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DNSEXT D. Blacka
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Internet-Draft VeriSign, Inc.
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Intended status: Standards Track April 7, 2006
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Expires: October 9, 2006
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DNSSEC Experiments
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draft-ietf-dnsext-dnssec-experiments-03
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Status of this Memo
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By submitting this Internet-Draft, each author represents that any
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applicable patent or other IPR claims of which he or she is aware
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have been or will be disclosed, and any of which he or she becomes
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aware will be disclosed, in accordance with Section 6 of BCP 79.
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Internet-Drafts are working documents of the Internet Engineering
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Task Force (IETF), its areas, and its working groups. Note that
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other groups may also distribute working documents as Internet-
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Drafts.
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Internet-Drafts are draft documents valid for a maximum of six months
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and may be updated, replaced, or obsoleted by other documents at any
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time. It is inappropriate to use Internet-Drafts as reference
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material or to cite them other than as "work in progress."
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The list of current Internet-Drafts can be accessed at
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http://www.ietf.org/ietf/1id-abstracts.txt.
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The list of Internet-Draft Shadow Directories can be accessed at
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http://www.ietf.org/shadow.html.
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This Internet-Draft will expire on October 9, 2006.
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Copyright Notice
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Copyright (C) The Internet Society (2006).
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Blacka Expires October 9, 2006 [Page 1]
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Internet-Draft DNSSEC Experiments April 2006
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Abstract
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This document describes a methodology for deploying alternate, non-
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backwards-compatible, DNSSEC methodologies in an experimental fashion
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without disrupting the deployment of standard DNSSEC.
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Table of Contents
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1. Definitions and Terminology . . . . . . . . . . . . . . . . . 3
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2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
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3. Experiments . . . . . . . . . . . . . . . . . . . . . . . . . 5
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4. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
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5. Defining an Experiment . . . . . . . . . . . . . . . . . . . . 8
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6. Considerations . . . . . . . . . . . . . . . . . . . . . . . . 9
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7. Use in Non-Experiments . . . . . . . . . . . . . . . . . . . . 10
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8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
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9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
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10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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10.1. Normative References . . . . . . . . . . . . . . . . . . 13
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10.2. Informative References . . . . . . . . . . . . . . . . . 13
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Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
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Intellectual Property and Copyright Statements . . . . . . . . . . 15
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Blacka Expires October 9, 2006 [Page 2]
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Internet-Draft DNSSEC Experiments April 2006
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1. Definitions and Terminology
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Throughout this document, familiarity with the DNS system (RFC 1035
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[5]) and the DNS security extensions ([2], [3], and [4] is assumed.
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The key words "MUST, "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY, and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119 [1].
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Blacka Expires October 9, 2006 [Page 3]
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Internet-Draft DNSSEC Experiments April 2006
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2. Overview
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Historically, experimentation with DNSSEC alternatives has been a
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problematic endeavor. There has typically been a desire to both
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introduce non-backwards-compatible changes to DNSSEC and to try these
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changes on real zones in the public DNS. This creates a problem when
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the change to DNSSEC would make all or part of the zone using those
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changes appear bogus (bad) or otherwise broken to existing security-
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aware resolvers.
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This document describes a standard methodology for setting up DNSSEC
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experiments. This methodology addresses the issue of co-existence
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with standard DNSSEC and DNS by using unknown algorithm identifiers
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to hide the experimental DNSSEC protocol modifications from standard
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security-aware resolvers.
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Blacka Expires October 9, 2006 [Page 4]
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Internet-Draft DNSSEC Experiments April 2006
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3. Experiments
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When discussing DNSSEC experiments, it is necessary to classify these
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experiments into two broad categories:
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Backwards-Compatible: describes experimental changes that, while not
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strictly adhering to the DNSSEC standard, are nonetheless
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interoperable with clients and servers that do implement the
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DNSSEC standard.
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Non-Backwards-Compatible: describes experiments that would cause a
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standard security-aware resolver to (incorrectly) determine that
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all or part of a zone is bogus, or to otherwise not interoperate
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with standard DNSSEC clients and servers.
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Not included in these terms are experiments with the core DNS
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protocol itself.
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The methodology described in this document is not necessary for
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backwards-compatible experiments, although it certainly may be used
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if desired.
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Blacka Expires October 9, 2006 [Page 5]
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Internet-Draft DNSSEC Experiments April 2006
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4. Method
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The core of the methodology is the use of strictly unknown algorithm
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identifiers when signing the experimental zone, and more importantly,
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having only unknown algorithm identifiers in the DS records for the
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delegation to the zone at the parent.
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This technique works because of the way DNSSEC-compliant validators
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are expected to work in the presence of a DS set with only unknown
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algorithm identifiers. From [4], Section 5.2:
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If the validator does not support any of the algorithms listed in
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an authenticated DS RRset, then the resolver has no supported
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authentication path leading from the parent to the child. The
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resolver should treat this case as it would the case of an
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authenticated NSEC RRset proving that no DS RRset exists, as
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described above.
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And further:
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If the resolver does not support any of the algorithms listed in
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an authenticated DS RRset, then the resolver will not be able to
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verify the authentication path to the child zone. In this case,
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the resolver SHOULD treat the child zone as if it were unsigned.
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While this behavior isn't strictly mandatory (as marked by MUST), it
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is likely that a validator would implement this behavior, or, more to
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the point, it would handle this situation in a safe way (see below
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(Section 6).)
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Because we are talking about experiments, it is RECOMMENDED that
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private algorithm numbers be used (see [3], appendix A.1.1. Note
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that secure handling of private algorithms requires special handing
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by the validator logic. See [6] for further details.) Normally,
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instead of actually inventing new signing algorithms, the recommended
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path is to create alternate algorithm identifiers that are aliases
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for the existing, known algorithms. While, strictly speaking, it is
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only necessary to create an alternate identifier for the mandatory
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algorithms, it is suggested that all optional defined algorithms be
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aliased as well.
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It is RECOMMENDED that for a particular DNSSEC experiment, a
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particular domain name base is chosen for all new algorithms, then
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the algorithm number (or name) is prepended to it. For example, for
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experiment A, the base name of "dnssec-experiment-a.example.com" is
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chosen. Then, aliases for algorithms 3 (DSA) and 5 (RSASHA1) are
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defined to be "3.dnssec-experiment-a.example.com" and
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"5.dnssec-experiment-a.example.com". However, any unique identifier
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Blacka Expires October 9, 2006 [Page 6]
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Internet-Draft DNSSEC Experiments April 2006
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will suffice.
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Using this method, resolvers (or, more specifically, DNSSEC
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validators) essentially indicate their ability to understand the
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DNSSEC experiment's semantics by understanding what the new algorithm
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identifiers signify.
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This method creates two classes of security-aware servers and
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resolvers: servers and resolvers that are aware of the experiment
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(and thus recognize the experiment's algorithm identifiers and
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experimental semantics), and servers and resolvers that are unaware
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of the experiment.
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This method also precludes any zone from being both in an experiment
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and in a classic DNSSEC island of security. That is, a zone is
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either in an experiment and only experimentally validatable, or it is
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not.
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Blacka Expires October 9, 2006 [Page 7]
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Internet-Draft DNSSEC Experiments April 2006
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5. Defining an Experiment
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The DNSSEC experiment MUST define the particular set of (previously
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unknown) algorithm identifiers that identify the experiment, and
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define what each unknown algorithm identifier means. Typically,
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unless the experiment is actually experimenting with a new DNSSEC
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algorithm, this will be a mapping of private algorithm identifiers to
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existing, known algorithms.
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Normally the experiment will choose a DNS name as the algorithm
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identifier base. This DNS name SHOULD be under the control of the
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authors of the experiment. Then the experiment will define a mapping
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between known mandatory and optional algorithms into this private
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algorithm identifier space. Alternately, the experiment MAY use the
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OID private algorithm space instead (using algorithm number 254), or
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MAY choose non-private algorithm numbers, although this would require
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an IANA allocation.
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For example, an experiment might specify in its description the DNS
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name "dnssec-experiment-a.example.com" as the base name, and declare
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that "3.dnssec-experiment-a.example.com" is an alias of DNSSEC
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algorithm 3 (DSA), and that "5.dnssec-experiment-a.example.com" is an
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alias of DNSSEC algorithm 5 (RSASHA1).
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Resolvers MUST only recognize the experiment's semantics when present
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in a zone signed by one or more of these algorithm identifiers. This
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is necessary to isolate the semantics of one experiment from any
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others that the resolver might understand.
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In general, resolvers involved in the experiment are expected to
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understand both standard DNSSEC and the defined experimental DNSSEC
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protocol, although this isn't required.
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Blacka Expires October 9, 2006 [Page 8]
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Internet-Draft DNSSEC Experiments April 2006
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6. Considerations
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There are a number of considerations with using this methodology.
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1. Under some circumstances, it may be that the experiment will not
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be sufficiently masked by this technique and may cause resolution
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problem for resolvers not aware of the experiment. For instance,
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the resolver may look at a non-validatable response and conclude
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that the response is bogus, either due to local policy or
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implementation details. This is not expected to be a common
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case, however.
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2. It will not be possible for security-aware resolvers unaware of
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the experiment to build a chain of trust through an experimental
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zone.
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Blacka Expires October 9, 2006 [Page 9]
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Internet-Draft DNSSEC Experiments April 2006
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7. Use in Non-Experiments
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This general methodology MAY be used for non-backwards compatible
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DNSSEC protocol changes that start out as or become standards. In
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this case:
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o The protocol change SHOULD use public IANA allocated algorithm
|
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identifiers instead of private algorithm identifiers. This will
|
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help identify the protocol change as a standard, rather than an
|
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experiment.
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o Resolvers MAY recognize the protocol change in zones not signed
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(or not solely signed) using the new algorithm identifiers.
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Blacka Expires October 9, 2006 [Page 10]
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Internet-Draft DNSSEC Experiments April 2006
|
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8. Security Considerations
|
||||
|
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Zones using this methodology will be considered insecure by all
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resolvers except those aware of the experiment. It is not generally
|
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possible to create a secure delegation from an experimental zone that
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will be followed by resolvers unaware of the experiment.
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Blacka Expires October 9, 2006 [Page 11]
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Internet-Draft DNSSEC Experiments April 2006
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9. IANA Considerations
|
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This document has no IANA actions.
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Blacka Expires October 9, 2006 [Page 12]
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|
||||
Internet-Draft DNSSEC Experiments April 2006
|
||||
|
||||
|
||||
10. References
|
||||
|
||||
10.1. Normative References
|
||||
|
||||
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
|
||||
Levels", BCP 14, RFC 2119, March 1997.
|
||||
|
||||
[2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
|
||||
"DNS Security Introduction and Requirements", RFC 4033,
|
||||
March 2005.
|
||||
|
||||
[3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
|
||||
"Resource Records for the DNS Security Extensions", RFC 4034,
|
||||
March 2005.
|
||||
|
||||
[4] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
|
||||
"Protocol Modifications for the DNS Security Extensions",
|
||||
RFC 4035, March 2005.
|
||||
|
||||
10.2. Informative References
|
||||
|
||||
[5] Mockapetris, P., "Domain names - implementation and
|
||||
specification", STD 13, RFC 1035, November 1987.
|
||||
|
||||
[6] Austein, R. and S. Weiler, "Clarifications and Implementation
|
||||
Notes for DNSSECbis", draft-ietf-dnsext-dnssec-bis-updates-02
|
||||
(work in progress), January 2006.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Blacka Expires October 9, 2006 [Page 13]
|
||||
|
||||
Internet-Draft DNSSEC Experiments April 2006
|
||||
|
||||
|
||||
Author's Address
|
||||
|
||||
David Blacka
|
||||
VeriSign, Inc.
|
||||
21355 Ridgetop Circle
|
||||
Dulles, VA 20166
|
||||
US
|
||||
|
||||
Phone: +1 703 948 3200
|
||||
Email: davidb@verisign.com
|
||||
URI: http://www.verisignlabs.com
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Blacka Expires October 9, 2006 [Page 14]
|
||||
|
||||
Internet-Draft DNSSEC Experiments April 2006
|
||||
|
||||
|
||||
Full Copyright Statement
|
||||
|
||||
Copyright (C) The Internet Society (2006).
|
||||
|
||||
This document is subject to the rights, licenses and restrictions
|
||||
contained in BCP 78, and except as set forth therein, the authors
|
||||
retain all their rights.
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||||
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
||||
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
|
||||
Intellectual Property
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in
|
||||
this document or the extent to which any license under such rights
|
||||
might or might not be available; nor does it represent that it has
|
||||
made any independent effort to identify any such rights. Information
|
||||
on the procedures with respect to rights in RFC documents can be
|
||||
found in BCP 78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an
|
||||
attempt made to obtain a general license or permission for the use of
|
||||
such proprietary rights by implementers or users of this
|
||||
specification can be obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary
|
||||
rights that may cover technology that may be required to implement
|
||||
this standard. Please address the information to the IETF at
|
||||
ietf-ipr@ietf.org.
|
||||
|
||||
|
||||
Acknowledgment
|
||||
|
||||
Funding for the RFC Editor function is provided by the IETF
|
||||
Administrative Support Activity (IASA).
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Blacka Expires October 9, 2006 [Page 15]
|
||||
|
||||
@@ -1,17 +0,0 @@
|
||||
|
||||
This Internet-Draft, draft-ietf-dnsext-forgery-resilience-01.txt, has expired, and has been deleted
|
||||
from the Internet-Drafts directory. An Internet-Draft expires 185 days from
|
||||
the date that it is posted unless it is replaced by an updated version, or the
|
||||
Secretariat has been notified that the document is under official review by the
|
||||
IESG or has been passed to the RFC Editor for review and/or publication as an
|
||||
RFC. This Internet-Draft was not published as an RFC.
|
||||
|
||||
Internet-Drafts are not archival documents, and copies of Internet-Drafts that have
|
||||
been deleted from the directory are not available. The Secretariat does not have
|
||||
any information regarding the future plans of the author(s) or working group, if
|
||||
applicable, with respect to this deleted Internet-Draft. For more information, or
|
||||
to request a copy of the document, please contact the author(s) directly.
|
||||
|
||||
Draft Author(s):
|
||||
Remco van Mook <remco@virtu.nl>,
|
||||
Bert Hubert <bert.hubert@netherlabs.nl>
|
||||
File diff suppressed because it is too large
Load Diff
@@ -1,464 +0,0 @@
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
OBSOLETES: RFC 2536 Donald E. Eastlake 3rd
|
||||
Motorola Laboratories
|
||||
Expires: September 2006 March 2006
|
||||
|
||||
|
||||
DSA Keying and Signature Information in the DNS
|
||||
--- ------ --- --------- ----------- -- --- ---
|
||||
<draft-ietf-dnsext-rfc2536bis-dsa-07.txt>
|
||||
Donald E. Eastlake 3rd
|
||||
|
||||
|
||||
Status of This Document
|
||||
|
||||
By submitting this Internet-Draft, each author represents that any
|
||||
applicable patent or other IPR claims of which he or she is aware
|
||||
have been or will be disclosed, and any of which he or she becomes
|
||||
aware will be disclosed, in accordance with Section 6 of BCP 79.
|
||||
|
||||
Distribution of this document is unlimited. Comments should be sent
|
||||
to the DNS extensions working group mailing list
|
||||
<namedroppers@ops.ietf.org>.
|
||||
|
||||
Internet-Drafts are working documents of the Internet Engineering
|
||||
Task Force (IETF), its areas, and its working groups. Note that
|
||||
other groups may also distribute working documents as Internet-
|
||||
Drafts.
|
||||
|
||||
Internet-Drafts are draft documents valid for a maximum of six months
|
||||
and may be updated, replaced, or obsoleted by other documents at any
|
||||
time. It is inappropriate to use Internet-Drafts as reference
|
||||
material or to cite them other than as "work in progress."
|
||||
|
||||
The list of current Internet-Drafts can be accessed at
|
||||
http://www.ietf.org/1id-abstracts.html
|
||||
|
||||
The list of Internet-Draft Shadow Directories can be accessed at
|
||||
http://www.ietf.org/shadow.html
|
||||
|
||||
|
||||
|
||||
Abstract
|
||||
|
||||
The standard method of encoding US Government Digital Signature
|
||||
Algorithm keying and signature information for use in the Domain Name
|
||||
System is specified.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 1]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
Table of Contents
|
||||
|
||||
Status of This Document....................................1
|
||||
Abstract...................................................1
|
||||
|
||||
Table of Contents..........................................2
|
||||
|
||||
1. Introduction............................................3
|
||||
2. DSA Keying Information..................................3
|
||||
3. DSA Signature Information...............................4
|
||||
4. Performance Considerations..............................4
|
||||
5. Security Considerations.................................5
|
||||
6. IANA Considerations.....................................5
|
||||
Copyright, Disclaimer, and Additional IPR Provisions.......5
|
||||
|
||||
Normative References.......................................7
|
||||
Informative References.....................................7
|
||||
|
||||
Author's Address...........................................8
|
||||
Expiration and File Name...................................8
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 2]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
1. Introduction
|
||||
|
||||
The Domain Name System (DNS) is the global hierarchical replicated
|
||||
distributed database system for Internet addressing, mail proxy, and
|
||||
other information [RFC 1034, 1035]. The DNS has been extended to
|
||||
include digital signatures and cryptographic keys as described in
|
||||
[RFC 4033, 4034, 4035] and additional work is underway which would
|
||||
require the storage of keying and signature information in the DNS.
|
||||
|
||||
This document describes how to encode US Government Digital Signature
|
||||
Algorithm (DSA) keys and signatures in the DNS. Familiarity with the
|
||||
US Digital Signature Algorithm is assumed [FIPS 186-2, Schneier].
|
||||
|
||||
|
||||
|
||||
2. DSA Keying Information
|
||||
|
||||
When DSA public keys are stored in the DNS, the structure of the
|
||||
relevant part of the RDATA part of the RR being used is the fields
|
||||
listed below in the order given.
|
||||
|
||||
The period of key validity is not included in this data but is
|
||||
indicated separately, for example by an RR such as RRSIG which signs
|
||||
and authenticates the RR containing the keying information.
|
||||
|
||||
Field Size
|
||||
----- ----
|
||||
T 1 octet
|
||||
Q 20 octets
|
||||
P 64 + T*8 octets
|
||||
G 64 + T*8 octets
|
||||
Y 64 + T*8 octets
|
||||
|
||||
As described in [FIPS 186-2] and [Schneier], T is a key size
|
||||
parameter chosen such that 0 <= T <= 8. (The meaning if the T octet
|
||||
is greater than 8 is reserved and the remainder of the data may have
|
||||
a different format in that case.) Q is a prime number selected at
|
||||
key generation time such that 2**159 < Q < 2**160. Thus Q is always
|
||||
20 octets long and, as with all other fields, is stored in "big-
|
||||
endian" network order. P, G, and Y are calculated as directed by the
|
||||
[FIPS 186-2] key generation algorithm [Schneier]. P is in the range
|
||||
2**(511+64T) < P < 2**(512+64T) and thus is 64 + 8*T octets long. G
|
||||
and Y are quantities modulo P and so can be up to the same length as
|
||||
P and are allocated fixed size fields with the same number of octets
|
||||
as P.
|
||||
|
||||
During the key generation process, a random number X must be
|
||||
generated such that 1 <= X <= Q-1. X is the private key and is used
|
||||
in the final step of public key generation where Y is computed as
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 3]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
Y = G**X mod P
|
||||
|
||||
|
||||
|
||||
3. DSA Signature Information
|
||||
|
||||
The portion of the RDATA area used for US Digital Signature Algorithm
|
||||
signature information is shown below with fields in the order they
|
||||
are listed and the contents of each multi-octet field in "big-endian"
|
||||
network order.
|
||||
|
||||
Field Size
|
||||
----- ----
|
||||
T 1 octet
|
||||
R 20 octets
|
||||
S 20 octets
|
||||
|
||||
First, the data signed must be determined. Then the following steps
|
||||
are taken, as specified in [FIPS 186-2], where Q, P, G, and Y are as
|
||||
specified in the public key [Schneier]:
|
||||
|
||||
hash = SHA-1 ( data )
|
||||
|
||||
Generate a random K such that 0 < K < Q.
|
||||
|
||||
R = ( G**K mod P ) mod Q
|
||||
|
||||
S = ( K**(-1) * (hash + X*R) ) mod Q
|
||||
|
||||
For information on the SHA-1 hash function see [FIPS 180-2] and [RFC
|
||||
3174].
|
||||
|
||||
Since Q is 160 bits long, R and S can not be larger than 20 octets,
|
||||
which is the space allocated.
|
||||
|
||||
T is copied from the public key. It is not logically necessary in
|
||||
the SIG but is present so that values of T > 8 can more conveniently
|
||||
be used as an escape for extended versions of DSA or other algorithms
|
||||
as later standardized.
|
||||
|
||||
|
||||
|
||||
4. Performance Considerations
|
||||
|
||||
General signature generation speeds are roughly the same for RSA [RFC
|
||||
3110] and DSA. With sufficient pre-computation, signature generation
|
||||
with DSA is faster than RSA. Key generation is also faster for DSA.
|
||||
However, signature verification is an order of magnitude slower than
|
||||
RSA when the RSA public exponent is chosen to be small, as is
|
||||
recommended for some applications.
