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div class="refentry" lang="en">
0N/A<
div class="refnamediv">
0N/A<
p><
span class="application">nsupdate</
span> — Dynamic DNS update utility</
p>
2488N/A<
div class="refsynopsisdiv">
0N/A<
div class="cmdsynopsis"><
p><
code class="command">nsupdate</
code> [<
code class="option">-d</
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>
0N/A<
div class="refsect1" lang="en">
0N/A<
a name="id2543433"></
a><
h2>DESCRIPTION</
h2>
0N/A<
p><
span><
strong class="command">nsupdate</
strong></
span>
0N/A is used to submit Dynamic DNS Update requests as defined in RFC2136
0N/A This allows resource records to be added or removed from a zone
0N/A without manually editing the zone file.
0N/A A single update request can contain requests to add or remove more than
0N/A Zones that are under dynamic control via
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A or a DHCP server should not be edited by hand.
0N/A conflict with dynamic updates and cause data to be lost.
0N/A The resource records that are dynamically added or removed with
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A have to be in the same zone.
0N/A Requests are sent to the zone's master server.
0N/A This is identified by the MNAME field of the zone's SOA record.
0N/A <
code class="option">-d</
code>
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A operate in debug mode.
0N/A This provides tracing information about the update requests that are
0N/A made and the replies received from the name server.
0N/A Transaction signatures can be used to authenticate the Dynamic DNS
0N/A These use the TSIG resource record type described in RFC2845 or the
0N/A SIG(0) record described in RFC3535 and RFC2931.
0N/A TSIG relies on a shared secret that should only be known to
2488N/A <
span><
strong class="command">nsupdate</
strong></
span> and the name server.
0N/A Currently, the only supported encryption algorithm for TSIG is
0N/A HMAC-MD5, which is defined in RFC 2104.
0N/A Once other algorithms are defined for TSIG, applications will need to
0N/A ensure they select the appropriate algorithm as well as the key when
4005N/A <
span class="type">key</
span>
4005N/A <
span class="type">server</
span>
4005N/A statements would be added to
0N/A so that the name server can associate the appropriate secret key
0N/A and algorithm with the IP address of the
0N/A client application that will be using TSIG authentication.
2488N/A SIG(0) uses public key cryptography. To use a SIG(0) key, the public
0N/A key must be stored in a KEY record in a zone served by the name server.
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A<
p><
span><
strong class="command">nsupdate</
strong></
span>
0N/A uses the <
code class="option">-y</
code> or <
code class="option">-k</
code> option
0N/A to provide the shared secret needed to generate a TSIG record
2488N/A for authenticating Dynamic DNS update requests, default type
0N/A HMAC-MD5. These options are mutually exclusive. With the
0N/A <
code class="option">-k</
code> option, <
span><
strong class="command">nsupdate</
strong></
span> reads
0N/A the shared secret from the file <
em class="parameter"><
code>keyfile</
code></
em>,
0N/A whose name is of the form
0N/A <
code class="filename">K{name}.+157.+{random}.private</
code>. For
0N/A historical reasons, the file
0N/A <
code class="filename">K{name}.+157.+{random}.key</
code> must also be
2488N/A present. When the <
code class="option">-y</
code> option is used, a
0N/A signature is generated from
0N/A [<
span class="optional"><
em class="parameter"><
code>hmac:</
code></
em></
span>]<
em class="parameter"><
code>keyname:secret.</
code></
em>
0N/A <
em class="parameter"><
code>keyname</
code></
em> is the name of the key, and
0N/A <
em class="parameter"><
code>secret</
code></
em> is the base64 encoded shared
0N/A secret. Use of the <
code class="option">-y</
code> option is discouraged
0N/A because the shared secret is supplied as a command line
0N/A argument in clear text. This may be visible in the output
0N/A <
span class="citerefentry"><
span class="refentrytitle">ps</
span>(1)</
span> or in a history file maintained by the user's
0N/A The <
code class="option">-k</
code> may also be used to specify a SIG(0) key used
0N/A to authenticate Dynamic DNS update requests. In this case, the key
0N/A specified is not an HMAC-MD5 key.
