nsupdate(1)						      General Commands Manual						       nsupdate(1)

NAME

       nsupdate - Dynamic DNS update utility

SYNOPSIS

       keyfile | udpretries] timeout] udptimeout] [filename]

DESCRIPTION

       submits	Dynamic DNS update requests to a name server, as defined in RFC 2136.  This allows resource records to be added to 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 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 have to be in the same zone.   Requests	are  sent  to  the  zone's  master
       server.	This is identified by the field of the zone's record.

       Transaction  signatures	can  be used to authenticate the Dynamic DNS updates.  These use the resource record type described in RFC 2845 or
       the SIG(0) record described in RFC 2535 and RFC 2931.  relies on a shared secret that should only be known to and the  name  server.   Cur-
       rently, the only supported encryption algorithm for is which is defined in RFC 2104.

       Once  other  algorithms	are  defined  for  applications  will need to ensure they select the appropriate algorithm as well as the key when
       authenticating each other.  For instance, suitable and statements would be added to 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 authentication.  SIG(0) uses public key cryptog-
       raphy.  To use a SIG(0) key, the public key must be stored in a record in a zone served by the name server.  does not read

   Options
       Operate in debug mode.
		 This provides tracing information about the update requests that are made and the replies received from the name server.

       Provide the shared secret needed to
		 generate a record for authenticating Dynamic DNS update requests.  With this option, reads the shared secret from the	file  key-
		 file, whose name is of the form

		 For  historical  reasons, the file must also be present.  This option is mutually exclusive with the option.  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 key.

       Set the number of UDP retries.
		 The default is 3.  If set to zero only one update request will be made.

       Set the maximum time in seconds a update request can take before it is
		 aborted.  The default is 300 seconds.	Zero can be used to disable the timeout.

       Set the UDP retry interval in seconds.
		 The default is 3 seconds.  If set to zero the interval will be computed from the timeout interval and number of UDP retries.

       Use a TCP connection to send update requests to the name server.
		 By default, uses UDP to send update requests.	This may be preferable when a batch of update requests is made.

       Generate a signature from
		 keyname and secret.  keyname is the name of the key, and secret is the base-64-encoded shared secret.	The use of the	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.

   Operands
       filename
	      A file of commands, as described in the section.	The default is standard input.

   Input Format
       reads commands from filename or standard input.	Each command is supplied on exactly one line of input.	Some commands are for  administra-
       tive  purposes;	others	are either update instructions or prerequisite checks on the contents of the zone.  The 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.  The command or a blank input line causes  the  accumu-
       lated commands to be sent as one Dynamic DNS update request to the name server.

   The Commands
       The command formats and their meaning are as follows:

       Lines beginning with a semicolon are comments and are ignored.

       Sends all dynamic update requests to the name server
		      servername.   When  no  statement  is  provided,	sends updates to the master server of the correct zone.  The field of that
		      zone's record identifies the master server for that zone.  port is the port number on servername where  the  dynamic  update
		      requests are 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 statement is provided, sends 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 assigns one.

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

       Specifies the default class.
		      If no class is specified, the default class is

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

       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, (Internet) is assumed.

       Requires that a resource record of the specified
		      type, class, and domain-name must exist.	If class is omitted, (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  (resource  records).   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 are provided, only matching resource records will be removed.  The Internet class is  assumed
		      if class is not supplied.

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

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

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

       Displays the answer.

EXAMPLES

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

   Example 1
       Any A records for are deleted.  An A record for with IP address 172.16.1.1 is added.  The newly-added record has a 1 day  TTL  (86400  sec-
       onds)

   Example 2
       The  prerequisite  condition  gets  the	name  server  to check that there are no resource records of any type for If there are, the update
       request fails.  If this name does not exist, a for it is added.	This ensures that when the record 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

       (The rule has been updated for DNSSEC in RFC 2535 to allow records to have and records.)

WARNINGS

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

AUTHOR

       was developed by the Internet Systems Consortium (ISC).

FILES

       Used to identify default name server.

       Base-64 encoding of	     key created by

       Base-64 encoding of	     key created by

SEE ALSO

       dnssec-keygen(1), named(1M).

       Requests for Comments (RFC): 1034, 2104, 2136, 2137, 2535, 2845, 2931, available online at

       available online at

       available from the Internet Systems Consortium at

								     BIND 9.3							       nsupdate(1)