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 4]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
Current DNS implementations are optimized for small transfers,
|
||||
typically less than 512 bytes including DNS overhead. Larger
|
||||
transfers will perform correctly and extensions have been
|
||||
standardized [RFC 2671] to make larger transfers more efficient, it
|
||||
is still advisable at this time to make reasonable efforts to
|
||||
minimize the size of RR sets containing keying and/or signature
|
||||
inforamtion consistent with adequate security.
|
||||
|
||||
|
||||
|
||||
5. Security Considerations
|
||||
|
||||
Keys retrieved from the DNS should not be trusted unless (1) they
|
||||
have been securely obtained from a secure resolver or independently
|
||||
verified by the user and (2) this secure resolver and secure
|
||||
obtainment or independent verification conform to security policies
|
||||
acceptable to the user. As with all cryptographic algorithms,
|
||||
evaluating the necessary strength of the key is essential and
|
||||
dependent on local policy.
|
||||
|
||||
The key size limitation of a maximum of 1024 bits ( T = 8 ) in the
|
||||
current DSA standard may limit the security of DSA. For particular
|
||||
applications, implementors are encouraged to consider the range of
|
||||
available algorithms and key sizes.
|
||||
|
||||
DSA assumes the ability to frequently generate high quality random
|
||||
numbers. See [random] for guidance. DSA is designed so that if
|
||||
biased rather than random numbers are used, high bandwidth covert
|
||||
channels are possible. See [Schneier] and more recent research. The
|
||||
leakage of an entire DSA private key in only two DSA signatures has
|
||||
been demonstrated. DSA provides security only if trusted
|
||||
implementations, including trusted random number generation, are
|
||||
used.
|
||||
|
||||
|
||||
|
||||
6. IANA Considerations
|
||||
|
||||
Allocation of meaning to values of the T parameter that are not
|
||||
defined herein (i.e., > 8 ) requires an IETF standards actions. It
|
||||
is intended that values unallocated herein be used to cover future
|
||||
extensions of the DSS standard.
|
||||
|
||||
|
||||
|
||||
Copyright, Disclaimer, and Additional IPR Provisions
|
||||
|
||||
Copyright (C) The Internet Society (2006). This document is subject to
|
||||
the rights, licenses and restrictions contained in BCP 78, and except
|
||||
as set forth therein, the authors retain all their rights.
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 5]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||||
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
||||
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in
|
||||
this document or the extent to which any license under such rights
|
||||
might or might not be available; nor does it represent that it has
|
||||
made any independent effort to identify any such rights. Information
|
||||
on the procedures with respect to rights in RFC documents can be
|
||||
found in BCP 78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an
|
||||
attempt made to obtain a general license or permission for the use of
|
||||
such proprietary rights by implementers or users of this
|
||||
specification can be obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary
|
||||
rights that may cover technology that may be required to implement
|
||||
this standard. Please address the information to the IETF at ietf-
|
||||
ipr@ietf.org.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 6]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
Normative References
|
||||
|
||||
[FIPS 186-2] - U.S. Federal Information Processing Standard: Digital
|
||||
Signature Standard, 27 January 2000.
|
||||
|
||||
[RFC 4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
|
||||
March 2005.
|
||||
|
||||
|
||||
|
||||
Informative References
|
||||
|
||||
[RFC 1034] - "Domain names - concepts and facilities", P.
|
||||
Mockapetris, 11/01/1987.
|
||||
|
||||
[RFC 1035] - "Domain names - implementation and specification", P.
|
||||
Mockapetris, 11/01/1987.
|
||||
|
||||
[RFC 2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August
|
||||
1999.
|
||||
|
||||
[RFC 3110] - "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System
|
||||
(DNS)", D. Eastlake 3rd. May 2001.
|
||||
|
||||
[RFC 3174] - "US Secure Hash Algorithm 1 (SHA1)", D. Eastlake, P.
|
||||
Jones, September 2001.
|
||||
|
||||
[RFC 4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "DNS Security Introduction and Requirements", RFC 4033, March
|
||||
2005.
|
||||
|
||||
[RFC 4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Protocol Modifications for the DNS Security Extensions", RFC
|
||||
4035, March 2005.
|
||||
|
||||
[RFC 4086] - Eastlake, D., 3rd, Schiller, J., and S. Crocker,
|
||||
"Randomness Requirements for Security", BCP 106, RFC 4086, June 2005.
|
||||
|
||||
[Schneier] - "Applied Cryptography Second Edition: protocols,
|
||||
algorithms, and source code in C" (second edition), Bruce Schneier,
|
||||
1996, John Wiley and Sons, ISBN 0-471-11709-9.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 7]
|
||||
|
||||
|
||||
INTERNET-DRAFT DSA Information in the DNS
|
||||
|
||||
|
||||
Author's Address
|
||||
|
||||
Donald E. Eastlake 3rd
|
||||
Motorola Labortories
|
||||
155 Beaver Street
|
||||
Milford, MA 01757 USA
|
||||
|
||||
Telephone: +1-508-786-7554(w)
|
||||
EMail: Donald.Eastlake@motorola.com
|
||||
|
||||
|
||||
|
||||
Expiration and File Name
|
||||
|
||||
This draft expires in September 2006.
|
||||
|
||||
Its file name is draft-ietf-dnsext-rfc2536bis-dsa-07.txt.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 8]
|
||||
|
||||
@@ -1,580 +0,0 @@
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
OBSOLETES: RFC 2539 Donald E. Eastlake 3rd
|
||||
Motorola Laboratories
|
||||
Expires: September 2006 March 2006
|
||||
|
||||
|
||||
|
||||
|
||||
Storage of Diffie-Hellman Keying Information in the DNS
|
||||
------- -- -------------- ------ ----------- -- --- ---
|
||||
<draft-ietf-dnsext-rfc2539bis-dhk-07.txt>
|
||||
|
||||
|
||||
|
||||
Status of This Document
|
||||
|
||||
By submitting this Internet-Draft, each author represents that any
|
||||
applicable patent or other IPR claims of which he or she is aware
|
||||
have been or will be disclosed, and any of which he or she becomes
|
||||
aware will be disclosed, in accordance with Section 6 of BCP 79.
|
||||
|
||||
Distribution of this document is unlimited. Comments should be sent
|
||||
to the DNS extensions working group mailing list
|
||||
<namedroppers@ops.ietf.org>.
|
||||
|
||||
Internet-Drafts are working documents of the Internet Engineering
|
||||
Task Force (IETF), its areas, and its working groups. Note that
|
||||
other groups may also distribute working documents as Internet-
|
||||
Drafts.
|
||||
|
||||
Internet-Drafts are draft documents valid for a maximum of six months
|
||||
and may be updated, replaced, or obsoleted by other documents at any
|
||||
time. It is inappropriate to use Internet-Drafts as reference
|
||||
material or to cite them other than as "work in progress."
|
||||
|
||||
The list of current Internet-Drafts can be accessed at
|
||||
http://www.ietf.org/1id-abstracts.html
|
||||
|
||||
The list of Internet-Draft Shadow Directories can be accessed at
|
||||
http://www.ietf.org/shadow.html
|
||||
|
||||
|
||||
Abstract
|
||||
|
||||
The standard method for encoding Diffie-Hellman keys in the Domain
|
||||
Name System is specified.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 1]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
Acknowledgements
|
||||
|
||||
Part of the format for Diffie-Hellman keys and the description
|
||||
thereof was taken from a work in progress by Ashar Aziz, Tom Markson,
|
||||
and Hemma Prafullchandra. In addition, the following persons
|
||||
provided useful comments that were incorporated into the predecessor
|
||||
of this document: Ran Atkinson, Thomas Narten.
|
||||
|
||||
|
||||
|
||||
Table of Contents
|
||||
|
||||
Status of This Document....................................1
|
||||
Abstract...................................................1
|
||||
|
||||
Acknowledgements...........................................2
|
||||
Table of Contents..........................................2
|
||||
|
||||
1. Introduction............................................3
|
||||
1.1 About This Document....................................3
|
||||
1.2 About Diffie-Hellman...................................3
|
||||
2. Encoding Diffie-Hellman Keying Information..............4
|
||||
3. Performance Considerations..............................5
|
||||
4. IANA Considerations.....................................5
|
||||
5. Security Considerations.................................5
|
||||
Copyright, Disclaimer, and Additional IPR Provisions.......5
|
||||
|
||||
Normative References.......................................7
|
||||
Informative Refences.......................................7
|
||||
|
||||
Author's Address...........................................8
|
||||
Expiration and File Name...................................8
|
||||
|
||||
Appendix A: Well known prime/generator pairs...............9
|
||||
A.1. Well-Known Group 1: A 768 bit prime..................9
|
||||
A.2. Well-Known Group 2: A 1024 bit prime.................9
|
||||
A.3. Well-Known Group 3: A 1536 bit prime................10
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 2]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
1. Introduction
|
||||
|
||||
The Domain Name System (DNS) is the global hierarchical replicated
|
||||
distributed database system for Internet addressing, mail proxy, and
|
||||
similar information [RFC 1034, 1035]. The DNS has been extended to
|
||||
include digital signatures and cryptographic keys as described in
|
||||
[RFC 4033, 4034, 4035] and additonal work is underway which would use
|
||||
the storage of keying information in the DNS.
|
||||
|
||||
|
||||
|
||||
1.1 About This Document
|
||||
|
||||
This document describes how to store Diffie-Hellman keys in the DNS.
|
||||
Familiarity with the Diffie-Hellman key exchange algorithm is assumed
|
||||
[Schneier, RFC 2631].
|
||||
|
||||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
||||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
||||
document are to be interpreted as described in RFC 2119.
|
||||
|
||||
|
||||
|
||||
1.2 About Diffie-Hellman
|
||||
|
||||
Diffie-Hellman requires two parties to interact to derive keying
|
||||
information which can then be used for authentication. Thus Diffie-
|
||||
Hellman is inherently a key agreement algorithm. As a result, no
|
||||
format is defined for Diffie-Hellman "signature information". For
|
||||
example, assume that two parties have local secrets "i" and "j".
|
||||
Assume they each respectively calculate X and Y as follows:
|
||||
|
||||
X = g**i ( mod p )
|
||||
|
||||
Y = g**j ( mod p )
|
||||
|
||||
They exchange these quantities and then each calculates a Z as
|
||||
follows:
|
||||
|
||||
Zi = Y**i ( mod p )
|
||||
|
||||
Zj = X**j ( mod p )
|
||||
|
||||
Zi and Zj will both be equal to g**(i*j)(mod p) and will be a shared
|
||||
secret between the two parties that an adversary who does not know i
|
||||
or j will not be able to learn from the exchanged messages (unless
|
||||
the adversary can derive i or j by performing a discrete logarithm
|
||||
mod p which is hard for strong p and g).
|
||||
|
||||
The private key for each party is their secret i (or j). The public
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 3]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
key is the pair p and g, which is the same for both parties, and
|
||||
their individual X (or Y).
|
||||
|
||||
For further information about Diffie-Hellman and precautions to take
|
||||
in deciding on a p and g, see [RFC 2631].
|
||||
|
||||
|
||||
|
||||
2. Encoding Diffie-Hellman Keying Information
|
||||
|
||||
When Diffie-Hellman keys appear within the RDATA portion of a RR,
|
||||
they are encoded as shown below.
|
||||
|
||||
The period of key validity is not included in this data but is
|
||||
indicated separately, for example by an RR such as RRSIG which signs
|
||||
and authenticates the RR containing the keying information.
|
||||
|
||||
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
|
||||
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
| KEY flags | protocol | algorithm=2 |
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
| prime length (or flag) | prime (p) (or special) /
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
/ prime (p) (variable length) | generator length |
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
| generator (g) (variable length) |
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
| public value length | public value (variable length)/
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
/ public value (g^i mod p) (variable length) |
|
||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
||||
|
||||
Prime length is the length of the Diffie-Hellman prime (p) in bytes
|
||||
if it is 16 or greater. Prime contains the binary representation of
|
||||
the Diffie-Hellman prime with most significant byte first (i.e., in
|
||||
network order). If "prime length" field is 1 or 2, then the "prime"
|
||||
field is actually an unsigned index into a table of 65,536
|
||||
prime/generator pairs and the generator length SHOULD be zero. See
|
||||
Appedix A for defined table entries and Section 4 for information on
|
||||
allocating additional table entries. The meaning of a zero or 3
|
||||
through 15 value for "prime length" is reserved.
|
||||
|
||||
Generator length is the length of the generator (g) in bytes.
|
||||
Generator is the binary representation of generator with most
|
||||
significant byte first. PublicValueLen is the Length of the Public
|
||||
Value (g**i (mod p)) in bytes. PublicValue is the binary
|
||||
representation of the DH public value with most significant byte
|
||||
first.
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 4]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
3. Performance Considerations
|
||||
|
||||
Current DNS implementations are optimized for small transfers,
|
||||
typically less than 512 bytes including DNS overhead. Larger
|
||||
transfers will perform correctly and extensions have been
|
||||
standardized [RFC 2671] to make larger transfers more efficient. But
|
||||
it is still advisable at this time to make reasonable efforts to
|
||||
minimize the size of RR sets containing keying information consistent
|
||||
with adequate security.
|
||||
|
||||
|
||||
|
||||
4. IANA Considerations
|
||||
|
||||
Assignment of meaning to Prime Lengths of 0 and 3 through 15 requires
|
||||
an IETF consensus as defined in [RFC 2434].
|
||||
|
||||
Well known prime/generator pairs number 0x0000 through 0x07FF can
|
||||
only be assigned by an IETF standards action. [RFC 2539], the
|
||||
Proposed Standard predecessor of this document, assigned 0x0001
|
||||
through 0x0002. This document additionally assigns 0x0003. Pairs
|
||||
number 0s0800 through 0xBFFF can be assigned based on RFC
|
||||
documentation. Pairs number 0xC000 through 0xFFFF are available for
|
||||
private use and are not centrally coordinated. Use of such private
|
||||
pairs outside of a closed environment may result in conflicts and/or
|
||||
security failures.
|
||||
|
||||
|
||||
|
||||
5. Security Considerations
|
||||
|
||||
Keying information retrieved from the DNS should not be trusted
|
||||
unless (1) it has been securely obtained from a secure resolver or
|
||||
independently verified by the user and (2) this secure resolver and
|
||||
secure obtainment or independent verification conform to security
|
||||
policies acceptable to the user. As with all cryptographic
|
||||
algorithms, evaluating the necessary strength of the key is important
|
||||
and dependent on security policy.
|
||||
|
||||
In addition, the usual Diffie-Hellman key strength considerations
|
||||
apply. (p-1)/2 SHOULD also be prime, g SHOULD be primitive mod p, p
|
||||
SHOULD be "large", etc. See [RFC 2631, Schneier].
|
||||
|
||||
|
||||
|
||||
Copyright, Disclaimer, and Additional IPR Provisions
|
||||
|
||||
Copyright (C) The Internet Society (2006). This document is subject to
|
||||
the rights, licenses and restrictions contained in BCP 78, and except
|
||||
as set forth therein, the authors retain all their rights.
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 5]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||||
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
||||
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in
|
||||
this document or the extent to which any license under such rights
|
||||
might or might not be available; nor does it represent that it has
|
||||
made any independent effort to identify any such rights. Information
|
||||
on the procedures with respect to rights in RFC documents can be
|
||||
found in BCP 78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an
|
||||
attempt made to obtain a general license or permission for the use of
|
||||
such proprietary rights by implementers or users of this
|
||||
specification can be obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary
|
||||
rights that may cover technology that may be required to implement
|
||||
this standard. Please address the information to the IETF at ietf-
|
||||
ipr@ietf.org.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 6]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
Normative References
|
||||
|
||||
[RFC 2119] - Bradner, S., "Key words for use in RFCs to Indicate
|
||||
Requirement Levels", BCP 14, RFC 2119, March 1997.
|
||||
|
||||
[RFC 2434] - "Guidelines for Writing an IANA Considerations Section
|
||||
in RFCs", T. Narten, H. Alvestrand, October 1998.
|
||||
|
||||
[RFC 2631] - "Diffie-Hellman Key Agreement Method", E. Rescorla, June
|
||||
1999.
|
||||
|
||||
[RFC 4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
|
||||
March 2005.
|
||||
|
||||
|
||||
|
||||
Informative Refences
|
||||
|
||||
[RFC 1034] - "Domain names - concepts and facilities", P.
|
||||
Mockapetris, November 1987.
|
||||
|
||||
[RFC 1035] - "Domain names - implementation and specification", P.
|
||||
Mockapetris, November 1987.
|
||||
|
||||
[RFC 2539] - "Storage of Diffie-Hellman Keys in the Domain Name
|
||||
System (DNS)", D. Eastlake, March 1999, obsoleted by this RFC.
|
||||
|
||||
[RFC 2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August
|
||||
1999.
|
||||
|
||||
[RFC 4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "DNS Security Introduction and Requirements", RFC 4033, March
|
||||
2005.
|
||||
|
||||
[RFC 4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Protocol Modifications for the DNS Security Extensions", RFC
|
||||
4035, March 2005.
|
||||
|
||||
[Schneier] - Bruce Schneier, "Applied Cryptography: Protocols,
|
||||
Algorithms, and Source Code in C" (Second Edition), 1996, John Wiley
|
||||
and Sons.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 7]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
Author's Address
|
||||
|
||||
Donald E. Eastlake 3rd
|
||||
Motorola Laboratories
|
||||
155 Beaver Street
|
||||
Milford, MA 01757 USA
|
||||
|
||||
Telephone: +1-508-786-7554
|
||||
EMail: Donald.Eastlake@motorola.com
|
||||
|
||||
|
||||
|
||||
Expiration and File Name
|
||||
|
||||
This draft expires in September 2006.
|
||||
|
||||
Its file name is draft-ietf-dnsext-rfc2539bis-dhk-07.txt.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 8]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
Appendix A: Well known prime/generator pairs
|
||||
|
||||
These numbers are copied from the IPSEC effort where the derivation
|
||||
of these values is more fully explained and additional information is
|
||||
available. Richard Schroeppel performed all the mathematical and
|
||||
computational work for this appendix.
|
||||
|
||||
|
||||
|
||||
A.1. Well-Known Group 1: A 768 bit prime
|
||||
|
||||
The prime is 2^768 - 2^704 - 1 + 2^64 * { [2^638 pi] + 149686 }. Its
|
||||
decimal value is
|
||||
155251809230070893513091813125848175563133404943451431320235
|
||||
119490296623994910210725866945387659164244291000768028886422
|
||||
915080371891804634263272761303128298374438082089019628850917
|
||||
0691316593175367469551763119843371637221007210577919
|
||||
|
||||
Prime modulus: Length (32 bit words): 24, Data (hex):
|
||||
FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
|
||||
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
|
||||
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
|
||||
E485B576 625E7EC6 F44C42E9 A63A3620 FFFFFFFF FFFFFFFF
|
||||
|
||||
Generator: Length (32 bit words): 1, Data (hex): 2
|
||||
|
||||
|
||||
|
||||
A.2. Well-Known Group 2: A 1024 bit prime
|
||||
|
||||
The prime is 2^1024 - 2^960 - 1 + 2^64 * { [2^894 pi] + 129093 }.
|
||||
Its decimal value is
|
||||
179769313486231590770839156793787453197860296048756011706444
|
||||
423684197180216158519368947833795864925541502180565485980503
|
||||
646440548199239100050792877003355816639229553136239076508735
|
||||
759914822574862575007425302077447712589550957937778424442426
|
||||
617334727629299387668709205606050270810842907692932019128194
|
||||
467627007
|
||||
|
||||
Prime modulus: Length (32 bit words): 32, Data (hex):
|
||||
FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
|
||||
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
|
||||
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
|
||||
E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
|
||||
EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381
|
||||
FFFFFFFF FFFFFFFF
|
||||
|
||||
Generator: Length (32 bit words): 1, Data (hex): 2
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 9]
|
||||
|
||||
|
||||
INTERNET-DRAFT Diffie-Hellman Information in the DNS
|
||||
|
||||
|
||||
A.3. Well-Known Group 3: A 1536 bit prime
|
||||
|
||||
The prime is 2^1536 - 2^1472 - 1 + 2^64 * { [2^1406 pi] + 741804 }.
