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NSUPDATE(1)			     BIND9			   NSUPDATE(1)

NAME
       nsupdate	- Dynamic DNS update utility

SYNOPSIS
       nsupdate	[-d] [-D] [-L level] [[-g] | [-o] | [-l] |
		[-y [hmac:]keyname:secret] | [-k keyfile]] [-t timeout]
		[-u udptimeout]	[-r udpretries]	[-R randomdev] [-v] [-V]
		[filename]

DESCRIPTION
       nsupdate	is used	to submit Dynamic DNS Update requests as defined in
       RFC 2136	to a name server. This allows resource records to be added or
       removed from a zone without manually editing the	zone file. A single
       update request can contain requests to add or remove more than one
       resource	record.

       Zones that are under dynamic control via	nsupdate or a DHCP server
       should not be edited by hand. Manual edits could	conflict with dynamic
       updates and cause data to be lost.

       The resource records that are dynamically added or removed with
       nsupdate	have to	be in the same zone. Requests are sent to the zone's
       master server. This is identified by the	MNAME field of the zone's SOA
       record.

       Transaction signatures can be used to authenticate the Dynamic DNS
       updates.	These use the TSIG resource record type	described in RFC 2845
       or the SIG(0) record described in RFC 2535 and RFC 2931 or GSS-TSIG as
       described in RFC	3645.

       TSIG relies on a	shared secret that should only be known	to nsupdate
       and the name server. For	instance, suitable key and server statements
       would be	added to /usr/local/etc/namedb/named.conf so that the name
       server can associate the	appropriate secret key and algorithm with the
       IP address of the client	application that will be using TSIG
       authentication. You can use ddns-confgen	to generate suitable
       configuration fragments.	 nsupdate uses the -y or -k options to provide
       the TSIG	shared secret. These options are mutually exclusive.

       SIG(0) uses public key cryptography. To use a SIG(0) key, the public
       key must	be stored in a KEY record in a zone served by the name server.

       GSS-TSIG	uses Kerberos credentials. Standard GSS-TSIG mode is switched
       on with the -g flag. A non-standards-compliant variant of GSS-TSIG used
       by Windows 2000 can be switched on with the -o flag.

OPTIONS
       -d
	   Debug mode. This provides tracing information about the update
	   requests that are made and the replies received from	the name
	   server.

       -D
	   Extra debug mode.

       -k keyfile
	   The file containing the TSIG	authentication key. Keyfiles may be in
	   two formats:	a single file containing a named.conf-format key
	   statement, which may	be generated automatically by ddns-confgen, or
	   a pair of files whose names are of the format
	   K{name}.+157.+{random}.key and K{name}.+157.+{random}.private,
	   which can be	generated by dnssec-keygen. The	-k may also be used to
	   specify a SIG(0) key	used to	authenticate Dynamic DNS update
	   requests. In	this case, the key specified is	not an HMAC-MD5	key.

       -l
	   Local-host only mode. This sets the server address to localhost
	   (disabling the server so that the server address cannot be
	   overridden).	Connections to the local server	will use a TSIG	key
	   found in /var/run/named/session.key,	which is automatically
	   generated by	named if any local master zone has set update-policy
	   to local. The location of this key file can be overridden with the
	   -k option.

       -L level
	   Set the logging debug level.	If zero, logging is disabled.

       -p port
	   Set the port	to use for connections to a name server. The default
	   is 53.

       -r udpretries
	   The number of UDP retries. The default is 3.	If zero, only one
	   update request will be made.

       -R randomdev
	   Where to obtain randomness. If the operating	system does not
	   provide a /dev/random or equivalent device, the default source of
	   randomness is keyboard input.  randomdev specifies the name of a
	   character device or file containing random data to be used instead
	   of the default. The special value keyboard indicates	that keyboard
	   input should	be used. This option may be specified multiple times.

       -t timeout
	   The maximum time an update request can take before it is aborted.
	   The default is 300 seconds. Zero can	be used	to disable the
	   timeout.

