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bind9/bin/named/named.rst
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..
Copyright (C) Internet Systems Consortium, Inc. ("ISC")
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
See the COPYRIGHT file distributed with this work for additional
information regarding copyright ownership.
..
Copyright (C) Internet Systems Consortium, Inc. ("ISC")
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
See the COPYRIGHT file distributed with this work for additional
information regarding copyright ownership.
.. highlight: console
.. _man_named:
named - Internet domain name server
-----------------------------------
Synopsis
~~~~~~~~
:program:`named` [ [**-4**] | [**-6**] ] [**-c** config-file] [**-d** debug-level] [**-D** string] [**-E** engine-name] [**-f**] [**-g**] [**-L** logfile] [**-M** option] [**-m** flag] [**-n** #cpus] [**-p** port] [**-s**] [**-S** #max-socks] [**-t** directory] [**-U** #listeners] [**-u** user] [**-v**] [**-V**] [**-X** lock-file] [**-x** cache-file]
Description
~~~~~~~~~~~
``named`` is a Domain Name System (DNS) server, part of the BIND 9
distribution from ISC. For more information on the DNS, see :rfc:`1033`,
:rfc:`1034`, and :rfc:`1035`.
When invoked without arguments, ``named`` will read the default
configuration file ``/etc/named.conf``, read any initial data, and
listen for queries.
Options
~~~~~~~
**-4**
Use IPv4 only even if the host machine is capable of IPv6. ``-4`` and
``-6`` are mutually exclusive.
**-6**
Use IPv6 only even if the host machine is capable of IPv4. ``-4`` and
``-6`` are mutually exclusive.
**-c** config-file
Use config-file as the configuration file instead of the default,
``/etc/named.conf``. To ensure that reloading the configuration file
continues to work after the server has changed its working directory
due to to a possible ``directory`` option in the configuration file,
config-file should be an absolute pathname.
**-d** debug-level
Set the daemon's debug level to debug-level. Debugging traces from
``named`` become more verbose as the debug level increases.
**-D** string
Specifies a string that is used to identify a instance of ``named``
in a process listing. The contents of string are not examined.
**-E** engine-name
When applicable, specifies the hardware to use for cryptographic
operations, such as a secure key store used for signing.
When BIND is built with OpenSSL PKCS#11 support, this defaults to the
string "pkcs11", which identifies an OpenSSL engine that can drive a
cryptographic accelerator or hardware service module. When BIND is
built with native PKCS#11 cryptography (--enable-native-pkcs11), it
defaults to the path of the PKCS#11 provider library specified via
"--with-pkcs11".
**-f**
Run the server in the foreground (i.e. do not daemonize).
**-g**
Run the server in the foreground and force all logging to ``stderr``.
**-L** logfile
Log to the file ``logfile`` by default instead of the system log.
**-M** option
Sets the default memory context options. If set to external, this
causes the internal memory manager to be bypassed in favor of
system-provided memory allocation functions. If set to fill, blocks
of memory will be filled with tag values when allocated or freed, to
assist debugging of memory problems. (nofill disables this behavior,
and is the default unless ``named`` has been compiled with developer
options.)
**-m** flag
Turn on memory usage debugging flags. Possible flags are usage,
trace, record, size, and mctx. These correspond to the
ISC_MEM_DEBUGXXXX flags described in ``<isc/mem.h>``.
**-n** #cpus
Create #cpus worker threads to take advantage of multiple CPUs. If
not specified, ``named`` will try to determine the number of CPUs
present and create one thread per CPU. If it is unable to determine
the number of CPUs, a single worker thread will be created.
**-p** port
Listen for queries on port port. If not specified, the default is
port 53.
**-s**
Write memory usage statistics to ``stdout`` on exit.
.. note::
This option is mainly of interest to BIND 9 developers and may be
removed or changed in a future release.
**-S** #max-socks
Allow ``named`` to use up to #max-socks sockets. The default value is
21000 on systems built with default configuration options, and 4096
on systems built with "configure --with-tuning=small".
.. warning::
This option should be unnecessary for the vast majority of users.
The use of this option could even be harmful because the specified
value may exceed the limitation of the underlying system API. It
is therefore set only when the default configuration causes
exhaustion of file descriptors and the operational environment is
known to support the specified number of sockets. Note also that
the actual maximum number is normally a little fewer than the
specified value because ``named`` reserves some file descriptors
for its internal use.
**-t** directory
Chroot to directory after processing the command line arguments, but
before reading the configuration file.
.. warning::
This option should be used in conjunction with the ``-u`` option,
as chrooting a process running as root doesn't enhance security on
most systems; the way ``chroot(2)`` is defined allows a process
with root privileges to escape a chroot jail.
**-U** #listeners
Use #listeners worker threads to listen for incoming UDP packets on
each address. If not specified, ``named`` will calculate a default
value based on the number of detected CPUs: 1 for 1 CPU, and the
number of detected CPUs minus one for machines with more than 1 CPU.
This cannot be increased to a value higher than the number of CPUs.
If ``-n`` has been set to a higher value than the number of detected
CPUs, then ``-U`` may be increased as high as that value, but no
higher. On Windows, the number of UDP listeners is hardwired to 1 and
this option has no effect.
**-u** user
Setuid to user after completing privileged operations, such as
creating sockets that listen on privileged ports.
.. note::
On Linux, ``named`` uses the kernel's capability mechanism to drop
all root privileges except the ability to ``bind(2)`` to a
privileged port and set process resource limits. Unfortunately,
this means that the ``-u`` option only works when ``named`` is run
on kernel 2.2.18 or later, or kernel 2.3.99-pre3 or later, since
previous kernels did not allow privileges to be retained after
``setuid(2)``.
**-v**
Report the version number and exit.
**-V**
Report the version number and build options, and exit.
**-X** lock-file
Acquire a lock on the specified file at runtime; this helps to
prevent duplicate ``named`` instances from running simultaneously.
Use of this option overrides the ``lock-file`` option in
``named.conf``. If set to ``none``, the lock file check is disabled.
**-x** cache-file
Load data from cache-file into the cache of the default view.
.. warning::
This option must not be used. It is only of interest to BIND 9
developers and may be removed or changed in a future release.
Signals
~~~~~~~
In routine operation, signals should not be used to control the
nameserver; ``rndc`` should be used instead.
SIGHUP
Force a reload of the server.
SIGINT, SIGTERM
Shut down the server.
The result of sending any other signals to the server is undefined.
Configuration
~~~~~~~~~~~~~
The ``named`` configuration file is too complex to describe in detail
here. A complete description is provided in the BIND 9 Administrator
Reference Manual.
``named`` inherits the ``umask`` (file creation mode mask) from the
parent process. If files created by ``named``, such as journal files,
need to have custom permissions, the ``umask`` should be set explicitly
in the script used to start the ``named`` process.
Files
~~~~~
``/etc/named.conf``
The default configuration file.
``/var/run/named/named.pid``
The default process-id file.
See Also
~~~~~~~~
:rfc:`1033`, :rfc:`1034`, :rfc:`1035`, :manpage:`named-checkconf(8)`, :manpage:`named-checkzone(8)`, :manpage:`rndc(8), :manpage:`named.conf(5)`, BIND 9 Administrator Reference Manual.