4.1. named --- DNS nameserver daemon

4.1.1. Synopsis

named [[-4] | [-6]] [-c <config-file>] [-d <debug-level>] [-D <id-string>] [-E <engine-name>] [-f] [-g] [-n <thread-count>] [-p <port>] [-s] [-S <maximum-sockets>] [-t <directory>] [-U <listener-count>] [-u <user>] [-v] [-x <cache-file>]

4.1.2. Description

named is a Domain Name System (DNS) nameserver.

When invoked without arguments, named will read its default configuration file /etc/loop/named.conf, read any initial data, and listen for queries. A complete description of the named configuration file is provided as a chapter in the Loop User 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.

4.1.3. 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 named configuration file. The default is /etc/loop/named.conf.

Note

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. Log messages from named become more verbose as the debug level increases. The default is 0.

-D <id-string>

Specifies a string that may be used to identify a named process in a process listing. The contents of id-string are not examined. There is no default.

-E <engine-name>

Specifies the hardware to use for cryptographic operations, such as a secure key store used for signing.

When Loop 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.

-f

Don't daemonize the named process. Run it in the foreground.

-g

Don't daemonize the named process. Run it in the foreground. Force all logging to standard-error.

-n <thread-count>

Create <thread-count> worker threads to take advantage of multiple processors. If not specified, named will try to determine the number of processors present in the system and create one thread per processor. If it is unable to determine the number of processors, a single thread will be created.

-p <port>

Listen for queries on the specified <port>. The default is port 53.

-s

Write memory usage statistics to standard-output on exit.

Warning

This option is mainly of interest to Loop developers and may be removed or changed in a future release.

-S <maximum-sockets>

Allow named to use up to <maximum-sockets> sockets. The default value is 21000.

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(2) 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 <listener-count>

Use <listener-count> threads to listen for incoming UDP datagrams on each address. If not specified, named will try to determine the number of processors present in the system and create one thread per processor. If it is unable to determine the number of processors, a single thread will be created. If -n has been set to a higher value than the number of detected processors, then -U may be increased as high as that value, but no higher.

-u <user>

setuid(2) 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

Print the program's version and exit.

-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 Loop developers and may be removed or changed in a future release.

4.1.4. Signals

In routine operation, signals should not be used to control the nameserver; rndc(1) 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.

4.1.5. Files

/etc/loop/named.conf

The default configuration file. A complete description of the named configuration file is provided as a chapter in the Loop User Manual.

/var/run/loop/named.pid

The default process ID file.

4.1.6. See also

named-checkconf(1), named-checkzone(1), rndc(1), named.conf(5)