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A uses UDP to send update requests to the name server unless they are too
0N/A large to fit in a UDP request in which case TCP will be used.
0N/A <
code class="option">-v</
code>
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A use a TCP connection.
0N/A This may be preferable when a batch of update requests is made.
0N/A The <
code class="option">-t</
code> option sets the maximum time an update request
0N/A take before it is aborted. The default is 300 seconds. Zero can be
0N/A to disable the timeout.
0N/A The <
code class="option">-u</
code> option sets the UDP retry interval. The default
0N/A 3 seconds. If zero, the interval will be computed from the timeout
0N/A and number of UDP retries.
0N/A The <
code class="option">-r</
code> option sets the number of UDP retries. The
0N/A 3. If zero, only one update request will be made.
0N/A The <
code class="option">-R <
em class="replaceable"><
code>randomdev</
code></
em></
code> option
0N/A specifies a source of randomness. If the operating system
0N/A does not provide a <
code class="filename">/
dev/
random</
code> or
0N/A equivalent device, the default source of randomness is keyboard
0N/A input. <
code class="filename">randomdev</
code> specifies the name of
0N/A a character device or file containing random data to be used
0N/A instead of the default. The special value
0N/A <
code class="filename">keyboard</
code> indicates that keyboard input
0N/A should be used. This option may be specified multiple times.
0N/A<
div class="refsect1" lang="en">
0N/A<
a name="id2543682"></
a><
h2>INPUT FORMAT</
h2>
0N/A<
p><
span><
strong class="command">nsupdate</
strong></
span>
0N/A <
em class="parameter"><
code>filename</
code></
em>
0N/A Each command is supplied on exactly one line of input.
0N/A Some commands are for administrative purposes.
0N/A The others are either update instructions or prerequisite checks on the
0N/A contents of the zone.
0N/A These checks set conditions that some name or set of
0N/A resource records (RRset) either exists or is absent from the zone.
0N/A These conditions must be met if the entire update request is to succeed.
0N/A Updates will be rejected if the tests for the prerequisite conditions
4005N/A Every update request consists of zero or more prerequisites
4005N/A This allows a suitably authenticated update request to proceed if some
4005N/A specified resource records are present or missing from the zone.
4005N/A A blank input line (or the <
span><
strong class="command">send</
strong></
span> command)
4005N/A accumulated commands to be sent as one Dynamic DNS update request to the
4005N/A The command formats and their meaning are as follows:
4005N/A<
div class="variablelist"><
dl>
4005N/A <
span><
strong class="command">server</
strong></
span>
4005N/A Sends all dynamic update requests to the name server
4005N/A <
em class="parameter"><
code>servername</
code></
em>.
0N/A When no server statement is provided,
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A will send updates to the master server of the correct zone.
0N/A The MNAME field of that zone's SOA record will identify the
0N/A server for that zone.
0N/A <
em class="parameter"><
code>port</
code></
em>
0N/A is the port number on
0N/A <
em class="parameter"><
code>servername</
code></
em>
0N/A where the dynamic update requests get sent.
0N/A If no port number is specified, the default DNS port number of
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">local</
strong></
span>
0N/A Sends all dynamic update requests using the local
0N/A <
em class="parameter"><
code>address</
code></
em>.
0N/A When no local statement is provided,
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
0N/A will send updates using an address and port chosen by the
0N/A <
em class="parameter"><
code>port</
code></
em>
0N/A can additionally be used to make requests come from a specific
0N/A If no port number is specified, the system will assign one.
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">zone</
strong></
span>
0N/A Specifies that all updates are to be made to the zone
0N/A <
em class="parameter"><
code>zonename</
code></
em>.