       -u udptimeout
	   The UDP retry interval. The default is 3 seconds. If	zero, the
	   interval will be computed from the timeout interval and number of
	   UDP retries.

       -v
	   Use TCP even	for small update requests. By default, nsupdate	uses
	   UDP to send update requests to the name server unless they are too
	   large to fit	in a UDP request in which case TCP will	be used. TCP
	   may be preferable when a batch of update requests is	made.

       -V
	   Print the version number and	exit.

       -y [hmac:]keyname:secret
	   Literal TSIG	authentication key.  keyname is	the name of the	key,
	   and secret is the base64 encoded shared secret.  hmac is the	name
	   of the key algorithm; valid choices are hmac-md5, hmac-sha1,
	   hmac-sha224,	hmac-sha256, hmac-sha384, or hmac-sha512. If hmac is
	   not specified, the default is hmac-md5.

	   NOTE: Use of	the -y option is discouraged because the shared	secret
	   is supplied as a command line argument in clear text. This may be
	   visible in the output from ps(1) or in a history file maintained by
	   the user's shell.

INPUT FORMAT
       nsupdate	reads input from filename or standard input. Each command is
       supplied	on exactly one line of input. Some commands are	for
       administrative purposes.	The others are either update instructions or
       prerequisite checks on the contents of the zone.	These checks set
       conditions that some name or set	of resource records (RRset) either
       exists or is absent from	the zone. These	conditions must	be met if the
       entire update request is	to succeed. Updates will be rejected if	the
       tests for the prerequisite conditions fail.

       Every update request consists of	zero or	more prerequisites and zero or
       more updates. This allows a suitably authenticated update request to
       proceed if some specified resource records are present or missing from
       the zone. A blank input line (or	the send command) causes the
       accumulated commands to be sent as one Dynamic DNS update request to
       the name	server.

       The command formats and their meaning are as follows:

       server {servername} [port]
	   Sends all dynamic update requests to	the name server	servername.
	   When	no server statement is provided, nsupdate will send updates to
	   the master server of	the correct zone. The MNAME field of that
	   zone's SOA record will identify the master server for that zone.
	   port	is the port number on servername where the dynamic update
	   requests get	sent. If no port number	is specified, the default DNS
	   port	number of 53 is	used.

       local {address} [port]
	   Sends all dynamic update requests using the local address. When no
	   local statement is provided,	nsupdate will send updates using an
	   address and port chosen by the system.  port	can additionally be
	   used	to make	requests come from a specific port. If no port number
	   is specified, the system will assign	one.

       zone {zonename}
	   Specifies that all updates are to be	made to	the zone zonename. If
	   no zone statement is	provided, nsupdate will	attempt	determine the
	   correct zone	to update based	on the rest of the input.

       class {classname}
	   Specify the default class. If no class is specified,	the default
	   class is IN.

       ttl {seconds}
	   Specify the default time to live for	records	to be added. The value
	   none	will clear the default ttl.

       key [hmac:] {keyname} {secret}
	   Specifies that all updates are to be	TSIG-signed using the keyname
	   secret pair.	If hmac	is specified, then it sets the signing
	   algorithm in	use; the default is hmac-md5. The key command
	   overrides any key specified on the command line via -y or -k.

       gsstsig
	   Use GSS-TSIG	to sign	the updated. This is equivalent	to specifying
	   -g on the commandline.

       oldgsstsig
	   Use the Windows 2000	version	of GSS-TSIG to sign the	updated. This
	   is equivalent to specifying -o on the commandline.

       realm {[realm_name]}
	   When	using GSS-TSIG use realm_name rather than the default realm in
	   krb5.conf. If no realm is specified the saved realm is cleared.

       [prereq]	nxdomain {domain-name}
	   Requires that no resource record of any type	exists with name
	   domain-name.

       [prereq]	yxdomain {domain-name}
	   Requires that domain-name exists (has as at least one resource
	   record, of any type).

