			log.Printf("nativessh: password auth succeeded for %q", username)
+			return nil
+		}
+	} else {
+		log.Printf("nativessh: no password provided for %q", username)
+	}
+	return fmt.Errorf("authentication failed for user %q", username)
+}

nativessh/pam_linux.go

@@ -0,0 +1,99 @@
+//go:build linux
+
+package nativessh
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+
+	"github.com/go-crypt/crypt"
+	"github.com/go-crypt/x/yescrypt"
+)
+
+// VerifySystemPassword authenticates username/password by reading /etc/shadow.
+// Supports yescrypt ($y$), bcrypt ($2b$/$2a$/$2y$), SHA-512 ($6$), SHA-256
+// ($5$), argon2, scrypt, and other schemes handled by go-crypt/crypt.
+func VerifySystemPassword(username, password string) error {
+	hash, err := readShadowHash(username)
+	if err != nil {
+		log.Printf("nativessh/pam: readShadowHash for %q failed: %v", username, err)
+		return fmt.Errorf("shadow: %w", err)
+	}
+
+	// Log the scheme prefix only (never the full hash).
+	scheme := "unknown"
+	for _, prefix := range []string{"$y$", "$2a$", "$2b$", "$2y$", "$6$", "$5$", "$1$"} {
+		if strings.HasPrefix(hash, prefix) {
+			scheme = prefix
+			break
+		}
+	}
+	log.Printf("nativessh/pam: verifying password for %q using scheme %s", username, scheme)
+
+	// Yescrypt ($y$) is not in go-crypt/crypt's default decoder; handle it directly.
+	if strings.HasPrefix(hash, "$y$") {
+		computed, err := yescrypt.Hash([]byte(password), []byte(hash))
+		if err != nil {
+			log.Printf("nativessh/pam: yescrypt.Hash for %q failed: %v", username, err)
+			return fmt.Errorf("yescrypt: %w", err)
+		}
+		if !bytes.Equal(computed, []byte(hash)) {
+			log.Printf("nativessh/pam: yescrypt mismatch for %q", username)
+			return errors.New("authentication failed")
+		}
+		return nil
+	}
+
+	decoder, err := crypt.NewDefaultDecoder()
+	if err != nil {
+		return fmt.Errorf("crypt decoder: %w", err)
+	}
+
+	digest, err := decoder.Decode(hash)
+	if err != nil {
+		log.Printf("nativessh/pam: failed to decode hash for %q: %v", username, err)
+		return fmt.Errorf("unsupported password hash scheme %q: %w", scheme, err)
+	}
+
+	match, err := digest.MatchAdvanced(password)
+	if err != nil {
+		log.Printf("nativessh/pam: MatchAdvanced for %q failed: %v", username, err)
+		return err
+	}
+	if !match {
+		log.Printf("nativessh/pam: password mismatch for %q", username)
+		return errors.New("authentication failed")
+	}
+	return nil
+}
+
+// readShadowHash reads /etc/shadow and returns the password hash for username.
+func readShadowHash(username string) (string, error) {
+	f, err := os.Open("/etc/shadow")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		fields := strings.SplitN(scanner.Text(), ":", 3)
+		if len(fields) < 2 || fields[0] != username {
+			continue
+		}
+		h := fields[1]
+		if h == "" || h == "*" || strings.HasPrefix(h, "!") || h == "x" {
+			return "", errors.New("account locked or has no password")
+		}
+		return h, nil
+	}
+	if err := scanner.Err(); err != nil {
+		return "", err
+	}
+	return "", errors.New("user not found in shadow database")
+}

nativessh/pam_other.go

@@ -0,0 +1,11 @@
+//go:build !linux
+
+package nativessh
+
+import "errors"
+
+// VerifySystemPassword is not supported on non-Linux platforms; it always
+// returns an error so that password authentication is never accepted.
+func VerifySystemPassword(username, password string) error {
+	return errors.New("password authentication not supported on this platform")
+}

nativessh/pty.go

@@ -0,0 +1,130 @@
+//go:build !windows
+
+package nativessh
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"os/user"
+	"strings"
+	"sync"
+
+	"github.com/creack/pty"
+)
+
+// PTYSession is a running shell process attached to a PTY.
+// It implements io.ReadWriteCloser so it can be bridged to any transport.
+type PTYSession struct {
+	ptmx     *os.File
+	cmd      *exec.Cmd
+	waitOnce sync.Once
+	exitCode int
+}
+
+// findShell returns the path to the best available interactive shell by
+// checking preferred shells in order, falling back to /bin/sh.
+func findShell() string {
+	preferred := []string{"zsh", "bash", "fish", "ksh", "sh"}
+	for _, name := range preferred {
+		if path, err := exec.LookPath(name); err == nil {
+			return path
+		}
+	}
+	return "/bin/sh"
+}
+
+// userShell returns the login shell configured for u in /etc/passwd.
+// If the field is empty or the binary does not exist, it falls back to
+// findShell so there is always a usable shell.
+func userShell(u *user.User) string {
+	if shell := passwdShell(u.Username); shell != "" {
+		if _, err := exec.LookPath(shell); err == nil {
+			return shell
+		}
+	}
+	return findShell()
+}
+
+// passwdShell reads /etc/passwd and returns the login shell for the named user.
+// Returns "" if the user is not found or the file cannot be read.
+func passwdShell(username string) string {
+	f, err := os.Open("/etc/passwd")
+	if err != nil {
+		return ""
+	}
+	defer f.Close()
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" || line[0] == '#' {
+			continue
+		}
+		// Fields: username:password:uid:gid:gecos:home:shell
+		fields := strings.SplitN(line, ":", 7)
+		if len(fields) == 7 && fields[0] == username {
+			return fields[6]
+		}
+	}
+	_ = scanner.Err()
+	return ""
+}
+
+// NewPTYSession spawns the best available shell in a PTY.
+func NewPTYSession() (*PTYSession, error) {
+	shell := findShell()
+	cmd := exec.Command(shell)
+	cmd.Env = append(os.Environ(), "TERM=xterm-256color")
+	ptmx, err := pty.Start(cmd)
+	if err != nil {
+		return nil, fmt.Errorf("pty start: %w", err)
+	}
+	return &PTYSession{ptmx: ptmx, cmd: cmd}, nil
+}
+
+// Read reads output from the PTY.
+func (p *PTYSession) Read(b []byte) (int, error) {
+	return p.ptmx.Read(b)
+}
+
+// Write writes input to the PTY.
+func (p *PTYSession) Write(b []byte) (int, error) {
+	return p.ptmx.Write(b)
+}
+
+// Resize changes the PTY window size.
+func (p *PTYSession) Resize(cols, rows uint16) error {
+	return pty.Setsize(p.ptmx, &pty.Winsize{Cols: cols, Rows: rows})
+}
+
+// wait waits for the child process to exit exactly once and records its exit
+// code. Safe to call concurrently or multiple times.
+func (p *PTYSession) wait() {
+	p.waitOnce.Do(func() {
+		err := p.cmd.Wait()
+		if err != nil {
+			var exitErr *exec.ExitError
+			if errors.As(err, &exitErr) {
+				p.exitCode = exitErr.ExitCode()
+				return
+			}
+			p.exitCode = 1
+		}
+	})
+}
+
+// ExitCode waits for the shell process to exit and returns its exit code.
+// It is safe to call before or after Close.
+func (p *PTYSession) ExitCode() int {
+	p.wait()
+	return p.exitCode
+}
+
+// Close closes the PTY and waits for the child process to exit.
+func (p *PTYSession) Close() error {
+	err := p.ptmx.Close()
+	p.wait()
+	return err
+}

nativessh/pty_unix.go

@@ -0,0 +1,78 @@
+//go:build !windows
+
+package nativessh
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"os/user"
+	"strconv"
+	"syscall"
+
+	"github.com/creack/pty"
+)
+
+// NewPTYSessionAs spawns an interactive shell in a PTY running as the given
+// system user.  The calling process must have sufficient privileges (typically
+// root / CAP_SETUID) to switch to a different UID/GID.
+func NewPTYSessionAs(username string) (*PTYSession, error) {
+	u, err := user.Lookup(username)
+	if err != nil {
+		return nil, fmt.Errorf("user lookup %q: %w", username, err)
+	}
+	uid, err := strconv.ParseUint(u.Uid, 10, 32)
+	if err != nil {
+		return nil, fmt.Errorf("parse uid: %w", err)
+	}
+	gid, err := strconv.ParseUint(u.Gid, 10, 32)
+	if err != nil {
+		return nil, fmt.Errorf("parse gid: %w", err)
+	}
+
+	// Collect supplementary group IDs.
+	groupIDs, err := u.GroupIds()
+	if err != nil {
+		groupIDs = []string{}
+	}
+	var groups []uint32
+	for _, g := range groupIDs {
+		gval, err := strconv.ParseUint(g, 10, 32)
+		if err == nil {
+			groups = append(groups, uint32(gval))
+		}
+	}
+
+	shell := userShell(u)
+
+	// Prefer the user's home directory as the working directory, but fall back
+	// to / if it does not exist (e.g. useradd was run without -m).
+	homeDir := u.HomeDir
+	if _, err := os.Stat(homeDir); err != nil {
+		homeDir = "/"
+	}
+
+	cmd := exec.Command(shell, "--login")
+	cmd.Env = []string{
+		"TERM=xterm-256color",
+		"HOME=" + u.HomeDir,
+		"USER=" + username,
+		"LOGNAME=" + username,
+		"SHELL=" + shell,
+		"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
+	}
+	cmd.Dir = homeDir
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Credential: &syscall.Credential{
+			Uid:    uint32(uid),
+			Gid:    uint32(gid),
+			Groups: groups,
+		},
+	}
+
+	ptmx, err := pty.Start(cmd)
+	if err != nil {
+		return nil, fmt.Errorf("pty start: %w", err)
+	}
+	return &PTYSession{ptmx: ptmx, cmd: cmd}, nil
+}

nativessh/server.go

@@ -0,0 +1,363 @@
+//go:build !windows
+
+package nativessh
+
+import (
+	"crypto/ed25519"
+	"crypto/rand"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"strings"
+	"sync"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// CredentialStore holds in-memory SSH credentials that can be updated at runtime.
+// It is safe for concurrent use.
+type CredentialStore struct {
+	mu         sync.RWMutex
+	caKey      ssh.PublicKey
+	principals map[string]map[string]struct{} // username -> set of allowed principals
+}
+
+// connMetaWithUser wraps ConnMetadata while overriding User() for cert checks.
+type connMetaWithUser struct {
+	ssh.ConnMetadata
+	user string
+}
+
+func (m connMetaWithUser) User() string { return m.user }
+
+// NewCredentialStore returns an empty, ready-to-use CredentialStore.
+func NewCredentialStore() *CredentialStore {
+	return &CredentialStore{
+		principals: make(map[string]map[string]struct{}),
+	}
+}
+
+// SetCAKey parses and stores the CA public key from authorized_keys-format data.
+func (s *CredentialStore) SetCAKey(authorizedKeyData string) error {
+	key, _, _, _, err := ssh.ParseAuthorizedKey([]byte(authorizedKeyData))
+	if err != nil {
+		return fmt.Errorf("parse CA key: %w", err)
+	}
+	s.mu.Lock()
+	s.caKey = key
+	s.mu.Unlock()
+	return nil
+}
+
+// AddPrincipals records username and niceId as allowed principals for username.
+// Both values are stored; either can appear in the certificate's ValidPrincipals
+// field to satisfy the standard cert-auth principal check.
+func (s *CredentialStore) AddPrincipals(username, niceId string) {
+	username = strings.TrimSpace(username)
+	niceId = strings.TrimSpace(niceId)
+	if username == "" {
+		return
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.principals[username] == nil {
+		s.principals[username] = make(map[string]struct{})
+	}
+	s.principals[username][username] = struct{}{}
+	if niceId != "" {
+		s.principals[username][niceId] = struct{}{}
+	}
+}
+
+// get returns the CA key and the principal set for username under a read lock.
+func (s *CredentialStore) get(username string) (ssh.PublicKey, map[string]struct{}) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.caKey, s.principals[username]
+}
+
+// ServerConfig holds configuration for the native SSH server.
+type ServerConfig struct {
+	// ListenAddr is the TCP address to listen on. Defaults to ":2222".
+	ListenAddr string
+	// Credentials provides in-memory CA key and per-user principals.
+	// Updates to the store are reflected immediately for new connections.
+	// If nil or the store has no CA key set, all connections are rejected.
+	Credentials *CredentialStore
+}
+
+// Server is a simple SSH server that authenticates clients via SSH certificate
+// auth only. Certificates must be signed by the configured CA and the
+// connecting username must appear in both the certificate's principal list and
+// the local principals file.
+type Server struct {
+	cfg ServerConfig
+}
+
+// NewServer creates a new Server. The ListenAddr defaults to ":2222" when empty.
+func NewServer(cfg ServerConfig) *Server {
+	if cfg.ListenAddr == "" {
+		cfg.ListenAddr = ":2222"
+	}
+	return &Server{cfg: cfg}
+}
+
+// buildSSHConfig builds the ssh.ServerConfig with multi-method authentication:
+//  1. Public key: host ~/.ssh/authorized_keys, then CA certificate.
+//  2. Password: system PAM stack (Linux only).
+func (s *Server) buildSSHConfig() (*ssh.ServerConfig, error) {
+	hostSigner, err := generateHostKey()
+	if err != nil {
+		return nil, fmt.Errorf("host key: %w", err)
+	}
+	cfg := &ssh.ServerConfig{
+		PublicKeyCallback: makePublicKeyCallback(s.cfg.Credentials),
+		PasswordCallback:  makePasswordCallback(),
+	}
+	cfg.AddHostKey(hostSigner)
+	return cfg, nil
+}
+
+// Serve accepts connections on ln and handles them. It returns when ln is
+// closed or a non-temporary Accept error occurs.
+func (s *Server) Serve(ln net.Listener) error {
+	sshCfg, err := s.buildSSHConfig()
+	if err != nil {
+		return err
+	}
+	log.Printf("nativessh: server listening on %s", ln.Addr())
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			return err
+		}
+		go s.handleConn(conn, sshCfg)
+	}
+}
+
+// ListenAndServe starts the SSH server on the host network and blocks until
+// the listener is closed.
+func (s *Server) ListenAndServe() error {
+	ln, err := net.Listen("tcp", s.cfg.ListenAddr)
+	if err != nil {
+		return fmt.Errorf("listen %s: %w", s.cfg.ListenAddr, err)
+	}
+	defer ln.Close()
+	return s.Serve(ln)
+}
+
+func (s *Server) handleConn(conn net.Conn, cfg *ssh.ServerConfig) {
+	defer conn.Close()
+	sshConn, chans, reqs, err := ssh.NewServerConn(conn, cfg)
+	if err != nil {
+		log.Printf("nativessh: handshake failed from %s: %v", conn.RemoteAddr(), err)
+		return
+	}
+	defer sshConn.Close()
+	log.Printf("nativessh: connection from %s user=%s", conn.RemoteAddr(), sshConn.User())
+
+	go ssh.DiscardRequests(reqs)
+
+	for newChan := range chans {
+		if newChan.ChannelType() != "session" {
+			_ = newChan.Reject(ssh.UnknownChannelType, "unknown channel type")
+			continue
+		}
+		ch, requests, err := newChan.Accept()
+		if err != nil {
+			log.Printf("nativessh: channel accept error: %v", err)
+			return
+		}
+		go s.handleSession(ch, requests, sshConn.User())
+	}
+}
+
+// handleSession drives a single SSH session channel. It waits for a pty-req
+// followed by a shell request and then bridges the PTY to the channel.
+func (s *Server) handleSession(ch ssh.Channel, requests <-chan *ssh.Request, username string) {
+	defer ch.Close()
+
+	var (
+		sess    *PTYSession
+		started bool
+	)
+
+	for req := range requests {
+		switch req.Type {
+		case "pty-req":
+			var err error
+			if sess == nil {
+				sess, err = NewPTYSessionAs(username)
+				if err != nil {
+					log.Printf("nativessh: PTY start error: %v", err)
+					if req.WantReply {
+						_ = req.Reply(false, nil)
+					}
+					return
+				}
+			}
+			cols, rows := parsePTYReq(req.Payload)
+			_ = sess.Resize(cols, rows)
+			if req.WantReply {
+				_ = req.Reply(true, nil)
+			}
+
+		case "shell":
+			if req.WantReply {
+				_ = req.Reply(true, nil)
+			}
+			if started || sess == nil {
+				continue
+			}
+			started = true
+			// PTY output → SSH channel.
+			go func() {
+				_, _ = io.Copy(ch, sess)
+				// Notify the client of the shell's exit status so it can
+				// disconnect cleanly instead of requiring a manual disconnect.
+				exitCode := sess.ExitCode()
+				exitStatusPayload := ssh.Marshal(struct{ Status uint32 }{uint32(exitCode)})
+				_, _ = ch.SendRequest("exit-status", false, exitStatusPayload)
+				_ = ch.CloseWrite()
+				sess.Close() //nolint:errcheck
+				// Close the channel so the ssh library closes the requests
+				// channel, which unblocks the for-range loop in handleSession
+				// and allows the deferred ch.Close() to run. Without this,
+				// handleSession blocks forever waiting for requests to drain.
+				_ = ch.Close()
+			}()
+			// SSH channel input → PTY stdin.
+			go func() {
+				_, _ = io.Copy(sess, ch)
+			}()
+
+		case "window-change":
+			if sess != nil {
+				cols, rows := parseWindowChange(req.Payload)
+				_ = sess.Resize(cols, rows)
+			}
+			if req.WantReply {
+				_ = req.Reply(true, nil)
+			}
+
+		default:
+			if req.WantReply {
+				_ = req.Reply(false, nil)
+			}
+		}
+	}
+
+	if sess != nil && !started {
+		sess.Close() //nolint:errcheck
+	}
+}
+
+// makePublicKeyCallback returns a PublicKeyCallback that tries, in order:
+//  1. Host authorized_keys  – matches any key in the OS user's
+//     ~/.ssh/authorized_keys file.
+//  2. CA certificate        – validates an SSH certificate signed by the
+//     configured CA and checks that the user appears in the principals map.
+//
+// store may be nil or empty; those paths are simply skipped.
+func makePublicKeyCallback(store *CredentialStore) func(ssh.ConnMetadata, ssh.PublicKey) (*ssh.Permissions, error) {
+	return func(meta ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
+		// 1. Host authorized_keys.
+		if CheckAuthorizedKeys(meta.User(), key) {
+			log.Printf("nativessh: authorized_keys auth for user %q", meta.User())
+			return &ssh.Permissions{}, nil
+		}
+
+		// 2. CA certificate.
+		if store != nil {
+			caKey, userPrincipals := store.get(meta.User())
+			if caKey != nil {
+				checker := &ssh.CertChecker{
+					IsUserAuthority: func(auth ssh.PublicKey) bool {
+						return ssh.FingerprintSHA256(auth) == ssh.FingerprintSHA256(caKey)
+					},
+				}
+
+				if len(userPrincipals) == 0 {
+					return nil, fmt.Errorf("user %q not in allowed principals list", meta.User())
+				}
+
+				var lastErr error
+				for principal := range userPrincipals {
+					perms, err := checker.Authenticate(connMetaWithUser{ConnMetadata: meta, user: principal}, key)
+					if err == nil {
+						log.Printf("nativessh: CA cert auth for user %q principal=%q", meta.User(), principal)
+						return perms, nil
+					}
+					lastErr = err
+				}
+
+				if lastErr != nil {
+					log.Printf("nativessh: CA cert rejected for user %q: %v", meta.User(), lastErr)
+				}
+			}
+		}
+
+		return nil, fmt.Errorf("public key not authorized for user %q", meta.User())
+	}
+}
+
+// makePasswordCallback returns a PasswordCallback that validates the supplied
+// password via the host OS PAM stack.  On non-Linux platforms this always
+// fails (see pam_other.go).
+func makePasswordCallback() func(ssh.ConnMetadata, []byte) (*ssh.Permissions, error) {
+	return func(meta ssh.ConnMetadata, password []byte) (*ssh.Permissions, error) {
+		if err := VerifySystemPassword(meta.User(), string(password)); err != nil {
+			// Return a generic message to the client; log the real reason.
+			log.Printf("nativessh: password auth failed for user %q: %v", meta.User(), err)
+			return nil, fmt.Errorf("permission denied")
+		}
+		log.Printf("nativessh: password auth for user %q", meta.User())
+		return &ssh.Permissions{}, nil
+	}
+}
+
+// generateHostKey generates a fresh ephemeral Ed25519 host key in memory.
+// A new key is created on every server start; nothing is written to disk.
+func generateHostKey() (ssh.Signer, error) {
+	_, priv, err := ed25519.GenerateKey(rand.Reader)
+	if err != nil {
+		return nil, fmt.Errorf("generate host key: %w", err)
+	}
+	log.Printf("nativessh: generated ephemeral Ed25519 host key")
+	return ssh.NewSignerFromKey(priv)
+}
+
+// ptyRequestMsg mirrors the SSH wire format for pty-req (RFC 4254 §6.2).
+type ptyRequestMsg struct {
+	Term     string
+	Columns  uint32
+	Rows     uint32
+	Width    uint32
+	Height   uint32
+	Modelist string
+}
+
+func parsePTYReq(payload []byte) (cols, rows uint16) {
+	var req ptyRequestMsg
+	if err := ssh.Unmarshal(payload, &req); err != nil {
+		return 80, 24
+	}
+	return uint16(req.Columns), uint16(req.Rows)
+}
+
+// windowChangeMsg mirrors the SSH wire format for window-change (RFC 4254 §6.7).
+type windowChangeMsg struct {
+	Columns uint32
+	Rows    uint32
+	Width   uint32
+	Height  uint32
+}
+
+func parseWindowChange(payload []byte) (cols, rows uint16) {
+	var msg windowChangeMsg
+	if err := ssh.Unmarshal(payload, &msg); err != nil {
+		return 80, 24
+	}
+	return uint16(msg.Columns), uint16(msg.Rows)
+}

