NSUPDATE linux command manual

NSUPDATE(8)                                                    NSUPDATE(8)

       nsupdate - Dynamic DNS update utility

       nsupdate  [  -d ]  [  [ -y keyname:secret ]  [ -k keyfile ]  ]  [ -v ]
       [ filename ]

       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  nsup-
       date  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.   The  signatures rely 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 authenti-
       cation.  nsupdate does not read /etc/named.conf.

       nsupdate uses the -y or -k option 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.

       By  default  nsupdate  uses  UDP  to  send update requests to the name
       server.  The -v option makes nsupdate use a TCP connection.  This  may
       be preferable when a batch of update requests is made.

       nsupdate reads input from filename or standard input.  Each command is
       supplied on exactly one line of input.  Some commands are for adminis-
       trative  purposes.   The others are either update instructions or pre-
       requisite 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 server-
              name.  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  speci-
              fied, 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 addi-
              tionally 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  deter-
              mine the correct zone to update based on the rest of the input.

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

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

       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 delete 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 sup-
              plied. The ttl is ignored, and is only allowed for  compatibil-

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

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

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

       Lines beginning with a semicolon are comments, and are ignored.

       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

       Any A records for oldhost.example.com are deleted.  and  an  A  record
       for newhost.example.com it IP address 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

       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
       SIG, KEY and NXT records.)

              used to identify default name server

              base-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).

              base-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).

       RFC2136,   RFC3007,  RFC2104,  RFC2845,  RFC1034,  RFC2535,  named(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 releases.

BIND9                            Jun 30, 2000                     NSUPDATE(8)