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5612N/A<
tr><
th colspan="3" align="center"><
span class="application">nsupdate</
span></
th></
tr>
5612N/A<
td width="20%" align="left">
5612N/A<
th width="60%" align="center">Manual pages</
th>
5612N/A<
div class="refentry" lang="en">
5612N/A<
p><
span class="application">nsupdate</
span> — Dynamic DNS update utility</
p>
5612N/A<
div class="refsynopsisdiv">
5612N/A<
div class="cmdsynopsis"><
p><
code class="command">nsupdate</
code> [<
code class="option">-d</
code>] [<
code class="option">-D</
code>] [[<
code class="option">-g</
code>] | [<
code class="option">-o</
code>] | [<
code class="option">-l</
code>] | [<
code class="option">-y <
em class="replaceable"><
code>[<
span class="optional">hmac:</
span>]keyname:secret</
code></
em></
code>] | [<
code class="option">-k <
em class="replaceable"><
code>keyfile</
code></
em></
code>]] [<
code class="option">-t <
em class="replaceable"><
code>timeout</
code></
em></
code>] [<
code class="option">-u <
em class="replaceable"><
code>udptimeout</
code></
em></
code>] [<
code class="option">-r <
em class="replaceable"><
code>udpretries</
code></
em></
code>] [<
code class="option">-R <
em class="replaceable"><
code>randomdev</
code></
em></
code>] [<
code class="option">-v</
code>] [filename]</
p></
div>
5612N/A<
div class="refsect1" lang="en">
5612N/A<
a name="id2628724"></
a><
h2>DESCRIPTION</
h2>
5612N/A<
p><
span><
strong class="command">nsupdate</
strong></
span>
5612N/A is used to submit Dynamic DNS Update requests as defined in RFC 2136
5612N/A This allows resource records to be added or removed from a zone
5612N/A without manually editing the zone file.
5612N/A A single update request can contain requests to add or remove more than
5612N/A Zones that are under dynamic control via
5612N/A <
span><
strong class="command">nsupdate</
strong></
span>
5612N/A or a DHCP server should not be edited by hand.
5612N/A conflict with dynamic updates and cause data to be lost.
5612N/A The resource records that are dynamically added or removed with
5612N/A <
span><
strong class="command">nsupdate</
strong></
span>
5612N/A have to be in the same zone.
5612N/A Requests are sent to the zone's master server.
5612N/A This is identified by the MNAME field of the zone's SOA record.
5612N/A <
code class="option">-d</
code>
5612N/A <
span><
strong class="command">nsupdate</
strong></
span>
5612N/A This provides tracing information about the update requests that are
5612N/A made and the replies received from the name server.
5612N/A The <
code class="option">-D</
code> option makes <
span><
strong class="command">nsupdate</
strong></
span>
5612N/A report additional debugging information to <
code class="option">-d</
code>.
5612N/A The <
code class="option">-L</
code> option with an integer argument of zero or
5612N/A higher sets the logging debug level. If zero, logging is disabled.
5612N/A Transaction signatures can be used to authenticate the Dynamic
5612N/A DNS updates. These use the TSIG resource record type described
5612N/A in RFC 2845 or the SIG(0) record described in RFC 2535 and
5612N/A RFC 2931 or GSS-TSIG as described in RFC 3645. TSIG relies on
5612N/A a shared secret that should only be known to
5612N/A <
span><
strong class="command">nsupdate</
strong></
span> and the name server. Currently,
5612N/A the only supported encryption algorithm for TSIG is HMAC-MD5,
5612N/A which is defined in RFC 2104. Once other algorithms are
5612N/A defined for TSIG, applications will need to ensure they select
5612N/A the appropriate algorithm as well as the key when authenticating
5612N/A each other. For instance, suitable <
span class="type">key</
span> and
5612N/A <
span class="type">server</
span> statements would be added to
5612N/A can associate the appropriate secret key and algorithm with
5612N/A the IP address of the client application that will be using
5612N/A TSIG authentication. SIG(0) uses public key cryptography.
5612N/A To use a SIG(0) key, the public key must be stored in a KEY
5612N/A record in a zone served by the name server.