nativessh/server_windows.go

@@ -0,0 +1,64 @@
+//go:build windows
+
+package nativessh
+
+import (
+	"errors"
+	"log"
+	"net"
+	"sync"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// CredentialStore is a stub on Windows. Native SSH is not supported on Windows.
+type CredentialStore struct {
+	mu         sync.RWMutex
+	principals map[string]map[string]struct{}
+}
+
+// NewCredentialStore returns an empty CredentialStore stub.
+// Native SSH is not supported on Windows; a warning is logged.
+func NewCredentialStore() *CredentialStore {
+	log.Println("WARNING: native SSH is not supported on Windows and will be disabled")
+	return &CredentialStore{
+		principals: make(map[string]map[string]struct{}),
+	}
+}
+
+// SetCAKey is a no-op stub on Windows.
+func (s *CredentialStore) SetCAKey(_ string) error {
+	return errors.New("native SSH not supported on Windows")
+}
+
+// AddPrincipals is a no-op stub on Windows.
+func (s *CredentialStore) AddPrincipals(_, _ string) {}
+
+// get returns nil CA key and empty principals on Windows.
+func (s *CredentialStore) get(_ string) (ssh.PublicKey, map[string]struct{}) {
+	return nil, nil
+}
+
+// ServerConfig holds configuration for the native SSH server (stub on Windows).
+type ServerConfig struct {
+	ListenAddr  string
+	Credentials *CredentialStore
+}
+
+// Server is a stub on Windows.
+type Server struct{}
+
+// NewServer returns a stub Server and logs a warning.
+func NewServer(cfg ServerConfig) *Server {
+	return &Server{}
+}
+
+// ListenAndServe always returns an error on Windows.
+func (s *Server) ListenAndServe() error {
+	return errors.New("native SSH not supported on Windows")
+}
+
+// Serve always returns an error on Windows.
+func (s *Server) Serve(_ net.Listener) error {
+	return errors.New("native SSH not supported on Windows")
+}

netstack2/access_log.go

@@ -0,0 +1,514 @@
+package netstack2
+
+import (
+	"bytes"
+	"compress/zlib"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"net"
+	"sort"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+)
+
+const (
+	// flushInterval is how often the access logger flushes completed sessions to the server
+	flushInterval = 60 * time.Second
+
+	// maxBufferedSessions is the max number of completed sessions to buffer before forcing a flush
+	maxBufferedSessions = 100
+
+	// sessionGapThreshold is the maximum gap between the end of one connection
+	// and the start of the next for them to be considered part of the same session.
+	// If the gap exceeds this, a new consolidated session is created.
+	sessionGapThreshold = 5 * time.Second
+
+	// minConnectionsToConsolidate is the minimum number of connections in a group
+	// before we bother consolidating. Groups smaller than this are sent as-is.
+	minConnectionsToConsolidate = 2
+)
+
+// SendFunc is a callback that sends compressed access log data to the server.
+// The data is a base64-encoded zlib-compressed JSON array of AccessSession objects.
+type SendFunc func(data string) error
+
+// AccessSession represents a tracked access session through the proxy
+type AccessSession struct {
+	SessionID       string    `json:"sessionId"`
+	ResourceID      int       `json:"resourceId"`
+	SourceAddr      string    `json:"sourceAddr"`
+	DestAddr        string    `json:"destAddr"`
+	Protocol        string    `json:"protocol"`
+	StartedAt       time.Time `json:"startedAt"`
+	EndedAt         time.Time `json:"endedAt,omitempty"`
+	BytesTx         int64     `json:"bytesTx"`
+	BytesRx         int64     `json:"bytesRx"`
+	ConnectionCount int       `json:"connectionCount,omitempty"` // number of raw connections merged into this session (0 or 1 = single)
+}
+
+// udpSessionKey identifies a unique UDP "session" by src -> dst
+type udpSessionKey struct {
+	srcAddr  string
+	dstAddr  string
+	protocol string
+}
+
+// consolidationKey groups connections that may be part of the same logical session.
+// Source port is intentionally excluded so that many ephemeral-port connections
+// from the same source IP to the same destination are grouped together.
+type consolidationKey struct {
+	sourceIP   string // IP only, no port
+	destAddr   string // full host:port of the destination
+	protocol   string
+	resourceID int
+}
+
+// AccessLogger tracks access sessions for resources and periodically
+// flushes completed sessions to the server via a configurable SendFunc.
+type AccessLogger struct {
+	mu                sync.Mutex
+	sessions          map[string]*AccessSession       // active sessions: sessionID -> session
+	udpSessions       map[udpSessionKey]*AccessSession // active UDP sessions for dedup
+	completedSessions []*AccessSession                 // completed sessions waiting to be flushed
+	udpTimeout        time.Duration
+	sendFn            SendFunc
+	stopCh            chan struct{}
+	flushDone         chan struct{} // closed after the flush goroutine exits
+}
+
+// NewAccessLogger creates a new access logger.
+// udpTimeout controls how long a UDP session is kept alive without traffic before being ended.
+func NewAccessLogger(udpTimeout time.Duration) *AccessLogger {
+	al := &AccessLogger{
+		sessions:          make(map[string]*AccessSession),
+		udpSessions:       make(map[udpSessionKey]*AccessSession),
+		completedSessions: make([]*AccessSession, 0),
+		udpTimeout:        udpTimeout,
+		stopCh:            make(chan struct{}),
+		flushDone:         make(chan struct{}),
+	}
+	go al.backgroundLoop()
+	return al
+}
+
+// SetSendFunc sets the callback used to send compressed access log batches
+// to the server. This can be called after construction once the websocket
+// client is available.
+func (al *AccessLogger) SetSendFunc(fn SendFunc) {
+	al.mu.Lock()
+	defer al.mu.Unlock()
+	al.sendFn = fn
+}
+
+// generateSessionID creates a random session identifier
+func generateSessionID() string {
+	b := make([]byte, 8)
+	rand.Read(b)
+	return hex.EncodeToString(b)
+}
+
+// StartTCPSession logs the start of a TCP session and returns a session ID.
+func (al *AccessLogger) StartTCPSession(resourceID int, srcAddr, dstAddr string) string {
+	sessionID := generateSessionID()
+	now := time.Now()
+
+	session := &AccessSession{
+		SessionID:  sessionID,
+		ResourceID: resourceID,
+		SourceAddr: srcAddr,
+		DestAddr:   dstAddr,
+		Protocol:   "tcp",
+		StartedAt:  now,
+	}
+
+	al.mu.Lock()
+	al.sessions[sessionID] = session
+	al.mu.Unlock()
+
+	logger.Info("ACCESS START session=%s resource=%d proto=tcp src=%s dst=%s time=%s",
+		sessionID, resourceID, srcAddr, dstAddr, now.Format(time.RFC3339))
+
+	return sessionID
+}
+
+// EndTCPSession logs the end of a TCP session and queues it for sending.
+func (al *AccessLogger) EndTCPSession(sessionID string) {
+	now := time.Now()
+
+	al.mu.Lock()
+	session, ok := al.sessions[sessionID]
+	if ok {
+		session.EndedAt = now
+		delete(al.sessions, sessionID)
+		al.completedSessions = append(al.completedSessions, session)
+	}
+	shouldFlush := len(al.completedSessions) >= maxBufferedSessions
+	al.mu.Unlock()
+
+	if ok {
+		duration := now.Sub(session.StartedAt)
+		logger.Info("ACCESS END session=%s resource=%d proto=tcp src=%s dst=%s started=%s ended=%s duration=%s",
+			sessionID, session.ResourceID, session.SourceAddr, session.DestAddr,
+			session.StartedAt.Format(time.RFC3339), now.Format(time.RFC3339), duration)
+	}
+
+	if shouldFlush {
+		al.flush()
+	}
+}
+
+// TrackUDPSession starts or returns an existing UDP session. Returns the session ID.
+func (al *AccessLogger) TrackUDPSession(resourceID int, srcAddr, dstAddr string) string {
+	key := udpSessionKey{
+		srcAddr:  srcAddr,
+		dstAddr:  dstAddr,
+		protocol: "udp",
+	}
+
+	al.mu.Lock()
+	defer al.mu.Unlock()
+
+	if existing, ok := al.udpSessions[key]; ok {
+		return existing.SessionID
+	}
+
+	sessionID := generateSessionID()
+	now := time.Now()
+
+	session := &AccessSession{
+		SessionID:  sessionID,
+		ResourceID: resourceID,
+		SourceAddr: srcAddr,
+		DestAddr:   dstAddr,
+		Protocol:   "udp",
+		StartedAt:  now,
+	}
+
+	al.sessions[sessionID] = session
+	al.udpSessions[key] = session
+
+	logger.Info("ACCESS START session=%s resource=%d proto=udp src=%s dst=%s time=%s",
+		sessionID, resourceID, srcAddr, dstAddr, now.Format(time.RFC3339))
+
+	return sessionID
+}
+
+// EndUDPSession ends a UDP session and queues it for sending.
+func (al *AccessLogger) EndUDPSession(sessionID string) {
+	now := time.Now()
+
+	al.mu.Lock()
+	session, ok := al.sessions[sessionID]
+	if ok {
+		session.EndedAt = now
+		delete(al.sessions, sessionID)
+		key := udpSessionKey{
+			srcAddr:  session.SourceAddr,
+			dstAddr:  session.DestAddr,
+			protocol: "udp",
+		}
+		delete(al.udpSessions, key)
+		al.completedSessions = append(al.completedSessions, session)
+	}
+	shouldFlush := len(al.completedSessions) >= maxBufferedSessions
+	al.mu.Unlock()
+
+	if ok {
+		duration := now.Sub(session.StartedAt)
+		logger.Info("ACCESS END session=%s resource=%d proto=udp src=%s dst=%s started=%s ended=%s duration=%s",
+			sessionID, session.ResourceID, session.SourceAddr, session.DestAddr,
+			session.StartedAt.Format(time.RFC3339), now.Format(time.RFC3339), duration)
+	}
+
+	if shouldFlush {
+		al.flush()
+	}
+}
+
+// backgroundLoop handles periodic flushing and stale session reaping.
+func (al *AccessLogger) backgroundLoop() {
+	defer close(al.flushDone)
+
+	flushTicker := time.NewTicker(flushInterval)
+	defer flushTicker.Stop()
+
+	reapTicker := time.NewTicker(30 * time.Second)
+	defer reapTicker.Stop()
+
+	for {
+		select {
+		case <-al.stopCh:
+			return
+		case <-flushTicker.C:
+			al.flush()
+		case <-reapTicker.C:
+			al.reapStaleSessions()
+		}
+	}
+}
+
+// reapStaleSessions cleans up UDP sessions that were not properly ended.
+func (al *AccessLogger) reapStaleSessions() {
+	al.mu.Lock()
+	defer al.mu.Unlock()
+
+	staleThreshold := time.Now().Add(-5 * time.Minute)
+
+	for key, session := range al.udpSessions {
+		if session.StartedAt.Before(staleThreshold) && session.EndedAt.IsZero() {
+			now := time.Now()
+			session.EndedAt = now
+			duration := now.Sub(session.StartedAt)
+			logger.Info("ACCESS END (reaped) session=%s resource=%d proto=udp src=%s dst=%s started=%s ended=%s duration=%s",
+				session.SessionID, session.ResourceID, session.SourceAddr, session.DestAddr,
+				session.StartedAt.Format(time.RFC3339), now.Format(time.RFC3339), duration)
+			al.completedSessions = append(al.completedSessions, session)
+			delete(al.sessions, session.SessionID)
+			delete(al.udpSessions, key)
+		}
+	}
+}
+
+// extractIP strips the port from an address string and returns just the IP.
+// If the address has no port component it is returned as-is.
+func extractIP(addr string) string {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		// Might already be a bare IP
+		return addr
+	}
+	return host
+}
+
+// consolidateSessions takes a slice of completed sessions and merges bursts of
+// short-lived connections from the same source IP to the same destination into
+// single higher-level session entries.
+//
+// The algorithm:
+//  1. Group sessions by (sourceIP, destAddr, protocol, resourceID).
+//  2. Within each group, sort by StartedAt.
+//  3. Walk through the sorted list and merge consecutive sessions whose gap
+//     (previous EndedAt → next StartedAt) is ≤ sessionGapThreshold.
+//  4. For merged sessions the earliest StartedAt and latest EndedAt are kept,
+//     bytes are summed, and ConnectionCount records how many raw connections
+//     were folded in. If the merged connections used more than one source port,
+//     SourceAddr is set to just the IP (port omitted).
+//  5. Groups with fewer than minConnectionsToConsolidate members are passed
+//     through unmodified.
+func consolidateSessions(sessions []*AccessSession) []*AccessSession {
+	if len(sessions) <= 1 {
+		return sessions
+	}
+
+	// Group sessions by consolidation key
+	groups := make(map[consolidationKey][]*AccessSession)
+	for _, s := range sessions {
+		key := consolidationKey{
+			sourceIP:   extractIP(s.SourceAddr),
+			destAddr:   s.DestAddr,
+			protocol:   s.Protocol,
+			resourceID: s.ResourceID,
+		}
+		groups[key] = append(groups[key], s)
+	}
+
+	result := make([]*AccessSession, 0, len(sessions))
+
+	for key, group := range groups {
+		// Small groups don't need consolidation
+		if len(group) < minConnectionsToConsolidate {
+			result = append(result, group...)
+			continue
+		}
+
+		// Sort the group by start time so we can detect gaps
+		sort.Slice(group, func(i, j int) bool {
+			return group[i].StartedAt.Before(group[j].StartedAt)
+		})
+
+		// Walk through and merge runs that are within the gap threshold
+		var merged []*AccessSession
+		cur := cloneSession(group[0])
+		cur.ConnectionCount = 1
+		sourcePorts := make(map[string]struct{})
+		sourcePorts[cur.SourceAddr] = struct{}{}
+
+		for i := 1; i < len(group); i++ {
+			s := group[i]
+
+			// Determine the gap: from the latest end time we've seen so far to the
+			// start of the next connection.
+			gapRef := cur.EndedAt
+			if gapRef.IsZero() {
+				gapRef = cur.StartedAt
+			}
+			gap := s.StartedAt.Sub(gapRef)
+
+			if gap <= sessionGapThreshold {
+				// Merge into the current consolidated session
+				cur.ConnectionCount++
+				cur.BytesTx += s.BytesTx
+				cur.BytesRx += s.BytesRx
+				sourcePorts[s.SourceAddr] = struct{}{}
+
+				// Extend EndedAt to the latest time
+				endTime := s.EndedAt
+				if endTime.IsZero() {
+					endTime = s.StartedAt
+				}
+				if endTime.After(cur.EndedAt) {
+					cur.EndedAt = endTime
+				}
+			} else {
+				// Gap exceeded — finalize the current session and start a new one
+				finalizeMergedSourceAddr(cur, key.sourceIP, sourcePorts)
+				merged = append(merged, cur)
+
+				cur = cloneSession(s)
+				cur.ConnectionCount = 1
+				sourcePorts = make(map[string]struct{})
+				sourcePorts[s.SourceAddr] = struct{}{}
+			}
+		}
+
+		// Finalize the last accumulated session
+		finalizeMergedSourceAddr(cur, key.sourceIP, sourcePorts)
+		merged = append(merged, cur)
+
+		result = append(result, merged...)
+	}
+
+	return result
+}
+
+// cloneSession creates a shallow copy of an AccessSession.
+func cloneSession(s *AccessSession) *AccessSession {
+	cp := *s
+	return &cp
+}
+
+// finalizeMergedSourceAddr sets the SourceAddr on a consolidated session.
+// If multiple distinct source addresses (ports) were seen, the port is
+// stripped and only the IP is kept so the log isn't misleading.
+func finalizeMergedSourceAddr(s *AccessSession, sourceIP string, ports map[string]struct{}) {
+	if len(ports) > 1 {
+		// Multiple source ports — just report the IP
+		s.SourceAddr = sourceIP
+	}
+	// Otherwise keep the original SourceAddr which already has ip:port
+}
+
+// flush drains the completed sessions buffer, consolidates bursts of
+// short-lived connections, compresses with zlib, and sends via the SendFunc.
+func (al *AccessLogger) flush() {
+	al.mu.Lock()
+	if len(al.completedSessions) == 0 {
+		al.mu.Unlock()
+		return
+	}
+	batch := al.completedSessions
+	al.completedSessions = make([]*AccessSession, 0)
+	sendFn := al.sendFn
+	al.mu.Unlock()
+
+	if sendFn == nil {
+		logger.Debug("Access logger: no send function configured, discarding %d sessions", len(batch))
+		return
+	}
+
+	// Consolidate bursts of short-lived connections into higher-level sessions
+	originalCount := len(batch)
+	batch = consolidateSessions(batch)
+	if len(batch) != originalCount {
+		logger.Info("Access logger: consolidated %d raw connections into %d sessions", originalCount, len(batch))
+	}
+
+	compressed, err := compressSessions(batch)
+	if err != nil {
+		logger.Error("Access logger: failed to compress %d sessions: %v", len(batch), err)
+		return
+	}
+
+	if err := sendFn(compressed); err != nil {
+		logger.Error("Access logger: failed to send %d sessions: %v", len(batch), err)
+		// Re-queue the batch so we don't lose data
+		al.mu.Lock()
+		al.completedSessions = append(batch, al.completedSessions...)
+		// Cap re-queued data to prevent unbounded growth if server is unreachable
+		if len(al.completedSessions) > maxBufferedSessions*5 {
+			dropped := len(al.completedSessions) - maxBufferedSessions*5
+			al.completedSessions = al.completedSessions[:maxBufferedSessions*5]
+			logger.Warn("Access logger: buffer overflow, dropped %d oldest sessions", dropped)
+		}
+		al.mu.Unlock()
+		return
+	}
+
+	logger.Info("Access logger: sent %d sessions to server", len(batch))
+}
+
+// compressSessions JSON-encodes the sessions, compresses with zlib, and returns
+// a base64-encoded string suitable for embedding in a JSON message.
+func compressSessions(sessions []*AccessSession) (string, error) {
+	jsonData, err := json.Marshal(sessions)
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	w, err := zlib.NewWriterLevel(&buf, zlib.BestCompression)
+	if err != nil {
+		return "", err
+	}
+	if _, err := w.Write(jsonData); err != nil {
+		w.Close()
+		return "", err
+	}
+	if err := w.Close(); err != nil {
+		return "", err
+	}
+
+	return base64.StdEncoding.EncodeToString(buf.Bytes()), nil
+}
+
+// Close shuts down the background loop, ends all active sessions,
+// and performs one final flush to send everything to the server.
+func (al *AccessLogger) Close() {
+	// Signal the background loop to stop
+	select {
+	case <-al.stopCh:
+		// Already closed
+		return
+	default:
+		close(al.stopCh)
+	}
+
+	// Wait for the background loop to exit so we don't race on flush
+	<-al.flushDone
+
+	al.mu.Lock()
+	now := time.Now()
+
+	// End all active sessions and move them to the completed buffer
+	for _, session := range al.sessions {
+		if session.EndedAt.IsZero() {
+			session.EndedAt = now
+			duration := now.Sub(session.StartedAt)
+			logger.Info("ACCESS END (shutdown) session=%s resource=%d proto=%s src=%s dst=%s started=%s ended=%s duration=%s",
+				session.SessionID, session.ResourceID, session.Protocol, session.SourceAddr, session.DestAddr,
+				session.StartedAt.Format(time.RFC3339), now.Format(time.RFC3339), duration)
+			al.completedSessions = append(al.completedSessions, session)
+		}
+	}
+
+	al.sessions = make(map[string]*AccessSession)
+	al.udpSessions = make(map[udpSessionKey]*AccessSession)
+	al.mu.Unlock()
+
+	// Final flush to send all remaining sessions to the server
+	al.flush()
+}