|
||||
Its decimal value is
|
||||
241031242692103258855207602219756607485695054850245994265411
|
||||
694195810883168261222889009385826134161467322714147790401219
|
||||
650364895705058263194273070680500922306273474534107340669624
|
||||
601458936165977404102716924945320037872943417032584377865919
|
||||
814376319377685986952408894019557734611984354530154704374720
|
||||
774996976375008430892633929555996888245787241299381012913029
|
||||
459299994792636526405928464720973038494721168143446471443848
|
||||
8520940127459844288859336526896320919633919
|
||||
|
||||
Prime modulus Length (32 bit words): 48, Data (hex):
|
||||
FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
|
||||
29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
|
||||
EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
|
||||
E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
|
||||
EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
|
||||
C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
|
||||
83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
|
||||
670C354E 4ABC9804 F1746C08 CA237327 FFFFFFFF FFFFFFFF
|
||||
|
||||
Generator: Length (32 bit words): 1, Data (hex): 2
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
D. Eastlake 3rd [Page 10]
|
||||
|
||||
@@ -1,480 +0,0 @@
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
DNSEXT Working Group Paul Vixie, ISC
|
||||
INTERNET-DRAFT
|
||||
<draft-ietf-dnsext-rfc2671bis-edns0-01.txt> March 17, 2008
|
||||
|
||||
Intended Status: Standards Track
|
||||
Obsoletes: 2671 (if approved)
|
||||
|
||||
|
||||
Revised extension mechanisms for DNS (EDNS0)
|
||||
|
||||
|
||||
Status of this Memo
|
||||
By submitting this Internet-Draft, each author represents that any
|
||||
applicable patent or other IPR claims of which he or she is aware
|
||||
have been or will be disclosed, and any of which he or she becomes
|
||||
aware will be disclosed, in accordance with Section 6 of BCP 79.
|
||||
|
||||
Internet-Drafts are working documents of the Internet Engineering
|
||||
Task Force (IETF), its areas, and its working groups. Note that
|
||||
other groups may also distribute working documents as Internet-
|
||||
Drafts.
|
||||
|
||||
Internet-Drafts are draft documents valid for a maximum of six months
|
||||
and may be updated, replaced, or obsoleted by other documents at any
|
||||
time. It is inappropriate to use Internet-Drafts as reference
|
||||
material or to cite them other than as "work in progress."
|
||||
|
||||
The list of current Internet-Drafts can be accessed at
|
||||
http://www.ietf.org/ietf/1id-abstracts.txt
|
||||
|
||||
The list of Internet-Draft Shadow Directories can be accessed at
|
||||
http://www.ietf.org/shadow.html.
|
||||
|
||||
Copyright Notice
|
||||
|
||||
Copyright (C) The IETF Trust (2007).
|
||||
|
||||
|
||||
Abstract
|
||||
|
||||
The Domain Name System's wire protocol includes a number of fixed
|
||||
fields whose range has been or soon will be exhausted and does not
|
||||
allow clients to advertise their capabilities to servers. This
|
||||
document describes backward compatible mechanisms for allowing the
|
||||
protocol to grow.
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 1]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
1 - Introduction
|
||||
|
||||
1.1. DNS (see [RFC1035]) specifies a Message Format and within such
|
||||
messages there are standard formats for encoding options, errors, and
|
||||
name compression. The maximum allowable size of a DNS Message is fixed.
|
||||
Many of DNS's protocol limits are too small for uses which are or which
|
||||
are desired to become common. There is no way for implementations to
|
||||
advertise their capabilities.
|
||||
|
||||
1.2. Unextended agents will not know how to interpret the protocol
|
||||
extensions detailed here. In practice, these clients will be upgraded
|
||||
when they have need of a new feature, and only new features will make
|
||||
use of the extensions. Extended agents must be prepared for behaviour
|
||||
of unextended clients in the face of new protocol elements, and fall
|
||||
back gracefully to unextended DNS. RFC 2671 originally has proposed
|
||||
extensions to the basic DNS protocol to overcome these deficiencies.
|
||||
This memo refines that specification and obsoletes RFC 2671.
|
||||
|
||||
1.3. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
||||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
||||
document are to be interpreted as described in RFC 2119 [RFC2119].
|
||||
|
||||
2 - Affected Protocol Elements
|
||||
|
||||
2.1. The DNS Message Header's (see [RFC1035 4.1.1]) second full 16-bit
|
||||
word is divided into a 4-bit OPCODE, a 4-bit RCODE, and a number of
|
||||
1-bit flags. The original reserved Z bits have been allocated to
|
||||
various purposes, and most of the RCODE values are now in use. More
|
||||
flags and more possible RCODEs are needed. The OPT pseudo-RR specified
|
||||
in Section 4 contains subfields that carry a bit field extension of the
|
||||
RCODE field and additional flag bits, respectively; for details see
|
||||
Section 4.6 below.
|
||||
|
||||
2.2. The first two bits of a wire format domain label are used to denote
|
||||
the type of the label. [RFC1035 4.1.4] allocates two of the four
|
||||
possible types and reserves the other two. Proposals for use of the
|
||||
remaining types far outnumber those available. More label types were
|
||||
needed, and an extension mechanism was proposed in RFC 2671 [RFC2671
|
||||
Section 3]. Section 3 of this document reserves DNS labels with a first
|
||||
octet in the range of 64-127 decimal (label type 01) for future
|
||||
standardization of Extended DNS Labels.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 2]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
2.3. DNS Messages are limited to 512 octets in size when sent over UDP.
|
||||
While the minimum maximum reassembly buffer size still allows a limit of
|
||||
512 octets of UDP payload, most of the hosts now connected to the
|
||||
Internet are able to reassemble larger datagrams. Some mechanism must
|
||||
be created to allow requestors to advertise larger buffer sizes to
|
||||
responders. To this end, the OPT pseudo-RR specified in Section 4
|
||||
contains a maximum payload size field; for details see Section 4.5
|
||||
below.
|
||||
|
||||
3 - Extended Label Types
|
||||
|
||||
The first octet in the on-the-wire representation of a DNS label
|
||||
specifies the label type; the basic DNS specification [RFC1035]
|
||||
dedicates the two most significant bits of that octet for this purpose.
|
||||
|
||||
This document reserves DNS label type 0b01 for use as an indication for
|
||||
Extended Label Types. A specific extended label type is selected by the
|
||||
6 least significant bits of the first octet. Thus, Extended Label Types
|
||||
are indicated by the values 64-127 (0b01xxxxxx) in the first octet of
|
||||
the label.
|
||||
|
||||
Allocations from this range are to be made for IETF documents fully
|
||||
describing the syntax and semantics as well as the applicability of the
|
||||
particular Extended Label Type.
|
||||
|
||||
This document does not describe any specific Extended Label Type.
|
||||
|
||||
4 - OPT pseudo-RR
|
||||
|
||||
4.1. One OPT pseudo-RR (RR type 41) MAY be added to the additional data
|
||||
section of a request, and to responses to such requests. An OPT is
|
||||
called a pseudo-RR because it pertains to a particular transport level
|
||||
message and not to any actual DNS data. OPT RRs MUST NOT be cached,
|
||||
forwarded, or stored in or loaded from master files. The quantity of
|
||||
OPT pseudo-RRs per message MUST be either zero or one, but not greater.
|
||||
|
||||
4.2. An OPT RR has a fixed part and a variable set of options expressed
|
||||
as {attribute, value} pairs. The fixed part holds some DNS meta data
|
||||
and also a small collection of new protocol elements which we expect to
|
||||
be so popular that it would be a waste of wire space to encode them as
|
||||
{attribute, value} pairs.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 3]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
4.3. The fixed part of an OPT RR is structured as follows:
|
||||
|
||||
Field Name Field Type Description
|
||||
------------------------------------------------------
|
||||
NAME domain name empty (root domain)
|
||||
TYPE u_int16_t OPT (41)
|
||||
CLASS u_int16_t sender's UDP payload size
|
||||
TTL u_int32_t extended RCODE and flags
|
||||
RDLEN u_int16_t describes RDATA
|
||||
RDATA octet stream {attribute,value} pairs
|
||||
|
||||
|
||||
4.4. The variable part of an OPT RR is encoded in its RDATA and is
|
||||
structured as zero or more of the following:
|
||||
|
||||
: +0 (MSB) : +1 (LSB) :
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
0: | OPTION-CODE |
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
2: | OPTION-LENGTH |
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
4: | |
|
||||
/ OPTION-DATA /
|
||||
/ /
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
|
||||
|
||||
OPTION-CODE (Assigned by IANA.)
|
||||
|
||||
OPTION-LENGTH Size (in octets) of OPTION-DATA.
|
||||
|
||||
OPTION-DATA Varies per OPTION-CODE.
|
||||
|
||||
4.4.1. Order of appearance of option tuples is never relevant. Any
|
||||
option whose meaning is affected by other options is so affected no
|
||||
matter which one comes first in the OPT RDATA.
|
||||
|
||||
4.4.2. Any OPTION-CODE values not understood by a responder or requestor
|
||||
MUST be ignored. So, specifications of such options might wish to
|
||||
include some kind of signalled acknowledgement. For example, an option
|
||||
specification might say that if a responder sees option XYZ, it SHOULD
|
||||
include option XYZ in its response.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 4]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
4.5. The sender's UDP payload size (which OPT stores in the RR CLASS
|
||||
field) is the number of octets of the largest UDP payload that can be
|
||||
reassembled and delivered in the sender's network stack. Note that path
|
||||
MTU, with or without fragmentation, may be smaller than this. Values
|
||||
lower than 512 are undefined, and may be treated as format errors, or
|
||||
may be treated as equal to 512, at the implementor's discretion.
|
||||
|
||||
4.5.1. Note that a 512-octet UDP payload requires a 576-octet IP
|
||||
reassembly buffer. Choosing 1280 on an Ethernet connected requestor
|
||||
would be reasonable. The consequence of choosing too large a value may
|
||||
be an ICMP message from an intermediate gateway, or even a silent drop
|
||||
of the response message.
|
||||
|
||||
4.5.2. Both requestors and responders are advised to take account of the
|
||||
path's discovered MTU (if already known) when considering message sizes.
|
||||
|
||||
4.5.3. The requestor's maximum payload size can change over time, and
|
||||
therefore MUST NOT be cached for use beyond the transaction in which it
|
||||
is advertised.
|
||||
|
||||
4.5.4. The responder's maximum payload size can change over time, but
|
||||
can be reasonably expected to remain constant between two sequential
|
||||
transactions; for example, a meaningless QUERY to discover a responder's
|
||||
maximum UDP payload size, followed immediately by an UPDATE which takes
|
||||
advantage of this size. (This is considered preferrable to the outright
|
||||
use of TCP for oversized requests, if there is any reason to suspect
|
||||
that the responder implements EDNS, and if a request will not fit in the
|
||||
default 512 payload size limit.)
|
||||
|
||||
4.5.5. Due to transaction overhead, it is unwise to advertise an
|
||||
architectural limit as a maximum UDP payload size. Just because your
|
||||
stack can reassemble 64KB datagrams, don't assume that you want to spend
|
||||
more than about 4KB of state memory per ongoing transaction.
|
||||
|
||||
4.6. The extended RCODE and flags (which OPT stores in the RR TTL field)
|
||||
are structured as follows:
|
||||
|
||||
: +0 (MSB) : +1 (LSB) :
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
0: | EXTENDED-RCODE | VERSION |
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
2: | DO| Z |
|
||||
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 5]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
EXTENDED-RCODE Forms upper 8 bits of extended 12-bit RCODE. Note that
|
||||
EXTENDED-RCODE value zero (0) indicates that an
|
||||
unextended RCODE is in use (values zero (0) through
|
||||
fifteen (15)).
|
||||
|
||||
VERSION Indicates the implementation level of whoever sets it.
|
||||
Full conformance with this specification is indicated by
|
||||
version zero (0). Requestors are encouraged to set this
|
||||
to the lowest implemented level capable of expressing a
|
||||
transaction, to minimize the responder and network load
|
||||
of discovering the greatest common implementation level
|
||||
between requestor and responder. A requestor's version
|
||||
numbering strategy should ideally be a run time
|
||||
configuration option.
|
||||
|
||||
If a responder does not implement the VERSION level of
|
||||
the request, then it answers with RCODE=BADVERS. All
|
||||
responses MUST be limited in format to the VERSION level
|
||||
of the request, but the VERSION of each response MUST be
|
||||
the highest implementation level of the responder. In
|
||||
this way a requestor will learn the implementation level
|
||||
of a responder as a side effect of every response,
|
||||
including error responses, including RCODE=BADVERS.
|
||||
|
||||
DO DNSSEC OK bit [RFC3225].
|
||||
|
||||
Z Set to zero by senders and ignored by receivers, unless
|
||||
modified in a subsequent specification [IANAFLAGS].
|
||||
|
||||
5 - Transport Considerations
|
||||
|
||||
5.1. The presence of an OPT pseudo-RR in a request is an indication that
|
||||
the requestor fully implements the given version of EDNS, and can
|
||||
correctly understand any response that conforms to that feature's
|
||||
specification.
|
||||
|
||||
5.2. Lack of use of these features in a request is an indication that
|
||||
the requestor does not implement any part of this specification and that
|
||||
the responder SHOULD NOT use any protocol extension described here in
|
||||
its response.
|
||||
|
||||
5.3. Responders who do not understand these protocol extensions are
|
||||
expected to send a response with RCODE NOTIMPL, FORMERR, or SERVFAIL, or
|
||||
to appear to "time out" due to inappropriate action by a "middle box"
|
||||
such as a NAT, or to ignore extensions and respond only to unextended
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 6]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
protocol elements. Therefore use of extensions SHOULD be "probed" such
|
||||
that a responder who isn't known to support them be allowed a retry with
|
||||
no extensions if it responds with such an RCODE, or does not respond.
|
||||
If a responder's capability level is cached by a requestor, a new probe
|
||||
SHOULD be sent periodically to test for changes to responder capability.
|
||||
|
||||
5.4. If EDNS is used in a request, and the response arrives with TC set
|
||||
and with no EDNS OPT RR, a requestor should assume that truncation
|
||||
prevented the OPT RR from being appended by the responder, and further,
|
||||
that EDNS is not used in the response. Correspondingly, an EDNS
|
||||
responder who cannot fit all necessary elements (including an OPT RR)
|
||||
into a response, should respond with a normal (unextended) DNS response,
|
||||
possibly setting TC if the response will not fit in the unextended
|
||||
response message's 512-octet size.
|
||||
|
||||
6 - Security Considerations
|
||||
|
||||
Requestor-side specification of the maximum buffer size may open a new
|
||||
DNS denial of service attack if responders can be made to send messages
|
||||
which are too large for intermediate gateways to forward, thus leading
|
||||
to potential ICMP storms between gateways and responders.
|
||||
|
||||
7 - IANA Considerations
|
||||
|
||||
IANA has allocated RR type code 41 for OPT.
|
||||
|
||||
This document controls the following IANA sub-registries in registry
|
||||
"DOMAIN NAME SYSTEM PARAMETERS":
|
||||
|
||||
"EDNS Extended Label Type"
|
||||
"EDNS Option Codes"
|
||||
"EDNS Version Numbers"
|
||||
"Domain System Response Code"
|
||||
|
||||
IANA is advised to re-parent these subregistries to this document.
|
||||
|
||||
This document assigns label type 0b01xxxxxx as "EDNS Extended Label
|
||||
Type." We request that IANA record this assignment.
|
||||
|
||||
This document assigns option code 65535 to "Reserved for future
|
||||
expansion."
|
||||
|
||||
This document assigns EDNS Extended RCODE "16" to "BADVERS".
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 7]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
IESG approval is required to create new entries in the EDNS Extended
|
||||
Label Type or EDNS Version Number registries, while any published RFC
|
||||
(including Informational, Experimental, or BCP) is grounds for
|
||||
allocation of an EDNS Option Code.
|
||||
|
||||
8 - Acknowledgements
|
||||
|
||||
Paul Mockapetris, Mark Andrews, Robert Elz, Don Lewis, Bob Halley,
|
||||
Donald Eastlake, Rob Austein, Matt Crawford, Randy Bush, Thomas Narten,
|
||||
Alfred Hoenes and Markku Savela were each instrumental in creating and
|
||||
refining this specification.
|
||||
|
||||
9 - References
|
||||
|
||||
[RFC1035] P. Mockapetris, "Domain Names - Implementation and
|
||||
Specification," RFC 1035, USC/Information Sciences
|
||||
Institute, November 1987.
|
||||
|
||||
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
|
||||
Requirement Levels," RFC 2119, Harvard University, March
|
||||
1997.
|
||||
|
||||
[RFC2671] P. Vixie, "Extension mechanisms for DNS (EDNS0)," RFC 2671,
|
||||
Internet Software Consortium, August 1999.
|
||||
|
||||
[RFC3225] D. Conrad, "Indicating Resolver Support of DNSSEC," RFC
|
||||
3225, Nominum Inc., December 2001.
|
||||
|
||||
[IANAFLAGS] IANA, "DNS Header Flags and EDNS Header Flags," web site
|
||||
http://www.iana.org/assignments/dns-header-flags, as of
|
||||
June 2005 or later.
|
||||
|
||||
10 - Author's Address
|
||||
|
||||
Paul Vixie
|
||||
Internet Systems Consortium
|
||||
950 Charter Street
|
||||
Redwood City, CA 94063
|
||||
+1 650 423 1301
|
||||
EMail: vixie@isc.org
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 8]
|
||||
|
||||
INTERNET-DRAFT EDNS0 March 2008
|
||||
|
||||
|
||||
Full Copyright Statement
|
||||
|
||||
Copyright (C) IETF Trust (2007).
|
||||
|
||||
This document is subject to the rights, licenses and restrictions
|
||||
contained in BCP 78, and except as set forth therein, the authors retain
|
||||
all their rights.