0N/A <
em class="parameter"><
code>zone</
code></
em>
0N/A statement is provided,
0N/A <
span><
strong class="command">nsupdate</
strong></
span>
2614N/A will attempt determine the correct zone to update based on the
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">class</
strong></
span>
0N/A Specify the default class.
2728N/A If no <
em class="parameter"><
code>class</
code></
em> is specified, the
2728N/A <
em class="parameter"><
code>IN</
code></
em>.
2728N/A <
span><
strong class="command">key</
strong></
span>
2728N/A Specifies that all updates are to be TSIG-signed using the
2728N/A <
em class="parameter"><
code>keyname</
code></
em> <
em class="parameter"><
code>keysecret</
code></
em> pair.
2728N/A The <
span><
strong class="command">key</
strong></
span> command
2728N/A overrides any key specified on the command line via
2728N/A <
code class="option">-y</
code> or <
code class="option">-k</
code>.
2728N/A <
span><
strong class="command">prereq nxdomain</
strong></
span>
0N/A Requires that no resource record of any type exists with name
0N/A <
em class="parameter"><
code>domain-name</
code></
em>.
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">prereq yxdomain</
strong></
span>
0N/A <
em class="parameter"><
code>domain-name</
code></
em>
0N/A exists (has as at least one resource record, of any type).
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">prereq nxrrset</
strong></
span>
0N/A Requires that no resource record exists of the specified
0N/A <
em class="parameter"><
code>type</
code></
em>,
0N/A <
em class="parameter"><
code>class</
code></
em>
0N/A <
em class="parameter"><
code>domain-name</
code></
em>.
0N/A <
em class="parameter"><
code>class</
code></
em>
0N/A is omitted, IN (internet) is assumed.
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">prereq yxrrset</
strong></
span>
4005N/A This requires that a resource record of the specified
0N/A <
em class="parameter"><
code>type</
code></
em>,
0N/A <
em class="parameter"><
code>class</
code></
em>
0N/A <
em class="parameter"><
code>domain-name</
code></
em>
0N/A <
em class="parameter"><
code>class</
code></
em>
0N/A is omitted, IN (internet) is assumed.
0N/A<
dt><
span class="term">
0N/A <
span><
strong class="command">prereq yxrrset</
strong></
span>
0N/A <
em class="parameter"><
code>data</
code></
em>
0N/A from each set of prerequisites of this form
0N/A <
em class="parameter"><
code>type</
code></
em>,
0N/A <
em class="parameter"><
code>class</
code></
em>,
0N/A <
em class="parameter"><
code>domain-name</
code></
em>
0N/A are combined to form a set of RRs. This set of RRs must
0N/A exactly match the set of RRs existing in the zone at the
0N/A <
em class="parameter"><
code>type</
code></
em>,
2488N/A <
em class="parameter"><
code>class</
code></
em>,
2488N/A <
em class="parameter"><
code>domain-name</
code></
em>.
2488N/A <
em class="parameter"><
code>data</
code></
em>
2488N/A are written in the standard text representation of the resource
2488N/A <
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>
Lines beginning with a semicolon are comments and are ignored.
<
div class="refsect1" lang="en">
<
a name="id2544684"></
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 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.)
<
div class="refsect1" lang="en">
<
a name="id2544728"></
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
<
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="id2544797"></
a><
h2>SEE ALSO</
h2>
<
p><
span class="citerefentry"><
span class="refentrytitle">RFC2136</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">RFC3007</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">RFC2104</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">RFC2845</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">RFC1034</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">RFC2535</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">RFC2931</
span></
span>,
<
span class="citerefentry"><
span class="refentrytitle">named</
span>(8)</
span>,
<
span class="citerefentry"><
span class="refentrytitle">dnssec-keygen</
span>(8)</
span>.
<
div class="refsect1" lang="en">
<
a name="id2544868"></
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