netstack2/access_log_test.go

@@ -0,0 +1,811 @@
+package netstack2
+
+import (
+	"testing"
+	"time"
+)
+
+func TestExtractIP(t *testing.T) {
+	tests := []struct {
+		name     string
+		addr     string
+		expected string
+	}{
+		{"ipv4 with port", "192.168.1.1:12345", "192.168.1.1"},
+		{"ipv4 without port", "192.168.1.1", "192.168.1.1"},
+		{"ipv6 with port", "[::1]:12345", "::1"},
+		{"ipv6 without port", "::1", "::1"},
+		{"empty string", "", ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := extractIP(tt.addr)
+			if result != tt.expected {
+				t.Errorf("extractIP(%q) = %q, want %q", tt.addr, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestConsolidateSessions_Empty(t *testing.T) {
+	result := consolidateSessions(nil)
+	if result != nil {
+		t.Errorf("expected nil, got %v", result)
+	}
+
+	result = consolidateSessions([]*AccessSession{})
+	if len(result) != 0 {
+		t.Errorf("expected empty slice, got %d items", len(result))
+	}
+}
+
+func TestConsolidateSessions_SingleSession(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "abc123",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(1 * time.Second),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 session, got %d", len(result))
+	}
+	if result[0].SourceAddr != "10.0.0.1:5000" {
+		t.Errorf("expected source addr preserved, got %q", result[0].SourceAddr)
+	}
+}
+
+func TestConsolidateSessions_MergesBurstFromSameSourceIP(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+			BytesTx:    100,
+			BytesRx:    200,
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+			BytesTx:    150,
+			BytesRx:    250,
+		},
+		{
+			SessionID:  "s3",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5002",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(400 * time.Millisecond),
+			EndedAt:    now.Add(500 * time.Millisecond),
+			BytesTx:    50,
+			BytesRx:    75,
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 consolidated session, got %d", len(result))
+	}
+
+	s := result[0]
+	if s.ConnectionCount != 3 {
+		t.Errorf("expected ConnectionCount=3, got %d", s.ConnectionCount)
+	}
+	if s.SourceAddr != "10.0.0.1" {
+		t.Errorf("expected source addr to be IP only (multiple ports), got %q", s.SourceAddr)
+	}
+	if s.DestAddr != "192.168.1.100:443" {
+		t.Errorf("expected dest addr preserved, got %q", s.DestAddr)
+	}
+	if s.StartedAt != now {
+		t.Errorf("expected StartedAt to be earliest time")
+	}
+	if s.EndedAt != now.Add(500*time.Millisecond) {
+		t.Errorf("expected EndedAt to be latest time")
+	}
+	expectedTx := int64(300)
+	expectedRx := int64(525)
+	if s.BytesTx != expectedTx {
+		t.Errorf("expected BytesTx=%d, got %d", expectedTx, s.BytesTx)
+	}
+	if s.BytesRx != expectedRx {
+		t.Errorf("expected BytesRx=%d, got %d", expectedRx, s.BytesRx)
+	}
+}
+
+func TestConsolidateSessions_SameSourcePortPreserved(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 session, got %d", len(result))
+	}
+	if result[0].SourceAddr != "10.0.0.1:5000" {
+		t.Errorf("expected source addr with port preserved when all ports are the same, got %q", result[0].SourceAddr)
+	}
+	if result[0].ConnectionCount != 2 {
+		t.Errorf("expected ConnectionCount=2, got %d", result[0].ConnectionCount)
+	}
+}
+
+func TestConsolidateSessions_GapSplitsSessions(t *testing.T) {
+	now := time.Now()
+
+	// First burst
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+		// Big gap here (10 seconds)
+		{
+			SessionID:  "s3",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5002",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(10 * time.Second),
+			EndedAt:    now.Add(10*time.Second + 100*time.Millisecond),
+		},
+		{
+			SessionID:  "s4",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5003",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(10*time.Second + 200*time.Millisecond),
+			EndedAt:    now.Add(10*time.Second + 300*time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 2 {
+		t.Fatalf("expected 2 consolidated sessions (gap split), got %d", len(result))
+	}
+
+	// Find the sessions by their start time
+	var first, second *AccessSession
+	for _, s := range result {
+		if s.StartedAt.Equal(now) {
+			first = s
+		} else {
+			second = s
+		}
+	}
+
+	if first == nil || second == nil {
+		t.Fatal("could not find both consolidated sessions")
+	}
+
+	if first.ConnectionCount != 2 {
+		t.Errorf("first burst: expected ConnectionCount=2, got %d", first.ConnectionCount)
+	}
+	if second.ConnectionCount != 2 {
+		t.Errorf("second burst: expected ConnectionCount=2, got %d", second.ConnectionCount)
+	}
+}
+
+func TestConsolidateSessions_DifferentDestinationsNotMerged(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:8080",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	// Each goes to a different dest port so they should not be merged
+	if len(result) != 2 {
+		t.Fatalf("expected 2 sessions (different destinations), got %d", len(result))
+	}
+}
+
+func TestConsolidateSessions_DifferentProtocolsNotMerged(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "udp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 2 {
+		t.Fatalf("expected 2 sessions (different protocols), got %d", len(result))
+	}
+}
+
+func TestConsolidateSessions_DifferentResourceIDsNotMerged(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 2,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 2 {
+		t.Fatalf("expected 2 sessions (different resource IDs), got %d", len(result))
+	}
+}
+
+func TestConsolidateSessions_DifferentSourceIPsNotMerged(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.2:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 2 {
+		t.Fatalf("expected 2 sessions (different source IPs), got %d", len(result))
+	}
+}
+
+func TestConsolidateSessions_OutOfOrderInput(t *testing.T) {
+	now := time.Now()
+	// Provide sessions out of chronological order to verify sorting
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s3",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5002",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(400 * time.Millisecond),
+			EndedAt:    now.Add(500 * time.Millisecond),
+			BytesTx:    30,
+		},
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+			BytesTx:    10,
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+			BytesTx:    20,
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 consolidated session, got %d", len(result))
+	}
+
+	s := result[0]
+	if s.ConnectionCount != 3 {
+		t.Errorf("expected ConnectionCount=3, got %d", s.ConnectionCount)
+	}
+	if s.StartedAt != now {
+		t.Errorf("expected StartedAt to be earliest time")
+	}
+	if s.EndedAt != now.Add(500*time.Millisecond) {
+		t.Errorf("expected EndedAt to be latest time")
+	}
+	if s.BytesTx != 60 {
+		t.Errorf("expected BytesTx=60, got %d", s.BytesTx)
+	}
+}
+
+func TestConsolidateSessions_ExactlyAtGapThreshold(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			// Starts exactly sessionGapThreshold after s1 ends — should still merge
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(100*time.Millisecond + sessionGapThreshold),
+			EndedAt:    now.Add(100*time.Millisecond + sessionGapThreshold + 50*time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 session (gap exactly at threshold merges), got %d", len(result))
+	}
+	if result[0].ConnectionCount != 2 {
+		t.Errorf("expected ConnectionCount=2, got %d", result[0].ConnectionCount)
+	}
+}
+
+func TestConsolidateSessions_JustOverGapThreshold(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			// Starts 1ms over the gap threshold after s1 ends — should split
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(100*time.Millisecond + sessionGapThreshold + 1*time.Millisecond),
+			EndedAt:    now.Add(100*time.Millisecond + sessionGapThreshold + 50*time.Millisecond),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 2 {
+		t.Fatalf("expected 2 sessions (gap just over threshold splits), got %d", len(result))
+	}
+}
+
+func TestConsolidateSessions_UDPSessions(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		{
+			SessionID:  "u1",
+			ResourceID: 5,
+			SourceAddr: "10.0.0.1:6000",
+			DestAddr:   "192.168.1.100:53",
+			Protocol:   "udp",
+			StartedAt:  now,
+			EndedAt:    now.Add(50 * time.Millisecond),
+			BytesTx:    64,
+			BytesRx:    512,
+		},
+		{
+			SessionID:  "u2",
+			ResourceID: 5,
+			SourceAddr: "10.0.0.1:6001",
+			DestAddr:   "192.168.1.100:53",
+			Protocol:   "udp",
+			StartedAt:  now.Add(100 * time.Millisecond),
+			EndedAt:    now.Add(150 * time.Millisecond),
+			BytesTx:    64,
+			BytesRx:    256,
+		},
+		{
+			SessionID:  "u3",
+			ResourceID: 5,
+			SourceAddr: "10.0.0.1:6002",
+			DestAddr:   "192.168.1.100:53",
+			Protocol:   "udp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(250 * time.Millisecond),
+			BytesTx:    64,
+			BytesRx:    128,
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 consolidated UDP session, got %d", len(result))
+	}
+
+	s := result[0]
+	if s.Protocol != "udp" {
+		t.Errorf("expected protocol=udp, got %q", s.Protocol)
+	}
+	if s.ConnectionCount != 3 {
+		t.Errorf("expected ConnectionCount=3, got %d", s.ConnectionCount)
+	}
+	if s.SourceAddr != "10.0.0.1" {
+		t.Errorf("expected source addr to be IP only, got %q", s.SourceAddr)
+	}
+	if s.BytesTx != 192 {
+		t.Errorf("expected BytesTx=192, got %d", s.BytesTx)
+	}
+	if s.BytesRx != 896 {
+		t.Errorf("expected BytesRx=896, got %d", s.BytesRx)
+	}
+}
+
+func TestConsolidateSessions_MixedGroupsSomeConsolidatedSomeNot(t *testing.T) {
+	now := time.Now()
+	sessions := []*AccessSession{
+		// Group 1: 3 connections to :443 from same IP — should consolidate
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(100 * time.Millisecond),
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(200 * time.Millisecond),
+			EndedAt:    now.Add(300 * time.Millisecond),
+		},
+		{
+			SessionID:  "s3",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5002",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(400 * time.Millisecond),
+			EndedAt:    now.Add(500 * time.Millisecond),
+		},
+		// Group 2: 1 connection to :8080 from different IP — should pass through
+		{
+			SessionID:  "s4",
+			ResourceID: 2,
+			SourceAddr: "10.0.0.2:6000",
+			DestAddr:   "192.168.1.200:8080",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(1 * time.Second),
+			EndedAt:    now.Add(2 * time.Second),
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 2 {
+		t.Fatalf("expected 2 sessions total, got %d", len(result))
+	}
+
+	var consolidated, passthrough *AccessSession
+	for _, s := range result {
+		if s.ConnectionCount > 1 {
+			consolidated = s
+		} else {
+			passthrough = s
+		}
+	}
+
+	if consolidated == nil {
+		t.Fatal("expected a consolidated session")
+	}
+	if consolidated.ConnectionCount != 3 {
+		t.Errorf("consolidated: expected ConnectionCount=3, got %d", consolidated.ConnectionCount)
+	}
+
+	if passthrough == nil {
+		t.Fatal("expected a passthrough session")
+	}
+	if passthrough.SessionID != "s4" {
+		t.Errorf("passthrough: expected session s4, got %s", passthrough.SessionID)
+	}
+}
+
+func TestConsolidateSessions_OverlappingConnections(t *testing.T) {
+	now := time.Now()
+	// Connections that overlap in time (not sequential)
+	sessions := []*AccessSession{
+		{
+			SessionID:  "s1",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5000",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now,
+			EndedAt:    now.Add(5 * time.Second),
+			BytesTx:    100,
+		},
+		{
+			SessionID:  "s2",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5001",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(1 * time.Second),
+			EndedAt:    now.Add(3 * time.Second),
+			BytesTx:    200,
+		},
+		{
+			SessionID:  "s3",
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:5002",
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(2 * time.Second),
+			EndedAt:    now.Add(6 * time.Second),
+			BytesTx:    300,
+		},
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 1 {
+		t.Fatalf("expected 1 consolidated session, got %d", len(result))
+	}
+
+	s := result[0]
+	if s.ConnectionCount != 3 {
+		t.Errorf("expected ConnectionCount=3, got %d", s.ConnectionCount)
+	}
+	if s.StartedAt != now {
+		t.Error("expected StartedAt to be earliest")
+	}
+	if s.EndedAt != now.Add(6*time.Second) {
+		t.Error("expected EndedAt to be the latest end time")
+	}
+	if s.BytesTx != 600 {
+		t.Errorf("expected BytesTx=600, got %d", s.BytesTx)
+	}
+}
+
+func TestConsolidateSessions_DoesNotMutateOriginals(t *testing.T) {
+	now := time.Now()
+	s1 := &AccessSession{
+		SessionID:  "s1",
+		ResourceID: 1,
+		SourceAddr: "10.0.0.1:5000",
+		DestAddr:   "192.168.1.100:443",
+		Protocol:   "tcp",
+		StartedAt:  now,
+		EndedAt:    now.Add(100 * time.Millisecond),
+		BytesTx:    100,
+	}
+	s2 := &AccessSession{
+		SessionID:  "s2",
+		ResourceID: 1,
+		SourceAddr: "10.0.0.1:5001",
+		DestAddr:   "192.168.1.100:443",
+		Protocol:   "tcp",
+		StartedAt:  now.Add(200 * time.Millisecond),
+		EndedAt:    now.Add(300 * time.Millisecond),
+		BytesTx:    200,
+	}
+
+	// Save original values
+	origS1Addr := s1.SourceAddr
+	origS1Bytes := s1.BytesTx
+	origS2Addr := s2.SourceAddr
+	origS2Bytes := s2.BytesTx
+
+	_ = consolidateSessions([]*AccessSession{s1, s2})
+
+	if s1.SourceAddr != origS1Addr {
+		t.Errorf("s1.SourceAddr was mutated: %q -> %q", origS1Addr, s1.SourceAddr)
+	}
+	if s1.BytesTx != origS1Bytes {
+		t.Errorf("s1.BytesTx was mutated: %d -> %d", origS1Bytes, s1.BytesTx)
+	}
+	if s2.SourceAddr != origS2Addr {
+		t.Errorf("s2.SourceAddr was mutated: %q -> %q", origS2Addr, s2.SourceAddr)
+	}
+	if s2.BytesTx != origS2Bytes {
+		t.Errorf("s2.BytesTx was mutated: %d -> %d", origS2Bytes, s2.BytesTx)
+	}
+}
+
+func TestConsolidateSessions_ThreeBurstsWithGaps(t *testing.T) {
+	now := time.Now()
+
+	sessions := make([]*AccessSession, 0, 9)
+
+	// Burst 1: 3 connections at t=0
+	for i := 0; i < 3; i++ {
+		sessions = append(sessions, &AccessSession{
+			SessionID:  generateSessionID(),
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:" + string(rune('A'+i)),
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(time.Duration(i*100) * time.Millisecond),
+			EndedAt:    now.Add(time.Duration(i*100+50) * time.Millisecond),
+		})
+	}
+
+	// Burst 2: 3 connections at t=20s (well past the 5s gap)
+	for i := 0; i < 3; i++ {
+		sessions = append(sessions, &AccessSession{
+			SessionID:  generateSessionID(),
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:" + string(rune('D'+i)),
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(20*time.Second + time.Duration(i*100)*time.Millisecond),
+			EndedAt:    now.Add(20*time.Second + time.Duration(i*100+50)*time.Millisecond),
+		})
+	}
+
+	// Burst 3: 3 connections at t=40s
+	for i := 0; i < 3; i++ {
+		sessions = append(sessions, &AccessSession{
+			SessionID:  generateSessionID(),
+			ResourceID: 1,
+			SourceAddr: "10.0.0.1:" + string(rune('G'+i)),
+			DestAddr:   "192.168.1.100:443",
+			Protocol:   "tcp",
+			StartedAt:  now.Add(40*time.Second + time.Duration(i*100)*time.Millisecond),
+			EndedAt:    now.Add(40*time.Second + time.Duration(i*100+50)*time.Millisecond),
+		})
+	}
+
+	result := consolidateSessions(sessions)
+	if len(result) != 3 {
+		t.Fatalf("expected 3 consolidated sessions (3 bursts), got %d", len(result))
+	}
+
+	for _, s := range result {
+		if s.ConnectionCount != 3 {
+			t.Errorf("expected each burst to have ConnectionCount=3, got %d (started=%v)", s.ConnectionCount, s.StartedAt)
+		}
+	}
+}
+
+func TestFinalizeMergedSourceAddr(t *testing.T) {
+	s := &AccessSession{SourceAddr: "10.0.0.1:5000"}
+	ports := map[string]struct{}{"10.0.0.1:5000": {}}
+	finalizeMergedSourceAddr(s, "10.0.0.1", ports)
+	if s.SourceAddr != "10.0.0.1:5000" {
+		t.Errorf("single port: expected addr preserved, got %q", s.SourceAddr)
+	}
+
+	s2 := &AccessSession{SourceAddr: "10.0.0.1:5000"}
+	ports2 := map[string]struct{}{"10.0.0.1:5000": {}, "10.0.0.1:5001": {}}
+	finalizeMergedSourceAddr(s2, "10.0.0.1", ports2)
+	if s2.SourceAddr != "10.0.0.1" {
+		t.Errorf("multiple ports: expected IP only, got %q", s2.SourceAddr)
+	}
+}
+
+func TestCloneSession(t *testing.T) {
+	original := &AccessSession{
+		SessionID:  "test",
+		ResourceID: 42,
+		SourceAddr: "1.2.3.4:100",
+		DestAddr:   "5.6.7.8:443",
+		Protocol:   "tcp",
+		BytesTx:    999,
+	}
+
+	clone := cloneSession(original)
+
+	if clone == original {
+		t.Error("clone should be a different pointer")
+	}
+	if clone.SessionID != original.SessionID {
+		t.Error("clone should have same SessionID")
+	}
+
+	// Mutating clone should not affect original
+	clone.BytesTx = 0
+	clone.SourceAddr = "changed"
+	if original.BytesTx != 999 {
+		t.Error("mutating clone affected original BytesTx")
+	}
+	if original.SourceAddr != "1.2.3.4:100" {
+		t.Error("mutating clone affected original SourceAddr")
+	}
+}