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR
|
||||
IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE
|
||||
INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
|
||||
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
Intellectual Property
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in this
|
||||
document or the extent to which any license under such rights might or
|
||||
might not be available; nor does it represent that it has made any
|
||||
independent effort to identify any such rights. Information on the
|
||||
procedures with respect to rights in RFC documents can be found in BCP
|
||||
78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an attempt
|
||||
made to obtain a general license or permission for the use of such
|
||||
proprietary rights by implementers or users of this specification can be
|
||||
obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary rights
|
||||
that may cover technology that may be required to implement this
|
||||
standard. Please address the information to the IETF at
|
||||
ietf-ipr@ietf.org.
|
||||
|
||||
Acknowledgement
|
||||
|
||||
Funding for the RFC Editor function is provided by the IETF
|
||||
Administrative Support Activity (IASA).
|
||||
|
||||
|
||||
|
||||
|
||||
Expires September 2008 [Page 9]
|
||||
|
||||
@@ -1,729 +0,0 @@
|
||||
|
||||
|
||||
|
||||
Network Working Group M. StJohns
|
||||
Internet-Draft Nominum, Inc.
|
||||
Intended status: Informational November 29, 2006
|
||||
Expires: June 2, 2007
|
||||
|
||||
|
||||
Automated Updates of DNSSEC Trust Anchors
|
||||
draft-ietf-dnsext-trustupdate-timers-05
|
||||
|
||||
Status of this Memo
|
||||
|
||||
By submitting this Internet-Draft, each author represents that any
|
||||
applicable patent or other IPR claims of which he or she is aware
|
||||
have been or will be disclosed, and any of which he or she becomes
|
||||
aware will be disclosed, in accordance with Section 6 of BCP 79.
|
||||
|
||||
Internet-Drafts are working documents of the Internet Engineering
|
||||
Task Force (IETF), its areas, and its working groups. Note that
|
||||
other groups may also distribute working documents as Internet-
|
||||
Drafts.
|
||||
|
||||
Internet-Drafts are draft documents valid for a maximum of six months
|
||||
and may be updated, replaced, or obsoleted by other documents at any
|
||||
time. It is inappropriate to use Internet-Drafts as reference
|
||||
material or to cite them other than as "work in progress."
|
||||
|
||||
The list of current Internet-Drafts can be accessed at
|
||||
http://www.ietf.org/ietf/1id-abstracts.txt.
|
||||
|
||||
The list of Internet-Draft Shadow Directories can be accessed at
|
||||
http://www.ietf.org/shadow.html.
|
||||
|
||||
This Internet-Draft will expire on June 2, 2007.
|
||||
|
||||
Copyright Notice
|
||||
|
||||
Copyright (C) The Internet Society (2006).
|
||||
|
||||
Abstract
|
||||
|
||||
This document describes a means for automated, authenticated and
|
||||
authorized updating of DNSSEC "trust anchors". The method provides
|
||||
protection against N-1 key compromises of N keys in the trust point
|
||||
key set. Based on the trust established by the presence of a current
|
||||
anchor, other anchors may be added at the same place in the
|
||||
hierarchy, and, ultimately, supplant the existing anchor(s).
|
||||
|
||||
This mechanism will require changes to resolver management behavior
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 1]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
(but not resolver resolution behavior), and the addition of a single
|
||||
flag bit to the DNSKEY record.
|
||||
|
||||
|
||||
Table of Contents
|
||||
|
||||
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
|
||||
1.1. Compliance Nomenclature . . . . . . . . . . . . . . . . . 3
|
||||
2. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 4
|
||||
2.1. Revocation . . . . . . . . . . . . . . . . . . . . . . . . 4
|
||||
2.2. Add Hold-Down . . . . . . . . . . . . . . . . . . . . . . 5
|
||||
2.3. Active Refresh . . . . . . . . . . . . . . . . . . . . . . 5
|
||||
2.4. Resolver Parameters . . . . . . . . . . . . . . . . . . . 6
|
||||
2.4.1. Add Hold-Down Time . . . . . . . . . . . . . . . . . . 6
|
||||
2.4.2. Remove Hold-Down Time . . . . . . . . . . . . . . . . 6
|
||||
2.4.3. Minimum Trust Anchors per Trust Point . . . . . . . . 6
|
||||
3. Changes to DNSKEY RDATA Wire Format . . . . . . . . . . . . . 6
|
||||
4. State Table . . . . . . . . . . . . . . . . . . . . . . . . . 6
|
||||
4.1. Events . . . . . . . . . . . . . . . . . . . . . . . . . . 7
|
||||
4.2. States . . . . . . . . . . . . . . . . . . . . . . . . . . 8
|
||||
5. Trust Point Deletion . . . . . . . . . . . . . . . . . . . . . 8
|
||||
6. Scenarios - Informative . . . . . . . . . . . . . . . . . . . 9
|
||||
6.1. Adding a Trust Anchor . . . . . . . . . . . . . . . . . . 9
|
||||
6.2. Deleting a Trust Anchor . . . . . . . . . . . . . . . . . 9
|
||||
6.3. Key Roll-Over . . . . . . . . . . . . . . . . . . . . . . 10
|
||||
6.4. Active Key Compromised . . . . . . . . . . . . . . . . . . 10
|
||||
6.5. Stand-by Key Compromised . . . . . . . . . . . . . . . . . 10
|
||||
6.6. Trust Point Deletion . . . . . . . . . . . . . . . . . . . 10
|
||||
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
|
||||
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
|
||||
8.1. Key Ownership vs Acceptance Policy . . . . . . . . . . . . 11
|
||||
8.2. Multiple Key Compromise . . . . . . . . . . . . . . . . . 11
|
||||
8.3. Dynamic Updates . . . . . . . . . . . . . . . . . . . . . 11
|
||||
9. Normative References . . . . . . . . . . . . . . . . . . . . . 12
|
||||
Editorial Comments . . . . . . . . . . . . . . . . . . . . . . . .
|
||||
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12
|
||||
Intellectual Property and Copyright Statements . . . . . . . . . . 13
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 2]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
1. Introduction
|
||||
|
||||
As part of the reality of fielding DNSSEC (Domain Name System
|
||||
Security Extensions) [RFC4033] [RFC4034] [RFC4035], the community has
|
||||
come to the realization that there will not be one signed name space,
|
||||
but rather islands of signed name space each originating from
|
||||
specific points (i.e. 'trust points') in the DNS tree. Each of those
|
||||
islands will be identified by the trust point name, and validated by
|
||||
at least one associated public key. For the purpose of this document
|
||||
we'll call the association of that name and a particular key a 'trust
|
||||
anchor'. A particular trust point can have more than one key
|
||||
designated as a trust anchor.
|
||||
|
||||
For a DNSSEC-aware resolver to validate information in a DNSSEC
|
||||
protected branch of the hierarchy, it must have knowledge of a trust
|
||||
anchor applicable to that branch. It may also have more than one
|
||||
trust anchor for any given trust point. Under current rules, a chain
|
||||
of trust for DNSSEC-protected data that chains its way back to ANY
|
||||
known trust anchor is considered 'secure'.
|
||||
|
||||
Because of the probable balkanization of the DNSSEC tree due to
|
||||
signing voids at key locations, a resolver may need to know literally
|
||||
thousands of trust anchors to perform its duties. (e.g. Consider an
|
||||
unsigned ".COM".) Requiring the owner of the resolver to manually
|
||||
manage this many relationships is problematic. It's even more
|
||||
problematic when considering the eventual requirement for key
|
||||
replacement/update for a given trust anchor. The mechanism described
|
||||
herein won't help with the initial configuration of the trust anchors
|
||||
in the resolvers, but should make trust point key replacement/
|
||||
rollover more viable.
|
||||
|
||||
As mentioned above, this document describes a mechanism whereby a
|
||||
resolver can update the trust anchors for a given trust point, mainly
|
||||
without human intervention at the resolver. There are some corner
|
||||
cases discussed (e.g. multiple key compromise) that may require
|
||||
manual intervention, but they should be few and far between. This
|
||||
document DOES NOT discuss the general problem of the initial
|
||||
configuration of trust anchors for the resolver.
|
||||
|
||||
1.1. Compliance Nomenclature
|
||||
|
||||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
||||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
||||
document are to be interpreted as described in BCP 14, [RFC2119].
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 3]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
2. Theory of Operation
|
||||
|
||||
The general concept of this mechanism is that existing trust anchors
|
||||
can be used to authenticate new trust anchors at the same point in
|
||||
the DNS hierarchy. When a zone operator adds a new SEP key (i.e. a
|
||||
DNSKEY with the Secure Entry Point bit set) (see [RFC4034]section
|
||||
2.1.1) to a trust point DNSKEY RRSet, and when that RRSet is
|
||||
validated by an existing trust anchor, then the resolver can add the
|
||||
new key to its valid set of trust anchors for that trust point.
|
||||
|
||||
There are some issues with this approach which need to be mitigated.
|
||||
For example, a compromise of one of the existing keys could allow an
|
||||
attacker to add their own 'valid' data. This implies a need for a
|
||||
method to revoke an existing key regardless of whether or not that
|
||||
key is compromised. As another example, assuming a single key
|
||||
compromise, we need to prevent an attacker from adding a new key and
|
||||
revoking all the other old keys.
|
||||
|
||||
2.1. Revocation
|
||||
|
||||
Assume two trust anchor keys A and B. Assume that B has been
|
||||
compromised. Without a specific revocation bit, B could invalidate A
|
||||
simply by sending out a signed trust point key set which didn't
|
||||
contain A. To fix this, we add a mechanism which requires knowledge
|
||||
of the private key of a DNSKEY to revoke that DNSKEY.
|
||||
|
||||
A key is considered revoked when the resolver sees the key in a self-
|
||||
signed RRSet and the key has the REVOKE bit (see Section 7 below) set
|
||||
to '1'. Once the resolver sees the REVOKE bit, it MUST NOT use this
|
||||
key as a trust anchor or for any other purposes except validating the
|
||||
RRSIG it signed over the DNSKEY RRSet specifically for the purpose of
|
||||
validating the revocation. Unlike the 'Add' operation below,
|
||||
revocation is immediate and permanent upon receipt of a valid
|
||||
revocation at the resolver.
|
||||
|
||||
A self-signed RRSet is a DNSKEY RRSet which contains the specific
|
||||
DNSKEY and for which there is a corresponding validated RRSIG record.
|
||||
It's not a special DNSKEY RRSet, just a way of describing the
|
||||
validation requirements for that RRSet.
|
||||
|
||||
N.B. A DNSKEY with the REVOKE bit set has a different fingerprint
|
||||
than one without the bit set. This affects the matching of a DNSKEY
|
||||
to DS records in the parent, or the fingerprint stored at a resolver
|
||||
used to configure a trust point.
|
||||
|
||||
In the given example, the attacker could revoke B because it has
|
||||
knowledge of B's private key, but could not revoke A.
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 4]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
2.2. Add Hold-Down
|
||||
|
||||
Assume two trust point keys A and B. Assume that B has been
|
||||
compromised. An attacker could generate and add a new trust anchor
|
||||
key - C (by adding C to the DNSKEY RRSet and signing it with B), and
|
||||
then invalidate the compromised key. This would result in both the
|
||||
attacker and owner being able to sign data in the zone and have it
|
||||
accepted as valid by resolvers.
|
||||
|
||||
To mitigate but not completely solve this problem, we add a hold-down
|
||||
time to the addition of the trust anchor. When the resolver sees a
|
||||
new SEP key in a validated trust point DNSKEY RRSet, the resolver
|
||||
starts an acceptance timer, and remembers all the keys that validated
|
||||
the RRSet. If the resolver ever sees the DNSKEY RRSet without the
|
||||
new key but validly signed, it stops the acceptance process for that
|
||||
key and resets the acceptance timer. If all of the keys which were
|
||||
originally used to validate this key are revoked prior to the timer
|
||||
expiring, the resolver stops the acceptance process and resets the
|
||||
timer.
|
||||
|
||||
Once the timer expires, the new key will be added as a trust anchor
|
||||
the next time the validated RRSet with the new key is seen at the
|
||||
resolver. The resolver MUST NOT treat the new key as a trust anchor
|
||||
until the hold down time expires AND it has retrieved and validated a
|
||||
DNSKEY RRSet after the hold down time which contains the new key.
|
||||
|
||||
N.B.: Once the resolver has accepted a key as a trust anchor, the key
|
||||
MUST be considered a valid trust anchor by that resolver until
|
||||
explictly revoked as described above.
|
||||
|
||||
In the given example, the zone owner can recover from a compromise by
|
||||
revoking B and adding a new key D and signing the DNSKEY RRSet with
|
||||
both A and B.
|
||||
|
||||
The reason this does not completely solve the problem has to do with
|
||||
the distributed nature of DNS. The resolver only knows what it sees.
|
||||
A determined attacker who holds one compromised key could keep a
|
||||
single resolver from realizing that key had been compromised by
|
||||
intercepting 'real' data from the originating zone and substituting
|
||||
their own (e.g. using the example, signed only by B). This is no
|
||||
worse than the current situation assuming a compromised key.
|
||||
|
||||
2.3. Active Refresh
|
||||
|
||||
A resolver which has been configured for automatic update of keys
|
||||
from a particular trust point MUST query that trust point (e.g. do a
|
||||
lookup for the DNSKEY RRSet and related RRSIG records) no less often
|
||||
than the lesser of 15 days or half the original TTL for the DNSKEY
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 5]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
RRSet or half the RRSIG expiration interval and no more often than
|
||||
once per hour. The expiration interval is the amount of time from
|
||||
when the RRSIG was last retrieved until the expiration time in the
|
||||
RRSIG.
|
||||
|
||||
If the query fails, the resolver MUST repeat the query until
|
||||
satisfied no more often than once an hour and no less often than the
|
||||
lesser of 1 day or 10% of the original TTL or 10% of the original
|
||||
expiration interval. I.e.: retryTime = MAX (1 hour, MIN (1 day, .1 *
|
||||
origTTL, .1 * expireInterval)).
|
||||
|
||||
2.4. Resolver Parameters
|
||||
|
||||
2.4.1. Add Hold-Down Time
|
||||
|
||||
The add hold-down time is 30 days or the expiration time of the
|
||||
original TTL of the first trust point DNSKEY RRSet which contained
|
||||
the new key, whichever is greater. This ensures that at least two
|
||||
validated DNSKEY RRSets which contain the new key MUST be seen by the
|
||||
resolver prior to the key's acceptance.
|
||||
|
||||
2.4.2. Remove Hold-Down Time
|
||||
|
||||
The remove hold-down time is 30 days. This parameter is solely a key
|
||||
management database bookeeping parameter. Failure to remove
|
||||
information about the state of defunct keys from the database will
|
||||
not adversely impact the security of this protocol, but may end up
|
||||
with a database cluttered with obsolete key information.
|
||||
|
||||
2.4.3. Minimum Trust Anchors per Trust Point
|
||||
|
||||
A compliant resolver MUST be able to manage at least five SEP keys
|
||||
per trust point.
|
||||
|
||||
|
||||
3. Changes to DNSKEY RDATA Wire Format
|
||||
|
||||
Bit n [msj2]of the DNSKEY Flags field is designated as the 'REVOKE'
|
||||
flag. If this bit is set to '1', AND the resolver sees an
|
||||
RRSIG(DNSKEY) signed by the associated key, then the resolver MUST
|
||||
consider this key permanently invalid for all purposes except for
|
||||
validating the revocation.
|
||||
|
||||
|
||||
4. State Table
|
||||
|
||||
The most important thing to understand is the resolver's view of any
|
||||
key at a trust point. The following state table describes that view
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 6]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
at various points in the key's lifetime. The table is a normative
|
||||
part of this specification. The initial state of the key is 'Start'.
|
||||
The resolver's view of the state of the key changes as various events
|
||||
occur.
|
||||
|
||||
This is the state of a trust point key as seen from the resolver.
|
||||
The column on the left indicates the current state. The header at
|
||||
the top shows the next state. The intersection of the two shows the
|
||||
event that will cause the state to transition from the current state
|
||||
to the next.
|
||||
|
||||
|
||||
NEXT STATE
|
||||
--------------------------------------------------
|
||||
FROM |Start |AddPend |Valid |Missing|Revoked|Removed|
|
||||
----------------------------------------------------------
|
||||
Start | |NewKey | | | | |
|
||||
----------------------------------------------------------
|
||||
AddPend |KeyRem | |AddTime| | |
|
||||
----------------------------------------------------------
|
||||
Valid | | | |KeyRem |Revbit | |
|
||||
----------------------------------------------------------
|
||||
Missing | | |KeyPres| |Revbit | |
|
||||
----------------------------------------------------------
|
||||
Revoked | | | | | |RemTime|
|
||||
----------------------------------------------------------
|
||||
Removed | | | | | | |
|
||||
----------------------------------------------------------
|
||||
|
||||
|
||||
State Table
|
||||
|
||||
4.1. Events
|
||||
NewKey The resolver sees a valid DNSKEY RRSet with a new SEP key.
|
||||
That key will become a new trust anchor for the named trust point
|
||||
after it's been present in the RRSet for at least 'add time'.
|
||||
KeyPres The key has returned to the valid DNSKEY RRSet.
|
||||
KeyRem The resolver sees a valid DNSKEY RRSet that does not contain
|
||||
this key.
|
||||
AddTime The key has been in every valid DNSKEY RRSet seen for at
|
||||
least the 'add time'.
|
||||
RemTime A revoked key has been missing from the trust point DNSKEY
|
||||
RRSet for sufficient time to be removed from the trust set.
|
||||
RevBit The key has appeared in the trust anchor DNSKEY RRSet with
|
||||
its "REVOKED" bit set, and there is an RRSig over the DNSKEY RRSet
|
||||
signed by this key.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 7]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
4.2. States
|
||||
Start The key doesn't yet exist as a trust anchor at the resolver.
|
||||
It may or may not exist at the zone server, but either hasn't yet
|
||||
been seen at the resolver or was seen but was absent from the last
|
||||
DNSKEY RRSet (e.g. KeyRem event).
|
||||
AddPend The key has been seen at the resolver, has its 'SEP' bit
|
||||
set, and has been included in a validated DNSKEY RRSet. There is
|
||||
a hold-down time for the key before it can be used as a trust
|
||||
anchor.
|
||||
Valid The key has been seen at the resolver and has been included in
|
||||
all validated DNSKEY RRSets from the time it was first seen up
|
||||
through the hold-down time. It is now valid for verifying RRSets
|
||||
that arrive after the hold down time. Clarification: The DNSKEY
|
||||
RRSet does not need to be continuously present at the resolver
|
||||
(e.g. its TTL might expire). If the RRSet is seen, and is
|
||||
validated (i.e. verifies against an existing trust anchor), this
|
||||
key MUST be in the RRSet otherwise a 'KeyRem' event is triggered.
|
||||
Missing This is an abnormal state. The key remains as a valid trust
|
||||
point key, but was not seen at the resolver in the last validated
|
||||
DNSKEY RRSet. This is an abnormal state because the zone operator
|
||||
should be using the REVOKE bit prior to removal.
|
||||
Revoked This is the state a key moves to once the resolver sees an
|
||||
RRSIG(DNSKEY) signed by this key where that DNSKEY RRSet contains
|
||||
this key with its REVOKE bit set to '1'. Once in this state, this
|
||||
key MUST permanently be considered invalid as a trust anchor.
|
||||
Removed After a fairly long hold-down time, information about this
|
||||
key may be purged from the resolver. A key in the removed state
|
||||
MUST NOT be considered a valid trust anchor. (Note: this state is
|
||||
more or less equivalent to the "Start" state, except that it's bad
|
||||
practice to re-introduce previously used keys - think of this as
|
||||
the holding state for all the old keys for which the resolver no
|
||||
longer needs to track state.)
|
||||
|
||||
|
||||
5. Trust Point Deletion
|
||||
|
||||
A trust point which has all of its trust anchors revoked is
|
||||
considered deleted and is treated as if the trust point was never
|
||||
configured. If there are no superior configured trust points, data
|
||||
at and below the deleted trust point are considered insecure by the
|
||||
resolver. If there ARE superior configured trust points, data at and
|
||||
below the deleted trust point are evaluated with respect to the
|
||||
superior trust point(s).
|
||||
|
||||
Alternately, a trust point which is subordinate to another configured
|
||||
trust point MAY be deleted by a resolver after 180 days where such
|
||||
subordinate trust point validly chains to a superior trust point.
|
||||
The decision to delete the subordinate trust anchor is a local
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 8]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
configuration decision. Once the subordinate trust point is deleted,
|
||||
validation of the subordinate zone is dependent on validating the
|
||||
chain of trust to the superior trust point.
|
||||
|
||||
|
||||
6. Scenarios - Informative
|
||||
|
||||
The suggested model for operation is to have one active key and one
|
||||
stand-by key at each trust point. The active key will be used to
|
||||
sign the DNSKEY RRSet. The stand-by key will not normally sign this
|
||||
RRSet, but the resolver will accept it as a trust anchor if/when it
|
||||
sees the signature on the trust point DNSKEY RRSet.
|
||||
|
||||
Since the stand-by key is not in active signing use, the associated
|
||||
private key may (and should) be provided with additional protections
|
||||
not normally available to a key that must be used frequently. E.g.
|
||||
locked in a safe, split among many parties, etc. Notionally, the
|
||||
stand-by key should be less subject to compromise than an active key,
|
||||
but that will be dependent on operational concerns not addressed
|
||||
here.
|
||||
|
||||
6.1. Adding a Trust Anchor
|
||||
|
||||
Assume an existing trust anchor key 'A'.
|
||||
1. Generate a new key pair.
|
||||
2. Create a DNSKEY record from the key pair and set the SEP and Zone
|
||||
Key bits.
|
||||
3. Add the DNSKEY to the RRSet.
|
||||
4. Sign the DNSKEY RRSet ONLY with the existing trust anchor key -
|
||||
'A'.
|
||||
5. Wait a while (i.e. for various resolvers timers to go off and for
|
||||
them to retrieve the new DNSKEY RRSet and signatures).
|
||||
6. The new trust anchor will be populated at the resolvers on the
|
||||
schedule described by the state table and update algorithm - see
|
||||
Section 2 above
|
||||
|
||||
6.2. Deleting a Trust Anchor
|
||||
|
||||
Assume existing trust anchors 'A' and 'B' and that you want to revoke
|
||||
and delete 'A'.
|
||||
1. Set the revocation bit on key 'A'.
|
||||
2. Sign the DNSKEY RRSet with both 'A' and 'B'.
|
||||
'A' is now revoked. The operator should include the revoked 'A' in
|
||||
the RRSet for at least the remove hold-down time, but then may remove
|
||||
it from the DNSKEY RRSet.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 9]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
6.3. Key Roll-Over
|
||||
|
||||
Assume existing keys A and B. 'A' is actively in use (i.e. has been
|
||||
signing the DNSKEY RRSet.) 'B' was the stand-by key. (i.e. has been
|
||||
in the DNSKEY RRSet and is a valid trust anchor, but wasn't being
|
||||
used to sign the RRSet.)
