contrib/bind-9.5.2/bin/nsupdate/nsupdate.html

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  21 <title>nsupdate</title>
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  24 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
  25 <a name="id2476275"></a><div class="titlepage"></div>
  26 <div class="refnamediv">
  27 <h2>Name</h2>
  28 <p>nsupdate &#8212; Dynamic DNS update utility</p>
  29 </div>
  30 <div class="refsynopsisdiv">
  31 <h2>Synopsis</h2>
  32 <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>
  33 </div>
  34 <div class="refsect1" lang="en">
  35 <a name="id2543432"></a><h2>DESCRIPTION</h2>
  36 <p><span><strong class="command">nsupdate</strong></span>
  37       is used to submit Dynamic DNS Update requests as defined in RFC2136
  38       to a name server.
  39       This allows resource records to be added or removed from a zone
  40       without manually editing the zone file.
  41       A single update request can contain requests to add or remove more than
  42       one
  43       resource record.
  44     </p>
  45 <p>
  46       Zones that are under dynamic control via
  47       <span><strong class="command">nsupdate</strong></span>
  48       or a DHCP server should not be edited by hand.
  49       Manual edits could
  50       conflict with dynamic updates and cause data to be lost.
  51     </p>
  52 <p>
  53       The resource records that are dynamically added or removed with
  54       <span><strong class="command">nsupdate</strong></span>
  55       have to be in the same zone.
  56       Requests are sent to the zone's master server.
  57       This is identified by the MNAME field of the zone's SOA record.
  58     </p>
  59 <p>
  60       The
  61       <code class="option">-d</code>
  62       option makes
  63       <span><strong class="command">nsupdate</strong></span>
  64       operate in debug mode.
  65       This provides tracing information about the update requests that are
  66       made and the replies received from the name server.
  67     </p>
  68 <p>
  69       Transaction signatures can be used to authenticate the Dynamic DNS
  70       updates.
  71       These use the TSIG resource record type described in RFC2845 or the
  72       SIG(0) record described in RFC3535 and RFC2931.
  73       TSIG relies on a shared secret that should only be known to
  74       <span><strong class="command">nsupdate</strong></span> and the name server.
  75       Currently, the only supported encryption algorithm for TSIG is
  76       HMAC-MD5, which is defined in RFC 2104.
  77       Once other algorithms are defined for TSIG, applications will need to
  78       ensure they select the appropriate algorithm as well as the key when
  79       authenticating each other.
  80       For instance, suitable
  81       <span class="type">key</span>
  82       and
  83       <span class="type">server</span>
  84       statements would be added to
  85       <code class="filename">/etc/named.conf</code>
  86       so that the name server can associate the appropriate secret key
  87       and algorithm with the IP address of the
  88       client application that will be using TSIG authentication.
  89       SIG(0) uses public key cryptography.  To use a SIG(0) key, the public
  90       key must be stored in a KEY record in a zone served by the name server.
  91       <span><strong class="command">nsupdate</strong></span>
  92       does not read
  93       <code class="filename">/etc/named.conf</code>.
  94     </p>
  95 <p><span><strong class="command">nsupdate</strong></span>
  96       uses the <code class="option">-y</code> or <code class="option">-k</code> option
  97       to provide the shared secret needed to generate a TSIG record
  98       for authenticating Dynamic DNS update requests, default type
  99       HMAC-MD5.  These options are mutually exclusive.  With the
 100       <code class="option">-k</code> option, <span><strong class="command">nsupdate</strong></span> reads
 101       the shared secret from the file <em class="parameter"><code>keyfile</code></em>,
 102       whose name is of the form
 103       <code class="filename">K{name}.+157.+{random}.private</code>.  For
 104       historical reasons, the file
 105       <code class="filename">K{name}.+157.+{random}.key</code> must also be
 106       present.  When the <code class="option">-y</code> option is used, a
 107       signature is generated from
 108       [<span class="optional"><em class="parameter"><code>hmac:</code></em></span>]<em class="parameter"><code>keyname:secret.</code></em>
 109       <em class="parameter"><code>keyname</code></em> is the name of the key, and
 110       <em class="parameter"><code>secret</code></em> is the base64 encoded shared
 111       secret.  Use of the <code class="option">-y</code> option is discouraged
 112       because the shared secret is supplied as a command line
 113       argument in clear text.  This may be visible in the output
 114       from
 115       <span class="citerefentry"><span class="refentrytitle">ps</span>(1)</span> or in a history file maintained by the user's
 116       shell.
 117     </p>
 118 <p>
 119       The <code class="option">-k</code> may also be used to specify a SIG(0) key used
 120       to authenticate Dynamic DNS update requests.  In this case, the key
 121       specified is not an HMAC-MD5 key.