netstack2/handlers.go

@@ -0,0 +1,776 @@
+package netstack2
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/netip"
+	"os/exec"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"golang.org/x/net/icmp"
+	"golang.org/x/net/ipv4"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
+	"gvisor.dev/gvisor/pkg/tcpip/checksum"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+const (
+	// defaultWndSize if set to zero, the default
+	// receive window buffer size is used instead.
+	defaultWndSize = 0
+
+	// maxConnAttempts specifies the maximum number
+	// of in-flight tcp connection attempts.
+	maxConnAttempts = 2 << 10
+
+	// tcpKeepaliveCount is the maximum number of
+	// TCP keep-alive probes to send before giving up
+	// and killing the connection if no response is
+	// obtained from the other end.
+	tcpKeepaliveCount = 9
+
+	// tcpKeepaliveIdle specifies the time a connection
+	// must remain idle before the first TCP keepalive
+	// packet is sent. Once this time is reached,
+	// tcpKeepaliveInterval option is used instead.
+	tcpKeepaliveIdle = 60 * time.Second
+
+	// tcpKeepaliveInterval specifies the interval
+	// time between sending TCP keepalive packets.
+	tcpKeepaliveInterval = 30 * time.Second
+
+	// tcpConnectTimeout is the default timeout for TCP handshakes.
+	tcpConnectTimeout = 5 * time.Second
+
+	// tcpWaitTimeout implements a TCP half-close timeout.
+	tcpWaitTimeout = 60 * time.Second
+
+	// udpSessionTimeout is the default timeout for UDP sessions.
+	udpSessionTimeout = 60 * time.Second
+
+	// Buffer size for copying data
+	bufferSize = 32 * 1024
+
+	// icmpTimeout is the default timeout for ICMP ping requests.
+	icmpTimeout = 5 * time.Second
+)
+
+// TCPHandler handles TCP connections from netstack
+type TCPHandler struct {
+	stack        *stack.Stack
+	proxyHandler *ProxyHandler
+}
+
+// UDPHandler handles UDP connections from netstack
+type UDPHandler struct {
+	stack        *stack.Stack
+	proxyHandler *ProxyHandler
+}
+
+// ICMPHandler handles ICMP packets from netstack
+type ICMPHandler struct {
+	stack        *stack.Stack
+	proxyHandler *ProxyHandler
+}
+
+// NewTCPHandler creates a new TCP handler
+func NewTCPHandler(s *stack.Stack, ph *ProxyHandler) *TCPHandler {
+	return &TCPHandler{stack: s, proxyHandler: ph}
+}
+
+// NewUDPHandler creates a new UDP handler
+func NewUDPHandler(s *stack.Stack, ph *ProxyHandler) *UDPHandler {
+	return &UDPHandler{stack: s, proxyHandler: ph}
+}
+
+// NewICMPHandler creates a new ICMP handler
+func NewICMPHandler(s *stack.Stack, ph *ProxyHandler) *ICMPHandler {
+	return &ICMPHandler{stack: s, proxyHandler: ph}
+}
+
+// InstallTCPHandler installs the TCP forwarder on the stack
+func (h *TCPHandler) InstallTCPHandler() error {
+	tcpForwarder := tcp.NewForwarder(h.stack, defaultWndSize, maxConnAttempts, func(r *tcp.ForwarderRequest) {
+		var (
+			wq  waiter.Queue
+			ep  tcpip.Endpoint
+			err tcpip.Error
+			id  = r.ID()
+		)
+
+		// Perform a TCP three-way handshake
+		ep, err = r.CreateEndpoint(&wq)
+		if err != nil {
+			// RST: prevent potential half-open TCP connection leak
+			r.Complete(true)
+			return
+		}
+		defer r.Complete(false)
+
+		// Set socket options
+		setTCPSocketOptions(h.stack, ep)
+
+		// Create TCP connection from netstack endpoint
+		netstackConn := gonet.NewTCPConn(&wq, ep)
+
+		// Handle the connection in a goroutine
+		go h.handleTCPConn(netstackConn, id)
+	})
+
+	h.stack.SetTransportProtocolHandler(tcp.ProtocolNumber, tcpForwarder.HandlePacket)
+	return nil
+}
+
+// handleTCPConn handles a TCP connection by proxying it to the actual target
+func (h *TCPHandler) handleTCPConn(netstackConn *gonet.TCPConn, id stack.TransportEndpointID) {
+	// Extract source and target address from the connection ID first so they
+	// are available for HTTP routing before any defer is set up.
+	srcIP := id.RemoteAddress.String()
+	srcPort := id.RemotePort
+	dstIP := id.LocalAddress.String()
+	dstPort := id.LocalPort
+
+	// Drop connection if blocking is enabled
+	if h.proxyHandler != nil && h.proxyHandler.IsBlocked() {
+		logger.Debug("TCP Forwarder: connection blocked: %s:%d -> %s:%d", srcIP, srcPort, dstIP, dstPort)
+		netstackConn.Close()
+		return
+	}
+
+	// For HTTP/HTTPS ports, look up the matching subnet rule. If the rule has
+	// Protocol configured, hand the connection off to the HTTP handler which
+	// takes full ownership of the lifecycle (the defer close must not be
+	// installed before this point).
+	if (dstPort == 80 || dstPort == 443) && h.proxyHandler != nil && h.proxyHandler.httpHandler != nil {
+		srcAddr, _ := netip.ParseAddr(srcIP)
+		dstAddr, _ := netip.ParseAddr(dstIP)
+		rule := h.proxyHandler.subnetLookup.Match(srcAddr, dstAddr, dstPort, tcp.ProtocolNumber)
+		if rule != nil && rule.Protocol != "" && len(rule.HTTPTargets) > 0 {
+			logger.Info("TCP Forwarder: Routing %s:%d -> %s:%d to HTTP handler (%s)",
+				srcIP, srcPort, dstIP, dstPort, rule.Protocol)
+			h.proxyHandler.httpHandler.HandleConn(netstackConn, rule)
+			return
+		}
+		// Otherwise fall through to raw TCP forwarding (e.g. CIDR resources
+		// that happen to use port 80/443 without HTTP configuration).
+	}
+
+	defer netstackConn.Close()
+
+	logger.Info("TCP Forwarder: Handling connection %s:%d -> %s:%d", srcIP, srcPort, dstIP, dstPort)
+
+	// Check if there's a destination rewrite for this connection (e.g., localhost targets)
+	actualDstIP := dstIP
+	if h.proxyHandler != nil {
+		if rewrittenAddr, ok := h.proxyHandler.LookupDestinationRewrite(srcIP, dstIP, dstPort, uint8(tcp.ProtocolNumber)); ok {
+			actualDstIP = rewrittenAddr.String()
+			logger.Info("TCP Forwarder: Using rewritten destination %s (original: %s)", actualDstIP, dstIP)
+		}
+	}
+
+	targetAddr := fmt.Sprintf("%s:%d", actualDstIP, dstPort)
+
+	// Look up resource ID and start access session if applicable
+	var accessSessionID string
+	if h.proxyHandler != nil {
+		resourceId := h.proxyHandler.LookupResourceId(srcIP, dstIP, dstPort, uint8(tcp.ProtocolNumber))
+		if resourceId != 0 {
+			if al := h.proxyHandler.GetAccessLogger(); al != nil {
+				srcAddr := fmt.Sprintf("%s:%d", srcIP, srcPort)
+				accessSessionID = al.StartTCPSession(resourceId, srcAddr, targetAddr)
+			}
+		}
+	}
+
+	// Create context with timeout for connection establishment
+	ctx, cancel := context.WithTimeout(context.Background(), tcpConnectTimeout)
+	defer cancel()
+
+	// Dial the actual target using standard net package
+	var d net.Dialer
+	targetConn, err := d.DialContext(ctx, "tcp", targetAddr)
+	if err != nil {
+		logger.Info("TCP Forwarder: Failed to connect to %s: %v", targetAddr, err)
+		// End access session on connection failure
+		if accessSessionID != "" {
+			if al := h.proxyHandler.GetAccessLogger(); al != nil {
+				al.EndTCPSession(accessSessionID)
+			}
+		}
+		// Connection failed, netstack will handle RST
+		return
+	}
+	defer targetConn.Close()
+
+	// End access session when connection closes
+	if accessSessionID != "" {
+		defer func() {
+			if al := h.proxyHandler.GetAccessLogger(); al != nil {
+				al.EndTCPSession(accessSessionID)
+			}
+		}()
+	}
+
+	logger.Info("TCP Forwarder: Successfully connected to %s, starting bidirectional copy", targetAddr)
+
+	// Bidirectional copy between netstack and target
+	pipeTCP(netstackConn, targetConn)
+}
+
+// pipeTCP copies data bidirectionally between two connections
+func pipeTCP(origin, remote net.Conn) {
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	go unidirectionalStreamTCP(remote, origin, "origin->remote", &wg)
+	go unidirectionalStreamTCP(origin, remote, "remote->origin", &wg)
+
+	wg.Wait()
+}
+
+// unidirectionalStreamTCP copies data in one direction
+func unidirectionalStreamTCP(dst, src net.Conn, dir string, wg *sync.WaitGroup) {
+	defer wg.Done()
+
+	buf := make([]byte, bufferSize)
+	_, _ = io.CopyBuffer(dst, src, buf)
+
+	// Do the upload/download side TCP half-close
+	if cr, ok := src.(interface{ CloseRead() error }); ok {
+		cr.CloseRead()
+	}
+	if cw, ok := dst.(interface{ CloseWrite() error }); ok {
+		cw.CloseWrite()
+	}
+
+	// Set TCP half-close timeout
+	dst.SetReadDeadline(time.Now().Add(tcpWaitTimeout))
+}
+
+// setTCPSocketOptions sets TCP socket options for better performance
+func setTCPSocketOptions(s *stack.Stack, ep tcpip.Endpoint) {
+	// TCP keepalive options
+	ep.SocketOptions().SetKeepAlive(true)
+
+	idle := tcpip.KeepaliveIdleOption(tcpKeepaliveIdle)
+	ep.SetSockOpt(&idle)
+
+	interval := tcpip.KeepaliveIntervalOption(tcpKeepaliveInterval)
+	ep.SetSockOpt(&interval)
+
+	ep.SetSockOptInt(tcpip.KeepaliveCountOption, tcpKeepaliveCount)
+
+	// TCP send/recv buffer size
+	var ss tcpip.TCPSendBufferSizeRangeOption
+	if err := s.TransportProtocolOption(tcp.ProtocolNumber, &ss); err == nil {
+		ep.SocketOptions().SetSendBufferSize(int64(ss.Default), false)
+	}
+
+	var rs tcpip.TCPReceiveBufferSizeRangeOption
+	if err := s.TransportProtocolOption(tcp.ProtocolNumber, &rs); err == nil {
+		ep.SocketOptions().SetReceiveBufferSize(int64(rs.Default), false)
+	}
+}
+
+// InstallUDPHandler installs the UDP forwarder on the stack
+func (h *UDPHandler) InstallUDPHandler() error {
+	udpForwarder := udp.NewForwarder(h.stack, func(r *udp.ForwarderRequest) {
+		var (
+			wq waiter.Queue
+			id = r.ID()
+		)
+
+		ep, err := r.CreateEndpoint(&wq)
+		if err != nil {
+			return
+		}
+
+		// Create UDP connection from netstack endpoint
+		netstackConn := gonet.NewUDPConn(&wq, ep)
+
+		// Handle the connection in a goroutine
+		go h.handleUDPConn(netstackConn, id)
+	})
+
+	h.stack.SetTransportProtocolHandler(udp.ProtocolNumber, udpForwarder.HandlePacket)
+	return nil
+}
+
+// handleUDPConn handles a UDP connection by proxying it to the actual target
+func (h *UDPHandler) handleUDPConn(netstackConn *gonet.UDPConn, id stack.TransportEndpointID) {
+	defer netstackConn.Close()
+
+	// Extract source and target address from the connection ID
+	srcIP := id.RemoteAddress.String()
+	srcPort := id.RemotePort
+	dstIP := id.LocalAddress.String()
+	dstPort := id.LocalPort
+
+	logger.Info("UDP Forwarder: Handling connection %s:%d -> %s:%d", srcIP, srcPort, dstIP, dstPort)
+
+	// Drop connection if blocking is enabled
+	if h.proxyHandler != nil && h.proxyHandler.IsBlocked() {
+		logger.Debug("UDP Forwarder: connection blocked: %s:%d -> %s:%d", srcIP, srcPort, dstIP, dstPort)
+		return
+	}
+
+	// Check if there's a destination rewrite for this connection (e.g., localhost targets)
+	actualDstIP := dstIP
+	if h.proxyHandler != nil {
+		if rewrittenAddr, ok := h.proxyHandler.LookupDestinationRewrite(srcIP, dstIP, dstPort, uint8(udp.ProtocolNumber)); ok {
+			actualDstIP = rewrittenAddr.String()
+			logger.Info("UDP Forwarder: Using rewritten destination %s (original: %s)", actualDstIP, dstIP)
+		}
+	}
+
+	targetAddr := fmt.Sprintf("%s:%d", actualDstIP, dstPort)
+
+	// Look up resource ID and start access session if applicable
+	var accessSessionID string
+	if h.proxyHandler != nil {
+		resourceId := h.proxyHandler.LookupResourceId(srcIP, dstIP, dstPort, uint8(udp.ProtocolNumber))
+		if resourceId != 0 {
+			if al := h.proxyHandler.GetAccessLogger(); al != nil {
+				srcAddr := fmt.Sprintf("%s:%d", srcIP, srcPort)
+				accessSessionID = al.TrackUDPSession(resourceId, srcAddr, targetAddr)
+			}
+		}
+	}
+
+	// End access session when UDP handler returns (timeout or error)
+	if accessSessionID != "" {
+		defer func() {
+			if al := h.proxyHandler.GetAccessLogger(); al != nil {
+				al.EndUDPSession(accessSessionID)
+			}
+		}()
+	}
+
+	// Resolve target address
+	remoteUDPAddr, err := net.ResolveUDPAddr("udp", targetAddr)
+	if err != nil {
+		logger.Info("UDP Forwarder: Failed to resolve %s: %v", targetAddr, err)
+		return
+	}
+
+	// Resolve client address (for sending responses back)
+	clientAddr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", srcIP, srcPort))
+	if err != nil {
+		logger.Info("UDP Forwarder: Failed to resolve client %s:%d: %v", srcIP, srcPort, err)
+		return
+	}
+
+	// Create unconnected UDP socket (so we can use WriteTo)
+	targetConn, err := net.ListenUDP("udp", nil)
+	if err != nil {
+		logger.Info("UDP Forwarder: Failed to create UDP socket: %v", err)
+		return
+	}
+	defer targetConn.Close()
+
+	logger.Info("UDP Forwarder: Successfully created UDP socket for %s, starting bidirectional copy", targetAddr)
+
+	// Bidirectional copy between netstack and target
+	pipeUDP(netstackConn, targetConn, remoteUDPAddr, clientAddr, udpSessionTimeout)
+}
+
+// pipeUDP copies UDP packets bidirectionally
+func pipeUDP(origin, remote net.PacketConn, serverAddr, clientAddr net.Addr, timeout time.Duration) {
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	// Read from origin (netstack), write to remote (target server)
+	go unidirectionalPacketStream(remote, origin, serverAddr, "origin->remote", &wg, timeout)
+	// Read from remote (target server), write to origin (netstack) with client address
+	go unidirectionalPacketStream(origin, remote, clientAddr, "remote->origin", &wg, timeout)
+
+	wg.Wait()
+}
+
+// unidirectionalPacketStream copies packets in one direction
+func unidirectionalPacketStream(dst, src net.PacketConn, to net.Addr, dir string, wg *sync.WaitGroup, timeout time.Duration) {
+	defer wg.Done()
+
+	logger.Info("UDP %s: Starting packet stream (to=%v)", dir, to)
+	err := copyPacketData(dst, src, to, timeout)
+	if err != nil {
+		logger.Info("UDP %s: Stream ended with error: %v", dir, err)
+	} else {
+		logger.Info("UDP %s: Stream ended (timeout)", dir)
+	}
+}
+
+// copyPacketData copies UDP packet data with timeout
+func copyPacketData(dst, src net.PacketConn, to net.Addr, timeout time.Duration) error {
+	buf := make([]byte, 65535) // Max UDP packet size
+
+	for {
+		src.SetReadDeadline(time.Now().Add(timeout))
+		n, srcAddr, err := src.ReadFrom(buf)
+		if ne, ok := err.(net.Error); ok && ne.Timeout() {
+			return nil // ignore I/O timeout
+		} else if err == io.EOF {
+			return nil // ignore EOF
+		} else if err != nil {
+			return err
+		}
+
+		logger.Info("UDP copyPacketData: Read %d bytes from %v", n, srcAddr)
+
+		// Determine write destination
+		writeAddr := to
+		if writeAddr == nil {
+			// If no destination specified, use the source address from the packet
+			writeAddr = srcAddr
+		}
+
+		written, err := dst.WriteTo(buf[:n], writeAddr)
+		if err != nil {
+			logger.Info("UDP copyPacketData: Write error to %v: %v", writeAddr, err)
+			return err
+		}
+		logger.Info("UDP copyPacketData: Wrote %d bytes to %v", written, writeAddr)
+
+		dst.SetReadDeadline(time.Now().Add(timeout))
+	}
+}
+
+// InstallICMPHandler installs the ICMP handler on the stack
+func (h *ICMPHandler) InstallICMPHandler() error {
+	h.stack.SetTransportProtocolHandler(header.ICMPv4ProtocolNumber, h.handleICMPPacket)
+	logger.Debug("ICMP Handler: Installed ICMP protocol handler")
+	return nil
+}
+
+// handleICMPPacket handles incoming ICMP packets
+func (h *ICMPHandler) handleICMPPacket(id stack.TransportEndpointID, pkt *stack.PacketBuffer) bool {
+	logger.Debug("ICMP Handler: Received ICMP packet from %s to %s", id.RemoteAddress, id.LocalAddress)
+
+	// Get the ICMP header from the packet
+	icmpData := pkt.TransportHeader().Slice()
+	if len(icmpData) < header.ICMPv4MinimumSize {
+		logger.Debug("ICMP Handler: Packet too small for ICMP header: %d bytes", len(icmpData))
+		return false
+	}
+
+	icmpHdr := header.ICMPv4(icmpData)
+	icmpType := icmpHdr.Type()
+	icmpCode := icmpHdr.Code()
+
+	logger.Debug("ICMP Handler: Type=%d, Code=%d, Ident=%d, Seq=%d",
+		icmpType, icmpCode, icmpHdr.Ident(), icmpHdr.Sequence())
+
+	// Only handle Echo Request (ping)
+	if icmpType != header.ICMPv4Echo {
+		logger.Debug("ICMP Handler: Ignoring non-echo ICMP type: %d", icmpType)
+		return false
+	}
+
+	// Extract source and destination addresses
+	srcIP := id.RemoteAddress.String()
+	dstIP := id.LocalAddress.String()
+
+	logger.Info("ICMP Handler: Echo Request from %s to %s (ident=%d, seq=%d)",
+		srcIP, dstIP, icmpHdr.Ident(), icmpHdr.Sequence())
+
+	// Convert to netip.Addr for subnet matching
+	srcAddr, err := netip.ParseAddr(srcIP)
+	if err != nil {
+		logger.Debug("ICMP Handler: Failed to parse source IP %s: %v", srcIP, err)
+		return false
+	}
+	dstAddr, err := netip.ParseAddr(dstIP)
+	if err != nil {
+		logger.Debug("ICMP Handler: Failed to parse dest IP %s: %v", dstIP, err)
+		return false
+	}
+
+	// Check subnet rules (use port 0 for ICMP since it doesn't have ports)
+	if h.proxyHandler == nil {
+		logger.Debug("ICMP Handler: No proxy handler configured")
+		return false
+	}
+
+	matchedRule := h.proxyHandler.subnetLookup.Match(srcAddr, dstAddr, 0, header.ICMPv4ProtocolNumber)
+	if matchedRule == nil {
+		logger.Debug("ICMP Handler: No matching subnet rule for %s -> %s", srcIP, dstIP)
+		return false
+	}
+
+	logger.Info("ICMP Handler: Matched subnet rule for %s -> %s", srcIP, dstIP)
+
+	// Determine actual destination (with possible rewrite)
+	actualDstIP := dstIP
+	if matchedRule.RewriteTo != "" {
+		resolvedAddr, err := h.proxyHandler.resolveRewriteAddress(matchedRule.RewriteTo)
+		if err != nil {
+			logger.Info("ICMP Handler: Failed to resolve rewrite address %s: %v", matchedRule.RewriteTo, err)
+		} else {
+			actualDstIP = resolvedAddr.String()
+			logger.Info("ICMP Handler: Using rewritten destination %s (original: %s)", actualDstIP, dstIP)
+		}
+	}
+
+	// Get the full ICMP payload (including the data after the header)
+	icmpPayload := pkt.Data().AsRange().ToSlice()
+
+	// Handle the ping in a goroutine to avoid blocking
+	go h.proxyPing(srcIP, dstIP, actualDstIP, icmpHdr.Ident(), icmpHdr.Sequence(), icmpPayload)
+
+	return true
+}
+
+// proxyPing sends a ping to the actual destination and injects the reply back
+func (h *ICMPHandler) proxyPing(srcIP, originalDstIP, actualDstIP string, ident, seq uint16, payload []byte) {
+	logger.Debug("ICMP Handler: Proxying ping from %s to %s (actual: %s), ident=%d, seq=%d",
+		srcIP, originalDstIP, actualDstIP, ident, seq)
+
+	// Try three methods in order: ip4:icmp -> udp4 -> ping command
+	// Track which method succeeded so we can handle identifier matching correctly
+	method, success := h.tryICMPMethods(actualDstIP, ident, seq, payload)
+
+	if !success {
+		logger.Info("ICMP Handler: All ping methods failed for %s", actualDstIP)
+		return
+	}
+
+	logger.Info("ICMP Handler: Ping successful to %s using %s, injecting reply (ident=%d, seq=%d)",
+		actualDstIP, method, ident, seq)
+
+	// Build the reply packet to inject back into the netstack
+	// The reply should appear to come from the original destination (before rewrite)
+	h.injectICMPReply(srcIP, originalDstIP, ident, seq, payload)
+}
+
+// tryICMPMethods tries all available ICMP methods in order
+func (h *ICMPHandler) tryICMPMethods(actualDstIP string, ident, seq uint16, payload []byte) (string, bool) {
+	if h.tryRawICMP(actualDstIP, ident, seq, payload, false) {
+		return "raw ICMP", true
+	}
+	if h.tryUnprivilegedICMP(actualDstIP, ident, seq, payload) {
+		return "unprivileged ICMP", true
+	}
+	if h.tryPingCommand(actualDstIP, ident, seq, payload) {
+		return "ping command", true
+	}
+	return "", false
+}
+
+// tryRawICMP attempts to ping using raw ICMP sockets (requires CAP_NET_RAW or root)
+func (h *ICMPHandler) tryRawICMP(actualDstIP string, ident, seq uint16, payload []byte, ignoreIdent bool) bool {
+	conn, err := icmp.ListenPacket("ip4:icmp", "0.0.0.0")
+	if err != nil {
+		logger.Debug("ICMP Handler: Raw ICMP socket not available: %v", err)
+		return false
+	}
+	defer conn.Close()
+
+	logger.Debug("ICMP Handler: Using raw ICMP socket")
+	return h.sendAndReceiveICMP(conn, actualDstIP, ident, seq, payload, false, ignoreIdent)
+}
+
+// tryUnprivilegedICMP attempts to ping using unprivileged ICMP (requires ping_group_range configured)
+func (h *ICMPHandler) tryUnprivilegedICMP(actualDstIP string, ident, seq uint16, payload []byte) bool {
+	conn, err := icmp.ListenPacket("udp4", "0.0.0.0")
+	if err != nil {
+		logger.Debug("ICMP Handler: Unprivileged ICMP socket not available: %v", err)
+		return false
+	}
+	defer conn.Close()
+
+	logger.Debug("ICMP Handler: Using unprivileged ICMP socket")
+	// Unprivileged ICMP doesn't let us control the identifier, so we ignore it in matching
+	return h.sendAndReceiveICMP(conn, actualDstIP, ident, seq, payload, true, true)
+}
+
+// sendAndReceiveICMP sends an ICMP echo request and waits for the reply
+func (h *ICMPHandler) sendAndReceiveICMP(conn *icmp.PacketConn, actualDstIP string, ident, seq uint16, payload []byte, isUnprivileged bool, ignoreIdent bool) bool {
+	// Build the ICMP echo request message
+	echoMsg := &icmp.Message{
+		Type: ipv4.ICMPTypeEcho,
+		Code: 0,
+		Body: &icmp.Echo{
+			ID:   int(ident),
+			Seq:  int(seq),
+			Data: payload,
+		},
+	}
+
+	msgBytes, err := echoMsg.Marshal(nil)
+	if err != nil {
+		logger.Debug("ICMP Handler: Failed to marshal ICMP message: %v", err)
+		return false
+	}
+
+	// Resolve destination address based on socket type
+	var writeErr error
+	if isUnprivileged {
+		// For unprivileged ICMP, use UDP-style addressing
+		udpAddr := &net.UDPAddr{IP: net.ParseIP(actualDstIP)}
+		logger.Debug("ICMP Handler: Sending ping to %s (unprivileged)", udpAddr.String())
+		conn.SetDeadline(time.Now().Add(icmpTimeout))
+		_, writeErr = conn.WriteTo(msgBytes, udpAddr)
+	} else {
+		// For raw ICMP, use IP addressing
+		dst, err := net.ResolveIPAddr("ip4", actualDstIP)
+		if err != nil {
+			logger.Debug("ICMP Handler: Failed to resolve destination %s: %v", actualDstIP, err)
+			return false
+		}
+		logger.Debug("ICMP Handler: Sending ping to %s (raw)", dst.String())
+		conn.SetDeadline(time.Now().Add(icmpTimeout))
+		_, writeErr = conn.WriteTo(msgBytes, dst)
+	}
+
+	if writeErr != nil {
+		logger.Debug("ICMP Handler: Failed to send ping to %s: %v", actualDstIP, writeErr)
+		return false
+	}
+
+	logger.Debug("ICMP Handler: Ping sent to %s, waiting for reply (ident=%d, seq=%d)", actualDstIP, ident, seq)
+
+	// Wait for reply - loop to filter out non-matching packets
+	replyBuf := make([]byte, 1500)
+
+	for {
+		n, peer, err := conn.ReadFrom(replyBuf)
+		if err != nil {
+			logger.Debug("ICMP Handler: Failed to receive ping reply from %s: %v", actualDstIP, err)
+			return false
+		}
+
+		logger.Debug("ICMP Handler: Received %d bytes from %s", n, peer.String())
+
+		// Parse the reply
+		replyMsg, err := icmp.ParseMessage(1, replyBuf[:n])
+		if err != nil {
+			logger.Debug("ICMP Handler: Failed to parse ICMP message: %v", err)
+			continue
+		}
+
+		// Check if it's an echo reply (type 0), not an echo request (type 8)
+		if replyMsg.Type != ipv4.ICMPTypeEchoReply {
+			logger.Debug("ICMP Handler: Received non-echo-reply type: %v, continuing to wait", replyMsg.Type)
+			continue
+		}
+
+		reply, ok := replyMsg.Body.(*icmp.Echo)
+		if !ok {
+			logger.Debug("ICMP Handler: Invalid echo reply body type, continuing to wait")
+			continue
+		}
+
+		// Verify the sequence matches what we sent
+		// For unprivileged ICMP, the kernel controls the identifier, so we only check sequence
+		if reply.Seq != int(seq) {
+			logger.Debug("ICMP Handler: Reply seq mismatch: got seq=%d, want seq=%d", reply.Seq, seq)
+			continue
+		}
+
+		if !ignoreIdent && reply.ID != int(ident) {
+			logger.Debug("ICMP Handler: Reply ident mismatch: got ident=%d, want ident=%d", reply.ID, ident)
+			continue
+		}
+
+		// Found matching reply
+		logger.Debug("ICMP Handler: Received valid echo reply")
+		return true
+	}
+}
+
+// tryPingCommand attempts to ping using the system ping command (always works, but less control)
+func (h *ICMPHandler) tryPingCommand(actualDstIP string, ident, seq uint16, payload []byte) bool {
+	logger.Debug("ICMP Handler: Attempting to use system ping command")
+
+	ctx, cancel := context.WithTimeout(context.Background(), icmpTimeout)
+	defer cancel()
+
+	// Send one ping with timeout
+	// -c 1: count = 1 packet
+	// -W 5: timeout = 5 seconds
+	// -q: quiet output (just summary)
+	cmd := exec.CommandContext(ctx, "ping", "-c", "1", "-W", "5", "-q", actualDstIP)
+	output, err := cmd.CombinedOutput()
+
+	if err != nil {
+		logger.Debug("ICMP Handler: System ping command failed: %v, output: %s", err, string(output))
+		return false
+	}
+
+	logger.Debug("ICMP Handler: System ping command succeeded")
+	return true
+}
+
+// injectICMPReply creates an ICMP echo reply packet and queues it to be sent back through the tunnel
+func (h *ICMPHandler) injectICMPReply(dstIP, srcIP string, ident, seq uint16, payload []byte) {
+	logger.Debug("ICMP Handler: Creating reply from %s to %s (ident=%d, seq=%d)",
+		srcIP, dstIP, ident, seq)
+
+	// Parse addresses
+	srcAddr, err := netip.ParseAddr(srcIP)
+	if err != nil {
+		logger.Info("ICMP Handler: Failed to parse source IP for reply: %v", err)
+		return
+	}
+	dstAddr, err := netip.ParseAddr(dstIP)
+	if err != nil {
+		logger.Info("ICMP Handler: Failed to parse dest IP for reply: %v", err)
+		return
+	}
+
+	// Calculate total packet size
+	ipHeaderLen := header.IPv4MinimumSize
+	icmpHeaderLen := header.ICMPv4MinimumSize
+	totalLen := ipHeaderLen + icmpHeaderLen + len(payload)
+
+	// Create the packet buffer
+	pkt := make([]byte, totalLen)
+
+	// Build IPv4 header
+	ipHdr := header.IPv4(pkt[:ipHeaderLen])
+	ipHdr.Encode(&header.IPv4Fields{
+		TotalLength: uint16(totalLen),
+		TTL:         64,
+		Protocol:    uint8(header.ICMPv4ProtocolNumber),
+		SrcAddr:     tcpip.AddrFrom4(srcAddr.As4()),
+		DstAddr:     tcpip.AddrFrom4(dstAddr.As4()),
+	})
+	ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
+
+	// Build ICMP header
+	icmpHdr := header.ICMPv4(pkt[ipHeaderLen : ipHeaderLen+icmpHeaderLen])
+	icmpHdr.SetType(header.ICMPv4EchoReply)
+	icmpHdr.SetCode(0)
+	icmpHdr.SetIdent(ident)
+	icmpHdr.SetSequence(seq)
+
+	// Copy payload
+	copy(pkt[ipHeaderLen+icmpHeaderLen:], payload)
+
+	// Calculate ICMP checksum (covers ICMP header + payload)
+	icmpHdr.SetChecksum(0)
+	icmpData := pkt[ipHeaderLen:]
+	icmpHdr.SetChecksum(^checksum.Checksum(icmpData, 0))
+
+	logger.Debug("ICMP Handler: Built reply packet, total length=%d", totalLen)
+
+	// Queue the packet to be sent back through the tunnel
+	if h.proxyHandler != nil {
+		if h.proxyHandler.QueueICMPReply(pkt) {
+			logger.Info("ICMP Handler: Queued echo reply packet for transmission")
+		} else {
+			logger.Info("ICMP Handler: Failed to queue echo reply packet")
+		}
+	} else {
+		logger.Info("ICMP Handler: Cannot queue reply - proxy handler not available")
+	}
+}

