NAMED(8)

BIND9

NAMED(8)

NAME¶

named - Internet domain name server

SYNOPSIS¶

named [-4] [-6] [-c config-file] [-d debug-level] [-E engine-name] [-f] [-g] [-m flag] [-n #cpus] [-p port] [-s] [-S #max-socks] [-t directory] [-u user] [-v] [-V] [-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 RFCs 1033, 1034, and 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.

-E engine-name

Use a crypto hardware (OpenSSL engine) for the crypto operations it supports, for instance re-signing with private keys from a secure key store. When compiled with PKCS#11 support engine-name defaults to pkcs11, the empty name resets it to no engine.

-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.

-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.

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 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 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.

NOTES¶

Red Hat SELinux BIND Security Profile:

By default, Red Hat ships BIND with the most secure SELinux policy that will not prevent normal BIND operation and will prevent exploitation of all known BIND security vulnerabilities . See the selinux(8) man page for information about SElinux.

It is not necessary to run named in a chroot environment if the Red Hat SELinux policy for named is enabled. When enabled, this policy is far more secure than a chroot environment. Users are recommended to enable SELinux and remove the bind-chroot package.

With this extra security comes some restrictions:

By default, the SELinux policy does not allow named to write any master zone database files. Only the root user may create files in the $ROOTDIR/var/named zone database file directory (the options { "directory" } option), where $ROOTDIR is set in /etc/sysconfig/named.

The "named" group must be granted read privelege to these files in order for named to be enabled to read them.

Any file created in the zone database file directory is automatically assigned the SELinux file context named_zone_t .

By default, SELinux prevents any role from modifying named_zone_t files; this means that files in the zone database directory cannot be modified by dynamic DNS (DDNS) updates or zone transfers.

The Red Hat BIND distribution and SELinux policy creates three directories where named is allowed to create and modify files: /var/named/slaves, /var/named/dynamic /var/named/data. By placing files you want named to modify, such as slave or DDNS updateable zone files and database / statistics dump files in these directories, named will work normally and no further operator action is required. Files in these directories are automatically assigned the 'named_cache_t' file context, which SELinux allows named to write.

Red Hat BIND SDB support:

Red Hat ships named with compiled in Simplified Database Backend modules that ISC provides in the "contrib/sdb" directory. Install bind-sdb package if you want use them

The SDB modules for LDAP, PostGreSQL, DirDB and SQLite are compiled into named-sdb.

See the documentation for the various SDB modules in /usr/share/doc/bind-sdb-*/ .

AUTHOR¶

Internet Systems Consortium

COPYRIGHT¶

May 21, 2009