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NSUPDATE(8)
NAME
  nsupdate - Dynamic DNS update utility

SYNOPSIS
  nsupdate [-d] [[-y keyname:secret] | [-k keyfile]] [-t timeout]
	   [-u udptimeout] [-r udpretries] [-v] [filename]

DESCRIPTION
  nsupdate is used to submit Dynamic DNS Update requests as defined in
  RFC2136 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.

  The -d option makes nsupdate operate in debug mode. This provides tracing
  information about the update requests that are made and the replies
  received from the name server.

  Transaction signatures can be used to authenticate the Dynamic DNS updates.
  These use the TSIG resource record type described in RFC2845 or the SIG(0)
  record described in RFC3535 and RFC2931. TSIG relies on a shared secret
  that should only be known to nsupdate and the name server. Currently, the
  only supported encryption algorithm for TSIG is HMAC-MD5, which is defined
  in RFC 2104. Once other algorithms are defined for TSIG, applications will
  need to ensure they select the appropriate algorithm as well as the key
  when authenticating each other. For instance suitable key and server
  statements would be added to /etc/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. 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.	nsupdate does not
  read /etc/named.conf.

  nsupdate uses the -y or -k option (with an HMAC-MD5 key) to provide the
  shared secret needed to generate a TSIG record for authenticating Dynamic
  DNS update requests. These options are mutually exclusive. With the -k
  option, nsupdate reads the shared secret from the file keyfile, whose name
  is of the form K{name}.+157.+{random}.private. For historical reasons, the
  file K{name}.+157.+{random}.key must also be present. When the -y option is
  used, a signature is generated from keyname:secret. keyname is the name of
  the key, and secret is the base64 encoded shared secret. 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.

  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.

  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. The -v option makes nsupdate use a TCP connection. This may be
  preferable when a batch of update requests is made.

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

  The -u option sets 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.

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

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:

	   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.

	  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.

	 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.

	  Specify the default class. If no
	class is specified the default class is IN.

	Specifies that all updates are to be TSIG signed using the
      keyname keysecret pair. The key command overrides any key specified on
      the command line via -y or -k.

		    Requires that no resource record of any type exists with name
		  domain-name.

		    Requires that
		  domain-name exists (has as at least one resource record, of
		  any type).

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

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

		   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.

		  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.

	       Adds a new resource record with the specified
	     ttl, class and data.

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

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

	   Displays the answer.

  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 it 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 RFC1034 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 RFC2535 to allow CNAMEs to have RRSIG, DNSKEY and NSEC records.)

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

  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
  RFC2136(), RFC3007(), RFC2104(), RFC2845(), RFC1034(), RFC2535(),
  RFC2931(), named(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, 2005 Internet Systems Consortium, Inc. ("ISC")

Index for Section 8

Alphabetical listing for N

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