NAMED(8) BIND9 NAMED(8)

NAME
named - Internet domain name server

SYNOPSIS
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 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.

-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. Currently the only supported option is external, which causes the internal memory manager to be bypassed in favor
of system-provided memory allocation functions.

-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 4096 on systems built with default configuration options, and 21000 on systems built with
"configure --with-tuning=large".

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.

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-*/ .

SEE ALSO
RFC 1033, RFC 1034, RFC 1035, named-checkconf(8), named-checkzone(8), rndc(8), lwresd(8), named.conf(5), BIND 9 Administrator Reference Manual.

AUTHOR
Internet Systems Consortium, Inc.

COPYRIGHT
Copyright © 2000, 2001, 2003-2009, 2011, 2013-2018 Internet Systems Consortium, Inc. ("ISC")

ISC 2014-02-19