 122     </p>
 123 <p>
 124       By default,
 125       <span><strong class="command">nsupdate</strong></span>
 126       uses UDP to send update requests to the name server unless they are too
 127       large to fit in a UDP request in which case TCP will be used.
 128       The
 129       <code class="option">-v</code>
 130       option makes
 131       <span><strong class="command">nsupdate</strong></span>
 132       use a TCP connection.
 133       This may be preferable when a batch of update requests is made.
 134     </p>
 135 <p>
 136       The <code class="option">-t</code> option sets the maximum time an update request
 137       can
 138       take before it is aborted.  The default is 300 seconds.  Zero can be
 139       used
 140       to disable the timeout.
 141     </p>
 142 <p>
 143       The <code class="option">-u</code> option sets the UDP retry interval.  The default
 144       is
 145       3 seconds.  If zero, the interval will be computed from the timeout
 146       interval
 147       and number of UDP retries.
 148     </p>
 149 <p>
 150       The <code class="option">-r</code> option sets the number of UDP retries. The
 151       default is
 152       3.  If zero, only one update request will be made.
 153     </p>
 154 <p>
 155       The <code class="option">-R <em class="replaceable"><code>randomdev</code></em></code> option
 156       specifies a source of randomness.  If the operating system
 157       does not provide a <code class="filename">/dev/random</code> or
 158       equivalent device, the default source of randomness is keyboard
 159       input.  <code class="filename">randomdev</code> specifies the name of
 160       a character device or file containing random data to be used
 161       instead of the default.  The special value
 162       <code class="filename">keyboard</code> indicates that keyboard input
 163       should be used.  This option may be specified multiple times.
 164     </p>
 165 </div>
 166 <div class="refsect1" lang="en">
 167 <a name="id2543681"></a><h2>INPUT FORMAT</h2>
 168 <p><span><strong class="command">nsupdate</strong></span>
 169       reads input from
 170       <em class="parameter"><code>filename</code></em>
 171       or standard input.
 172       Each command is supplied on exactly one line of input.
 173       Some commands are for administrative purposes.
 174       The others are either update instructions or prerequisite checks on the
 175       contents of the zone.
 176       These checks set conditions that some name or set of
 177       resource records (RRset) either exists or is absent from the zone.
 178       These conditions must be met if the entire update request is to succeed.
 179       Updates will be rejected if the tests for the prerequisite conditions
 180       fail.
 181     </p>
 182 <p>
 183       Every update request consists of zero or more prerequisites
 184       and zero or more updates.
 185       This allows a suitably authenticated update request to proceed if some
 186       specified resource records are present or missing from the zone.
 187       A blank input line (or the <span><strong class="command">send</strong></span> command)
 188       causes the
 189       accumulated commands to be sent as one Dynamic DNS update request to the
 190       name server.
 191     </p>
 192 <p>
 193       The command formats and their meaning are as follows:
 194       </p>
 195 <div class="variablelist"><dl>
 196 <dt><span class="term">
 197               <span><strong class="command">server</strong></span>
 198                {servername}
 199                [port]
 200             </span></dt>
 201 <dd><p>
 202               Sends all dynamic update requests to the name server
 203               <em class="parameter"><code>servername</code></em>.
 204               When no server statement is provided,
 205               <span><strong class="command">nsupdate</strong></span>
 206               will send updates to the master server of the correct zone.
 207               The MNAME field of that zone's SOA record will identify the
 208               master
 209               server for that zone.
 210               <em class="parameter"><code>port</code></em>
 211               is the port number on
 212               <em class="parameter"><code>servername</code></em>
 213               where the dynamic update requests get sent.
 214               If no port number is specified, the default DNS port number of
 215               53 is
 216               used.
 217             </p></dd>
 218 <dt><span class="term">
 219               <span><strong class="command">local</strong></span>
 220                {address}
 221                [port]
 222             </span></dt>
 223 <dd><p>
 224               Sends all dynamic update requests using the local
 225               <em class="parameter"><code>address</code></em>.
 226
 227               When no local statement is provided,
 228               <span><strong class="command">nsupdate</strong></span>
 229               will send updates using an address and port chosen by the
 230               system.
 231               <em class="parameter"><code>port</code></em>
 232               can additionally be used to make requests come from a specific
 233               port.
 234               If no port number is specified, the system will assign one.
 235             </p></dd>
 236 <dt><span class="term">
 237               <span><strong class="command">zone</strong></span>
 238                {zonename}
 239             </span></dt>
 240 <dd><p>
 241               Specifies that all updates are to be made to the zone
 242               <em class="parameter"><code>zonename</code></em>.
