3853N/A - Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC") 3853N/A - Copyright (C) 2001-2003 Internet Software Consortium. 3853N/A - Permission to use, copy, modify, and distribute this software for any 3853N/A - purpose with or without fee is hereby granted, provided that the above 3853N/A - copyright notice and this permission notice appear in all copies. 3853N/A - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 3853N/A - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 3853N/A - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 3853N/A - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 3853N/A - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 3853N/A - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 3853N/A - PERFORMANCE OF THIS SOFTWARE. 3853N/ACONTENT="Modular DocBook HTML Stylesheet Version 1.73 3853N/A>nsupdate -- Dynamic DNS update utility</
DIV is used to submit Dynamic DNS Update requests as defined in RFC2136
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
>Zones that are under dynamic control via
or a DHCP server should not be edited by hand.
conflict with dynamic updates and cause data to be lost.</
P>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 MNAME field of the zone's SOA record.</
PThis provides tracing information about the update requests that are
made and the replies received from the name server.</
P>Transaction signatures can be used to authenticate the Dynamic DNS
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
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.
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 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.
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.
reads the shared secret from the file
whose name is of the form
>K{name}.+157.+{random}.private</
TT>K{name}.+157.+{random}.key</
TTmust also be present. When the
option is used, a signature is generated from
is the base64 encoded shared secret.
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
or in a history file maintained by the user's shell.</
P> 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.</
Puses 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.
This may be preferable when a batch of update requests is made.</
P> 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.</
P> 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.</
P> option sets the number of UDP retries. The default is
3. If zero only one update request will be made.</
PEach 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
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.</
P>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 <
Baccumulated commands to be sent as one Dynamic DNS update request to the
>The command formats and their meaning are as follows:
>Sends all dynamic update requests to the name server
When no server statement is provided,
will send updates to the master server of the correct zone.
The MNAME field of that zone's SOA record will identify the master
where the dynamic update requests get sent.
If no port number is specified, the default DNS port number of 53 is
>Sends all dynamic update requests using the local
When no local statement is provided,
will send updates using an address and port chosen by the system.
can additionally be used to make requests come from a specific port.
If no port number is specified, the system will assign one. </
P>Specifies that all updates are to be made to the zone
will attempt determine the correct zone to update based on the rest of the input.</
P>Specify the default class.
> is specified the default class is
>Specifies that all updates are to be TSIG signed using the
overrides any key specified on the command line via
>Requires that no resource record of any type exists with name
exists (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</
TT>base-64 encoding of HMAC-MD5 key created by
>K{name}.+157.+{random}.private</
TT>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