|
||||
1. Generate a new key pair 'C'.
|
||||
2. Add 'C' to the DNSKEY RRSet.
|
||||
3. Set the revocation bit on key 'A'.
|
||||
4. Sign the RRSet with 'A' and 'B'.
|
||||
'A' is now revoked, 'B' is now the active key, and 'C' will be the
|
||||
stand-by key once the hold-down expires. The operator should include
|
||||
the revoked 'A' in the RRSet for at least the remove hold-down time,
|
||||
but may then remove it from the DNSKEY RRSet.
|
||||
|
||||
6.4. Active Key Compromised
|
||||
|
||||
This is the same as the mechanism for Key Roll-Over (Section 6.3)
|
||||
above assuming 'A' is the active key.
|
||||
|
||||
6.5. Stand-by Key Compromised
|
||||
|
||||
Using the same assumptions and naming conventions as Key Roll-Over
|
||||
(Section 6.3) above:
|
||||
1. Generate a new key pair 'C'.
|
||||
2. Add 'C' to the DNSKEY RRSet.
|
||||
3. Set the revocation bit on key 'B'.
|
||||
4. Sign the RRSet with 'A' and 'B'.
|
||||
'B' is now revoked, 'A' remains the active key, and 'C' will be the
|
||||
stand-by key once the hold-down expires. 'B' should continue to be
|
||||
included in the RRSet for the remove hold-down time.
|
||||
|
||||
6.6. Trust Point Deletion
|
||||
|
||||
To delete a trust point which is subordinate to another configured
|
||||
trust point (e.g. example.com to .com) requires some juggling of the
|
||||
data. The specific process is:
|
||||
1. Generate a new DNSKEY and DS record and provide the DS record to
|
||||
the parent along with DS records for the old keys
|
||||
2. Once the parent has published the DSs, add the new DNSKEY to the
|
||||
RRSet and revoke ALL of the old keys at the same time while
|
||||
signing the DNSKEY RRSet with all of the old and new keys.
|
||||
3. After 30 days stop publishing the old, revoked keys and remove
|
||||
any corresponding DS records in the parent.
|
||||
Revoking the old trust point keys at the same time as adding new keys
|
||||
that chain to a superior trust prevents the resolver from adding the
|
||||
new keys as trust anchors. Adding DS records for the old keys avoids
|
||||
a race condition where either the subordinate zone becomes unsecure
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 10]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
(because the trust point was deleted) or becomes bogus (because it
|
||||
didn't chain to the superior zone).
|
||||
|
||||
|
||||
7. IANA Considerations
|
||||
|
||||
The IANA will need to assign a bit in the DNSKEY flags field (see
|
||||
section 4.3 of [RFC3755]) for the REVOKE bit. There are no other
|
||||
IANA actions required.
|
||||
|
||||
|
||||
8. Security Considerations
|
||||
|
||||
In addition to the following sections, see also Theory of Operation
|
||||
above and especially Section 2.2 for related discussions.
|
||||
|
||||
8.1. Key Ownership vs Acceptance Policy
|
||||
|
||||
The reader should note that, while the zone owner is responsible for
|
||||
creating and distributing keys, it's wholly the decision of the
|
||||
resolver owner as to whether to accept such keys for the
|
||||
authentication of the zone information. This implies the decision to
|
||||
update trust anchor keys based on trust for a current trust anchor
|
||||
key is also the resolver owner's decision.
|
||||
|
||||
The resolver owner (and resolver implementers) MAY choose to permit
|
||||
or prevent key status updates based on this mechanism for specific
|
||||
trust points. If they choose to prevent the automated updates, they
|
||||
will need to establish a mechanism for manual or other out-of-band
|
||||
updates outside the scope of this document.
|
||||
|
||||
8.2. Multiple Key Compromise
|
||||
|
||||
This scheme permits recovery as long as at least one valid trust
|
||||
anchor key remains uncompromised. E.g. if there are three keys, you
|
||||
can recover if two of them are compromised. The zone owner should
|
||||
determine their own level of comfort with respect to the number of
|
||||
active valid trust anchors in a zone and should be prepared to
|
||||
implement recovery procedures once they detect a compromise. A
|
||||
manual or other out-of-band update of all resolvers will be required
|
||||
if all trust anchor keys at a trust point are compromised.
|
||||
|
||||
8.3. Dynamic Updates
|
||||
|
||||
Allowing a resolver to update its trust anchor set based on in-band
|
||||
key information is potentially less secure than a manual process.
|
||||
However, given the nature of the DNS, the number of resolvers that
|
||||
would require update if a trust anchor key were compromised, and the
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 11]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
lack of a standard management framework for DNS, this approach is no
|
||||
worse than the existing situation.
|
||||
|
||||
|
||||
9. Normative References
|
||||
|
||||
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
|
||||
Requirement Levels", BCP 14, RFC 2119, March 1997.
|
||||
|
||||
[RFC3755] Weiler, S., "Legacy Resolver Compatibility for Delegation
|
||||
Signer (DS)", RFC 3755, May 2004.
|
||||
|
||||
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "DNS Security Introduction and Requirements",
|
||||
RFC 4033, March 2005.
|
||||
|
||||
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Resource Records for the DNS Security Extensions",
|
||||
RFC 4034, March 2005.
|
||||
|
||||
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Protocol Modifications for the DNS Security
|
||||
Extensions", RFC 4035, March 2005.
|
||||
|
||||
Editorial Comments
|
||||
|
||||
[msj2] msj: To be assigned.
|
||||
|
||||
|
||||
Author's Address
|
||||
|
||||
Michael StJohns
|
||||
Nominum, Inc.
|
||||
2385 Bay Road
|
||||
Redwood City, CA 94063
|
||||
USA
|
||||
|
||||
Phone: +1-301-528-4729
|
||||
Email: Mike.StJohns@nominum.com
|
||||
URI: www.nominum.com
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 12]
|
||||
|
||||
Internet-Draft trustanchor-update November 2006
|
||||
|
||||
|
||||
Full Copyright Statement
|
||||
|
||||
Copyright (C) The Internet Society (2006).
|
||||
|
||||
This document is subject to the rights, licenses and restrictions
|
||||
contained in BCP 78, and except as set forth therein, the authors
|
||||
retain all their rights.
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||||
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
||||
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
|
||||
Intellectual Property
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in
|
||||
this document or the extent to which any license under such rights
|
||||
might or might not be available; nor does it represent that it has
|
||||
made any independent effort to identify any such rights. Information
|
||||
on the procedures with respect to rights in RFC documents can be
|
||||
found in BCP 78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an
|
||||
attempt made to obtain a general license or permission for the use of
|
||||
such proprietary rights by implementers or users of this
|
||||
specification can be obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary
|
||||
rights that may cover technology that may be required to implement
|
||||
this standard. Please address the information to the IETF at
|
||||
ietf-ipr@ietf.org.
|
||||
|
||||
|
||||
Acknowledgment
|
||||
|
||||
Funding for the RFC Editor function is provided by the IETF
|
||||
Administrative Support Activity (IASA).
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
StJohns Expires June 2, 2007 [Page 13]
|
||||
|
||||
|
||||
@@ -1,672 +0,0 @@
|
||||
|
||||
|
||||
|
||||
Network Working Group M. Andrews
|
||||
Internet-Draft ISC
|
||||
Intended status: BCP June 5, 2008
|
||||
Expires: December 7, 2008
|
||||
|
||||
|
||||
Locally-served DNS Zones
|
||||
draft-ietf-dnsop-default-local-zones-05
|
||||
|
||||
Status of this Memo
|
||||
|
||||
By submitting this Internet-Draft, each author represents that any
|
||||
applicable patent or other IPR claims of which he or she is aware
|
||||
have been or will be disclosed, and any of which he or she becomes
|
||||
aware will be disclosed, in accordance with Section 6 of BCP 79.
|
||||
|
||||
Internet-Drafts are working documents of the Internet Engineering
|
||||
Task Force (IETF), its areas, and its working groups. Note that
|
||||
other groups may also distribute working documents as Internet-
|
||||
Drafts.
|
||||
|
||||
Internet-Drafts are draft documents valid for a maximum of six months
|
||||
and may be updated, replaced, or obsoleted by other documents at any
|
||||
time. It is inappropriate to use Internet-Drafts as reference
|
||||
material or to cite them other than as "work in progress."
|
||||
|
||||
The list of current Internet-Drafts can be accessed at
|
||||
http://www.ietf.org/ietf/1id-abstracts.txt.
|
||||
|
||||
The list of Internet-Draft Shadow Directories can be accessed at
|
||||
http://www.ietf.org/shadow.html.
|
||||
|
||||
This Internet-Draft will expire on December 7, 2008.
|
||||
|
||||
Abstract
|
||||
|
||||
Experience has shown that there are a number of DNS zones all
|
||||
iterative resolvers and recursive nameservers should, unless
|
||||
configured otherwise, automatically serve. RFC 4193 specifies that
|
||||
this should occur for D.F.IP6.ARPA. This document extends the
|
||||
practice to cover the IN-ADDR.ARPA zones for RFC 1918 address space
|
||||
and other well known zones with similar characteristics.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 1]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
Table of Contents
|
||||
|
||||
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
|
||||
1.1. Reserved Words . . . . . . . . . . . . . . . . . . . . . . 3
|
||||
2. Effects on sites using RFC 1918 addresses. . . . . . . . . . . 4
|
||||
3. Changes to Iterative Resolver Behaviour. . . . . . . . . . . . 4
|
||||
4. Lists Of Zones Covered . . . . . . . . . . . . . . . . . . . . 5
|
||||
4.1. RFC 1918 Zones . . . . . . . . . . . . . . . . . . . . . . 5
|
||||
4.2. RFC 3330 Zones . . . . . . . . . . . . . . . . . . . . . . 6
|
||||
4.3. Local IPv6 Unicast Addresses . . . . . . . . . . . . . . . 6
|
||||
4.4. IPv6 Locally Assigned Local Addresses . . . . . . . . . . 6
|
||||
4.5. IPv6 Link Local Addresses . . . . . . . . . . . . . . . . 7
|
||||
5. Zones that are Out-Of-Scope . . . . . . . . . . . . . . . . . 7
|
||||
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
|
||||
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
|
||||
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
|
||||
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
|
||||
9.1. Normative References . . . . . . . . . . . . . . . . . . . 8
|
||||
9.2. Informative References . . . . . . . . . . . . . . . . . . 10
|
||||
Appendix A. Change History [To Be Removed on Publication] . . . . 10
|
||||
A.1. draft-ietf-dnsop-default-local-zones-05.txt . . . . . . . 10
|
||||
A.2. draft-ietf-dnsop-default-local-zones-04.txt . . . . . . . 10
|
||||
A.3. draft-ietf-dnsop-default-local-zones-03.txt . . . . . . . 10
|
||||
A.4. draft-ietf-dnsop-default-local-zones-02.txt . . . . . . . 10
|
||||
A.5. draft-ietf-dnsop-default-local-zones-01.txt . . . . . . . 11
|
||||
A.6. draft-ietf-dnsop-default-local-zones-00.txt . . . . . . . 11
|
||||
A.7. draft-andrews-full-service-resolvers-03.txt . . . . . . . 11
|
||||
A.8. draft-andrews-full-service-resolvers-02.txt . . . . . . . 11
|
||||
Appendix B. Proposed Status [To Be Removed on Publication] . . . 11
|
||||
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
|
||||
Intellectual Property and Copyright Statements . . . . . . . . . . 12
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 2]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
1. Introduction
|
||||
|
||||
Experience has shown that there are a number of DNS [RFC 1034] [RFC
|
||||
1035] zones that all iterative resolvers and recursive nameservers
|
||||
SHOULD, unless intentionally configured otherwise, automatically
|
||||
serve. These zones include, but are not limited to, the IN-ADDR.ARPA
|
||||
zones for the address space allocated by [RFC 1918] and the IP6.ARPA
|
||||
zones for locally assigned unique local IPv6 addresses, [RFC 4193].
|
||||
|
||||
This recommendation is made because data has shown that significant
|
||||
leakage of queries for these name spaces is occurring, despite
|
||||
instructions to restrict them, and because it has therefore become
|
||||
necessary to deploy sacrificial name servers to protect the immediate
|
||||
parent name servers for these zones from excessive, unintentional,
|
||||
query load [AS112] [I-D.draft-ietf-dnsop-as112-ops]
|
||||
[I-D.draft-ietf-dnsop-as112-under-attack-help-help]. There is every
|
||||
expectation that the query load will continue to increase unless
|
||||
steps are taken as outlined here.
|
||||
|
||||
Additionally, queries from clients behind badly configured firewalls
|
||||
that allow outgoing queries for these name spaces but drop the
|
||||
responses, put a significant load on the root servers (forward but no
|
||||
reverse zones configured). They also cause operational load for the
|
||||
root server operators as they have to reply to enquiries about why
|
||||
the root servers are "attacking" these clients. Changing the default
|
||||
configuration will address all these issues for the zones listed in
|
||||
Section 4.
|
||||
|
||||
[RFC 4193] recommends that queries for D.F.IP6.ARPA be handled
|
||||
locally. This document extends the recommendation to cover the IN-
|
||||
ADDR.ARPA zones for [RFC 1918] and other well known IN-ADDR.ARPA and
|
||||
IP6.ARPA zones for which queries should not appear on the public
|
||||
Internet.
|
||||
|
||||
It is hoped that by doing this the number of sacrificial servers
|
||||
[AS112] will not have to be increased, and may in time be reduced.
|
||||
|
||||
This recommendation should also help DNS responsiveness for sites
|
||||
which are using [RFC 1918] addresses but do not follow the last
|
||||
paragraph in Section 3 of [RFC 1918].
|
||||
|
||||
1.1. Reserved Words
|
||||
|
||||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
||||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
||||
document are to be interpreted as described in [RFC 2119].
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 3]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
2. Effects on sites using RFC 1918 addresses.
|
||||
|
||||
For most sites using [RFC 1918] addresses, the changes here will have
|
||||
little or no detrimental effect. If the site does not already have
|
||||
the reverse tree populated the only effect will be that the name
|
||||
error responses will be generated locally rather than remotely.
|
||||
|
||||
For sites that do have the reverse tree populated, most will either
|
||||
have a local copy of the zones or will be forwarding the queries to
|
||||
servers which have local copies of the zone. Therefore this
|
||||
recommendation will not be relevant.
|
||||
|
||||
The most significant impact will be felt at sites that make use of
|
||||
delegations for [RFC 1918] addresses and have populated these zones.
|
||||
These sites will need to override the default configuration expressed
|
||||
in this document to allow resolution to continue. Typically, such
|
||||
sites will be fully disconnected from the Internet and have their own
|
||||
root servers for their own non-Internet DNS tree.
|
||||
|
||||
|
||||
3. Changes to Iterative Resolver Behaviour.
|
||||
|
||||
Unless configured otherwise, an iterative resolver will now return
|
||||
authoritatively (aa=1) name errors (RCODE=3) for queries within the
|
||||
zones in Section 4, with the obvious exception of queries for the
|
||||
zone name itself where SOA, NS and "no data" responses will be
|
||||
returned as appropriate to the query type. One common way to do this
|
||||
is to serve empty (SOA and NS only) zones.
|
||||
|
||||
An implementation of this recommendation MUST provide a mechanism to
|
||||
disable this new behaviour, and SHOULD allow this decision on a zone
|
||||
by zone basis.
|
||||
|
||||
If using empty zones one SHOULD NOT use the same NS and SOA records
|
||||
as used on the public Internet servers as that will make it harder to
|
||||
detect the origin of the responses and thus any leakage to the public
|
||||
Internet servers. This document recommends that the NS record
|
||||
defaults to the name of the zone and the SOA MNAME defaults to the
|
||||
name of the only NS RR's target. The SOA RNAME should default to
|
||||
"nobody.invalid." [RFC 2606]. Implementations SHOULD provide a
|
||||
mechanism to set these values. No address records need to be
|
||||
provided for the name server.
|
||||
|
||||
Below is an example of a generic empty zone in master file format.
|
||||
It will produce a negative cache TTL of 3 hours.
|
||||
|
||||
@ 10800 IN SOA @ nobody.invalid. 1 3600 1200 604800 10800
|
||||
@ 10800 IN NS @
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 4]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
The SOA RR is needed to support negative caching [RFC 2308] of name
|
||||
error responses and to point clients to the primary master for DNS
|
||||
dynamic updates.
|
||||
|
||||
SOA values of particular importance are the MNAME, the SOA RR's TTL
|
||||
and the negTTL value. Both TTL values SHOULD match. The rest of the
|
||||
SOA timer values MAY be chosen arbitrarily since they are not
|
||||
intended to control any zone transfer activity.
|
||||
|
||||
The NS RR is needed as some UPDATE [RFC 2136] clients use NS queries
|
||||
to discover the zone to be updated. Having no address records for
|
||||
the name server is expected to abort UPDATE processing in the client.
|
||||
|
||||
|
||||
4. Lists Of Zones Covered
|
||||
|
||||
The following subsections are intended to seed the IANA registry as
|
||||
requested in the IANA Considerations Section. The zone name is the
|
||||
entity to be registered.
|
||||
|
||||
4.1. RFC 1918 Zones
|
||||
|
||||
The following zones correspond to the IPv4 address space reserved in
|
||||
[RFC 1918].
|
||||
|
||||
+----------------------+
|
||||
| Zone |
|
||||
+----------------------+
|
||||
| 10.IN-ADDR.ARPA |
|
||||
| 16.172.IN-ADDR.ARPA |
|
||||
| 17.172.IN-ADDR.ARPA |
|
||||
| 18.172.IN-ADDR.ARPA |
|
||||
| 19.172.IN-ADDR.ARPA |
|
||||
| 20.172.IN-ADDR.ARPA |
|
||||
| 21.172.IN-ADDR.ARPA |
|
||||
| 22.172.IN-ADDR.ARPA |
|
||||
| 23.172.IN-ADDR.ARPA |
|
||||
| 24.172.IN-ADDR.ARPA |
|
||||
| 25.172.IN-ADDR.ARPA |
|
||||
| 26.172.IN-ADDR.ARPA |
|
||||
| 27.172.IN-ADDR.ARPA |
|
||||
| 28.172.IN-ADDR.ARPA |
|
||||
| 29.172.IN-ADDR.ARPA |
|
||||
| 30.172.IN-ADDR.ARPA |
|
||||
| 31.172.IN-ADDR.ARPA |
|
||||
| 168.192.IN-ADDR.ARPA |
|
||||
+----------------------+
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 5]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
4.2. RFC 3330 Zones
|
||||
|
||||
The following zones correspond to those address ranges from [RFC
|
||||
3330] that are not expected to appear as source or destination
|
||||
addresses on the public Internet and to not have a unique name to
|
||||
associate with.
|
||||
|
||||
The recommendation to serve an empty zone 127.IN-ADDR.ARPA is not a
|
||||
attempt to discourage any practice to provide a PTR RR for
|
||||
1.0.0.127.IN-ADDR.ARPA locally. In fact, a meaningful reverse
|
||||
mapping should exist, but the exact setup is out of the scope of this
|
||||
document. Similar logic applies to the reverse mapping for ::1
|
||||
(Section 4.3). The recommendations made here simply assume no other
|
||||
coverage for these domains exists.
|
||||
|
||||
+------------------------------+------------------------+
|
||||
| Zone | Description |
|
||||
+------------------------------+------------------------+
|
||||
| 0.IN-ADDR.ARPA | IPv4 "THIS" NETWORK |
|
||||
| 127.IN-ADDR.ARPA | IPv4 LOOP-BACK NETWORK |
|
||||
| 254.169.IN-ADDR.ARPA | IPv4 LINK LOCAL |
|
||||
| 2.0.192.IN-ADDR.ARPA | IPv4 TEST NET |
|
||||
| 255.255.255.255.IN-ADDR.ARPA | IPv4 BROADCAST |
|
||||
+------------------------------+------------------------+
|
||||
|
||||
4.3. Local IPv6 Unicast Addresses
|
||||
|
||||
The reverse mappings ([RFC 3596], Section 2.5 IP6.ARPA Domain) for
|
||||
the IPv6 Unspecified (::) and Loopback (::1) addresses ([RFC 4291],
|
||||
Sections 2.4, 2.5.2 and 2.5.3) are covered by these two zones:
|
||||
|
||||
+-------------------------------------------+
|
||||
| Zone |
|
||||
+-------------------------------------------+
|
||||
| 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.\ |
|
||||
| 0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA |
|
||||
| 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.\ |
|
||||
| 0.0.0.0.0.0.0.0.0.0.0.0.IP6.ARPA |
|
||||
+-------------------------------------------+
|
||||
|
||||
Note: Line breaks and a escapes '\' have been inserted above for
|
||||
readability and to adhere to line width constraints. They are not
|
||||
parts of the zone names.
|
||||
|
||||
4.4. IPv6 Locally Assigned Local Addresses
|
||||
|
||||
Section 4.4 of [RFC 4193] already required special treatment of:
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 6]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
+--------------+
|
||||
| Zone |
|
||||
+--------------+
|
||||
| D.F.IP6.ARPA |
|
||||
+--------------+
|
||||
|
||||
4.5. IPv6 Link Local Addresses
|
||||
|
||||
IPv6 Link-Local Addresses as of [RFC 4291], Section 2.5.6 are covered
|
||||
by four distinct reverse DNS zones:
|
||||
|
||||
+----------------+
|
||||
| Zone |
|
||||
+----------------+
|
||||
| 8.E.F.IP6.ARPA |
|
||||
| 9.E.F.IP6.ARPA |
|
||||
| A.E.F.IP6.ARPA |
|
||||
| B.E.F.IP6.ARPA |
|
||||
+----------------+
|
||||
|
||||
|
||||
5. Zones that are Out-Of-Scope
|
||||
|
||||
IPv6 site-local addresses, [RFC 4291] Sections 2.4 and 2.5.7, and
|
||||
IPv6 Non-Locally Assigned Local addresses [RFC 4193] are not covered
|
||||
here. It is expected that IPv6 site-local addresses will be self
|
||||
correcting as IPv6 implementations remove support for site-local
|
||||
addresses. However, sacrificial servers for C.E.F.IP6.ARPA through
|
||||
F.E.F.IP6.ARPA may still need to be deployed in the short term if the
|
||||
traffic becomes excessive.
|
||||
|
||||
For IPv6 Non-Locally Assigned Local addresses (L = 0) [RFC 4193],
|
||||
there has been no decision made about whether the Regional Internet
|
||||
Registries (RIRs) will provide delegations in this space or not. If
|
||||
they don't, then C.F.IP6.ARPA will need to be added to the list in
|
||||
Section 4.4. If they do, then registries will need to take steps to
|
||||
ensure that name servers are provided for these addresses.
|
||||
|
||||
This document also ignores IP6.INT. IP6.INT has been wound up with
|
||||
only legacy resolvers now generating reverse queries under IP6.INT
|
||||
[RFC 4159].
|
||||
|
||||
This document has also deliberately ignored names immediately under
|
||||
the root domain. While there is a subset of queries to the root name
|
||||
servers which could be addressed using the techniques described here
|
||||
(e.g. .local, .workgroup and IPv4 addresses), there is also a vast
|
||||
amount of traffic that requires a different strategy (e.g. lookups
|
||||
for unqualified hostnames, IPv6 addresses).