       [prereq]	nxrrset	{domain-name} [class] {type}
	   Requires that no resource record exists of the specified type,
	   class and domain-name. If class is omitted, IN (internet) is
	   assumed.

       [prereq]	yxrrset	{domain-name} [class] {type}
	   This	requires that a	resource record	of the specified type, class
	   and domain-name must	exist. If class	is omitted, IN (internet) is
	   assumed.

       [prereq]	yxrrset	{domain-name} [class] {type} {data...}
	   The data from each set of prerequisites of this form	sharing	a
	   common type,	class, and domain-name are combined to form a set of
	   RRs.	This set of RRs	must exactly match the set of RRs existing in
	   the zone at the given type, class, and domain-name. The data	are
	   written in the standard text	representation of the resource
	   record's RDATA.

       [update]	del[ete] {domain-name} [ttl] [class] [type [data...]]
	   Deletes any resource	records	named domain-name. If type and data is
	   provided, only matching resource records will be removed. The
	   internet class is assumed if	class is not supplied. The ttl is
	   ignored, and	is only	allowed	for compatibility.

       [update]	add {domain-name} {ttl}	[class]	{type} {data...}
	   Adds	a new resource record with the specified ttl, class and	data.

       show
	   Displays the	current	message, containing all	of the prerequisites
	   and updates specified since the last	send.

       send
	   Sends the current message. This is equivalent to entering a blank
	   line.

       answer
	   Displays the	answer.

       debug
	   Turn	on debugging.

       version
	   Print version number.

       help
	   Print a list	of commands.

       Lines beginning with a semicolon	are comments and are ignored.

EXAMPLES
       The examples below show how nsupdate could be used to insert and	delete
       resource	records	from the example.com zone. Notice that the input in
       each example contains a trailing	blank line so that a group of commands
       are sent	as one dynamic update request to the master name server	for
       example.com.

	   # nsupdate
	   > update delete oldhost.example.com A
	   > update add	newhost.example.com 86400 A 172.16.1.1
	   > send

       Any A records for oldhost.example.com are deleted. And an A record for
       newhost.example.com with	IP address 172.16.1.1 is added.	The
       newly-added record has a	1 day TTL (86400 seconds).

	   # nsupdate
	   > prereq nxdomain nickname.example.com
	   > update add	nickname.example.com 86400 CNAME somehost.example.com
	   > send

       The prerequisite	condition gets the name	server to check	that there are
       no resource records of any type for nickname.example.com. If there are,
       the update request fails. If this name does not exist, a	CNAME for it
       is added. This ensures that when	the CNAME is added, it cannot conflict
       with the	long-standing rule in RFC 1034 that a name must	not exist as
       any other record	type if	it exists as a CNAME. (The rule	has been
       updated for DNSSEC in RFC 2535 to allow CNAMEs to have RRSIG, DNSKEY
       and NSEC	records.)

FILES
       /etc/resolv.conf
	   used	to identify default name server

       /var/run/named/session.key
	   sets	the default TSIG key for use in	local-only mode

       K{name}.+157.+{random}.key
	   base-64 encoding of HMAC-MD5	key created by dnssec-keygen(8).

       K{name}.+157.+{random}.private
	   base-64 encoding of HMAC-MD5	key created by dnssec-keygen(8).

SEE ALSO
       RFC 2136, RFC 3007, RFC 2104, RFC 2845, RFC 1034, RFC 2535, RFC 2931,
       named(8), ddns-confgen(8), dnssec-keygen(8).

BUGS
       The TSIG	key is redundantly stored in two separate files. This is a
       consequence of nsupdate using the DST library for its cryptographic
       operations, and may change in future releases.

COPYRIGHT
       Copyright (C) 2004-2012,	2014, 2015 Internet Systems Consortium,	Inc.
       ("ISC")
       Copyright (C) 2000-2003 Internet	Software Consortium.

BIND9				April 18, 2014			   NSUPDATE(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | INPUT FORMAT | EXAMPLES | FILES | SEE ALSO | BUGS | COPYRIGHT

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