5612N/A <
span><
strong class="command">nsupdate</
strong></
span> does not read
5612N/A GSS-TSIG uses Kerberos credentials. Standard GSS-TSIG mode
5612N/A is switched on with the <
code class="option">-g</
code> flag. A
5612N/A non-standards-compliant variant of GSS-TSIG used by Windows
5612N/A 2000 can be switched on with the <
code class="option">-o</
code> flag.
5612N/A<
p><
span><
strong class="command">nsupdate</
strong></
span>
5612N/A uses the <
code class="option">-y</
code> or <
code class="option">-k</
code> option
5612N/A to provide the shared secret needed to generate a TSIG record
5612N/A for authenticating Dynamic DNS update requests, default type
5612N/A HMAC-MD5. These options are mutually exclusive.
5612N/A When the <
code class="option">-y</
code> option is used, a signature is
5612N/A [<
span class="optional"><
em class="parameter"><
code>hmac:</
code></
em></
span>]<
em class="parameter"><
code>keyname:secret.</
code></
em>
5612N/A <
em class="parameter"><
code>keyname</
code></
em> is the name of the key, and
5612N/A <
em class="parameter"><
code>secret</
code></
em> is the base64 encoded shared secret.
5612N/A Use of the <
code class="option">-y</
code> option is discouraged because the
5612N/A shared secret is supplied as a command line argument in clear text.
5612N/A This may be visible in the output from
5612N/A <
span class="citerefentry"><
span class="refentrytitle">ps</
span>(1)</
span>
5612N/A or in a history file maintained by the user's shell.
5612N/A <
code class="option">-k</
code> option, <
span><
strong class="command">nsupdate</
strong></
span> reads
5612N/A the shared secret from the file <
em class="parameter"><
code>keyfile</
code></
em>.
5612N/A Keyfiles may be in two formats: a single file containing
5612N/A a <
code class="filename">
named.conf</
code>-format <
span><
strong class="command">key</
strong></
span>
5612N/A statement, which may be generated automatically by
5612N/A <
span><
strong class="command">ddns-confgen</
strong></
span>, or a pair of files whose names are
5612N/A of the format <
code class="filename">K{name}.+157.+{random}.key</
code> and
5612N/A <
code class="filename">K{name}.+157.+{random}.private</
code>, which can be
5612N/A generated by <
span><
strong class="command">dnssec-keygen</
strong></
span>.
5612N/A The <
code class="option">-k</
code> may also be used to specify a SIG(0) key used
5612N/A to authenticate Dynamic DNS update requests. In this case, the key
5612N/A specified is not an HMAC-MD5 key.
5612N/A <
span><
strong class="command">nsupdate</
strong></
span> can be run in a local-host only mode
5612N/A using the <
code class="option">-l</
code> flag. This sets the server address to
5612N/A localhost (disabling the <
span><
strong class="command">server</
strong></
span> so that the server
5612N/A address cannot be overridden). Connections to the local server will
5612N/A which is automatically generated by <
span><
strong class="command">named</
strong></
span> if any
5612N/A local master zone has set <
span><
strong class="command">update-policy</
strong></
span> to
5612N/A <
span><
strong class="command">local</
strong></
span>. The location of this key file can be
5612N/A overridden with the <
code class="option">-k</
code> option.
5612N/A By default, <
span><
strong class="command">nsupdate</
strong></
span>
5612N/A uses UDP to send update requests to the name server unless they are too
5612N/A large to fit in a UDP request in which case TCP will be used.
5612N/A <
code class="option">-v</
code>
5612N/A <
span><
strong class="command">nsupdate</
strong></
span>
5612N/A This may be preferable when a batch of update requests is made.
5612N/A The <
code class="option">-p</
code> sets the default port number to use for
5612N/A connections to a name server. The default is 53.
5612N/A The <
code class="option">-t</
code> option sets the maximum time an update request
5612N/A take before it is aborted. The default is 300 seconds. Zero can be
5612N/A The <
code class="option">-u</
code> option sets the UDP retry interval. The default
5612N/A 3 seconds. If zero, the interval will be computed from the timeout
5612N/A The <
code class="option">-r</
code> option sets the number of UDP retries. The
5612N/A 3. If zero, only one update request will be made.
The <
code class="option">-R <
em class="replaceable"><
code>randomdev</
code></
em></
code> option
specifies a source of randomness. If the operating system
does not provide a <
code class="filename">/
dev/
random</
code> or
equivalent device, the default source of randomness is keyboard
input. <
code class="filename">randomdev</
code> specifies the name of
a character device or file containing random data to be used
instead of the default. The special value
<
code class="filename">keyboard</
code> indicates that keyboard input
should be used. This option may be specified multiple times.
