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178N/A<
tr><
th colspan="3" align="center"><
span class="application">nsupdate</
span></
th></
tr>
618N/A<
td width="20%" align="left">
178N/A<
th width="60%" align="center">Manual pages</
th>
178N/A<
div class="refentry" lang="en">
178N/A<
div class="refnamediv">
519N/A<
p><
span class="application">nsupdate</
span> — Dynamic DNS update utility</
p>
178N/A<
div class="refsynopsisdiv">
178N/A<
div class="cmdsynopsis"><
p><
code class="command">nsupdate</
code> [<
code class="option">-d</
code>] [<
code class="option">-D</
code>] [<
code class="option">-L <
em class="replaceable"><
code>level</
code></
em></
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>] [<
code class="option">-T</
code>] [<
code class="option">-P</
code>] [<
code class="option">-V</
code>] [filename]</
p></
div>
178N/A<
div class="refsect1" lang="en">
178N/A<
a name="id2657092"></
a><
h2>DESCRIPTION</
h2>
178N/A<
p><
span><
strong class="command">nsupdate</
strong></
span>
178N/A is used to submit Dynamic DNS Update requests as defined in RFC 2136
178N/A This allows resource records to be added or removed from a zone
178N/A without manually editing the zone file.
1387N/A A single update request can contain requests to add or remove more than
178N/A Zones that are under dynamic control via
178N/A <
span><
strong class="command">nsupdate</
strong></
span>
178N/A or a DHCP server should not be edited by hand.
1387N/A conflict with dynamic updates and cause data to be lost.
178N/A The resource records that are dynamically added or removed with
1387N/A <
span><
strong class="command">nsupdate</
strong></
span>
178N/A have to be in the same zone.
178N/A Requests are sent to the zone's master server.
178N/A This is identified by the MNAME field of the zone's SOA record.
178N/A Transaction signatures can be used to authenticate the Dynamic
178N/A DNS updates. These use the TSIG resource record type described
178N/A in RFC 2845 or the SIG(0) record described in RFC 2535 and
178N/A RFC 2931 or GSS-TSIG as described in RFC 3645.
1387N/A a shared secret that should only be known to
1387N/A <
span><
strong class="command">nsupdate</
strong></
span> and the name server.
1387N/A For instance, suitable <
span class="type">key</
span> and
1387N/A <
span class="type">server</
span> statements would be added to
1387N/A can associate the appropriate secret key and algorithm with
1387N/A the IP address of the client application that will be using
178N/A TSIG authentication. You can use <
span><
strong class="command">ddns-confgen</
strong></
span>
178N/A to generate suitable configuration fragments.
181N/A <
span><
strong class="command">nsupdate</
strong></
span>
178N/A uses the <
code class="option">-y</
code> or <
code class="option">-k</
code> options
1387N/A to provide the TSIG shared secret. These options are mutually exclusive.
1387N/A SIG(0) uses public key cryptography.
178N/A To use a SIG(0) key, the public key must be stored in a KEY
178N/A record in a zone served by the name server.
178N/A GSS-TSIG uses Kerberos credentials. Standard GSS-TSIG mode
178N/A is switched on with the <
code class="option">-g</
code> flag. A
178N/A non-standards-compliant variant of GSS-TSIG used by Windows
178N/A 2000 can be switched on with the <
code class="option">-o</
code> flag.
178N/A<
div class="refsect1" lang="en">
178N/A<
a name="id2659365"></
a><
h2>OPTIONS</
h2>
178N/A<
div class="variablelist"><
dl>
<
dt><
span class="term">-d</
span></
dt>
Debug mode. This provides tracing information about the
update requests that are made and the replies received
<
dt><
span class="term">-D</
span></
dt>
<
dt><
span class="term">-k <
em class="replaceable"><
code>keyfile</
code></
em></
span></
dt>
The file containing the TSIG authentication key.
Keyfiles may be in two formats: a single file containing
a <
code class="filename">
named.conf</
code>-format <
span><
strong class="command">key</
strong></
span>
statement, which may be generated automatically by
<
span><
strong class="command">ddns-confgen</
strong></
span>, or a pair of files whose names are
of the format <
code class="filename">K{name}.+157.+{random}.key</
code> and
<
code class="filename">K{name}.+157.+{random}.private</
code>, which can be
generated by <
span><
strong class="command">dnssec-keygen</
strong></
span>.
The <
code class="option">-k</
code> 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.
<
dt><
span class="term">-l</
span></
dt>
Local-host only mode. This sets the server address to
localhost (disabling the <
span><
strong class="command">server</
strong></
span> so that the server
address cannot be overridden). Connections to the local server will
which is automatically generated by <
span><
strong class="command">named</
strong></
span> if any
local master zone has set <
span><
strong class="command">update-policy</
strong></
span> to
<
span><
strong class="command">local</
strong></
span>. The location of this key file can be
overridden with the <
code class="option">-k</
code> option.
