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HEAD 2867N/A>nsupdate -- Dynamic DNS update utility</
DIV 2867N/Ais used to submit Dynamic DNS Update requests as defined in RFC2136
2867N/AThis allows resource records to be added or removed from a zone
2867N/Awithout manually editing the zone file.
2867N/AA single update request can contain requests to add or remove more than one
2867N/A>Zones that are under dynamic control via
2867N/Aor a DHCP server should not be edited by hand.
2867N/Aconflict with dynamic updates and cause data to be lost.</
P 2867N/A>The resource records that are dynamically added or removed with
2867N/Ahave to be in the same zone.
2867N/ARequests are sent to the zone's master server.
2867N/AThis is identified by the MNAME field of the zone's SOA record.</
P 2867N/AThis provides tracing information about the update requests that are
2867N/Amade and the replies received from the name server.</
P 2867N/A>Transaction signatures can be used to authenticate the Dynamic DNS
2867N/AThese use the TSIG resource record type described in RFC2845 or the
2867N/ASIG(0) record described in RFC3535 and RFC2931.
2867N/ATSIG relies on a shared secret that should only be known to
2867N/ACurrently, the only supported encryption algorithm for TSIG is
2867N/AHMAC-MD5, which is defined in RFC 2104.
2867N/AOnce other algorithms are defined for TSIG, applications will need to
2867N/Aensure they select the appropriate algorithm as well as the key when
2867N/Astatements would be added to
2867N/Aso that the name server can associate the appropriate secret key
2867N/Aand algorithm with the IP address of the
3017N/Aclient application that will be using TSIG authentication.
3017N/ASIG(0) uses public key cryptography. To use a SIG(0) key, the public
3017N/Akey must be stored in a KEY record in a zone served by the name server.
2867N/Aoption (with an HMAC-MD5 key) to provide the shared secret needed to generate
2867N/Aa TSIG record for authenticating Dynamic DNS update requests.
2867N/AThese options are mutually exclusive.
2872N/Areads the shared secret from the file
2872N/A>K{name}.+157.+{random}.private</
TT 2867N/A>K{name}.+157.+{random}.key</
TT 2867N/Amust also be present. When the
2867N/Aoption is used, a signature is generated from
2867N/Ais the base64 encoded shared secret.
2867N/Aoption is discouraged because the shared secret is supplied as a command
2867N/Aline argument in clear text.
2867N/AThis may be visible in the output from
2867N/Aor in a history file maintained by the user's shell.</
P 2867N/A> may also be used to specify a SIG(0) key used
3156N/Ato authenticate Dynamic DNS update requests. In this case, the key
3156N/Aspecified is not an HMAC-MD5 key.</
P 2953N/Auses UDP to send update requests to the name server unless they are too
2867N/Alarge to fit in a UDP request in which case TCP will be used.
2867N/AThis may be preferable when a batch of update requests is made.</
P 2867N/A> option sets the maximum time a update request can
2867N/Atake before it is aborted. The default is 300 seconds. Zero can be used
2867N/A> option sets the UDP retry interval. The default is
2867N/A3 seconds. If zero the interval will be computed from the timeout interval
2867N/Aand number of UDP retries.</
P 2867N/A> option sets the number of UDP retries. The default is
2867N/A3. If zero only one update request will be made.</
P 2867N/AEach command is supplied on exactly one line of input.
2867N/ASome commands are for administrative purposes.
2867N/AThe others are either update instructions or prerequisite checks on the
2867N/AThese checks set conditions that some name or set of
2867N/Aresource records (RRset) either exists or is absent from the zone.
3156N/AThese conditions must be met if the entire update request is to succeed.
2867N/AUpdates will be rejected if the tests for the prerequisite conditions fail.</
P 2867N/A>Every update request consists of zero or more prerequisites
3156N/AThis allows a suitably authenticated update request to proceed if some
2867N/Aspecified resource records are present or missing from the zone.
2867N/AA blank input line (or the <
B 2867N/Aaccumulated commands to be sent as one Dynamic DNS update request to the
2867N/A>The command formats and their meaning are as follows:
2867N/A>Sends all dynamic update requests to the name server
2867N/AWhen no server statement is provided,
2867N/Awill send updates to the master server of the correct zone.
2867N/AThe MNAME field of that zone's SOA record will identify the master
2867N/Awhere the dynamic update requests get sent.
2867N/AIf no port number is specified, the default DNS port number of 53 is
2867N/A>Sends all dynamic update requests using the local
2867N/AWhen no local statement is provided,
2867N/Awill send updates using an address and port chosen by the system.
3156N/Acan additionally be used to make requests come from a specific port.
3156N/AIf no port number is specified, the system will assign one. </
P 3156N/A>Specifies that all updates are to be made to the zone
2872N/Awill attempt determine the correct zone to update based on the rest of the input.</
P 2867N/A> is specified the default class is
2867N/A>Specifies that all updates are to be TSIG signed using the
2867N/Aoverrides any key specified on the command line via
2867N/A>Requires that no resource record of any type exists with name
2867N/Aexists (has as at least one resource record, of any type).</
P > {domain-name} [class] {type}</
P>Requires that no resource record exists of the specified
is omitted, IN (internet) is assumed.</
P> {domain-name} [class] {type}</
P>This requires that a resource record of the specified
is omitted, IN (internet) is assumed.</
P> {domain-name} [class] {type} {data...}</
Pfrom each set of prerequisites of this form
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
are written in the standard text representation of the resource record's
> {domain-name} [ttl] [class] [type [data...]]</
P>Deletes any resource records named
is provided, only matching resource records will be removed.
The internet class is assumed if
is ignored, and is only allowed for compatibility.</
P> {domain-name} {ttl} [class] {type} {data...}</
P>Adds a new resource record with the specified
>Displays the current message, containing all of the prerequisites and
updates specified since the last send.</
P>Sends the current message. This is equivalent to entering a blank line.</
P>Lines beginning with a semicolon are comments and are ignored.</
P>The examples below show how
could be used to insert and delete resource records from the
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
it IP address 172.16.1.1 is added.
The newly-added record has a 1 day TTL (86400 seconds)
>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 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.)</
P>used to identify default name server</
P>K{name}.+157.+{random}.key</
CODE>base-64 encoding of HMAC-MD5 key created by
>K{name}.+157.+{random}.private</
CODE>base-64 encoding of HMAC-MD5 key created by
>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