<
div class="refsect1" lang="en">
<
a name="id2638820"></
a><
h2>INPUT FORMAT</
h2>
<
p><
span><
strong class="command">nsupdate</
strong></
span>
<
em class="parameter"><
code>filename</
code></
em>
Each 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
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 <
span><
strong class="command">send</
strong></
span> command)
accumulated commands to be sent as one Dynamic DNS update request to the
The command formats and their meaning are as follows:
<
div class="variablelist"><
dl>
<
span><
strong class="command">server</
strong></
span>
Sends all dynamic update requests to the name server
<
em class="parameter"><
code>servername</
code></
em>.
When no server statement is provided,
<
span><
strong class="command">nsupdate</
strong></
span>
will send updates to the master server of the correct zone.
The MNAME field of that zone's SOA record will identify the
<
em class="parameter"><
code>port</
code></
em>
<
em class="parameter"><
code>servername</
code></
em>
where the dynamic update requests get sent.
If no port number is specified, the default DNS port number of
<
span><
strong class="command">local</
strong></
span>
Sends all dynamic update requests using the local
<
em class="parameter"><
code>address</
code></
em>.
When no local statement is provided,
<
span><
strong class="command">nsupdate</
strong></
span>
will send updates using an address and port chosen by the
<
em class="parameter"><
code>port</
code></
em>
can additionally be used to make requests come from a specific
If no port number is specified, the system will assign one.
<
span><
strong class="command">zone</
strong></
span>
Specifies that all updates are to be made to the zone
<
em class="parameter"><
code>zonename</
code></
em>.
<
em class="parameter"><
code>zone</
code></
em>
<
span><
strong class="command">nsupdate</
strong></
span>
will attempt determine the correct zone to update based on the
<
span><
strong class="command">class</
strong></
span>
Specify the default class.
If no <
em class="parameter"><
code>class</
code></
em> is specified, the
<
em class="parameter"><
code>IN</
code></
em>.
<
span><
strong class="command">ttl</
strong></
span>
Specify the default time to live for records to be added.
The value <
em class="parameter"><
code>none</
code></
em> will clear the default
<
span><
strong class="command">key</
strong></
span>
Specifies that all updates are to be TSIG-signed using the
<
em class="parameter"><
code>keyname</
code></
em> <
em class="parameter"><
code>keysecret</
code></
em> pair.
The <
span><
strong class="command">key</
strong></
span> command
overrides any key specified on the command line via
<
code class="option">-y</
code> or <
code class="option">-k</
code>.
<
span><
strong class="command">gsstsig</
strong></
span>
Use GSS-TSIG to sign the updated. This is equivalent to
specifying <
code class="option">-g</
code> on the commandline.
<
span><
strong class="command">oldgsstsig</
strong></
span>
Use the Windows 2000 version of GSS-TSIG to sign the updated.
This is equivalent to specifying <
code class="option">-o</
code> on the
<
span><
strong class="command">realm</
strong></
span>
{[<
span class="optional">realm_name</
span>]}
When using GSS-TSIG use <
em class="parameter"><
code>realm_name</
code></
em> rather
than the default realm in <
code class="filename">
krb5.conf</
code>. If no
realm is specified the saved realm is cleared.
<
span><
strong class="command">prereq nxdomain</
strong></
span>
Requires that no resource record of any type exists with name
<
em class="parameter"><
code>domain-name</
code></
em>.
<
span><
strong class="command">prereq yxdomain</
strong></
span>
<
em class="parameter"><
code>domain-name</
code></
em>
exists (has as at least one resource record, of any type).
<
span><
strong class="command">prereq nxrrset</
strong></
span>
Requires that no resource record exists of the specified
<
em class="parameter"><
code>type</
code></
em>,
<
em class="parameter"><
code>class</
code></
em>
<
em class="parameter"><
code>domain-name</
code></
em>.
<
em class="parameter"><
code>class</
code></
em>
is omitted, IN (internet) is assumed.