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 7]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
6. IANA Considerations
|
||||
|
||||
This document requests that IANA establish a registry of zones which
|
||||
require this default behaviour. The initial contents of which are in
|
||||
Section 4. Implementors are encouraged to check this registry and
|
||||
adjust their implementations to reflect changes therein.
|
||||
|
||||
This registry can be amended through "IETF Consensus" as per [RFC
|
||||
2434].
|
||||
|
||||
IANA should co-ordinate with the RIRs to ensure that, as DNSSEC is
|
||||
deployed in the reverse tree, delegations for these zones are made in
|
||||
the manner described in Section 7.
|
||||
|
||||
|
||||
7. Security Considerations
|
||||
|
||||
During the initial deployment phase, particularly where [RFC 1918]
|
||||
addresses are in use, there may be some clients that unexpectedly
|
||||
receive a name error rather than a PTR record. This may cause some
|
||||
service disruption until their recursive name server(s) have been re-
|
||||
configured.
|
||||
|
||||
As DNSSEC is deployed within the IN-ADDR.ARPA and IP6.ARPA
|
||||
namespaces, the zones listed above will need to be delegated as
|
||||
insecure delegations, or be within insecure zones. This will allow
|
||||
DNSSEC validation to succeed for queries in these spaces despite not
|
||||
being answered from the delegated servers.
|
||||
|
||||
It is recommended that sites actively using these namespaces secure
|
||||
them using DNSSEC [RFC 4035] by publishing and using DNSSEC trust
|
||||
anchors. This will protect the clients from accidental import of
|
||||
unsigned responses from the Internet.
|
||||
|
||||
|
||||
8. Acknowledgements
|
||||
|
||||
This work was supported by the US National Science Foundation
|
||||
(research grant SCI-0427144) and DNS-OARC.
|
||||
|
||||
|
||||
9. References
|
||||
|
||||
9.1. Normative References
|
||||
|
||||
[RFC 1034]
|
||||
Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES",
|
||||
STD 13, RFC 1034, November 1987.
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 8]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
[RFC 1035]
|
||||
Mockapetris, P., "DOMAIN NAMES - IMPLEMENTATION AND
|
||||
SPECIFICATION", STD 13, RFC 1035, November 1987.
|
||||
|
||||
[RFC 1918]
|
||||
Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
|
||||
and E. Lear, "Address Allocation for Private Internets",
|
||||
BCP 5, RFC 1918, February 1996.
|
||||
|
||||
[RFC 2119]
|
||||
Bradner, S., "Key words for use in RFCs to Indicate
|
||||
Requirement Levels", BCP 14, RFC 2119, March 1997.
|
||||
|
||||
[RFC 2136]
|
||||
Vixie, P., Thomson, A., Rekhter, Y., and J. Bound,
|
||||
"Dynamic Updates in the Domain Name System (DNS UPDATE)",
|
||||
RFC 2136, April 1997.
|
||||
|
||||
[RFC 2308]
|
||||
Andrews, M., "Negative Caching of DNS Queries (DNS
|
||||
NCACHE)", RFC 2398, March 1998.
|
||||
|
||||
[RFC 2434]
|
||||
Narten, T. and H. Alvestrand, "Guidelines for Writing an
|
||||
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
|
||||
October 1998.
|
||||
|
||||
[RFC 2606]
|
||||
Eastlake, D. and A. Panitz, "Reserved Top Level DNS
|
||||
Names", BCP 32, RFC 2606, June 1999.
|
||||
|
||||
[RFC 3596]
|
||||
Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
|
||||
"DNS Extensions to Support IPv6", RFC 3596, October 2003.
|
||||
|
||||
[RFC 4035]
|
||||
Arends, R., Austein, R., Larson, M., Massey, D., and S.
|
||||
Rose, "Protocol Modifications for the DNS Security
|
||||
Extensions", RFC 4035, March 2005.
|
||||
|
||||
[RFC 4159]
|
||||
Huston, G., "Deprecation of "ip6.int"", BCP 109, RFC 4159,
|
||||
August 2005.
|
||||
|
||||
[RFC 4193]
|
||||
Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
|
||||
Addresses", RFC 4193, October 2005.
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 9]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
[RFC 4291]
|
||||
Hinden, R. and S. Deering, "IP Version 6 Addressing
|
||||
Architecture", RFC 4291, February 2006.
|
||||
|
||||
9.2. Informative References
|
||||
|
||||
[AS112] "AS112 Project", <http://www.as112.net/>.
|
||||
|
||||
[I-D.draft-ietf-dnsop-as112-ops]
|
||||
Abley, J. and W. Maton, "AS112 Nameserver Operations",
|
||||
draft-ietf-dnsop-as112-ops-00 (work in progress),
|
||||
February 2007.
|
||||
|
||||
[I-D.draft-ietf-dnsop-as112-under-attack-help-help]
|
||||
Abley, J. and W. Maton, "I'm Being Attacked by
|
||||
PRISONER.IANA.ORG!",
|
||||
draft-ietf-dnsop-as112-under-attack-help-help-00 (work in
|
||||
progress), February 2007.
|
||||
|
||||
[RFC 3330]
|
||||
"Special-Use IPv4 Addresses", RFC 3330, September 2002.
|
||||
|
||||
|
||||
Appendix A. Change History [To Be Removed on Publication]
|
||||
|
||||
A.1. draft-ietf-dnsop-default-local-zones-05.txt
|
||||
|
||||
none, expiry prevention
|
||||
|
||||
A.2. draft-ietf-dnsop-default-local-zones-04.txt
|
||||
|
||||
Centrally Assigned Local addresses -> Non-Locally Assigned Local
|
||||
address
|
||||
|
||||
A.3. draft-ietf-dnsop-default-local-zones-03.txt
|
||||
|
||||
expanded section 4 descriptions
|
||||
|
||||
Added references [RFC 2136], [RFC 3596],
|
||||
[I-D.draft-ietf-dnsop-as112-ops] and
|
||||
[I-D.draft-ietf-dnsop-as112-under-attack-help-help].
|
||||
|
||||
Revised language.
|
||||
|
||||
A.4. draft-ietf-dnsop-default-local-zones-02.txt
|
||||
|
||||
RNAME now "nobody.invalid."
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 10]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
Revised language.
|
||||
|
||||
A.5. draft-ietf-dnsop-default-local-zones-01.txt
|
||||
|
||||
Revised impact description.
|
||||
|
||||
Updated to reflect change in IP6.INT status.
|
||||
|
||||
A.6. draft-ietf-dnsop-default-local-zones-00.txt
|
||||
|
||||
Adopted by DNSOP.
|
||||
|
||||
"Author's Note" re-titled "Zones that are Out-Of-Scope"
|
||||
|
||||
Add note that these zone are expected to seed the IANA registry.
|
||||
|
||||
Title changed.
|
||||
|
||||
A.7. draft-andrews-full-service-resolvers-03.txt
|
||||
|
||||
Added "Proposed Status".
|
||||
|
||||
A.8. draft-andrews-full-service-resolvers-02.txt
|
||||
|
||||
Added 0.IN-ADDR.ARPA.
|
||||
|
||||
|
||||
Appendix B. Proposed Status [To Be Removed on Publication]
|
||||
|
||||
This Internet-Draft is being submitted for eventual publication as an
|
||||
RFC with a proposed status of Best Current Practice.
|
||||
|
||||
|
||||
Author's Address
|
||||
|
||||
Mark P. Andrews
|
||||
Internet Systems Consortium
|
||||
950 Charter Street
|
||||
Redwood City, CA 94063
|
||||
US
|
||||
|
||||
Email: Mark_Andrews@isc.org
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 11]
|
||||
|
||||
Internet-Draft Locally-served DNS Zones June 2008
|
||||
|
||||
|
||||
Full Copyright Statement
|
||||
|
||||
Copyright (C) The IETF Trust (2008).
|
||||
|
||||
This document is subject to the rights, licenses and restrictions
|
||||
contained in BCP 78, and except as set forth therein, the authors
|
||||
retain all their rights.
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
|
||||
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
|
||||
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
|
||||
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
|
||||
Intellectual Property
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in
|
||||
this document or the extent to which any license under such rights
|
||||
might or might not be available; nor does it represent that it has
|
||||
made any independent effort to identify any such rights. Information
|
||||
on the procedures with respect to rights in RFC documents can be
|
||||
found in BCP 78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an
|
||||
attempt made to obtain a general license or permission for the use of
|
||||
such proprietary rights by implementers or users of this
|
||||
specification can be obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary
|
||||
rights that may cover technology that may be required to implement
|
||||
this standard. Please address the information to the IETF at
|
||||
ietf-ipr@ietf.org.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Andrews Expires December 7, 2008 [Page 12]
|
||||
|
||||
@@ -1,640 +0,0 @@
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
DNSOP Working Group Paul Vixie, ISC
|
||||
INTERNET-DRAFT Akira Kato, WIDE
|
||||
<draft-ietf-dnsop-respsize-06.txt> August 2006
|
||||
|
||||
DNS Referral Response Size Issues
|
||||
|
||||
Status of this Memo
|
||||
By submitting this Internet-Draft, each author represents that any
|
||||
applicable patent or other IPR claims of which he or she is aware
|
||||
have been or will be disclosed, and any of which he or she becomes
|
||||
aware will be disclosed, in accordance with Section 6 of BCP 79.
|
||||
|
||||
Internet-Drafts are working documents of the Internet Engineering
|
||||
Task Force (IETF), its areas, and its working groups. Note that
|
||||
other groups may also distribute working documents as Internet-
|
||||
Drafts.
|
||||
|
||||
Internet-Drafts are draft documents valid for a maximum of six months
|
||||
and may be updated, replaced, or obsoleted by other documents at any
|
||||
time. It is inappropriate to use Internet-Drafts as reference
|
||||
material or to cite them other than as "work in progress."
|
||||
|
||||
The list of current Internet-Drafts can be accessed at
|
||||
http://www.ietf.org/ietf/1id-abstracts.txt
|
||||
|
||||
The list of Internet-Draft Shadow Directories can be accessed at
|
||||
http://www.ietf.org/shadow.html.
|
||||
|
||||
Copyright Notice
|
||||
|
||||
Copyright (C) The Internet Society (2006). All Rights Reserved.
|
||||
|
||||
|
||||
|
||||
|
||||
Abstract
|
||||
|
||||
With a mandated default minimum maximum message size of 512 octets,
|
||||
the DNS protocol presents some special problems for zones wishing to
|
||||
expose a moderate or high number of authority servers (NS RRs). This
|
||||
document explains the operational issues caused by, or related to
|
||||
this response size limit, and suggests ways to optimize the use of
|
||||
this limited space. Guidance is offered to DNS server implementors
|
||||
and to DNS zone operators.
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 1]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
1 - Introduction and Overview
|
||||
|
||||
1.1. The DNS standard (see [RFC1035 4.2.1]) limits message size to 512
|
||||
octets. Even though this limitation was due to the required minimum IP
|
||||
reassembly limit for IPv4, it became a hard DNS protocol limit and is
|
||||
not implicitly relaxed by changes in transport, for example to IPv6.
|
||||
|
||||
1.2. The EDNS0 protocol extension (see [RFC2671 2.3, 4.5]) permits
|
||||
larger responses by mutual agreement of the requester and responder.
|
||||
The 512 octet message size limit will remain in practical effect until
|
||||
there is widespread deployment of EDNS0 in DNS resolvers on the
|
||||
Internet.
|
||||
|
||||
1.3. Since DNS responses include a copy of the request, the space
|
||||
available for response data is somewhat less than the full 512 octets.
|
||||
Negative responses are quite small, but for positive and delegation
|
||||
responses, every octet must be carefully and sparingly allocated. This
|
||||
document specifically addresses delegation response sizes.
|
||||
|
||||
2 - Delegation Details
|
||||
|
||||
2.1. RELEVANT PROTOCOL ELEMENTS
|
||||
|
||||
2.1.1. A delegation response will include the following elements:
|
||||
|
||||
Header Section: fixed length (12 octets)
|
||||
Question Section: original query (name, class, type)
|
||||
Answer Section: empty, or a CNAME/DNAME chain
|
||||
Authority Section: NS RRset (nameserver names)
|
||||
Additional Section: A and AAAA RRsets (nameserver addresses)
|
||||
|
||||
2.1.2. If the total response size exceeds 512 octets, and if the data
|
||||
that does not fit was "required", then the TC bit will be set
|
||||
(indicating truncation). This will usually cause the requester to retry
|
||||
using TCP, depending on what information was desired and what
|
||||
information was omitted. For example, truncation in the authority
|
||||
section is of no interest to a stub resolver who only plans to consume
|
||||
the answer section. If a retry using TCP is needed, the total cost of
|
||||
the transaction is much higher. See [RFC1123 6.1.3.2] for details on
|
||||
the requirement that UDP be attempted before falling back to TCP.
|
||||
|
||||
2.1.3. RRsets are never sent partially unless TC bit set to indicate
|
||||
truncation. When TC bit is set, the final apparent RRset in the final
|
||||
non-empty section must be considered "possibly damaged" (see [RFC1035
|
||||
6.2], [RFC2181 9]).
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 2]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
2.1.4. With or without truncation, the glue present in the additional
|
||||
data section should be considered "possibly incomplete", and requesters
|
||||
should be prepared to re-query for any damaged or missing RRsets. Note
|
||||
that truncation of the additional data section might not be signalled
|
||||
via the TC bit since additional data is often optional (see discussion
|
||||
in [RFC4472 B]).
|
||||
|
||||
2.1.5. DNS label compression allows a domain name to be instantiated
|
||||
only once per DNS message, and then referenced with a two-octet
|
||||
"pointer" from other locations in that same DNS message (see [RFC1035
|
||||
4.1.4]). If all nameserver names in a message share a common parent
|
||||
(for example, all ending in ".ROOT-SERVERS.NET"), then more space will
|
||||
be available for incompressable data (such as nameserver addresses).
|
||||
|
||||
2.1.6. The query name can be as long as 255 octets of network data. In
|
||||
this worst case scenario, the question section will be 259 octets in
|
||||
size, which would leave only 240 octets for the authority and additional
|
||||
sections (after deducting 12 octets for the fixed length header.)
|
||||
|
||||
2.2. ADVICE TO ZONE OWNERS
|
||||
|
||||
2.2.1. Average and maximum question section sizes can be predicted by
|
||||
the zone owner, since they will know what names actually exist, and can
|
||||
measure which ones are queried for most often. Note that if the zone
|
||||
contains any wildcards, it is possible for maximum length queries to
|
||||
require positive responses, but that it is reasonable to expect
|
||||
truncation and TCP retry in that case. For cost and performance
|
||||
reasons, the majority of requests should be satisfied without truncation
|
||||
or TCP retry.
|
||||
|
||||
2.2.2. Some queries to non-existing names can be large, but this is not
|
||||
a problem because negative responses need not contain any answer,
|
||||
authority or additional records. See [RFC2308 2.1] for more information
|
||||
about the format of negative responses.
|
||||
|
||||
2.2.3. The minimum useful number of name servers is two, for redundancy
|
||||
(see [RFC1034 4.1]). A zone's name servers should be reachable by all
|
||||
IP transport protocols (e.g., IPv4 and IPv6) in common use.
|
||||
|
||||
2.2.4. The best case is no truncation at all. This is because many
|
||||
requesters will retry using TCP immediately, or will automatically re-
|
||||
query for RRsets that are possibly truncated, without considering
|
||||
whether the omitted data was actually necessary.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 3]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
2.3. ADVICE TO SERVER IMPLEMENTORS
|
||||
|
||||
2.3.1. In case of multi-homed name servers, it is advantageous to
|
||||
include an address record from each of several name servers before
|
||||
including several address records for any one name server. If address
|
||||
records for more than one transport (for example, A and AAAA) are
|
||||
available, then it is advantageous to include records of both types
|
||||
early on, before the message is full.
|
||||
|
||||
2.3.2. Each added NS RR for a zone will add 12 fixed octets (name, type,
|
||||
class, ttl, and rdlen) plus 2 to 255 variable octets (for the NSDNAME).
|
||||
Each A RR will require 16 octets, and each AAAA RR will require 28
|
||||
octets.
|
||||
|
||||
2.3.3. While DNS distinguishes between necessary and optional resource
|
||||
records, this distinction is according to protocol elements necessary to
|
||||
signify facts, and takes no official notice of protocol content
|
||||
necessary to ensure correct operation. For example, a nameserver name
|
||||
that is in or below the zone cut being described by a delegation is
|
||||
"necessary content," since there is no way to reach that zone unless the
|
||||
parent zone's delegation includes "glue records" describing that name
|
||||
server's addresses.
|
||||
|
||||
2.3.4. It is also necessary to distinguish between "explicit truncation"
|
||||
where a message could not contain enough records to convey its intended
|
||||
meaning, and so the TC bit has been set, and "silent truncation", where
|
||||
the message was not large enough to contain some records which were "not
|
||||
required", and so the TC bit was not set.
|
||||
|
||||
2.3.5. A delegation response should prioritize glue records as follows.
|
||||
|
||||
first
|
||||
All glue RRsets for one name server whose name is in or below the
|
||||
zone being delegated, or which has multiple address RRsets (currently
|
||||
A and AAAA), or preferably both;
|
||||
|
||||
second
|
||||
Alternate between adding all glue RRsets for any name servers whose
|
||||
names are in or below the zone being delegated, and all glue RRsets
|
||||
for any name servers who have multiple address RRsets (currently A
|
||||
and AAAA);
|
||||
|
||||
thence
|
||||
All other glue RRsets, in any order.
