Provided by: bind9-dnsutils_9.18.4-2ubuntu2_amd64 bug


       nsupdate - dynamic DNS update utility


       nsupdate [-d] [-D] [-i] [-L level] [ [-g] | [-o] | [-l] | [-y [hmac:]keyname:secret] | [-k
       keyfile] ] [-t timeout] [-u udptimeout] [-r udpretries] [-v] [-T] [-P] [-V] [ [-4] |  [-6]
       ] [filename]


       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 must be in the
       same zone. Requests are sent to the zone's primary server,  which  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, 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 are added to /etc/bind/named.conf so that
       the name server can associate the appropriate secret key and algorithm with the IP address
       of the client application that is using TSIG  authentication.  ddns-confgen  can  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.


       -4     This option sets use of IPv4 only.

       -6     This option sets use of IPv6 only.

       -C     Overrides the default resolv.conf file. This is only intended for testing.

       -d     This  option  sets  debug mode, which provides tracing information about the update
              requests that are made and the replies received from the name server.

       -D     This option sets extra debug mode.

       -g     This option enables standard GSS-TSIG mode.

       -i     This option forces interactive mode, even when standard input is not a terminal.

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

       -L level
              This option sets the logging debug level. If zero, logging is disabled.

       -o     This option enables a non-standards-compliant variant of GSS-TSIG used  by  Windows

       -p port
              This  option  sets the port to use for connections to a name server. The default is

       -P     This option prints the list of private BIND-specific resource  record  types  whose
              format is understood by nsupdate. See also the -T option.

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

       -t timeout
              This option sets the maximum time an update request can take before it is  aborted.
              The default is 300 seconds. If zero, the timeout is disabled.

       -T     This  option prints the list of IANA standard resource record types whose format is
              understood by nsupdate. nsupdate exits after the lists are printed. The  -T  option
              can be combined with the -P option.

              Other  types can be entered using TYPEXXXXX where XXXXX is the decimal value of the
              type with no leading zeros. The rdata, if present,  is  parsed  using  the  UNKNOWN
              rdata format, (<backslash> <hash> <space> <length> <space> <hexstring>).

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

       -v     This option specifies that TCP should be used 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  is  used.  TCP  may  be
              preferable when a batch of update requests is made.

       -V     This option prints the version number and exits.

       -y [hmac:]keyname:secret
              This  option  sets  the 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,  or
              if MD5 was disabled, hmac-sha256.

              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  ps1
              or in a history file maintained by the user's shell.


       nsupdate  reads input from filename or standard input. Each command is supplied on exactly
       one line of input. Some commands are for administrative purposes; 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 are 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 either 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 meanings are as follows:

       server servername port
              This command sends all dynamic update requests to the name server servername.  When
              no  server  statement  is provided, nsupdate sends updates to the primary server of
              the correct zone. The MNAME field of that zone's SOA record  identify  the  primary
              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.

       local address port
              This  command  sends  all  dynamic update requests using the local address. When no
              local statement is provided, nsupdate sends  updates  using  an  address  and  port
              chosen  by  the  system.  port  can  also  be used to force requests to come from a
              specific port. If no port number is specified, the system assigns one.

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

       class classname
              This command specifies the default class. If no class  is  specified,  the  default
              class is IN.

       ttl seconds
              This  command  specifies  the  default  time-to-live, in seconds, for records to be
              added. The value none clears the default TTL.

       key hmac:keyname secret
              This  command  specifies  that  all  updates  are  to  be  TSIG-signed  using   the
              keyname-secret  pair.  If  hmac is specified, it sets the signing algorithm in use.
              The default is hmac-md5; if MD5 was disabled, the default is hmac-sha256.  The  key
              command overrides any key specified on the command line via -y or -k.

              This command uses GSS-TSIG to sign the updates. This is equivalent to specifying -g
              on the command line.

              This command uses the Windows 2000 version of GSS-TSIG to sign the updates. This is
              equivalent to specifying -o on the command line.

       realm [realm_name]
              When  using  GSS-TSIG, this command specifies the use of realm_name rather than the
              default realm in krb5.conf. If no realm is specified, the saved realm is cleared.

       check-names [yes_or_no]
              This command turns on or  off  check-names  processing  on  records  to  be  added.
              Check-names  has  no  effect on prerequisites or records to be deleted.  By default
              check-names processing is on. If check-names processing fails, the  record  is  not
              added to the UPDATE message.

       prereq nxdomain domain-name
              This  command  requires  that  no  resource  record of any type exist with the name

       prereq yxdomain domain-name
              This command requires that domain-name exist (as at least one resource  record,  of
              any type).

       prereq nxrrset domain-name class type
              This  command  requires that no resource record exist of the specified type, class,
              and domain-name. If class is omitted, IN (Internet) is assumed.

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

       prereq yxrrset domain-name class type data
              With  this  command, 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 delete domain-name ttl class type data
              This  command  deletes any resource records named domain-name. If type and data are
              provided, only matching resource  records  are  removed.   The  Internet  class  is
              assumed  if  class  is  not  supplied.  The ttl is ignored, and is only allowed for

       update add domain-name ttl class type data
              This command adds a new resource record with the specified ttl, class, and data.

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

       send   This  command  sends  the  current  message. This is equivalent to entering a blank

       answer This command displays the answer.

       debug  This command turns on debugging.

              This command prints the version number.

       help   This command prints a list of commands.

       Lines beginning with a semicolon (;) are comments and are ignored.


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

          # nsupdate
          > update delete A
          > update add 86400 A
          > send

       Any A records for are deleted, and an A record for
       with IP address is added. The newly added record has a  TTL  of  1  day  (86400

          # nsupdate
          > prereq nxdomain
          > update add 86400 CNAME
          > send

       The  prerequisite  condition  tells  the  name server to verify that there are no resource
       records of any type for 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.)


              Used to identify the default name server

              Sets the default TSIG key for use in local-only mode

              Base-64 encoding of the HMAC-MD5 key created by dnssec-keygen.

              Base-64 encoding of the HMAC-MD5 key created by dnssec-keygen.


       RFC 2136, RFC 3007,  RFC  2104,  RFC  2845,  RFC  1034,  RFC  2535,  RFC  2931,  named(8),
       dnssec-keygen(8), tsig-keygen(8).


       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


       Internet Systems Consortium


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