<
dt><
span class="term">-L <
em class="replaceable"><
code>level</
code></
em></
span></
dt>
Set the logging debug level. If zero, logging is disabled.
<
dt><
span class="term">-p <
em class="replaceable"><
code>port</
code></
em></
span></
dt>
Set the port to use for connections to a name server. The
<
dt><
span class="term">-P</
span></
dt>
Print the list of private BIND-specific resource record
types whose format is understood
by <
span><
strong class="command">nsupdate</
strong></
span>. See also
the <
code class="option">-T</
code> option.
<
dt><
span class="term">-r <
em class="replaceable"><
code>udpretries</
code></
em></
span></
dt>
The number of UDP retries. The default is 3. If zero, only
one update request will be made.
<
dt><
span class="term">-R <
em class="replaceable"><
code>randomdev</
code></
em></
span></
dt>
Where to obtain 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.
<
dt><
span class="term">-t <
em class="replaceable"><
code>timeout</
code></
em></
span></
dt>
The maximum time an update request can take before it is
aborted. The default is 300 seconds. Zero can be used to
<
dt><
span class="term">-T</
span></
dt>
Print the list of IANA standard resource record types
whose format is understood by <
span><
strong class="command">nsupdate</
strong></
span>.
<
span><
strong class="command">nsupdate</
strong></
span> will exit after the lists are
printed. The <
code class="option">-T</
code> option can be combined
with the <
code class="option">-P</
code> option.
Other types can be entered using "TYPEXXXXX" where "XXXXX" is the
decimal value of the type with no leading zeros. The rdata,
if present, will be parsed using the UNKNOWN rdata format,
(<backslash> <hash> <space> <length>
<space> <hexstring>).
<
dt><
span class="term">-u <
em class="replaceable"><
code>udptimeout</
code></
em></
span></
dt>
The UDP retry interval. The default is 3 seconds. If zero,
the interval will be computed from the timeout interval and
<
dt><
span class="term">-v</
span></
dt>
Use TCP even for small update requests.
By default, <
span><
strong class="command">nsupdate</
strong></
span>
uses 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.
TCP may be preferable when a batch of update requests is made.
<
dt><
span class="term">-V</
span></
dt>
Print the version number and exit.
<
dt><
span class="term">-y <
em class="replaceable"><
code>[<
span class="optional">hmac:</
span>]keyname:secret</
code></
em></
span></
dt>
Literal TSIG authentication key.
<
em class="parameter"><
code>keyname</
code></
em> is the name of the key, and
<
em class="parameter"><
code>secret</
code></
em> is the base64 encoded shared secret.
<
em class="parameter"><
code>hmac</
code></
em> is the name of the key algorithm;
valid choices are <
code class="literal">hmac-md5</
code>,
<
code class="literal">hmac-sha1</
code>, <
code class="literal">hmac-sha224</
code>,
<
code class="literal">hmac-sha256</
code>, <
code class="literal">hmac-sha384</
code>, or
<
code class="literal">hmac-sha512</
code>. If <
em class="parameter"><
code>hmac</
code></
em>
is not specified, the default is <
code class="literal">hmac-md5</
code>.
NOTE: Use of the <
code class="option">-y</
code> 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
<
span class="citerefentry"><
span class="refentrytitle">ps</
span>(1)</
span>
or in a history file maintained by the user's shell.
<
div class="refsect1" lang="en">
<
a name="id2689981"></
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>secret</
code></
em> pair.
If <
em class="parameter"><
code>hmac</
code></
em> is specified, then it sets the
signing algorithm in use; the default is
<
code class="literal">hmac-md5</
code>. 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 command line.
<
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">check-names</
strong></
span>
{[<
span class="optional">yes_or_no</
span>]}
Turn on or off check-names processing on records to
be added. Check-names has no effect on prerequisites
or records to be deleted. By default check-names
processing is on. If check-names processing fails
the record will not be added to the UPDATE message.
<
span><
strong class="command">[<
span class="optional">prereq</
span>] 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">[<
span class="optional">prereq</
span>] 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">[<
span class="optional">prereq</
span>] 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">[<
span class="optional">prereq</
span>] 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">[<
span class="optional">prereq</
span>] 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">[<
span class="optional">update</
span>] del[<
span class="optional">ete</
span>]</
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">[<
span class="optional">update</
span>] 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>
<
span><
strong class="command">version</
strong></
span>
<
span><
strong class="command">help</
strong></
span>
Print a list of commands.
Lines beginning with a semicolon are comments and are ignored.
<
div class="refsect1" lang="en">
<
a name="id2691123"></
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="id2691241"></
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="id2691328"></
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="id2691453"></
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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