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 4]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
Whenever there are multiple candidates for a position in this priority
|
||||
scheme, one should be chosen on a round-robin or fully random basis.
|
||||
|
||||
The goal of this priority scheme is to offer "necessary" glue first,
|
||||
avoiding silent truncation for this glue if possible.
|
||||
|
||||
2.3.6. If any "necessary content" is silently truncated, then it is
|
||||
advisable that the TC bit be set in order to force a TCP retry, rather
|
||||
than have the zone be unreachable. Note that a parent server's proper
|
||||
response to a query for in-child glue or below-child glue is a referral
|
||||
rather than an answer, and that this referral MUST be able to contain
|
||||
the in-child or below-child glue, and that in outlying cases, only EDNS
|
||||
or TCP will be large enough to contain that data.
|
||||
|
||||
3 - Analysis
|
||||
|
||||
3.1. An instrumented protocol trace of a best case delegation response
|
||||
follows. Note that 13 servers are named, and 13 addresses are given.
|
||||
This query was artificially designed to exactly reach the 512 octet
|
||||
limit.
|
||||
|
||||
;; flags: qr rd; QUERY: 1, ANS: 0, AUTH: 13, ADDIT: 13
|
||||
;; QUERY SECTION:
|
||||
;; [23456789.123456789.123456789.\
|
||||
123456789.123456789.123456789.com A IN] ;; @80
|
||||
|
||||
;; AUTHORITY SECTION:
|
||||
com. 86400 NS E.GTLD-SERVERS.NET. ;; @112
|
||||
com. 86400 NS F.GTLD-SERVERS.NET. ;; @128
|
||||
com. 86400 NS G.GTLD-SERVERS.NET. ;; @144
|
||||
com. 86400 NS H.GTLD-SERVERS.NET. ;; @160
|
||||
com. 86400 NS I.GTLD-SERVERS.NET. ;; @176
|
||||
com. 86400 NS J.GTLD-SERVERS.NET. ;; @192
|
||||
com. 86400 NS K.GTLD-SERVERS.NET. ;; @208
|
||||
com. 86400 NS L.GTLD-SERVERS.NET. ;; @224
|
||||
com. 86400 NS M.GTLD-SERVERS.NET. ;; @240
|
||||
com. 86400 NS A.GTLD-SERVERS.NET. ;; @256
|
||||
com. 86400 NS B.GTLD-SERVERS.NET. ;; @272
|
||||
com. 86400 NS C.GTLD-SERVERS.NET. ;; @288
|
||||
com. 86400 NS D.GTLD-SERVERS.NET. ;; @304
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 5]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
;; ADDITIONAL SECTION:
|
||||
A.GTLD-SERVERS.NET. 86400 A 192.5.6.30 ;; @320
|
||||
B.GTLD-SERVERS.NET. 86400 A 192.33.14.30 ;; @336
|
||||
C.GTLD-SERVERS.NET. 86400 A 192.26.92.30 ;; @352
|
||||
D.GTLD-SERVERS.NET. 86400 A 192.31.80.30 ;; @368
|
||||
E.GTLD-SERVERS.NET. 86400 A 192.12.94.30 ;; @384
|
||||
F.GTLD-SERVERS.NET. 86400 A 192.35.51.30 ;; @400
|
||||
G.GTLD-SERVERS.NET. 86400 A 192.42.93.30 ;; @416
|
||||
H.GTLD-SERVERS.NET. 86400 A 192.54.112.30 ;; @432
|
||||
I.GTLD-SERVERS.NET. 86400 A 192.43.172.30 ;; @448
|
||||
J.GTLD-SERVERS.NET. 86400 A 192.48.79.30 ;; @464
|
||||
K.GTLD-SERVERS.NET. 86400 A 192.52.178.30 ;; @480
|
||||
L.GTLD-SERVERS.NET. 86400 A 192.41.162.30 ;; @496
|
||||
M.GTLD-SERVERS.NET. 86400 A 192.55.83.30 ;; @512
|
||||
|
||||
;; MSG SIZE sent: 80 rcvd: 512
|
||||
|
||||
3.2. For longer query names, the number of address records supplied will
|
||||
be lower. Furthermore, it is only by using a common parent name (which
|
||||
is GTLD-SERVERS.NET in this example) that all 13 addresses are able to
|
||||
fit, due to the use of DNS compression pointers in the last 12
|
||||
occurances of the parent domain name. The following output from a
|
||||
response simulator demonstrates these properties.
|
||||
|
||||
% perl respsize.pl a.dns.br b.dns.br c.dns.br d.dns.br
|
||||
a.dns.br requires 10 bytes
|
||||
b.dns.br requires 4 bytes
|
||||
c.dns.br requires 4 bytes
|
||||
d.dns.br requires 4 bytes
|
||||
# of NS: 4
|
||||
For maximum size query (255 byte):
|
||||
only A is considered: # of A is 4 (green)
|
||||
A and AAAA are considered: # of A+AAAA is 3 (yellow)
|
||||
preferred-glue A is assumed: # of A is 4, # of AAAA is 3 (yellow)
|
||||
For average size query (64 byte):
|
||||
only A is considered: # of A is 4 (green)
|
||||
A and AAAA are considered: # of A+AAAA is 4 (green)
|
||||
preferred-glue A is assumed: # of A is 4, # of AAAA is 4 (green)
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 6]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
% perl respsize.pl ns-ext.isc.org ns.psg.com ns.ripe.net ns.eu.int
|
||||
ns-ext.isc.org requires 16 bytes
|
||||
ns.psg.com requires 12 bytes
|
||||
ns.ripe.net requires 13 bytes
|
||||
ns.eu.int requires 11 bytes
|
||||
# of NS: 4
|
||||
For maximum size query (255 byte):
|
||||
only A is considered: # of A is 4 (green)
|
||||
A and AAAA are considered: # of A+AAAA is 3 (yellow)
|
||||
preferred-glue A is assumed: # of A is 4, # of AAAA is 2 (yellow)
|
||||
For average size query (64 byte):
|
||||
only A is considered: # of A is 4 (green)
|
||||
A and AAAA are considered: # of A+AAAA is 4 (green)
|
||||
preferred-glue A is assumed: # of A is 4, # of AAAA is 4 (green)
|
||||
|
||||
(Note: The response simulator program is shown in Section 5.)
|
||||
|
||||
Here we use the term "green" if all address records could fit, or
|
||||
"yellow" if two or more could fit, or "orange" if only one could fit, or
|
||||
"red" if no address record could fit. It's clear that without a common
|
||||
parent for nameserver names, much space would be lost. For these
|
||||
examples we use an average/common name size of 15 octets, befitting our
|
||||
assumption of GTLD-SERVERS.NET as our common parent name.
|
||||
|
||||
We're assuming a medium query name size of 64 since that is the typical
|
||||
size seen in trace data at the time of this writing. If
|
||||
Internationalized Domain Name (IDN) or any other technology which
|
||||
results in larger query names be deployed significantly in advance of
|
||||
EDNS, then new measurements and new estimates will have to be made.
|
||||
|
||||
4 - Conclusions
|
||||
|
||||
4.1. The current practice of giving all nameserver names a common parent
|
||||
(such as GTLD-SERVERS.NET or ROOT-SERVERS.NET) saves space in DNS
|
||||
responses and allows for more nameservers to be enumerated than would
|
||||
otherwise be possible, since the common parent domain name only appears
|
||||
once in a DNS message and is referred to via "compression pointers"
|
||||
thereafter.
|
||||
|
||||
4.2. If all nameserver names for a zone share a common parent, then it
|
||||
is operationally advisable to make all servers for the zone thus served
|
||||
also be authoritative for the zone of that common parent. For example,
|
||||
the root name servers (?.ROOT-SERVERS.NET) can answer authoritatively
|
||||
for the ROOT-SERVERS.NET. This is to ensure that the zone's servers
|
||||
always have the zone's nameservers' glue available when delegating, and
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 7]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
will be able to respond with answers rather than referrals if a
|
||||
requester who wants that glue comes back asking for it. In this case
|
||||
the name server will likely be a "stealth server" -- authoritative but
|
||||
unadvertised in the glue zone's NS RRset. See [RFC1996 2] for more
|
||||
information about stealth servers.
|
||||
|
||||
4.3. Thirteen (13) is the effective maximum number of nameserver names
|
||||
usable traditional (non-extended) DNS, assuming a common parent domain
|
||||
name, and given that implicit referral response truncation is
|
||||
undesirable in the average case.
|
||||
|
||||
4.4. Multi-homing of name servers within a protocol family is
|
||||
inadvisable since the necessary glue RRsets (A or AAAA) are atomically
|
||||
indivisible, and will be larger than a single resource record. Larger
|
||||
RRsets are more likely to lead to or encounter truncation.
|
||||
|
||||
4.5. Multi-homing of name servers across protocol families is less
|
||||
likely to lead to or encounter truncation, partly because multiprotocol
|
||||
clients are more likely to speak EDNS which can use a larger response
|
||||
size limit, and partly because the resource records (A and AAAA) are in
|
||||
different RRsets and are therefore divisible from each other.
|
||||
|
||||
4.6. Name server names which are at or below the zone they serve are
|
||||
more sensitive to referral response truncation, and glue records for
|
||||
them should be considered "less optional" than other glue records, in
|
||||
the assembly of referral responses.
|
||||
|
||||
4.7. If a zone is served by thirteen (13) name servers having a common
|
||||
parent name (such as ?.ROOT-SERVERS.NET) and each such name server has a
|
||||
single address record in some protocol family (e.g., an A RR), then all
|
||||
thirteen name servers or any subset thereof could multi-home in a second
|
||||
protocol family by adding a second address record (e.g., an AAAA RR)
|
||||
without reducing the reachability of the zone thus served.
|
||||
|
||||
5 - Source Code
|
||||
|
||||
#!/usr/bin/perl
|
||||
#
|
||||
# SYNOPSIS
|
||||
# repsize.pl [ -z zone ] fqdn_ns1 fqdn_ns2 ...
|
||||
# if all queries are assumed to have a same zone suffix,
|
||||
# such as "jp" in JP TLD servers, specify it in -z option
|
||||
#
|
||||
use strict;
|
||||
use Getopt::Std;
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 8]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
my ($sz_msg) = (512);
|
||||
my ($sz_header, $sz_ptr, $sz_rr_a, $sz_rr_aaaa) = (12, 2, 16, 28);
|
||||
my ($sz_type, $sz_class, $sz_ttl, $sz_rdlen) = (2, 2, 4, 2);
|
||||
my (%namedb, $name, $nssect, %opts, $optz);
|
||||
my $n_ns = 0;
|
||||
|
||||
getopt('z', %opts);
|
||||
if (defined($opts{'z'})) {
|
||||
server_name_len($opts{'z'}); # just register it
|
||||
}
|
||||
|
||||
foreach $name (@ARGV) {
|
||||
my $len;
|
||||
$n_ns++;
|
||||
$len = server_name_len($name);
|
||||
print "$name requires $len bytes\n";
|
||||
$nssect += $sz_ptr + $sz_type + $sz_class + $sz_ttl
|
||||
+ $sz_rdlen + $len;
|
||||
}
|
||||
print "# of NS: $n_ns\n";
|
||||
arsect(255, $nssect, $n_ns, "maximum");
|
||||
arsect(64, $nssect, $n_ns, "average");
|
||||
|
||||
sub server_name_len {
|
||||
my ($name) = @_;
|
||||
my (@labels, $len, $n, $suffix);
|
||||
|
||||
$name =~ tr/A-Z/a-z/;
|
||||
@labels = split(/\./, $name);
|
||||
$len = length(join('.', @labels)) + 2;
|
||||
for ($n = 0; $#labels >= 0; $n++, shift @labels) {
|
||||
$suffix = join('.', @labels);
|
||||
return length($name) - length($suffix) + $sz_ptr
|
||||
if (defined($namedb{$suffix}));
|
||||
$namedb{$suffix} = 1;
|
||||
}
|
||||
return $len;
|
||||
}
|
||||
|
||||
sub arsect {
|
||||
my ($sz_query, $nssect, $n_ns, $cond) = @_;
|
||||
my ($space, $n_a, $n_a_aaaa, $n_p_aaaa, $ansect);
|
||||
$ansect = $sz_query + 1 + $sz_type + $sz_class;
|
||||
$space = $sz_msg - $sz_header - $ansect - $nssect;
|
||||
$n_a = atmost(int($space / $sz_rr_a), $n_ns);
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 9]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
$n_a_aaaa = atmost(int($space
|
||||
/ ($sz_rr_a + $sz_rr_aaaa)), $n_ns);
|
||||
$n_p_aaaa = atmost(int(($space - $sz_rr_a * $n_ns)
|
||||
/ $sz_rr_aaaa), $n_ns);
|
||||
printf "For %s size query (%d byte):\n", $cond, $sz_query;
|
||||
printf " only A is considered: ";
|
||||
printf "# of A is %d (%s)\n", $n_a, &judge($n_a, $n_ns);
|
||||
printf " A and AAAA are considered: ";
|
||||
printf "# of A+AAAA is %d (%s)\n",
|
||||
$n_a_aaaa, &judge($n_a_aaaa, $n_ns);
|
||||
printf " preferred-glue A is assumed: ";
|
||||
printf "# of A is %d, # of AAAA is %d (%s)\n",
|
||||
$n_a, $n_p_aaaa, &judge($n_p_aaaa, $n_ns);
|
||||
}
|
||||
|
||||
sub judge {
|
||||
my ($n, $n_ns) = @_;
|
||||
return "green" if ($n >= $n_ns);
|
||||
return "yellow" if ($n >= 2);
|
||||
return "orange" if ($n == 1);
|
||||
return "red";
|
||||
}
|
||||
|
||||
sub atmost {
|
||||
my ($a, $b) = @_;
|
||||
return 0 if ($a < 0);
|
||||
return $b if ($a > $b);
|
||||
return $a;
|
||||
}
|
||||
|
||||
6 - Security Considerations
|
||||
|
||||
The recommendations contained in this document have no known security
|
||||
implications.
|
||||
|
||||
7 - IANA Considerations
|
||||
|
||||
This document does not call for changes or additions to any IANA
|
||||
registry.
|
||||
|
||||
8 - Acknowledgement
|
||||
|
||||
The authors thank Peter Koch, Rob Austein, Joe Abley, and Mark Andrews
|
||||
for their valuable comments and suggestions.
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 10]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
This work was supported by the US National Science Foundation (research
|
||||
grant SCI-0427144) and DNS-OARC.
|
||||
|
||||
9 - References
|
||||
|
||||
[RFC1034] Mockapetris, P.V., "Domain names - Concepts and Facilities",
|
||||
RFC1034, November 1987.
|
||||
|
||||
[RFC1035] Mockapetris, P.V., "Domain names - Implementation and
|
||||
Specification", RFC1035, November 1987.
|
||||
|
||||
[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
|
||||
Application and Support", RFC1123, October 1989.
|
||||
|
||||
[RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone
|
||||
Changes (DNS NOTIFY)", RFC1996, August 1996.
|
||||
|
||||
[RFC2181] Elz, R., Bush, R., "Clarifications to the DNS Specification",
|
||||
RFC2181, July 1997.
|
||||
|
||||
[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS NCACHE)",
|
||||
RFC2308, March 1998.
|
||||
|
||||
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC2671,
|
||||
August 1999.
|
||||
|
||||
[RFC4472] Durand, A., Ihren, J., Savola, P., "Operational Consideration
|
||||
and Issues with IPV6 DNS", April 2006.
|
||||
|
||||
10 - Authors' Addresses
|
||||
|
||||
Paul Vixie
|
||||
Internet Systems Consortium, Inc.
|
||||
950 Charter Street
|
||||
Redwood City, CA 94063
|
||||
+1 650 423 1301
|
||||
vixie@isc.org
|
||||
|
||||
Akira Kato
|
||||
University of Tokyo, Information Technology Center
|
||||
2-11-16 Yayoi Bunkyo
|
||||
Tokyo 113-8658, JAPAN
|
||||
+81 3 5841 2750
|
||||
kato@wide.ad.jp
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 11]
|
||||
|
||||
INTERNET-DRAFT August 2006 RESPSIZE
|
||||
|
||||
|
||||
Full Copyright Statement
|
||||
|
||||
Copyright (C) The Internet Society (2006).
|
||||
|
||||
This document is subject to the rights, licenses and restrictions
|
||||
contained in BCP 78, and except as set forth therein, the authors retain
|
||||
all their rights.
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR
|
||||
IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||||
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
||||
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
Intellectual Property
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in this
|
||||
document or the extent to which any license under such rights might or
|
||||
might not be available; nor does it represent that it has made any
|
||||
independent effort to identify any such rights. Information on the
|
||||
procedures with respect to rights in RFC documents can be found in BCP
|
||||
78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an attempt
|
||||
made to obtain a general license or permission for the use of such
|
||||
proprietary rights by implementers or users of this specification can be
|
||||
obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary rights
|
||||
that may cover technology that may be required to implement this
|
||||
standard. Please address the information to the IETF at
|
||||
ietf-ipr@ietf.org.
|
||||
|
||||
Acknowledgement
|
||||
|
||||
Funding for the RFC Editor function is provided by the IETF
|
||||
Administrative Support Activity (IASA).
|
||||
|
||||
|
||||
|
||||
|
||||
Expires January 2007 [Page 12]
|
||||
|
||||
|
||||
1011
doc/rfc/rfc4648.txt
1011
doc/rfc/rfc4648.txt
File diff suppressed because it is too large
Load Diff
@@ -1,675 +0,0 @@
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Network Working Group M. Stapp
|
||||
Request for Comments: 4701 Cisco Systems, Inc.
|
||||
Category: Standards Track T. Lemon
|
||||
Nominum, Inc.
|
||||
A. Gustafsson
|
||||
Araneus Information Systems Oy
|
||||
October 2006
|
||||
|
||||
|
||||
A DNS Resource Record (RR) for Encoding
|
||||
Dynamic Host Configuration Protocol (DHCP) Information (DHCID RR)
|
||||
|
||||
Status of This Memo
|
||||
|
||||
This document specifies an Internet standards track protocol for the
|
||||
Internet community, and requests discussion and suggestions for
|
||||
improvements. Please refer to the current edition of the "Internet
|
||||
Official Protocol Standards" (STD 1) for the standardization state
|
||||
and status of this protocol. Distribution of this memo is unlimited.
|
||||
|
||||
Copyright Notice
|
||||
|
||||
Copyright (C) The Internet Society (2006).
|
||||
|
||||
Abstract
|
||||
|
||||
It is possible for Dynamic Host Configuration Protocol (DHCP) clients
|
||||
to attempt to update the same DNS Fully Qualified Domain Name (FQDN)
|
||||
or to update a DNS FQDN that has been added to the DNS for another
|
||||
purpose as they obtain DHCP leases. Whether the DHCP server or the
|
||||
clients themselves perform the DNS updates, conflicts can arise. To
|
||||
resolve such conflicts, RFC 4703 proposes storing client identifiers
|
||||
in the DNS to unambiguously associate domain names with the DHCP
|
||||
clients to which they refer. This memo defines a distinct Resource
|
||||
Record (RR) type for this purpose for use by DHCP clients and
|
||||
servers: the "DHCID" RR.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 1]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
Table of Contents
|
||||
|
||||
1. Introduction ....................................................3
|
||||
2. Terminology .....................................................3
|
||||
3. The DHCID RR ....................................................3
|
||||
3.1. DHCID RDATA Format .........................................3
|
||||
3.2. DHCID Presentation Format ..................................4
|
||||
3.3. The DHCID RR Identifier Type Codes .........................4
|
||||
3.4. The DHCID RR Digest Type Code ..............................4
|
||||
3.5. Computation of the RDATA ...................................5
|
||||
3.5.1. Using the Client's DUID .............................5
|
||||
3.5.2. Using the Client Identifier Option ..................6
|
||||
3.5.3. Using the Client's htype and chaddr .................6
|
||||
3.6. Examples ...................................................6
|
||||
3.6.1. Example 1 ...........................................6
|
||||
3.6.2. Example 2 ...........................................7
|
||||
3.6.3. Example 3 ...........................................7
|
||||
4. Use of the DHCID RR .............................................8
|
||||
5. Updater Behavior ................................................8
|
||||
6. Security Considerations .........................................8
|
||||
7. IANA Considerations .............................................9
|
||||
8. Acknowledgements ................................................9
|
||||
9. References ......................................................9
|
||||
9.1. Normative References .......................................9
|
||||
9.2. Informative References ....................................10
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 2]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
1. Introduction
|
||||
|
||||
A set of procedures to allow DHCP [7] [11] clients and servers to
|
||||
automatically update the DNS ([3], [4]) is proposed in [1].