 243               If no
 244               <em class="parameter"><code>zone</code></em>
 245               statement is provided,
 246               <span><strong class="command">nsupdate</strong></span>
 247               will attempt determine the correct zone to update based on the
 248               rest of the input.
 249             </p></dd>
 250 <dt><span class="term">
 251               <span><strong class="command">class</strong></span>
 252                {classname}
 253             </span></dt>
 254 <dd><p>
 255               Specify the default class.
 256               If no <em class="parameter"><code>class</code></em> is specified, the
 257               default class is
 258               <em class="parameter"><code>IN</code></em>.
 259             </p></dd>
 260 <dt><span class="term">
 261               <span><strong class="command">key</strong></span>
 262                {name}
 263                {secret}
 264             </span></dt>
 265 <dd><p>
 266               Specifies that all updates are to be TSIG-signed using the
 267               <em class="parameter"><code>keyname</code></em> <em class="parameter"><code>keysecret</code></em> pair.
 268               The <span><strong class="command">key</strong></span> command
 269               overrides any key specified on the command line via
 270               <code class="option">-y</code> or <code class="option">-k</code>.
 271             </p></dd>
 272 <dt><span class="term">
 273               <span><strong class="command">prereq nxdomain</strong></span>
 274                {domain-name}
 275             </span></dt>
 276 <dd><p>
 277               Requires that no resource record of any type exists with name
 278               <em class="parameter"><code>domain-name</code></em>.
 279             </p></dd>
 280 <dt><span class="term">
 281               <span><strong class="command">prereq yxdomain</strong></span>
 282                {domain-name}
 283             </span></dt>
 284 <dd><p>
 285               Requires that
 286               <em class="parameter"><code>domain-name</code></em>
 287               exists (has as at least one resource record, of any type).
 288             </p></dd>
 289 <dt><span class="term">
 290               <span><strong class="command">prereq nxrrset</strong></span>
 291                {domain-name}
 292                [class]
 293                {type}
 294             </span></dt>
 295 <dd><p>
 296               Requires that no resource record exists of the specified
 297               <em class="parameter"><code>type</code></em>,
 298               <em class="parameter"><code>class</code></em>
 299               and
 300               <em class="parameter"><code>domain-name</code></em>.
 301               If
 302               <em class="parameter"><code>class</code></em>
 303               is omitted, IN (internet) is assumed.
 304             </p></dd>
 305 <dt><span class="term">
 306               <span><strong class="command">prereq yxrrset</strong></span>
 307                {domain-name}
 308                [class]
 309                {type}
 310             </span></dt>
 311 <dd><p>
 312               This requires that a resource record of the specified
 313               <em class="parameter"><code>type</code></em>,
 314               <em class="parameter"><code>class</code></em>
 315               and
 316               <em class="parameter"><code>domain-name</code></em>
 317               must exist.
 318               If
 319               <em class="parameter"><code>class</code></em>
 320               is omitted, IN (internet) is assumed.
 321             </p></dd>
 322 <dt><span class="term">
 323               <span><strong class="command">prereq yxrrset</strong></span>
 324                {domain-name}
 325                [class]
 326                {type}
 327                {data...}
 328             </span></dt>
 329 <dd><p>
 330               The
 331               <em class="parameter"><code>data</code></em>
 332               from each set of prerequisites of this form
 333               sharing a common
 334               <em class="parameter"><code>type</code></em>,
 335               <em class="parameter"><code>class</code></em>,
 336               and
 337               <em class="parameter"><code>domain-name</code></em>
 338               are combined to form a set of RRs.  This set of RRs must
 339               exactly match the set of RRs existing in the zone at the
 340               given
 341               <em class="parameter"><code>type</code></em>,
 342               <em class="parameter"><code>class</code></em>,
 343               and
 344               <em class="parameter"><code>domain-name</code></em>.
 345               The
 346               <em class="parameter"><code>data</code></em>
 347               are written in the standard text representation of the resource
 348               record's
 349               RDATA.
 350             </p></dd>
 351 <dt><span class="term">
 352               <span><strong class="command">update delete</strong></span>
 353                {domain-name}
 354                [ttl]
 355                [class]
 356                [type [data...]]
 357             </span></dt>
 358 <dd><p>
 359               Deletes any resource records named
 360               <em class="parameter"><code>domain-name</code></em>.
 361               If
 362               <em class="parameter"><code>type</code></em>
 363               and
 364               <em class="parameter"><code>data</code></em>
 365               is provided, only matching resource records will be removed.
 366               The internet class is assumed if
 367               <em class="parameter"><code>class</code></em>
 368               is not supplied.  The
 369               <em class="parameter"><code>ttl</code></em>
 370               is ignored, and is only allowed for compatibility.