netstack2/http_handler.go

@@ -0,0 +1,420 @@
+package netstack2
+
+import (
+	"bufio"
+	"context"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+// ---------------------------------------------------------------------------
+// HTTPTarget
+// ---------------------------------------------------------------------------
+
+// HTTPTarget describes a single downstream HTTP or HTTPS service that the
+// proxy should forward requests to.
+type HTTPTarget struct {
+	DestAddr string `json:"destAddr"` // IP address or hostname of the downstream service
+	DestPort uint16 `json:"destPort"` // TCP port of the downstream service
+	Scheme   string `json:"scheme"`   // When true the outbound leg uses HTTPS
+}
+
+// ---------------------------------------------------------------------------
+// HTTPHandler
+// ---------------------------------------------------------------------------
+
+// HTTPHandler intercepts TCP connections from the netstack forwarder on ports
+// 80 and 443 and services them as HTTP or HTTPS, reverse-proxying each request
+// to downstream targets specified by the matching SubnetRule.
+//
+// HTTP and raw TCP are fully separate: a connection is only routed here when
+// its SubnetRule has Protocol set ("http" or "https"). All other connections
+// on those ports fall through to the normal raw-TCP path.
+//
+// Incoming TLS termination (Protocol == "https") is performed per-connection
+// using the certificate and key stored in the rule, so different subnet rules
+// can present different certificates without sharing any state.
+//
+// Outbound connections to downstream targets honour HTTPTarget.UseHTTPS
+// independently of the incoming protocol.
+type HTTPHandler struct {
+	stack         *stack.Stack
+	proxyHandler  *ProxyHandler
+	requestLogger *HTTPRequestLogger
+
+	listener *chanListener
+	server   *http.Server
+
+	// proxyCache holds pre-built *httputil.ReverseProxy values keyed by the
+	// canonical target URL string ("scheme://host:port"). Building a proxy is
+	// cheap, but reusing one preserves the underlying http.Transport connection
+	// pool, which matters for throughput.
+	proxyCache sync.Map // map[string]*httputil.ReverseProxy
+
+	// tlsCache holds pre-parsed *tls.Config values keyed by the concatenation
+	// of the PEM certificate and key. Parsing a keypair is relatively expensive
+	// and the same cert is likely reused across many connections.
+	tlsCache sync.Map // map[string]*tls.Config
+}
+
+// ---------------------------------------------------------------------------
+// chanListener – net.Listener backed by a channel
+// ---------------------------------------------------------------------------
+
+// chanListener implements net.Listener by receiving net.Conn values over a
+// buffered channel. This lets the netstack TCP forwarder hand off connections
+// directly to a running http.Server without any real OS socket.
+type chanListener struct {
+	connCh chan net.Conn
+	closed chan struct{}
+	once   sync.Once
+}
+
+func newChanListener() *chanListener {
+	return &chanListener{
+		connCh: make(chan net.Conn, 128),
+		closed: make(chan struct{}),
+	}
+}
+
+// Accept blocks until a connection is available or the listener is closed.
+func (l *chanListener) Accept() (net.Conn, error) {
+	select {
+	case conn, ok := <-l.connCh:
+		if !ok {
+			return nil, net.ErrClosed
+		}
+		return conn, nil
+	case <-l.closed:
+		return nil, net.ErrClosed
+	}
+}
+
+// Close shuts down the listener; subsequent Accept calls return net.ErrClosed.
+func (l *chanListener) Close() error {
+	l.once.Do(func() { close(l.closed) })
+	return nil
+}
+
+// Addr returns a placeholder address (the listener has no real OS socket).
+func (l *chanListener) Addr() net.Addr {
+	return &net.TCPAddr{}
+}
+
+// send delivers conn to the listener. Returns false if the listener is already
+// closed, in which case the caller is responsible for closing conn.
+func (l *chanListener) send(conn net.Conn) bool {
+	select {
+	case l.connCh <- conn:
+		return true
+	case <-l.closed:
+		return false
+	}
+}
+
+// ---------------------------------------------------------------------------
+// httpConnCtx – conn wrapper that carries a SubnetRule through the listener
+// ---------------------------------------------------------------------------
+
+// httpConnCtx wraps a net.Conn so the matching SubnetRule and TLS state can
+// be passed through the chanListener into the http.Server's ConnContext
+// callback, making them available to request handlers via the request context.
+type httpConnCtx struct {
+	net.Conn
+	rule  *SubnetRule
+	isTLS bool // true when the conn was wrapped with tls.Server
+}
+
+// connCtxKey is the unexported context key used to store a *SubnetRule on the
+// per-connection context created by http.Server.ConnContext.
+type connCtxKey struct{}
+
+// connTLSKey is the unexported context key used to store the isTLS flag on
+// the per-connection context created by http.Server.ConnContext.
+type connTLSKey struct{}
+
+// ---------------------------------------------------------------------------
+// Constructor and lifecycle
+// ---------------------------------------------------------------------------
+
+// NewHTTPHandler creates an HTTPHandler attached to the given stack and
+// ProxyHandler. Call Start to begin serving connections.
+func NewHTTPHandler(s *stack.Stack, ph *ProxyHandler) *HTTPHandler {
+	return &HTTPHandler{
+		stack:        s,
+		proxyHandler: ph,
+	}
+}
+
+// SetRequestLogger attaches an HTTPRequestLogger so that every proxied request
+// is recorded and periodically shipped to the server.
+func (h *HTTPHandler) SetRequestLogger(rl *HTTPRequestLogger) {
+	h.requestLogger = rl
+}
+
+// Start launches the internal http.Server that services connections delivered
+// via HandleConn. The server runs for the lifetime of the HTTPHandler; call
+// Close to stop it.
+func (h *HTTPHandler) Start() error {
+	h.listener = newChanListener()
+
+	h.server = &http.Server{
+		Handler: http.HandlerFunc(h.handleRequest),
+		// ConnContext runs once per accepted connection and attaches the
+		// SubnetRule carried by httpConnCtx to the connection's context so
+		// that handleRequest can retrieve it without any global state.
+		ConnContext: func(ctx context.Context, c net.Conn) context.Context {
+			if cc, ok := c.(*httpConnCtx); ok {
+				ctx = context.WithValue(ctx, connCtxKey{}, cc.rule)
+				ctx = context.WithValue(ctx, connTLSKey{}, cc.isTLS)
+			}
+			return ctx
+		},
+	}
+
+	go func() {
+		if err := h.server.Serve(h.listener); err != nil && err != http.ErrServerClosed {
+			logger.Error("HTTP handler: server exited unexpectedly: %v", err)
+		}
+	}()
+
+	logger.Debug("HTTP handler: ready — routing determined per SubnetRule on ports 80/443")
+	return nil
+}
+
+// HandleConn accepts a TCP connection from the netstack forwarder together
+// with the SubnetRule that matched it. The HTTP handler takes full ownership
+// of the connection's lifecycle; the caller must NOT close conn after this call.
+//
+// When rule.Protocol is "https", TLS termination is performed on conn using
+// the certificate and key stored in rule.TLSCert and rule.TLSKey before the
+// connection is passed to the HTTP server. The HTTP server itself is always
+// plain-HTTP; TLS is fully unwrapped at this layer.
+func (h *HTTPHandler) HandleConn(conn net.Conn, rule *SubnetRule) {
+	var effectiveConn net.Conn = conn
+
+	if rule.Protocol == "https" {
+		// Only perform TLS termination for connections arriving on port 443.
+		// Connections on port 80 are passed through as plain HTTP so that
+		// handleRequest can issue the HTTP→HTTPS redirect.
+		doTLS := false
+		if tcpAddr, ok := conn.LocalAddr().(*net.TCPAddr); ok {
+			doTLS = tcpAddr.Port == 443
+		}
+		if doTLS {
+			tlsCfg, err := h.getTLSConfig(rule)
+			if err != nil {
+				logger.Error("HTTP handler: cannot build TLS config for connection from %s: %v",
+					conn.RemoteAddr(), err)
+				conn.Close()
+				return
+			}
+			// tls.Server wraps the raw conn; the TLS handshake is deferred until
+			// the first Read, which the http.Server will trigger naturally.
+			effectiveConn = tls.Server(conn, tlsCfg)
+		}
+	}
+
+	wrapped := &httpConnCtx{Conn: effectiveConn, rule: rule, isTLS: effectiveConn != conn}
+	if !h.listener.send(wrapped) {
+		// Listener is already closed — clean up the orphaned connection.
+		effectiveConn.Close()
+	}
+}
+
+// Close gracefully shuts down the HTTP server and the underlying channel
+// listener, causing the goroutine started in Start to exit.
+func (h *HTTPHandler) Close() error {
+	if h.server != nil {
+		if err := h.server.Close(); err != nil {
+			return err
+		}
+	}
+	if h.listener != nil {
+		h.listener.Close()
+	}
+	return nil
+}
+
+// ---------------------------------------------------------------------------
+// Internal helpers
+// ---------------------------------------------------------------------------
+
+// getTLSConfig returns a *tls.Config for the cert/key pair in rule, using a
+// cache to avoid re-parsing the same keypair on every connection.
+// The cache key is the concatenation of the PEM cert and key strings, so
+// different rules that happen to share the same material hit the same entry.
+func (h *HTTPHandler) getTLSConfig(rule *SubnetRule) (*tls.Config, error) {
+	cacheKey := rule.TLSCert + "|" + rule.TLSKey
+	if v, ok := h.tlsCache.Load(cacheKey); ok {
+		return v.(*tls.Config), nil
+	}
+
+	cert, err := tls.X509KeyPair([]byte(rule.TLSCert), []byte(rule.TLSKey))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse TLS keypair: %w", err)
+	}
+	cfg := &tls.Config{
+		Certificates: []tls.Certificate{cert},
+	}
+	// LoadOrStore is safe under concurrent calls: if two goroutines race here
+	// both will produce a valid config; the loser's work is discarded.
+	actual, _ := h.tlsCache.LoadOrStore(cacheKey, cfg)
+	return actual.(*tls.Config), nil
+}
+
+// getProxy returns a cached *httputil.ReverseProxy for the given target,
+// creating one on first use. Reusing the proxy preserves its http.Transport
+// connection pool, avoiding repeated TCP/TLS handshakes to the downstream.
+func (h *HTTPHandler) getProxy(target HTTPTarget) *httputil.ReverseProxy {
+	scheme := target.Scheme
+	cacheKey := fmt.Sprintf("%s://%s:%d", scheme, target.DestAddr, target.DestPort)
+
+	if v, ok := h.proxyCache.Load(cacheKey); ok {
+		return v.(*httputil.ReverseProxy)
+	}
+
+	targetURL := &url.URL{
+		Scheme: scheme,
+		Host:   fmt.Sprintf("%s:%d", target.DestAddr, target.DestPort),
+	}
+	var transport http.RoundTripper = http.DefaultTransport
+	if target.Scheme == "https" {
+		// Allow self-signed certificates on downstream HTTPS targets.
+		transport = &http.Transport{
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: true, //nolint:gosec // downstream self-signed certs are a supported configuration
+			},
+		}
+	}
+
+	proxy := &httputil.ReverseProxy{
+		Rewrite: func(pr *httputil.ProxyRequest) {
+			pr.SetURL(targetURL)
+			if host := pr.In.Host; host != "" {
+				pr.Out.Host = host
+			}
+			// SetXForwarded sets X-Forwarded-For from the inbound request's
+			// RemoteAddr (the WireGuard/netstack client address), along with
+			// X-Forwarded-Host and X-Forwarded-Proto. Using Rewrite instead of
+			// Director means the proxy does not append its own automatic
+			// X-Forwarded-For entry, so the header is set exactly once.
+			pr.SetXForwarded()
+
+			// SetXForwarded derives X-Forwarded-Proto from pr.In.TLS,
+			// which is nil because httpConnCtx wraps *tls.Conn behind
+			// net.Conn. Override using the context flag set by ConnContext.
+			if isTLS, _ := pr.In.Context().Value(connTLSKey{}).(bool); isTLS {
+				pr.Out.Header.Set("X-Forwarded-Proto", "https")
+			}
+		},
+		Transport: transport,
+	}
+
+	proxy.ErrorHandler = func(w http.ResponseWriter, r *http.Request, err error) {
+		logger.Error("HTTP handler: upstream error (%s %s -> %s): %v",
+			r.Method, r.URL.RequestURI(), cacheKey, err)
+		http.Error(w, "Bad Gateway", http.StatusBadGateway)
+	}
+
+	actual, _ := h.proxyCache.LoadOrStore(cacheKey, proxy)
+	return actual.(*httputil.ReverseProxy)
+}
+
+// statusCapture wraps an http.ResponseWriter and records the HTTP status code
+// written by the upstream handler. If WriteHeader is never called the status
+// defaults to 200 (http.StatusOK), matching net/http semantics.
+type statusCapture struct {
+	http.ResponseWriter
+	status int
+}
+
+func (sc *statusCapture) WriteHeader(code int) {
+	sc.status = code
+	sc.ResponseWriter.WriteHeader(code)
+}
+
+func (sc *statusCapture) Unwrap() http.ResponseWriter {
+	return sc.ResponseWriter
+}
+
+func (sc *statusCapture) Flush() {
+	if flusher, ok := sc.ResponseWriter.(http.Flusher); ok {
+		flusher.Flush()
+	}
+}
+
+func (sc *statusCapture) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hijacker, ok := sc.ResponseWriter.(http.Hijacker)
+	if !ok {
+		return nil, nil, errors.New("underlying response writer does not support hijacking")
+	}
+	return hijacker.Hijack()
+}
+
+// handleRequest is the http.Handler entry point. It retrieves the SubnetRule
+// attached to the connection by ConnContext, selects the first configured
+// downstream target, and forwards the request via the cached ReverseProxy.
+//
+// TODO: add host/path-based routing across multiple HTTPTargets once the
+// configuration model evolves beyond a single target per rule.
+func (h *HTTPHandler) handleRequest(w http.ResponseWriter, r *http.Request) {
+	rule, _ := r.Context().Value(connCtxKey{}).(*SubnetRule)
+	if rule == nil || len(rule.HTTPTargets) == 0 {
+		logger.Error("HTTP handler: no downstream targets for request %s %s", r.Method, r.URL.RequestURI())
+		http.Error(w, "no targets configured", http.StatusBadGateway)
+		return
+	}
+
+	// If the rule is HTTPS but the incoming request arrived over plain HTTP
+	// (port 80), redirect to HTTPS. We use the isTLS flag stored on the
+	// connection context rather than r.TLS, because Go's http.Server calls
+	// ConnectionState() before the TLS handshake completes, so r.TLS.Version
+	// is 0 even for genuine TLS connections at that point.
+	isTLS, _ := r.Context().Value(connTLSKey{}).(bool)
+	if rule.Protocol == "https" && !isTLS {
+		host := r.Host
+		if host == "" {
+			host = r.URL.Host
+		}
+		httpsURL := "https://" + host + r.RequestURI
+		logger.Info("HTTP handler: redirecting %s %s -> %s (TLS cert present)", r.Method, r.URL.RequestURI(), httpsURL)
+		http.Redirect(w, r, httpsURL, http.StatusPermanentRedirect)
+		return
+	}
+
+	target := rule.HTTPTargets[0]
+	scheme := target.Scheme
+	logger.Info("HTTP handler: %s %s -> %s://%s:%d",
+		r.Method, r.URL.RequestURI(), scheme, target.DestAddr, target.DestPort)
+
+	timestamp := time.Now()
+	sc := &statusCapture{ResponseWriter: w, status: http.StatusOK}
+
+	h.getProxy(target).ServeHTTP(sc, r)
+
+	if h.requestLogger != nil && rule.ResourceId != 0 {
+		h.requestLogger.LogRequest(HTTPRequestLog{
+			ResourceID: rule.ResourceId,
+			Timestamp:  timestamp,
+			Method:     r.Method,
+			Scheme:     rule.Protocol,
+			Host:       r.Host,
+			Path:       r.URL.Path,
+			RawQuery:   r.URL.RawQuery,
+			UserAgent:  r.UserAgent(),
+			SourceAddr: r.RemoteAddr,
+			TLS:        rule.Protocol == "https",
+		})
+	}
+}