<
span><
strong class="command">prereq yxrrset</
strong></
span>
This requires that a resource record of the specified
<
em class="parameter"><
code>type</
code></
em>,
<
em class="parameter"><
code>class</
code></
em>
<
em class="parameter"><
code>domain-name</
code></
em>
<
em class="parameter"><
code>class</
code></
em>
is omitted, IN (internet) is assumed.
<
span><
strong class="command">prereq yxrrset</
strong></
span>
<
em class="parameter"><
code>data</
code></
em>
from each set of prerequisites of this form
<
em class="parameter"><
code>type</
code></
em>,
<
em class="parameter"><
code>class</
code></
em>,
<
em class="parameter"><
code>domain-name</
code></
em>
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
<
em class="parameter"><
code>type</
code></
em>,
<
em class="parameter"><
code>class</
code></
em>,
<
em class="parameter"><
code>domain-name</
code></
em>.
<
em class="parameter"><
code>data</
code></
em>
are written in the standard text representation of the resource
<
span><
strong class="command">update delete</
strong></
span>
Deletes any resource records named
<
em class="parameter"><
code>domain-name</
code></
em>.
<
em class="parameter"><
code>type</
code></
em>
<
em class="parameter"><
code>data</
code></
em>
is provided, only matching resource records will be removed.
The internet class is assumed if
<
em class="parameter"><
code>class</
code></
em>
<
em class="parameter"><
code>ttl</
code></
em>
is ignored, and is only allowed for compatibility.
<
span><
strong class="command">update add</
strong></
span>
Adds a new resource record with the specified
<
em class="parameter"><
code>ttl</
code></
em>,
<
em class="parameter"><
code>class</
code></
em>
<
em class="parameter"><
code>data</
code></
em>.
<
span><
strong class="command">show</
strong></
span>
Displays the current message, containing all of the
updates specified since the last send.
<
span><
strong class="command">send</
strong></
span>
Sends the current message. This is equivalent to entering a
<
span><
strong class="command">answer</
strong></
span>
<
span><
strong class="command">debug</
strong></
span>
Lines beginning with a semicolon are comments and are ignored.
<
div class="refsect1" lang="en">
<
a name="id2675913"></
a><
h2>EXAMPLES</
h2>
The examples below show how
<
span><
strong class="command">nsupdate</
strong></
span>
could be used to insert and delete resource records from the
Notice that the input in each example contains a trailing blank line so
a group of commands are sent as one dynamic update request to the
<
pre class="programlisting">
with IP address 172.16.1.1 is added.
The newly-added record has a 1 day TTL (86400 seconds).
<
pre class="programlisting">
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 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.)
<
div class="refsect1" lang="en">
<
a name="id2675963"></
a><
h2>FILES</
h2>
<
div class="variablelist"><
dl>
<
dt><
span class="term"><
code class="constant">/
etc/
resolv.conf</
code></
span></
dt>
used to identify default name server
sets the default TSIG key for use in local-only mode
<
dt><
span class="term"><
code class="constant">K{name}.+157.+{random}.key</
code></
span></
dt>
base-64 encoding of HMAC-MD5 key created by
<
span class="citerefentry"><
span class="refentrytitle">dnssec-keygen</
span>(8)</
span>.
<
dt><
span class="term"><
code class="constant">K{name}.+157.+{random}.private</
code></
span></
dt>
base-64 encoding of HMAC-MD5 key created by
<
span class="citerefentry"><
span class="refentrytitle">dnssec-keygen</
span>(8)</
span>.
<
div class="refsect1" lang="en">
<
a name="id2676046"></
a><
h2>SEE ALSO</
h2>
<
em class="citetitle">RFC 2136</
em>,
<
em class="citetitle">RFC 3007</
em>,
<
em class="citetitle">RFC 2104</
em>,
<
em class="citetitle">RFC 2845</
em>,
<
em class="citetitle">RFC 1034</
em>,
<
em class="citetitle">RFC 2535</
em>,
<
em class="citetitle">RFC 2931</
em>,
<
span class="citerefentry"><
span class="refentrytitle">named</
span>(8)</
span>,
<
span class="citerefentry"><
span class="refentrytitle">ddns-confgen</
span>(8)</
span>,
<
span class="citerefentry"><
span class="refentrytitle">dnssec-keygen</
span>(8)</
span>.
<
div class="refsect1" lang="en">
<
a name="id2676104"></
a><
h2>BUGS</
h2>
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
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