|
||||
|
||||
Conflicts can arise if multiple DHCP clients wish to use the same DNS
|
||||
name or a DHCP client attempts to use a name added for another
|
||||
purpose. To resolve such conflicts, [1] proposes storing client
|
||||
identifiers in the DNS to unambiguously associate domain names with
|
||||
the DHCP clients using them. In the interest of clarity, it is
|
||||
preferable for this DHCP information to use a distinct RR type. This
|
||||
memo defines a distinct RR for this purpose for use by DHCP clients
|
||||
or servers: the "DHCID" RR.
|
||||
|
||||
In order to obscure potentially sensitive client identifying
|
||||
information, the data stored is the result of a one-way SHA-256 hash
|
||||
computation. The hash includes information from the DHCP client's
|
||||
message as well as the domain name itself, so that the data stored in
|
||||
the DHCID RR will be dependent on both the client identification used
|
||||
in the DHCP protocol interaction and the domain name. This means
|
||||
that the DHCID RDATA will vary if a single client is associated over
|
||||
time with more than one name. This makes it difficult to 'track' a
|
||||
client as it is associated with various domain names.
|
||||
|
||||
2. Terminology
|
||||
|
||||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
||||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
||||
document are to be interpreted as described in [2].
|
||||
|
||||
3. The DHCID RR
|
||||
|
||||
The DHCID RR is defined with mnemonic DHCID and type code 49. The
|
||||
DHCID RR is only defined in the IN class. DHCID RRs cause no
|
||||
additional section processing.
|
||||
|
||||
3.1. DHCID RDATA Format
|
||||
|
||||
The RDATA section of a DHCID RR in transmission contains RDLENGTH
|
||||
octets of binary data. The format of this data and its
|
||||
interpretation by DHCP servers and clients are described below.
|
||||
|
||||
DNS software should consider the RDATA section to be opaque. DHCP
|
||||
clients or servers use the DHCID RR to associate a DHCP client's
|
||||
identity with a DNS name, so that multiple DHCP clients and servers
|
||||
may deterministically perform dynamic DNS updates to the same zone.
|
||||
From the updater's perspective, the DHCID resource record RDATA
|
||||
consists of a 2-octet identifier type, in network byte order,
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 3]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
followed by a 1-octet digest type, followed by one or more octets
|
||||
representing the actual identifier:
|
||||
|
||||
< 2 octets > Identifier type code
|
||||
< 1 octet > Digest type code
|
||||
< n octets > Digest (length depends on digest type)
|
||||
|
||||
3.2. DHCID Presentation Format
|
||||
|
||||
In DNS master files, the RDATA is represented as a single block in
|
||||
base-64 encoding identical to that used for representing binary data
|
||||
in [8], Section 3. The data may be divided up into any number of
|
||||
white-space-separated substrings, down to single base-64 digits,
|
||||
which are concatenated to form the complete RDATA. These substrings
|
||||
can span lines using the standard parentheses.
|
||||
|
||||
3.3. The DHCID RR Identifier Type Codes
|
||||
|
||||
The DHCID RR Identifier Type Code specifies what data from the DHCP
|
||||
client's request was used as input into the hash function. The
|
||||
identifier type codes are defined in a registry maintained by IANA,
|
||||
as specified in Section 7. The initial list of assigned values for
|
||||
the identifier type code and that type's identifier is:
|
||||
|
||||
|
||||
+------------------+------------------------------------------------+
|
||||
| Identifier Type | Identifier |
|
||||
| Code | |
|
||||
+------------------+------------------------------------------------+
|
||||
| 0x0000 | The 1-octet 'htype' followed by 'hlen' octets |
|
||||
| | of 'chaddr' from a DHCPv4 client's DHCPREQUEST |
|
||||
| | [7]. |
|
||||
| 0x0001 | The data octets (i.e., the Type and |
|
||||
| | Client-Identifier fields) from a DHCPv4 |
|
||||
| | client's Client Identifier option [10]. |
|
||||
| 0x0002 | The client's DUID (i.e., the data octets of a |
|
||||
| | DHCPv6 client's Client Identifier option [11] |
|
||||
| | or the DUID field from a DHCPv4 client's |
|
||||
| | Client Identifier option [6]). |
|
||||
| 0x0003 - 0xfffe | Undefined; available to be assigned by IANA. |
|
||||
| 0xffff | Undefined; RESERVED. |
|
||||
+------------------+------------------------------------------------+
|
||||
|
||||
3.4. The DHCID RR Digest Type Code
|
||||
|
||||
The DHCID RR Digest Type Code is an identifier for the digest
|
||||
algorithm used. The digest is calculated over an identifier and the
|
||||
canonical FQDN as described in the next section.
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 4]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
The digest type codes are defined in a registry maintained by IANA,
|
||||
as specified in Section 7. The initial list of assigned values for
|
||||
the digest type codes is: value 0 is reserved, and value 1 is
|
||||
SHA-256. Reserving other types requires IETF standards action.
|
||||
Defining new values will also require IETF standards action to
|
||||
document how DNS updaters are to deal with multiple digest types.
|
||||
|
||||
3.5. Computation of the RDATA
|
||||
|
||||
The DHCID RDATA is formed by concatenating the 2-octet identifier
|
||||
type code with variable-length data.
|
||||
|
||||
The RDATA for all type codes other than 0xffff, which is reserved for
|
||||
future expansion, is formed by concatenating the 2-octet identifier
|
||||
type code, the 1-octet digest type code, and the digest value (32
|
||||
octets for SHA-256).
|
||||
|
||||
< identifier-type > < digest-type > < digest >
|
||||
|
||||
The input to the digest hash function is defined to be:
|
||||
|
||||
digest = SHA-256(< identifier > < FQDN >)
|
||||
|
||||
The FQDN is represented in the buffer in the canonical wire format as
|
||||
described in [9], Section 6.2. The identifier type code and the
|
||||
identifier are related as specified in Section 3.3: the identifier
|
||||
type code describes the source of the identifier.
|
||||
|
||||
A DHCPv4 updater uses the 0x0002 type code if a Client Identifier
|
||||
option is present in the DHCPv4 messages and it is encoded as
|
||||
specified in [6]. Otherwise, the updater uses 0x0001 if a Client
|
||||
Identifier option is present, and 0x0000 if not.
|
||||
|
||||
A DHCPv6 updater always uses the 0x0002 type code.
|
||||
|
||||
3.5.1. Using the Client's DUID
|
||||
|
||||
When the updater is using the Client's DUID (either from a DHCPv6
|
||||
Client Identifier option or from a portion of the DHCPv4 Client
|
||||
Identifier option encoded as specified in [6]), the first two octets
|
||||
of the DHCID RR MUST be 0x0002, in network byte order. The third
|
||||
octet is the digest type code (1 for SHA-256). The rest of the DHCID
|
||||
RR MUST contain the results of computing the SHA-256 hash across the
|
||||
octets of the DUID followed by the FQDN.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 5]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
3.5.2. Using the Client Identifier Option
|
||||
|
||||
When the updater is using the DHCPv4 Client Identifier option sent by
|
||||
the client in its DHCPREQUEST message, the first two octets of the
|
||||
DHCID RR MUST be 0x0001, in network byte order. The third octet is
|
||||
the digest type code (1 for SHA-256). The rest of the DHCID RR MUST
|
||||
contain the results of computing the SHA-256 hash across the data
|
||||
octets (i.e., the Type and Client-Identifier fields) of the option,
|
||||
followed by the FQDN.
|
||||
|
||||
3.5.3. Using the Client's htype and chaddr
|
||||
|
||||
When the updater is using the client's link-layer address as the
|
||||
identifier, the first two octets of the DHCID RDATA MUST be zero.
|
||||
The third octet is the digest type code (1 for SHA-256). To generate
|
||||
the rest of the resource record, the updater computes a one-way hash
|
||||
using the SHA-256 algorithm across a buffer containing the client's
|
||||
network hardware type, link-layer address, and the FQDN data.
|
||||
Specifically, the first octet of the buffer contains the network
|
||||
hardware type as it appeared in the DHCP 'htype' field of the
|
||||
client's DHCPREQUEST message. All of the significant octets of the
|
||||
'chaddr' field in the client's DHCPREQUEST message follow, in the
|
||||
same order in which the octets appear in the DHCPREQUEST message.
|
||||
The number of significant octets in the 'chaddr' field is specified
|
||||
in the 'hlen' field of the DHCPREQUEST message. The FQDN data, as
|
||||
specified above, follows.
|
||||
|
||||
3.6. Examples
|
||||
|
||||
3.6.1. Example 1
|
||||
|
||||
A DHCP server allocates the IPv6 address 2001:DB8::1234:5678 to a
|
||||
client that included the DHCPv6 client-identifier option data 00:01:
|
||||
00:06:41:2d:f1:66:01:02:03:04:05:06 in its DHCPv6 request. The
|
||||
server updates the name "chi6.example.com" on the client's behalf and
|
||||
uses the DHCP client identifier option data as input in forming a
|
||||
DHCID RR. The DHCID RDATA is formed by setting the two type octets
|
||||
to the value 0x0002, the 1-octet digest type to 1 for SHA-256, and
|
||||
performing a SHA-256 hash computation across a buffer containing the
|
||||
14 octets from the client-id option and the FQDN (represented as
|
||||
specified in Section 3.5).
|
||||
|
||||
chi6.example.com. AAAA 2001:DB8::1234:5678
|
||||
chi6.example.com. DHCID ( AAIBY2/AuCccgoJbsaxcQc9TUapptP69l
|
||||
OjxfNuVAA2kjEA= )
|
||||
|
||||
If the DHCID RR type is not supported, the RDATA would be encoded
|
||||
[13] as:
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 6]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
\# 35 ( 000201636fc0b8271c82825bb1ac5c41cf5351aa69b4febd94e8f17cd
|
||||
b95000da48c40 )
|
||||
|
||||
3.6.2. Example 2
|
||||
|
||||
A DHCP server allocates the IPv4 address 192.0.2.2 to a client that
|
||||
included the DHCP client-identifier option data 01:07:08:09:0a:0b:0c
|
||||
in its DHCP request. The server updates the name "chi.example.com"
|
||||
on the client's behalf and uses the DHCP client identifier option
|
||||
data as input in forming a DHCID RR. The DHCID RDATA is formed by
|
||||
setting the two type octets to the value 0x0001, the 1-octet digest
|
||||
type to 1 for SHA-256, and performing a SHA-256 hash computation
|
||||
across a buffer containing the seven octets from the client-id option
|
||||
and the FQDN (represented as specified in Section 3.5).
|
||||
|
||||
chi.example.com. A 192.0.2.2
|
||||
chi.example.com. DHCID ( AAEBOSD+XR3Os/0LozeXVqcNc7FwCfQdW
|
||||
L3b/NaiUDlW2No= )
|
||||
|
||||
If the DHCID RR type is not supported, the RDATA would be encoded
|
||||
[13] as:
|
||||
|
||||
\# 35 ( 0001013920fe5d1dceb3fd0ba3379756a70d73b17009f41d58bddbfcd
|
||||
6a2503956d8da )
|
||||
|
||||
3.6.3. Example 3
|
||||
|
||||
A DHCP server allocating the IPv4 address 192.0.2.3 to a client with
|
||||
the Ethernet MAC address 01:02:03:04:05:06 using domain name
|
||||
"client.example.com" uses the client's link-layer address to identify
|
||||
the client. The DHCID RDATA is composed by setting the two type
|
||||
octets to zero, the 1-octet digest type to 1 for SHA-256, and
|
||||
performing an SHA-256 hash computation across a buffer containing the
|
||||
1-octet 'htype' value for Ethernet, 0x01, followed by the six octets
|
||||
of the Ethernet MAC address, and the domain name (represented as
|
||||
specified in Section 3.5).
|
||||
|
||||
client.example.com. A 192.0.2.3
|
||||
client.example.com. DHCID ( AAABxLmlskllE0MVjd57zHcWmEH3pCQ6V
|
||||
ytcKD//7es/deY= )
|
||||
|
||||
If the DHCID RR type is not supported, the RDATA would be encoded
|
||||
[13] as:
|
||||
|
||||
\# 35 ( 000001c4b9a5b249651343158dde7bcc77169841f7a4243a572b5c283
|
||||
fffedeb3f75e6 )
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 7]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
4. Use of the DHCID RR
|
||||
|
||||
This RR MUST NOT be used for any purpose other than that detailed in
|
||||
[1]. Although this RR contains data that is opaque to DNS servers,
|
||||
the data must be consistent across all entities that update and
|
||||
interpret this record. Therefore, new data formats may only be
|
||||
defined through actions of the DHC Working Group, as a result of
|
||||
revising [1].
|
||||
|
||||
5. Updater Behavior
|
||||
|
||||
The data in the DHCID RR allows updaters to determine whether more
|
||||
than one DHCP client desires to use a particular FQDN. This allows
|
||||
site administrators to establish policy about DNS updates. The DHCID
|
||||
RR does not establish any policy itself.
|
||||
|
||||
Updaters use data from a DHCP client's request and the domain name
|
||||
that the client desires to use to compute a client identity hash, and
|
||||
then compare that hash to the data in any DHCID RRs on the name that
|
||||
they wish to associate with the client's IP address. If an updater
|
||||
discovers DHCID RRs whose RDATA does not match the client identity
|
||||
that they have computed, the updater SHOULD conclude that a different
|
||||
client is currently associated with the name in question. The
|
||||
updater SHOULD then proceed according to the site's administrative
|
||||
policy. That policy might dictate that a different name be selected,
|
||||
or it might permit the updater to continue.
|
||||
|
||||
6. Security Considerations
|
||||
|
||||
The DHCID record as such does not introduce any new security problems
|
||||
into the DNS. In order to obscure the client's identity information,
|
||||
a one-way hash is used. Further, in order to make it difficult to
|
||||
'track' a client by examining the names associated with a particular
|
||||
hash value, the FQDN is included in the hash computation. Thus, the
|
||||
RDATA is dependent on both the DHCP client identification data and on
|
||||
each FQDN associated with the client.
|
||||
|
||||
However, it should be noted that an attacker that has some knowledge,
|
||||
such as of MAC addresses commonly used in DHCP client identification
|
||||
data, may be able to discover the client's DHCP identify by using a
|
||||
brute-force attack. Even without any additional knowledge, the
|
||||
number of unknown bits used in computing the hash is typically only
|
||||
48 to 80.
|
||||
|
||||
Administrators should be wary of permitting unsecured DNS updates to
|
||||
zones, whether or not they are exposed to the global Internet. Both
|
||||
DHCP clients and servers SHOULD use some form of update
|
||||
authentication (e.g., [12]) when performing DNS updates.
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 8]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
7. IANA Considerations
|
||||
|
||||
IANA has allocated a DNS RR type number for the DHCID record type.
|
||||
|
||||
This specification defines a new number-space for the 2-octet
|
||||
identifier type codes associated with the DHCID RR. IANA has
|
||||
established a registry of the values for this number-space. Three
|
||||
initial values are assigned in Section 3.3, and the value 0xFFFF is
|
||||
reserved for future use. New DHCID RR identifier type codes are
|
||||
assigned through Standards Action, as defined in [5].
|
||||
|
||||
This specification defines a new number-space for the 1-octet digest
|
||||
type codes associated with the DHCID RR. IANA has established a
|
||||
registry of the values for this number-space. Two initial values are
|
||||
assigned in Section 3.4. New DHCID RR digest type codes are assigned
|
||||
through Standards Action, as defined in [5].
|
||||
|
||||
8. Acknowledgements
|
||||
|
||||
Many thanks to Harald Alvestrand, Ralph Droms, Olafur Gudmundsson,
|
||||
Sam Hartman, Josh Littlefield, Pekka Savola, and especially Bernie
|
||||
Volz for their review and suggestions.
|
||||
|
||||
9. References
|
||||
|
||||
9.1. Normative References
|
||||
|
||||
[1] Stapp, M. and B. Volz, "Resolution of Fully Qualified Domain
|
||||
Name (FQDN) Conflicts among Dynamic Host Configuration Protocol
|
||||
(DHCP) Clients", RFC 4703, October 2006.
|
||||
|
||||
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
|
||||
Levels", BCP 14, RFC 2119, March 1997.
|
||||
|
||||
[3] Mockapetris, P., "Domain names - concepts and facilities",
|
||||
STD 13, RFC 1034, November 1987.
|
||||
|
||||
[4] Mockapetris, P., "Domain names - implementation and
|
||||
specification", STD 13, RFC 1035, November 1987.
|
||||
|
||||
[5] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
|
||||
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
|
||||
|
||||
[6] Lemon, T. and B. Sommerfeld, "Node-specific Client Identifiers
|
||||
for Dynamic Host Configuration Protocol Version Four (DHCPv4)",
|
||||
RFC 4361, February 2006.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 9]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
9.2. Informative References
|
||||
|
||||
[7] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
|
||||
March 1997.
|
||||
|
||||
[8] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
|
||||
RFC 3548, July 2003.
|
||||
|
||||
[9] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
|
||||
"Resource Records for the DNS Security Extensions", RFC 4034,
|
||||
March 2005.
|
||||
|
||||
[10] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
|
||||
Extensions", RFC 2132, March 1997.
|
||||
|
||||
[11] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
|
||||
Carney, "Dynamic Host Configuration Protocol for IPv6
|
||||
(DHCPv6)", RFC 3315, July 2003.
|
||||
|
||||
[12] Vixie, P., Gudmundsson, O., Eastlake, D., and B. Wellington,
|
||||
"Secret Key Transaction Authentication for DNS (TSIG)",
|
||||
RFC 2845, May 2000.
|
||||
|
||||
[13] Gustafsson, A., "Handling of Unknown DNS Resource Record (RR)
|
||||
Types", RFC 3597, September 2003.
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 10]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
Authors' Addresses
|
||||
|
||||
Mark Stapp
|
||||
Cisco Systems, Inc.
|
||||
1414 Massachusetts Ave.
|
||||
Boxborough, MA 01719
|
||||
USA
|
||||
|
||||
Phone: 978.936.1535
|
||||
EMail: mjs@cisco.com
|
||||
|
||||
|
||||
Ted Lemon
|
||||
Nominum, Inc.
|
||||
950 Charter St.
|
||||
Redwood City, CA 94063
|
||||
USA
|
||||
|
||||
EMail: mellon@nominum.com
|
||||
|
||||
|
||||
Andreas Gustafsson
|
||||
Araneus Information Systems Oy
|
||||
Ulappakatu 1
|
||||
02320 Espoo
|
||||
Finland
|
||||
|
||||
EMail: gson@araneus.fi
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 11]
|
||||
|
||||
RFC 4701 The DHCID RR October 2006
|
||||
|
||||
|
||||
Full Copyright Statement
|
||||
|
||||
Copyright (C) The Internet Society (2006).
|
||||
|
||||
This document is subject to the rights, licenses and restrictions
|
||||
contained in BCP 78, and except as set forth therein, the authors
|
||||
retain all their rights.
|
||||
|
||||
This document and the information contained herein are provided on an
|
||||
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
||||
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
||||
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
||||
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
||||
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
||||
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
||||
|
||||
Intellectual Property
|
||||
|
||||
The IETF takes no position regarding the validity or scope of any
|
||||
Intellectual Property Rights or other rights that might be claimed to
|
||||
pertain to the implementation or use of the technology described in
|
||||
this document or the extent to which any license under such rights
|
||||
might or might not be available; nor does it represent that it has
|
||||
made any independent effort to identify any such rights. Information
|
||||
on the procedures with respect to rights in RFC documents can be
|
||||
found in BCP 78 and BCP 79.
|
||||
|
||||
Copies of IPR disclosures made to the IETF Secretariat and any
|
||||
assurances of licenses to be made available, or the result of an
|
||||
attempt made to obtain a general license or permission for the use of
|
||||
such proprietary rights by implementers or users of this
|
||||
specification can be obtained from the IETF on-line IPR repository at
|
||||
http://www.ietf.org/ipr.
|
||||
|
||||
The IETF invites any interested party to bring to its attention any
|
||||
copyrights, patents or patent applications, or other proprietary
|
||||
rights that may cover technology that may be required to implement
|
||||
this standard. Please address the information to the IETF at
|
||||
ietf-ipr@ietf.org.
|
||||
|
||||
Acknowledgement
|
||||
|
||||
Funding for the RFC Editor function is provided by the IETF
|
||||
Administrative Support Activity (IASA).
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
Stapp, et al. Standards Track [Page 12]
|
||||
|
||||
2915
doc/rfc/rfc5155.txt
2915
doc/rfc/rfc5155.txt
File diff suppressed because it is too large
Load Diff
Reference in New Issue
Block a user