netstack2/http_handler_test.go

@@ -0,0 +1,97 @@
+package netstack2
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/gorilla/websocket"
+)
+
+func TestHTTPHandlerProxiesWebSocketUpgrade(t *testing.T) {
+	upgrader := websocket.Upgrader{}
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		conn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			t.Errorf("upgrade failed: %v", err)
+			return
+		}
+		defer conn.Close()
+
+		messageType, payload, err := conn.ReadMessage()
+		if err != nil {
+			t.Errorf("read failed: %v", err)
+			return
+		}
+		if err := conn.WriteMessage(messageType, append([]byte("echo:"), payload...)); err != nil {
+			t.Errorf("write failed: %v", err)
+		}
+	}))
+	defer backend.Close()
+
+	backendURL, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatalf("parse backend URL: %v", err)
+	}
+	backendHost, backendPort, err := net.SplitHostPort(backendURL.Host)
+	if err != nil {
+		t.Fatalf("split backend host: %v", err)
+	}
+	port, err := net.LookupPort("tcp", backendPort)
+	if err != nil {
+		t.Fatalf("parse backend port: %v", err)
+	}
+
+	handler := NewHTTPHandler(nil, nil)
+	rule := &SubnetRule{
+		Protocol: "http",
+		HTTPTargets: []HTTPTarget{
+			{
+				DestAddr: backendHost,
+				DestPort: uint16(port),
+				Scheme:   backendURL.Scheme,
+			},
+		},
+	}
+
+	frontend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := context.WithValue(r.Context(), connCtxKey{}, rule)
+		handler.handleRequest(w, r.WithContext(ctx))
+	}))
+	defer frontend.Close()
+
+	frontendURL, err := url.Parse(frontend.URL)
+	if err != nil {
+		t.Fatalf("parse frontend URL: %v", err)
+	}
+	wsURL := url.URL{
+		Scheme:   "ws",
+		Host:     frontendURL.Host,
+		Path:     "/socket",
+		RawQuery: "token=test",
+	}
+
+	conn, _, err := websocket.DefaultDialer.Dial(wsURL.String(), nil)
+	if err != nil {
+		t.Fatalf("dial websocket through proxy: %v", err)
+	}
+	defer conn.Close()
+
+	if err := conn.WriteMessage(websocket.TextMessage, []byte("hello")); err != nil {
+		t.Fatalf("write websocket message: %v", err)
+	}
+
+	messageType, payload, err := conn.ReadMessage()
+	if err != nil {
+		t.Fatalf("read websocket message: %v", err)
+	}
+	if messageType != websocket.TextMessage {
+		t.Fatalf("message type = %d, want %d", messageType, websocket.TextMessage)
+	}
+	if got, want := string(payload), "echo:hello"; got != want {
+		t.Fatalf("payload = %q, want %q", got, want)
+	}
+}

netstack2/http_request_log.go

@@ -0,0 +1,175 @@
+package netstack2
+
+import (
+	"bytes"
+	"compress/zlib"
+	"encoding/base64"
+	"encoding/json"
+	"sync"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+)
+
+// HTTPRequestLog represents a single HTTP/HTTPS request proxied through the handler.
+type HTTPRequestLog struct {
+	RequestID  string    `json:"requestId"`
+	ResourceID int       `json:"resourceId"`
+	Timestamp  time.Time `json:"timestamp"`
+	Method     string    `json:"method"`
+	Scheme     string    `json:"scheme"`
+	Host       string    `json:"host"`
+	Path       string    `json:"path"`
+	RawQuery   string    `json:"rawQuery,omitempty"`
+	UserAgent  string    `json:"userAgent,omitempty"`
+	SourceAddr string    `json:"sourceAddr"`
+	TLS        bool      `json:"tls"`
+}
+
+// HTTPRequestLogger buffers HTTP request logs and periodically flushes them
+// to the server via a configurable SendFunc.
+type HTTPRequestLogger struct {
+	mu        sync.Mutex
+	pending   []HTTPRequestLog
+	sendFn    SendFunc
+	stopCh    chan struct{}
+	flushDone chan struct{}
+}
+
+// NewHTTPRequestLogger creates a new HTTPRequestLogger and starts its background flush loop.
+func NewHTTPRequestLogger() *HTTPRequestLogger {
+	rl := &HTTPRequestLogger{
+		pending:   make([]HTTPRequestLog, 0),
+		stopCh:    make(chan struct{}),
+		flushDone: make(chan struct{}),
+	}
+	go rl.backgroundLoop()
+	return rl
+}
+
+// SetSendFunc sets the callback used to send compressed HTTP request log batches
+// to the server. This can be called after construction once the websocket
+// client is available.
+func (rl *HTTPRequestLogger) SetSendFunc(fn SendFunc) {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+	rl.sendFn = fn
+}
+
+// LogRequest adds an HTTP request log entry to the buffer. If the buffer
+// reaches maxBufferedSessions entries a flush is triggered immediately.
+func (rl *HTTPRequestLogger) LogRequest(log HTTPRequestLog) {
+	if log.RequestID == "" {
+		log.RequestID = generateSessionID()
+	}
+
+	rl.mu.Lock()
+	rl.pending = append(rl.pending, log)
+	shouldFlush := len(rl.pending) >= maxBufferedSessions
+	rl.mu.Unlock()
+
+	if shouldFlush {
+		rl.flush()
+	}
+}
+
+// backgroundLoop handles periodic flushing of buffered request logs.
+func (rl *HTTPRequestLogger) backgroundLoop() {
+	defer close(rl.flushDone)
+
+	ticker := time.NewTicker(flushInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-rl.stopCh:
+			return
+		case <-ticker.C:
+			rl.flush()
+		}
+	}
+}
+
+// flush drains the pending buffer, compresses with zlib, and sends via the SendFunc.
+// On send failure the batch is re-queued, capped at maxBufferedSessions*5 entries
+// to prevent unbounded memory growth when the server is unreachable.
+func (rl *HTTPRequestLogger) flush() {
+	rl.mu.Lock()
+	if len(rl.pending) == 0 {
+		rl.mu.Unlock()
+		return
+	}
+	batch := rl.pending
+	rl.pending = make([]HTTPRequestLog, 0)
+	sendFn := rl.sendFn
+	rl.mu.Unlock()
+
+	if sendFn == nil {
+		logger.Debug("HTTP request logger: no send function configured, discarding %d requests", len(batch))
+		return
+	}
+
+	compressed, err := compressRequestLogs(batch)
+	if err != nil {
+		logger.Error("HTTP request logger: failed to compress %d requests: %v", len(batch), err)
+		return
+	}
+
+	if err := sendFn(compressed); err != nil {
+		logger.Error("HTTP request logger: failed to send %d requests: %v", len(batch), err)
+		// Re-queue the batch so we don't lose data
+		rl.mu.Lock()
+		rl.pending = append(batch, rl.pending...)
+		// Cap re-queued data to prevent unbounded growth if server is unreachable
+		if len(rl.pending) > maxBufferedSessions*5 {
+			dropped := len(rl.pending) - maxBufferedSessions*5
+			rl.pending = rl.pending[:maxBufferedSessions*5]
+			logger.Warn("HTTP request logger: buffer overflow, dropped %d oldest requests", dropped)
+		}
+		rl.mu.Unlock()
+		return
+	}
+
+	logger.Info("HTTP request logger: sent %d requests to server", len(batch))
+}
+
+// compressRequestLogs JSON-encodes the request logs, compresses with zlib, and
+// returns a base64-encoded string suitable for embedding in a JSON message.
+func compressRequestLogs(logs []HTTPRequestLog) (string, error) {
+	jsonData, err := json.Marshal(logs)
+	if err != nil {
+		return "", err
+	}
+
+	var buf bytes.Buffer
+	w, err := zlib.NewWriterLevel(&buf, zlib.BestCompression)
+	if err != nil {
+		return "", err
+	}
+	if _, err := w.Write(jsonData); err != nil {
+		w.Close()
+		return "", err
+	}
+	if err := w.Close(); err != nil {
+		return "", err
+	}
+
+	return base64.StdEncoding.EncodeToString(buf.Bytes()), nil
+}
+
+// Close shuts down the background loop and performs one final flush to send
+// any remaining buffered requests to the server.
+func (rl *HTTPRequestLogger) Close() {
+	select {
+	case <-rl.stopCh:
+		// Already closed
+		return
+	default:
+		close(rl.stopCh)
+	}
+
+	// Wait for the background loop to exit so we don't race on flush
+	<-rl.flushDone
+
+	rl.flush()
+}

netstack2/proxy.go

@@ -0,0 +1,899 @@
+package netstack2
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/netip"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"gvisor.dev/gvisor/pkg/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/checksum"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+)
+
+const (
+	// udpAccessSessionTimeout is how long a UDP access session stays alive without traffic
+	// before being considered ended by the access logger
+	udpAccessSessionTimeout = 120 * time.Second
+)
+
+// PortRange represents an allowed range of ports (inclusive) with optional protocol filtering
+// Protocol can be "tcp", "udp", or "" (empty string means both protocols)
+type PortRange struct {
+	Min      uint16
+	Max      uint16
+	Protocol string // "tcp", "udp", or "" for both
+}
+
+// SubnetRule represents a subnet with optional port restrictions and source address
+// When RewriteTo is set, DNAT (Destination Network Address Translation) is performed:
+//   - Incoming packets: destination IP is rewritten to the resolved RewriteTo address
+//   - Outgoing packets: source IP is rewritten back to the original destination
+//
+// RewriteTo can be either:
+//   - An IP address with CIDR notation (e.g., "192.168.1.1/32")
+//   - A domain name (e.g., "example.com") which will be resolved at request time
+//
+// This allows transparent proxying where traffic appears to come from the rewritten address
+type SubnetRule struct {
+	SourcePrefix netip.Prefix // Source IP prefix (who is sending)
+	DestPrefix   netip.Prefix // Destination IP prefix (where it's going)
+	DisableIcmp  bool         // If true, ICMP traffic is blocked for this subnet
+	RewriteTo    string       // Optional rewrite address for DNAT - can be IP/CIDR or domain name
+	PortRanges   []PortRange  // empty slice means all ports allowed
+	ResourceId   int          // Optional resource ID from the server for access logging
+
+	// HTTP proxy configuration (optional).
+	// When Protocol is non-empty the TCP connection is handled by HTTPHandler
+	// instead of the raw TCP forwarder.
+	Protocol    string       // "", "http", or "https" — controls the incoming (client-facing) protocol
+	HTTPTargets []HTTPTarget // downstream services to proxy requests to
+	TLSCert     string       // PEM-encoded certificate for incoming HTTPS termination
+	TLSKey      string       // PEM-encoded private key for incoming HTTPS termination
+}
+
+// GetAllRules returns a copy of all subnet rules
+func (sl *SubnetLookup) GetAllRules() []SubnetRule {
+	sl.mu.RLock()
+	defer sl.mu.RUnlock()
+
+	var rules []SubnetRule
+	for _, destTriePtr := range sl.sourceTrie.All() {
+		if destTriePtr == nil {
+			continue
+		}
+		for _, rule := range destTriePtr.rules {
+			rules = append(rules, *rule)
+		}
+	}
+	return rules
+}
+
+// connKey uniquely identifies a connection for NAT tracking
+type connKey struct {
+	srcIP   string
+	srcPort uint16
+	dstIP   string
+	dstPort uint16
+	proto   uint8
+}
+
+// reverseConnKey uniquely identifies a connection for reverse NAT lookup (reply direction)
+// Key structure: (rewrittenTo, originalSrcIP, originalSrcPort, originalDstPort, proto)
+// This allows O(1) lookup of NAT entries for reply packets
+type reverseConnKey struct {
+	rewrittenTo     string // The address we rewrote to (becomes src in replies)
+	originalSrcIP   string // Original source IP (becomes dst in replies)
+	originalSrcPort uint16 // Original source port (becomes dst port in replies)
+	originalDstPort uint16 // Original destination port (becomes src port in replies)
+	proto           uint8
+}
+
+// destKey identifies a destination for handler lookups (without source port since it may change)
+type destKey struct {
+	srcIP   string
+	dstIP   string
+	dstPort uint16
+	proto   uint8
+}
+
+// natState tracks NAT translation state for reverse translation
+type natState struct {
+	originalDst netip.Addr // Original destination before DNAT
+	rewrittenTo netip.Addr // The address we rewrote to
+}
+
+// ProxyHandler handles packet injection and extraction for promiscuous mode
+type ProxyHandler struct {
+	proxyStack        *stack.Stack
+	proxyEp           *channel.Endpoint
+	proxyNotifyHandle *channel.NotificationHandle
+	tcpHandler        *TCPHandler
+	udpHandler        *UDPHandler
+	icmpHandler       *ICMPHandler
+	httpHandler       *HTTPHandler
+	subnetLookup      *SubnetLookup
+	natTable          map[connKey]*natState
+	reverseNatTable   map[reverseConnKey]*natState // Reverse lookup map for O(1) reply packet NAT
+	destRewriteTable  map[destKey]netip.Addr       // Maps original dest to rewritten dest for handler lookups
+	resourceTable     map[destKey]int              // Maps connection key to resource ID for access logging
+	natMu             sync.RWMutex
+	enabled           bool
+	icmpReplies       chan []byte          // Channel for ICMP reply packets to be sent back through the tunnel
+	notifiable        channel.Notification // Notification handler for triggering reads
+	accessLogger      *AccessLogger        // Access logger for tracking sessions
+	httpRequestLogger *HTTPRequestLogger   // HTTP request logger for proxied HTTP/HTTPS requests
+	blocked           atomic.Bool          // when true, all new connections are dropped
+}
+
+// ProxyHandlerOptions configures the proxy handler
+type ProxyHandlerOptions struct {
+	EnableTCP  bool
+	EnableUDP  bool
+	EnableICMP bool
+	MTU        int
+}
+
+// NewProxyHandler creates a new proxy handler for promiscuous mode
+func NewProxyHandler(options ProxyHandlerOptions) (*ProxyHandler, error) {
+	if !options.EnableTCP && !options.EnableUDP && !options.EnableICMP {
+		return nil, nil // No proxy needed
+	}
+
+	handler := &ProxyHandler{
+		enabled:          true,
+		subnetLookup:     NewSubnetLookup(),
+		natTable:         make(map[connKey]*natState),
+		reverseNatTable:  make(map[reverseConnKey]*natState),
+		destRewriteTable: make(map[destKey]netip.Addr),
+		resourceTable:    make(map[destKey]int),
+		icmpReplies:      make(chan []byte, 256), // Buffer for ICMP reply packets
+		accessLogger:     NewAccessLogger(udpAccessSessionTimeout),
+		proxyEp:          channel.New(1024, uint32(options.MTU), ""),
+		proxyStack: stack.New(stack.Options{
+			NetworkProtocols: []stack.NetworkProtocolFactory{
+				ipv4.NewProtocol,
+				ipv6.NewProtocol,
+			},
+			TransportProtocols: []stack.TransportProtocolFactory{
+				tcp.NewProtocol,
+				udp.NewProtocol,
+				icmp.NewProtocol4,
+				icmp.NewProtocol6,
+			},
+		}),
+	}
+
+	// Initialize TCP handler if enabled. The HTTP handler piggybacks on the
+	// TCP forwarder — TCPHandler.handleTCPConn checks the subnet rule for
+	// ports 80/443 and routes matching connections to the HTTP handler, so
+	// the HTTP handler is always initialised alongside TCP.
+	if options.EnableTCP {
+		handler.tcpHandler = NewTCPHandler(handler.proxyStack, handler)
+		if err := handler.tcpHandler.InstallTCPHandler(); err != nil {
+			return nil, fmt.Errorf("failed to install TCP handler: %v", err)
+		}
+
+		handler.httpHandler = NewHTTPHandler(handler.proxyStack, handler)
+		if err := handler.httpHandler.Start(); err != nil {
+			return nil, fmt.Errorf("failed to start HTTP handler: %v", err)
+		}
+
+		handler.httpRequestLogger = NewHTTPRequestLogger()
+		handler.httpHandler.SetRequestLogger(handler.httpRequestLogger)
+		logger.Debug("ProxyHandler: HTTP handler enabled")
+	}
+
+	// Initialize UDP handler if enabled
+	if options.EnableUDP {
+		handler.udpHandler = NewUDPHandler(handler.proxyStack, handler)
+		if err := handler.udpHandler.InstallUDPHandler(); err != nil {
+			return nil, fmt.Errorf("failed to install UDP handler: %v", err)
+		}
+	}
+
+	// Initialize ICMP handler if enabled
+	if options.EnableICMP {
+		handler.icmpHandler = NewICMPHandler(handler.proxyStack, handler)
+		if err := handler.icmpHandler.InstallICMPHandler(); err != nil {
+			return nil, fmt.Errorf("failed to install ICMP handler: %v", err)
+		}
+		logger.Debug("ProxyHandler: ICMP handler enabled")
+	}
+
+	// // Example 1: Add a rule with no port restrictions (all ports allowed)
+	// // This accepts all traffic FROM 10.0.0.0/24 TO 10.20.20.0/24
+	// sourceSubnet := netip.MustParsePrefix("10.0.0.0/24")
+	// destSubnet := netip.MustParsePrefix("10.20.20.0/24")
+	// handler.AddSubnetRule(sourceSubnet, destSubnet, nil)
+
+	// // Example 2: Add a rule with specific port ranges
+	// // This accepts traffic FROM 10.0.0.5/32 TO 10.20.21.21/32 only on ports 80, 443, and 8000-9000
+	// sourceIP := netip.MustParsePrefix("10.0.0.5/32")
+	// destIP := netip.MustParsePrefix("10.20.21.21/32")
+	// handler.AddSubnetRule(sourceIP, destIP, []PortRange{
+	// 	{Min: 80, Max: 80},
+	// 	{Min: 443, Max: 443},
+	// 	{Min: 8000, Max: 9000},
+	// })
+
+	return handler, nil
+}
+
+// AddSubnetRule adds a subnet rule to the proxy handler.
+// HTTP proxy behaviour is configured via rule.Protocol, rule.HTTPTargets,
+// rule.TLSCert, and rule.TLSKey; leave Protocol empty for raw TCP/UDP.
+func (p *ProxyHandler) AddSubnetRule(rule SubnetRule) {
+	if p == nil || !p.enabled {
+		return
+	}
+	p.subnetLookup.AddSubnet(rule)
+}
+
+// SetBlocked enables or disables connection blocking on this proxy handler.
+// When enabled, all new TCP/UDP connections from the tunnel are dropped immediately.
+func (p *ProxyHandler) SetBlocked(v bool) {
+	if p == nil {
+		return
+	}
+	p.blocked.Store(v)
+	if v {
+		logger.Debug("ProxyHandler: connection blocking enabled")
+	} else {
+		logger.Debug("ProxyHandler: connection blocking disabled")
+	}
+}
+
+// IsBlocked returns true if connection blocking is currently enabled.
+func (p *ProxyHandler) IsBlocked() bool {
+	if p == nil {
+		return false
+	}
+	return p.blocked.Load()
+}
+
+// RemoveSubnetRule removes a subnet from the proxy handler
+func (p *ProxyHandler) RemoveSubnetRule(sourcePrefix, destPrefix netip.Prefix) {
+	if p == nil || !p.enabled {
+		return
+	}
+	p.subnetLookup.RemoveSubnet(sourcePrefix, destPrefix)
+}
+
+// GetAllRules returns all subnet rules from the proxy handler
+func (p *ProxyHandler) GetAllRules() []SubnetRule {
+	if p == nil || !p.enabled {
+		return nil
+	}
+	return p.subnetLookup.GetAllRules()
+}
+
+// LookupResourceId looks up the resource ID for a connection
+// Returns 0 if no resource ID is associated with this connection
+func (p *ProxyHandler) LookupResourceId(srcIP, dstIP string, dstPort uint16, proto uint8) int {
+	if p == nil || !p.enabled {
+		return 0
+	}
+
+	key := destKey{
+		srcIP:   srcIP,
+		dstIP:   dstIP,
+		dstPort: dstPort,
+		proto:   proto,
+	}
+
+	p.natMu.RLock()
+	defer p.natMu.RUnlock()
+
+	return p.resourceTable[key]
+}
+
+// GetAccessLogger returns the access logger for session tracking
+func (p *ProxyHandler) GetAccessLogger() *AccessLogger {
+	if p == nil {
+		return nil
+	}
+	return p.accessLogger
+}
+
+// SetAccessLogSender configures the function used to send compressed access log
+// batches to the server. This should be called once the websocket client is available.
+func (p *ProxyHandler) SetAccessLogSender(fn SendFunc) {
+	if p == nil || !p.enabled || p.accessLogger == nil {
+		return
+	}
+	p.accessLogger.SetSendFunc(fn)
+}
+
+// GetHTTPRequestLogger returns the HTTP request logger.
+func (p *ProxyHandler) GetHTTPRequestLogger() *HTTPRequestLogger {
+	if p == nil {
+		return nil
+	}
+	return p.httpRequestLogger
+}
+
+// SetHTTPRequestLogSender configures the function used to send compressed HTTP
+// request log batches to the server. This should be called once the websocket
+// client is available.
+func (p *ProxyHandler) SetHTTPRequestLogSender(fn SendFunc) {
+	if p == nil || !p.enabled || p.httpRequestLogger == nil {
+		return
+	}
+	p.httpRequestLogger.SetSendFunc(fn)
+}
+
+// LookupDestinationRewrite looks up the rewritten destination for a connection
+// This is used by TCP/UDP handlers to find the actual target address
+func (p *ProxyHandler) LookupDestinationRewrite(srcIP, dstIP string, dstPort uint16, proto uint8) (netip.Addr, bool) {
+	if p == nil || !p.enabled {
+		return netip.Addr{}, false
+	}
+
+	key := destKey{
+		srcIP:   srcIP,
+		dstIP:   dstIP,
+		dstPort: dstPort,
+		proto:   proto,
+	}
+
+	p.natMu.RLock()
+	defer p.natMu.RUnlock()
+
+	addr, ok := p.destRewriteTable[key]
+	return addr, ok
+}
+
+// resolveRewriteAddress resolves a rewrite address which can be either:
+// - An IP address with CIDR notation (e.g., "192.168.1.1/32") - returns the IP directly
+// - A plain IP address (e.g., "192.168.1.1") - returns the IP directly
+// - A domain name (e.g., "example.com") - performs DNS lookup
+func (p *ProxyHandler) resolveRewriteAddress(rewriteTo string) (netip.Addr, error) {
+	logger.Debug("Resolving rewrite address: %s", rewriteTo)
+
+	// First, try to parse as a CIDR prefix (e.g., "192.168.1.1/32")
+	if prefix, err := netip.ParsePrefix(rewriteTo); err == nil {
+		return prefix.Addr(), nil
+	}
+
+	// Try to parse as a plain IP address (e.g., "192.168.1.1")
+	if addr, err := netip.ParseAddr(rewriteTo); err == nil {
+		return addr, nil
+	}
+
+	// Not an IP address, treat as domain name - perform DNS lookup
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	ips, err := net.DefaultResolver.LookupIP(ctx, "ip4", rewriteTo)
+	if err != nil {
+		return netip.Addr{}, fmt.Errorf("failed to resolve domain %s: %w", rewriteTo, err)
+	}
+
+	if len(ips) == 0 {
+		return netip.Addr{}, fmt.Errorf("no IP addresses found for domain %s", rewriteTo)
+	}
+
+	// Use the first resolved IP address
+	ip := ips[0]
+	if ip4 := ip.To4(); ip4 != nil {
+		addr := netip.AddrFrom4([4]byte{ip4[0], ip4[1], ip4[2], ip4[3]})
+		logger.Debug("Resolved %s to %s", rewriteTo, addr)
+		return addr, nil
+	}
+
+	return netip.Addr{}, fmt.Errorf("no IPv4 address found for domain %s", rewriteTo)
+}
+
+// Initialize sets up the promiscuous NIC with the netTun's notification system
+func (p *ProxyHandler) Initialize(notifiable channel.Notification) error {
+	if p == nil || !p.enabled {
+		return nil
+	}
+
+	// Store notifiable for triggering notifications on ICMP replies
+	p.notifiable = notifiable
+
+	// Add notification handler
+	p.proxyNotifyHandle = p.proxyEp.AddNotify(notifiable)
+
+	// Create NIC with promiscuous mode
+	tcpipErr := p.proxyStack.CreateNICWithOptions(1, p.proxyEp, stack.NICOptions{
+		Disabled: false,
+		QDisc:    nil,
+	})
+	if tcpipErr != nil {
+		return fmt.Errorf("CreateNIC (proxy): %v", tcpipErr)
+	}
+
+	// Enable promiscuous mode - accepts packets for any destination IP
+	if tcpipErr := p.proxyStack.SetPromiscuousMode(1, true); tcpipErr != nil {
+		return fmt.Errorf("SetPromiscuousMode: %v", tcpipErr)
+	}
+
+	// Enable spoofing - allows sending packets from any source IP
+	if tcpipErr := p.proxyStack.SetSpoofing(1, true); tcpipErr != nil {
+		return fmt.Errorf("SetSpoofing: %v", tcpipErr)
+	}
+
+	// Add default route
+	p.proxyStack.AddRoute(tcpip.Route{
+		Destination: header.IPv4EmptySubnet,
+		NIC:         1,
+	})
+
+	return nil
+}
+
+// HandleIncomingPacket processes incoming packets and determines if they should
+// be injected into the proxy stack
+func (p *ProxyHandler) HandleIncomingPacket(packet []byte) bool {
+	if p == nil || !p.enabled {
+		return false
+	}
+
+	// Check minimum packet size
+	if len(packet) < header.IPv4MinimumSize {
+		return false
+	}
+
+	// Only handle IPv4 for now
+	if packet[0]>>4 != 4 {
+		return false
+	}
+
+	// Parse IPv4 header
+	ipv4Header := header.IPv4(packet)
+	srcIP := ipv4Header.SourceAddress()
+	dstIP := ipv4Header.DestinationAddress()
+
+	// Convert gvisor tcpip.Address to netip.Addr
+	srcBytes := srcIP.As4()
+	srcAddr := netip.AddrFrom4(srcBytes)
+	dstBytes := dstIP.As4()
+	dstAddr := netip.AddrFrom4(dstBytes)
+
+	// Parse transport layer to get destination port
+	var dstPort uint16
+	protocol := ipv4Header.TransportProtocol()
+	headerLen := int(ipv4Header.HeaderLength())
+
+	// Extract port based on protocol
+	switch protocol {
+	case header.TCPProtocolNumber:
+		if len(packet) < headerLen+header.TCPMinimumSize {
+			return false
+		}
+		tcpHeader := header.TCP(packet[headerLen:])
+		dstPort = tcpHeader.DestinationPort()
+	case header.UDPProtocolNumber:
+		if len(packet) < headerLen+header.UDPMinimumSize {
+			return false
+		}
+		udpHeader := header.UDP(packet[headerLen:])
+		dstPort = udpHeader.DestinationPort()
+	case header.ICMPv4ProtocolNumber:
+		// ICMP doesn't have ports, use port 0 (must match rules with no port restrictions)
+		dstPort = 0
+		logger.Debug("HandleIncomingPacket: ICMP packet from %s to %s", srcAddr, dstAddr)
+	default:
+		// For other protocols, use port 0 (must match rules with no port restrictions)
+		dstPort = 0
+		logger.Debug("HandleIncomingPacket: Unknown protocol %d from %s to %s", protocol, srcAddr, dstAddr)
+	}
+
+	// Check if the source IP, destination IP, port, and protocol match any subnet rule
+	matchedRule := p.subnetLookup.Match(srcAddr, dstAddr, dstPort, protocol)
+	if matchedRule != nil {
+		logger.Debug("HandleIncomingPacket: Matched rule for %s -> %s (proto=%d, port=%d, resourceId=%d)",
+			srcAddr, dstAddr, protocol, dstPort, matchedRule.ResourceId)
+
+		// Store resource ID for connections without DNAT as well
+		if matchedRule.ResourceId != 0 && matchedRule.RewriteTo == "" {
+			dKey := destKey{
+				srcIP:   srcAddr.String(),
+				dstIP:   dstAddr.String(),
+				dstPort: dstPort,
+				proto:   uint8(protocol),
+			}
+			p.natMu.Lock()
+			p.resourceTable[dKey] = matchedRule.ResourceId
+			p.natMu.Unlock()
+		}
+
+		// Check if we need to perform DNAT
+		if matchedRule.RewriteTo != "" {
+			// Create connection tracking key using original destination
+			// This allows us to check if we've already resolved for this connection
+			var srcPort uint16
+			switch protocol {
+			case header.TCPProtocolNumber:
+				tcpHeader := header.TCP(packet[headerLen:])
+				srcPort = tcpHeader.SourcePort()
+			case header.UDPProtocolNumber:
+				udpHeader := header.UDP(packet[headerLen:])
+				srcPort = udpHeader.SourcePort()
+			}
+
+			// Key using original destination to track the connection
+			key := connKey{
+				srcIP:   srcAddr.String(),
+				srcPort: srcPort,
+				dstIP:   dstAddr.String(),
+				dstPort: dstPort,
+				proto:   uint8(protocol),
+			}
+
+			// Key for handler lookups (doesn't include srcPort for flexibility)
+			dKey := destKey{
+				srcIP:   srcAddr.String(),
+				dstIP:   dstAddr.String(),
+				dstPort: dstPort,
+				proto:   uint8(protocol),
+			}
+
+			// Store resource ID for access logging if present
+			if matchedRule.ResourceId != 0 {
+				p.natMu.Lock()
+				p.resourceTable[dKey] = matchedRule.ResourceId
+				p.natMu.Unlock()
+			}
+
+			// Check if we already have a NAT entry for this connection
+			p.natMu.RLock()
+			existingEntry, exists := p.natTable[key]
+			p.natMu.RUnlock()
+
+			var newDst netip.Addr
+			if exists {
+				// Use the previously resolved address for this connection
+				newDst = existingEntry.rewrittenTo
+				logger.Debug("Using existing NAT entry for connection: %s -> %s", dstAddr, newDst)
+			} else {
+				// New connection - resolve the rewrite address
+				var err error
+				newDst, err = p.resolveRewriteAddress(matchedRule.RewriteTo)
+				if err != nil {
+					// Failed to resolve, skip DNAT but still proxy the packet
+					logger.Debug("Failed to resolve rewrite address: %v", err)
+					pkb := stack.NewPacketBuffer(stack.PacketBufferOptions{
+						Payload: buffer.MakeWithData(packet),
+					})
+					p.proxyEp.InjectInbound(header.IPv4ProtocolNumber, pkb)
+					return true
+				}
+
+				// Store NAT state for this connection
+				p.natMu.Lock()
+				natEntry := &natState{
+					originalDst: dstAddr,
+					rewrittenTo: newDst,
+				}
+				p.natTable[key] = natEntry
+
+				// Create reverse lookup key for O(1) reply packet lookups
+				// Key: (rewrittenTo, originalSrcIP, originalSrcPort, originalDstPort, proto)
+				reverseKey := reverseConnKey{
+					rewrittenTo:     newDst.String(),
+					originalSrcIP:   srcAddr.String(),
+					originalSrcPort: srcPort,
+					originalDstPort: dstPort,
+					proto:           uint8(protocol),
+				}
+				p.reverseNatTable[reverseKey] = natEntry
+
+				// Store destination rewrite for handler lookups
+				p.destRewriteTable[dKey] = newDst
+
+				// Also store the resource ID under the rewritten destination key so that
+				// TCP/UDP handlers can find it after DNAT (they see the post-NAT dst IP).
+				if matchedRule.ResourceId != 0 {
+					rewrittenKey := destKey{
+						srcIP:   srcAddr.String(),
+						dstIP:   newDst.String(),
+						dstPort: dstPort,
+						proto:   uint8(protocol),
+					}
+					p.resourceTable[rewrittenKey] = matchedRule.ResourceId
+				}
+				p.natMu.Unlock()
+				logger.Debug("New NAT entry for connection: %s -> %s", dstAddr, newDst)
+			}
+
+			// Check if target is loopback - if so, don't rewrite packet destination
+			// as gVisor will drop martian packets. Instead, the handlers will use
+			// destRewriteTable to find the actual target address.
+			if !newDst.IsLoopback() {
+				// Rewrite the packet only for non-loopback destinations
+				packet = p.rewritePacketDestination(packet, newDst)
+				if packet == nil {
+					return false
+				}
+			} else {
+				logger.Debug("Target is loopback, not rewriting packet - handlers will use rewrite table")
+			}
+		}
+
+		// Inject into proxy stack
+		pkb := stack.NewPacketBuffer(stack.PacketBufferOptions{
+			Payload: buffer.MakeWithData(packet),
+		})
+		p.proxyEp.InjectInbound(header.IPv4ProtocolNumber, pkb)
+		logger.Debug("HandleIncomingPacket: Injected packet into proxy stack (proto=%d)", protocol)
+		return true
+	}
+
+	// logger.Debug("HandleIncomingPacket: No matching rule for %s -> %s (proto=%d, port=%d)",
+	// srcAddr, dstAddr, protocol, dstPort)
+	return false
+}
+
+// rewritePacketDestination rewrites the destination IP in a packet and recalculates checksums
+func (p *ProxyHandler) rewritePacketDestination(packet []byte, newDst netip.Addr) []byte {
+	if len(packet) < header.IPv4MinimumSize {
+		return nil
+	}
+
+	// Make a copy to avoid modifying the original
+	pkt := make([]byte, len(packet))
+	copy(pkt, packet)
+
+	ipv4Header := header.IPv4(pkt)
+	headerLen := int(ipv4Header.HeaderLength())
+
+	// Rewrite destination IP
+	newDstBytes := newDst.As4()
+	newDstAddr := tcpip.AddrFrom4(newDstBytes)
+	ipv4Header.SetDestinationAddress(newDstAddr)
+
+	// Recalculate IP checksum
+	ipv4Header.SetChecksum(0)
+	ipv4Header.SetChecksum(^ipv4Header.CalculateChecksum())
+
+	// Update transport layer checksum if needed
+	protocol := ipv4Header.TransportProtocol()
+	switch protocol {
+	case header.TCPProtocolNumber:
+		if len(pkt) >= headerLen+header.TCPMinimumSize {
+			tcpHeader := header.TCP(pkt[headerLen:])
+			tcpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.TCPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			tcpHeader.SetChecksum(^xsum)
+		}
+	case header.UDPProtocolNumber:
+		if len(pkt) >= headerLen+header.UDPMinimumSize {
+			udpHeader := header.UDP(pkt[headerLen:])
+			udpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.UDPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			udpHeader.SetChecksum(^xsum)
+		}
+	}
+
+	return pkt
+}
+
+// rewritePacketSource rewrites the source IP in a packet and recalculates checksums (for reverse NAT)
+func (p *ProxyHandler) rewritePacketSource(packet []byte, newSrc netip.Addr) []byte {
+	if len(packet) < header.IPv4MinimumSize {
+		return nil
+	}
+
+	// Make a copy to avoid modifying the original
+	pkt := make([]byte, len(packet))
+	copy(pkt, packet)
+
+	ipv4Header := header.IPv4(pkt)
+	headerLen := int(ipv4Header.HeaderLength())
+
+	// Rewrite source IP
+	newSrcBytes := newSrc.As4()
+	newSrcAddr := tcpip.AddrFrom4(newSrcBytes)
+	ipv4Header.SetSourceAddress(newSrcAddr)
+
+	// Recalculate IP checksum
+	ipv4Header.SetChecksum(0)
+	ipv4Header.SetChecksum(^ipv4Header.CalculateChecksum())
+
+	// Update transport layer checksum if needed
+	protocol := ipv4Header.TransportProtocol()
+	switch protocol {
+	case header.TCPProtocolNumber:
+		if len(pkt) >= headerLen+header.TCPMinimumSize {
+			tcpHeader := header.TCP(pkt[headerLen:])
+			tcpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.TCPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			tcpHeader.SetChecksum(^xsum)
+		}
+	case header.UDPProtocolNumber:
+		if len(pkt) >= headerLen+header.UDPMinimumSize {
+			udpHeader := header.UDP(pkt[headerLen:])
+			udpHeader.SetChecksum(0)
+			xsum := header.PseudoHeaderChecksum(
+				header.UDPProtocolNumber,
+				ipv4Header.SourceAddress(),
+				ipv4Header.DestinationAddress(),
+				uint16(len(pkt)-headerLen),
+			)
+			xsum = checksum.Checksum(pkt[headerLen:], xsum)
+			udpHeader.SetChecksum(^xsum)
+		}
+	}
+
+	return pkt
+}
+
+// ReadOutgoingPacket reads packets from the proxy stack that need to be
+// sent back through the tunnel
+func (p *ProxyHandler) ReadOutgoingPacket() *buffer.View {
+	if p == nil || !p.enabled {
+		return nil
+	}
+
+	// First check for ICMP reply packets (non-blocking)
+	select {
+	case icmpReply := <-p.icmpReplies:
+		logger.Debug("ReadOutgoingPacket: Returning ICMP reply packet (%d bytes)", len(icmpReply))
+		return buffer.NewViewWithData(icmpReply)
+	default:
+		// No ICMP reply available, continue to check proxy endpoint
+	}
+
+	pkt := p.proxyEp.Read()
+	if pkt != nil {
+		view := pkt.ToView()
+		pkt.DecRef()
+
+		// Check if we need to perform reverse NAT
+		packet := view.AsSlice()
+		if len(packet) >= header.IPv4MinimumSize && packet[0]>>4 == 4 {
+			ipv4Header := header.IPv4(packet)
+			srcIP := ipv4Header.SourceAddress()
+			dstIP := ipv4Header.DestinationAddress()
+			protocol := ipv4Header.TransportProtocol()
+			headerLen := int(ipv4Header.HeaderLength())
+
+			// Extract ports
+			var srcPort, dstPort uint16
+			switch protocol {
+			case header.TCPProtocolNumber:
+				if len(packet) >= headerLen+header.TCPMinimumSize {
+					tcpHeader := header.TCP(packet[headerLen:])
+					srcPort = tcpHeader.SourcePort()
+					dstPort = tcpHeader.DestinationPort()
+				}
+			case header.UDPProtocolNumber:
+				if len(packet) >= headerLen+header.UDPMinimumSize {
+					udpHeader := header.UDP(packet[headerLen:])
+					srcPort = udpHeader.SourcePort()
+					dstPort = udpHeader.DestinationPort()
+				}
+			case header.ICMPv4ProtocolNumber:
+				// ICMP packets don't need NAT translation in our implementation
+				// since we construct reply packets with the correct addresses
+				logger.Debug("ReadOutgoingPacket: ICMP packet from %s to %s", srcIP, dstIP)
+				return view
+			}
+
+			// Look up NAT state for reverse translation using O(1) reverse lookup map
+			// Key: (rewrittenTo, originalSrcIP, originalSrcPort, originalDstPort, proto)
+			// For reply packets:
+			// - reply's srcIP = rewrittenTo (the address we rewrote to)
+			// - reply's dstIP = originalSrcIP (original source IP)
+			// - reply's srcPort = originalDstPort (original destination port)
+			// - reply's dstPort = originalSrcPort (original source port)
+			p.natMu.RLock()
+			reverseKey := reverseConnKey{
+				rewrittenTo:     srcIP.String(), // Reply's source is the rewritten address
+				originalSrcIP:   dstIP.String(), // Reply's destination is the original source
+				originalSrcPort: dstPort,        // Reply's destination port is the original source port
+				originalDstPort: srcPort,        // Reply's source port is the original destination port
+				proto:           uint8(protocol),
+			}
+			natEntry := p.reverseNatTable[reverseKey]
+			p.natMu.RUnlock()
+
+			if natEntry != nil {
+				// Perform reverse NAT - rewrite source to original destination
+				packet = p.rewritePacketSource(packet, natEntry.originalDst)
+				if packet != nil {
+					return buffer.NewViewWithData(packet)
+				}
+			}
+		}
+
+		return view
+	}
+
+	return nil
+}
+
+// QueueICMPReply queues an ICMP reply packet to be sent back through the tunnel
+func (p *ProxyHandler) QueueICMPReply(packet []byte) bool {
+	if p == nil || !p.enabled {
+		return false
+	}
+
+	select {
+	case p.icmpReplies <- packet:
+		logger.Debug("QueueICMPReply: Queued ICMP reply packet (%d bytes)", len(packet))
+		// Trigger notification so WriteNotify picks up the packet
+		if p.notifiable != nil {
+			p.notifiable.WriteNotify()
+		}
+		return true
+	default:
+		logger.Info("QueueICMPReply: ICMP reply channel full, dropping packet")
+		return false
+	}
+}
+
+// Close cleans up the proxy handler resources
+func (p *ProxyHandler) Close() error {
+	if p == nil || !p.enabled {
+		return nil
+	}
+
+	// Shut down access logger
+	if p.accessLogger != nil {
+		p.accessLogger.Close()
+	}
+
+	// Shut down HTTP request logger
+	if p.httpRequestLogger != nil {
+		p.httpRequestLogger.Close()
+	}
+
+	// Shut down HTTP handler
+	if p.httpHandler != nil {
+		p.httpHandler.Close()
+	}
+
+	// Close ICMP replies channel
+	if p.icmpReplies != nil {
+		close(p.icmpReplies)
+	}
+
+	if p.proxyStack != nil {
+		p.proxyStack.RemoveNIC(1)
+		p.proxyStack.Close()
+	}
+
+	if p.proxyEp != nil {
+		if p.proxyNotifyHandle != nil {
+			p.proxyEp.RemoveNotify(p.proxyNotifyHandle)
+		}
+		p.proxyEp.Close()
+	}
+
+	return nil
+}

netstack2/subnet_lookup.go

@@ -0,0 +1,201 @@
+package netstack2
+
+import (
+	"net/netip"
+	"sync"
+
+	"github.com/gaissmai/bart"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+)
+
+// SubnetLookup provides fast IP subnet and port matching using BART (Binary Aggregated Range Tree)
+// This uses BART Table for O(log n) prefix matching with Supernets() for efficient lookups
+//
+// Architecture:
+// - Two-level BART structure for matching both source AND destination prefixes
+// - Level 1: Source prefix -> Level 2 (destination prefix -> rules)
+// - This reduces search space: only check destination prefixes for matching source prefixes
+type SubnetLookup struct {
+	mu sync.RWMutex
+	// Two-level BART structure:
+	// Level 1: Source prefix -> Level 2 (destination prefix -> rules)
+	// This allows us to first match source prefix, then only check destination prefixes
+	// for matching source prefixes, reducing the search space significantly
+	sourceTrie *bart.Table[*destTrie]
+}
+
+// destTrie is a BART for destination prefixes, containing the actual rules
+type destTrie struct {
+	trie  *bart.Table[[]*SubnetRule]
+	rules []*SubnetRule // All rules for this source prefix (for iteration if needed)
+}
+
+// NewSubnetLookup creates a new subnet lookup table using BART
+func NewSubnetLookup() *SubnetLookup {
+	return &SubnetLookup{
+		sourceTrie: &bart.Table[*destTrie]{},
+	}
+}
+
+// prefixEqual compares two prefixes after masking to handle host bits correctly.
+// For example, 10.0.0.5/24 and 10.0.0.0/24 are treated as equal.
+func prefixEqual(a, b netip.Prefix) bool {
+	return a.Masked() == b.Masked()
+}
+
+// AddSubnet adds a subnet rule to the lookup table.
+// If rule.PortRanges is nil or empty, all ports are allowed.
+// rule.RewriteTo can be either an IP/CIDR (e.g., "192.168.1.1/32") or a domain name (e.g., "example.com").
+// HTTP proxy behaviour is driven by rule.Protocol, rule.HTTPTargets, rule.TLSCert, and rule.TLSKey.
+func (sl *SubnetLookup) AddSubnet(rule SubnetRule) {
+	sl.mu.Lock()
+	defer sl.mu.Unlock()
+
+	rulePtr := &rule
+
+	// Canonicalize source prefix to handle host bits correctly
+	canonicalSourcePrefix := rule.SourcePrefix.Masked()
+
+	// Get or create destination trie for this source prefix
+	destTriePtr, exists := sl.sourceTrie.Get(canonicalSourcePrefix)
+	if !exists {
+		// Create new destination trie for this source prefix
+		destTriePtr = &destTrie{
+			trie:  &bart.Table[[]*SubnetRule]{},
+			rules: make([]*SubnetRule, 0),
+		}
+		sl.sourceTrie.Insert(canonicalSourcePrefix, destTriePtr)
+	}
+
+	// Canonicalize destination prefix to handle host bits correctly
+	// BART masks prefixes internally, so we need to match that behavior in our bookkeeping
+	canonicalDestPrefix := rule.DestPrefix.Masked()
+
+	// Add rule to destination trie
+	// Original behavior: overwrite if same (sourcePrefix, destPrefix) exists
+	// Store as single-element slice to match original overwrite behavior
+	destTriePtr.trie.Insert(canonicalDestPrefix, []*SubnetRule{rulePtr})
+
+	// Update destTriePtr.rules - remove old rule with same canonical prefix if exists, then add new one
+	// Use canonical comparison to handle cases like 10.0.0.5/24 vs 10.0.0.0/24
+	newRules := make([]*SubnetRule, 0, len(destTriePtr.rules)+1)
+	for _, r := range destTriePtr.rules {
+		if !prefixEqual(r.DestPrefix, canonicalDestPrefix) || !prefixEqual(r.SourcePrefix, canonicalSourcePrefix) {
+			newRules = append(newRules, r)
+		}
+	}
+	newRules = append(newRules, rulePtr)
+	destTriePtr.rules = newRules
+}
+
+// RemoveSubnet removes a subnet rule from the lookup table
+func (sl *SubnetLookup) RemoveSubnet(sourcePrefix, destPrefix netip.Prefix) {
+	sl.mu.Lock()
+	defer sl.mu.Unlock()
+
+	// Canonicalize prefixes to handle host bits correctly
+	canonicalSourcePrefix := sourcePrefix.Masked()
+	canonicalDestPrefix := destPrefix.Masked()
+
+	destTriePtr, exists := sl.sourceTrie.Get(canonicalSourcePrefix)
+	if !exists {
+		return
+	}
+
+	// Remove the rule - original behavior: delete exact (sourcePrefix, destPrefix) combination
+	// BART masks prefixes internally, so Delete works with canonical form
+	destTriePtr.trie.Delete(canonicalDestPrefix)
+
+	// Also remove from destTriePtr.rules using canonical comparison
+	// This ensures we remove rules even if they were added with host bits set
+	newDestRules := make([]*SubnetRule, 0, len(destTriePtr.rules))
+	for _, r := range destTriePtr.rules {
+		if !prefixEqual(r.DestPrefix, canonicalDestPrefix) || !prefixEqual(r.SourcePrefix, canonicalSourcePrefix) {
+			newDestRules = append(newDestRules, r)
+		}
+	}
+	destTriePtr.rules = newDestRules
+
+	// Check if the trie is actually empty using BART's Size() method
+	// This is more efficient than iterating and ensures we clean up empty tries
+	// even if there were stale entries in the rules slice (which shouldn't happen
+	// with proper canonicalization, but this provides a definitive check)
+	if destTriePtr.trie.Size() == 0 {
+		sl.sourceTrie.Delete(canonicalSourcePrefix)
+	}
+}
+
+// Match checks if a source IP, destination IP, port, and protocol match any subnet rule
+// Returns the matched rule if ALL of these conditions are met:
+//   - The source IP is in the rule's source prefix
+//   - The destination IP is in the rule's destination prefix
+//   - The port is in an allowed range (or no port restrictions exist)
+//   - The protocol matches (or the port range allows both protocols)
+//
+// proto should be header.TCPProtocolNumber, header.UDPProtocolNumber, or header.ICMPv4ProtocolNumber
+// Returns nil if no rule matches
+// This uses BART's Supernets() for O(log n) prefix matching instead of O(n) iteration
+func (sl *SubnetLookup) Match(srcIP, dstIP netip.Addr, port uint16, proto tcpip.TransportProtocolNumber) *SubnetRule {
+	sl.mu.RLock()
+	defer sl.mu.RUnlock()
+
+	// Convert IP addresses to /32 (IPv4) or /128 (IPv6) prefixes
+	// Supernets() finds all prefixes that contain this IP (i.e., are supernets of /32 or /128)
+	srcPrefix := netip.PrefixFrom(srcIP, srcIP.BitLen())
+	dstPrefix := netip.PrefixFrom(dstIP, dstIP.BitLen())
+
+	// Step 1: Find all source prefixes that contain srcIP using BART's Supernets
+	// This is O(log n) instead of O(n) iteration
+	// Supernets returns all prefixes that are supernets (contain) the given prefix
+	for _, destTriePtr := range sl.sourceTrie.Supernets(srcPrefix) {
+		if destTriePtr == nil {
+			continue
+		}
+
+		// Step 2: Find all destination prefixes that contain dstIP
+		// This is also O(log n) for each matching source prefix
+		for _, rules := range destTriePtr.trie.Supernets(dstPrefix) {
+			if rules == nil {
+				continue
+			}
+
+			// Step 3: Check each rule for ICMP and port restrictions
+			for _, rule := range rules {
+				// Handle ICMP before port range check — ICMP has no ports
+				if proto == header.ICMPv4ProtocolNumber || proto == header.ICMPv6ProtocolNumber {
+					if rule.DisableIcmp {
+						return nil
+					}
+					// ICMP is allowed; port ranges don't apply to ICMP
+					return rule
+				}
+
+				// Check port restrictions
+				if len(rule.PortRanges) == 0 {
+					// No port restrictions, match!
+					return rule
+				}
+
+				// Check if port and protocol are in any of the allowed ranges
+				for _, pr := range rule.PortRanges {
+					if port >= pr.Min && port <= pr.Max {
+						// Check protocol compatibility
+						if pr.Protocol == "" {
+							// Empty protocol means allow both TCP and UDP
+							return rule
+						}
+						// Check if the packet protocol matches the port range protocol
+						if (pr.Protocol == "tcp" && proto == header.TCPProtocolNumber) ||
+							(pr.Protocol == "udp" && proto == header.UDPProtocolNumber) {
+							return rule
+						}
+						// Port matches but protocol doesn't - continue checking other ranges
+					}
+				}
+			}
+		}
+	}
+
+	return nil
+}

network/interface.go

@@ -0,0 +1,169 @@
+package network
+
+import (
+	"fmt"
+	"net"
+	"os/exec"
+	"regexp"
+	"runtime"
+	"strconv"
+	"time"
+
+	"github.com/fosrl/newt/logger"
+	"github.com/vishvananda/netlink"
+)
+
+// ConfigureInterface configures a network interface with an IP address and brings it up
+func ConfigureInterface(interfaceName string, tunnelIp string, mtu int) error {
+	logger.Info("The tunnel IP is: %s", tunnelIp)
+
+	// Parse the IP address and network
+	ip, ipNet, err := net.ParseCIDR(tunnelIp)
+	if err != nil {
+		return fmt.Errorf("invalid IP address: %v", err)
+	}
+
+	// Convert CIDR mask to dotted decimal format (e.g., 255.255.255.0)
+	mask := net.IP(ipNet.Mask).String()
+	destinationAddress := ip.String()
+
+	logger.Debug("The destination address is: %s", destinationAddress)
+
+	// network.SetTunnelRemoteAddress() // what does this do?
+	SetIPv4Settings([]string{destinationAddress}, []string{mask})
+	SetMTU(mtu)
+
+	if interfaceName == "" {
+		return nil
+	}
+
+	switch runtime.GOOS {
+	case "linux":
+		return configureLinux(interfaceName, ip, ipNet)
+	case "darwin":
+		return configureDarwin(interfaceName, ip, ipNet)
+	case "windows":
+		return configureWindows(interfaceName, ip, ipNet)
+	case "android":
+		return nil
+	case "ios":
+		return nil
+	}
+
+	return nil
+}
+
+// waitForInterfaceUp polls the network interface until it's up or times out
+func waitForInterfaceUp(interfaceName string, expectedIP net.IP, timeout time.Duration) error {
+	logger.Info("Waiting for interface %s to be up with IP %s", interfaceName, expectedIP)
+	deadline := time.Now().Add(timeout)
+	pollInterval := 500 * time.Millisecond
+
+	for time.Now().Before(deadline) {
+		// Check if interface exists and is up
+		iface, err := net.InterfaceByName(interfaceName)
+		if err == nil {
+			// Check if interface is up
+			if iface.Flags&net.FlagUp != 0 {
+				// Check if it has the expected IP
+				addrs, err := iface.Addrs()
+				if err == nil {
+					for _, addr := range addrs {
+						ipNet, ok := addr.(*net.IPNet)
+						if ok && ipNet.IP.Equal(expectedIP) {
+							logger.Info("Interface %s is up with correct IP", interfaceName)
+							return nil // Interface is up with correct IP
+						}
+					}
+					logger.Info("Interface %s is up but doesn't have expected IP yet", interfaceName)
+				}
+			} else {
+				logger.Info("Interface %s exists but is not up yet", interfaceName)
+			}
+		} else {
+			logger.Info("Interface %s not found yet: %v", interfaceName, err)
+		}
+
+		// Wait before next check
+		time.Sleep(pollInterval)
+	}
+
+	return fmt.Errorf("timed out waiting for interface %s to be up with IP %s", interfaceName, expectedIP)
+}
+
+func FindUnusedUTUN() (string, error) {
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		return "", fmt.Errorf("failed to list interfaces: %v", err)
+	}
+	used := make(map[int]bool)
+	re := regexp.MustCompile(`^utun(\d+)$`)
+	for _, iface := range ifaces {
+		if matches := re.FindStringSubmatch(iface.Name); len(matches) == 2 {
+			if num, err := strconv.Atoi(matches[1]); err == nil {
+				used[num] = true
+			}
+		}
+	}
+	// Try utun0 up to utun255.
+	for i := 0; i < 256; i++ {
+		if !used[i] {
+			return fmt.Sprintf("utun%d", i), nil
+		}
+	}
+	return "", fmt.Errorf("no unused utun interface found")
+}
+
+func configureDarwin(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	logger.Info("Configuring darwin interface: %s", interfaceName)
+
+	prefix, _ := ipNet.Mask.Size()
+	ipStr := fmt.Sprintf("%s/%d", ip.String(), prefix)
+
+	cmd := exec.Command("/sbin/ifconfig", interfaceName, "inet", ipStr, ip.String(), "alias")
+	logger.Info("Running command: %v", cmd)
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("ifconfig command failed: %v, output: %s", err, out)
+	}
+
+	// Bring up the interface
+	cmd = exec.Command("/sbin/ifconfig", interfaceName, "up")
+	logger.Info("Running command: %v", cmd)
+
+	out, err = cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("ifconfig up command failed: %v, output: %s", err, out)
+	}
+
+	return nil
+}
+
+func configureLinux(interfaceName string, ip net.IP, ipNet *net.IPNet) error {
+	// Get the interface
+	link, err := netlink.LinkByName(interfaceName)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %s: %v", interfaceName, err)
+	}
+
+	// Create the IP address attributes
+	addr := &netlink.Addr{
+		IPNet: &net.IPNet{
+			IP:   ip,
+			Mask: ipNet.Mask,
+		},
+	}
+
+	// Add the IP address to the interface
+	if err := netlink.AddrAdd(link, addr); err != nil {
+		return fmt.Errorf("failed to add IP address: %v", err)
+	}
+
+	// Bring up the interface
+	if err := netlink.LinkSetUp(link); err != nil {
+		return fmt.Errorf("failed to bring up interface: %v", err)
+	}
+
+	return nil
+}