 371             </p></dd>
 372 <dt><span class="term">
 373               <span><strong class="command">update add</strong></span>
 374                {domain-name}
 375                {ttl}
 376                [class]
 377                {type}
 378                {data...}
 379             </span></dt>
 380 <dd><p>
 381               Adds a new resource record with the specified
 382               <em class="parameter"><code>ttl</code></em>,
 383               <em class="parameter"><code>class</code></em>
 384               and
 385               <em class="parameter"><code>data</code></em>.
 386             </p></dd>
 387 <dt><span class="term">
 388               <span><strong class="command">show</strong></span>
 389             </span></dt>
 390 <dd><p>
 391               Displays the current message, containing all of the
 392               prerequisites and
 393               updates specified since the last send.
 394             </p></dd>
 395 <dt><span class="term">
 396               <span><strong class="command">send</strong></span>
 397             </span></dt>
 398 <dd><p>
 399               Sends the current message.  This is equivalent to entering a
 400               blank line.
 401             </p></dd>
 402 <dt><span class="term">
 403               <span><strong class="command">answer</strong></span>
 404             </span></dt>
 405 <dd><p>
 406               Displays the answer.
 407             </p></dd>
 408 </dl></div>
 409 <p>
 410     </p>
 411 <p>
 412       Lines beginning with a semicolon are comments and are ignored.
 413     </p>
 414 </div>
 415 <div class="refsect1" lang="en">
 416 <a name="id2544478"></a><h2>EXAMPLES</h2>
 417 <p>
 418       The examples below show how
 419       <span><strong class="command">nsupdate</strong></span>
 420       could be used to insert and delete resource records from the
 421       <span class="type">example.com</span>
 422       zone.
 423       Notice that the input in each example contains a trailing blank line so
 424       that
 425       a group of commands are sent as one dynamic update request to the
 426       master name server for
 427       <span class="type">example.com</span>.
 428
 429       </p>
 430 <pre class="programlisting">
 431 # nsupdate
 432 &gt; update delete oldhost.example.com A
 433 &gt; update add newhost.example.com 86400 A 172.16.1.1
 434 &gt; send
 435 </pre>
 436 <p>
 437     </p>
 438 <p>
 439       Any A records for
 440       <span class="type">oldhost.example.com</span>
 441       are deleted.
 442       And an A record for
 443       <span class="type">newhost.example.com</span>
 444       with IP address 172.16.1.1 is added.
 445       The newly-added record has a 1 day TTL (86400 seconds).
 446       </p>
 447 <pre class="programlisting">
 448 # nsupdate
 449 &gt; prereq nxdomain nickname.example.com
 450 &gt; update add nickname.example.com 86400 CNAME somehost.example.com
 451 &gt; send
 452 </pre>
 453 <p>
 454     </p>
 455 <p>
 456       The prerequisite condition gets the name server to check that there
 457       are no resource records of any type for
 458       <span class="type">nickname.example.com</span>.
 459
 460       If there are, the update request fails.
 461       If this name does not exist, a CNAME for it is added.
 462       This ensures that when the CNAME is added, it cannot conflict with the
 463       long-standing rule in RFC1034 that a name must not exist as any other
 464       record type if it exists as a CNAME.
 465       (The rule has been updated for DNSSEC in RFC2535 to allow CNAMEs to have
 466       RRSIG, DNSKEY and NSEC records.)
 467     </p>
 468 </div>
 469 <div class="refsect1" lang="en">
 470 <a name="id2544522"></a><h2>FILES</h2>
 471 <div class="variablelist"><dl>
 472 <dt><span class="term"><code class="constant">/etc/resolv.conf</code></span></dt>
 473 <dd><p>
 474             used to identify default name server
 475           </p></dd>
 476 <dt><span class="term"><code class="constant">K{name}.+157.+{random}.key</code></span></dt>
 477 <dd><p>
 478             base-64 encoding of HMAC-MD5 key created by
 479             <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
 480           </p></dd>
 481 <dt><span class="term"><code class="constant">K{name}.+157.+{random}.private</code></span></dt>
 482 <dd><p>
 483             base-64 encoding of HMAC-MD5 key created by
 484             <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
 485           </p></dd>
 486 </dl></div>
 487 </div>
 488 <div class="refsect1" lang="en">
 489 <a name="id2542134"></a><h2>SEE ALSO</h2>
 490 <p><span class="citerefentry"><span class="refentrytitle">RFC2136</span></span>,
 491       <span class="citerefentry"><span class="refentrytitle">RFC3007</span></span>,
 492       <span class="citerefentry"><span class="refentrytitle">RFC2104</span></span>,
 493       <span class="citerefentry"><span class="refentrytitle">RFC2845</span></span>,
 494       <span class="citerefentry"><span class="refentrytitle">RFC1034</span></span>,
 495       <span class="citerefentry"><span class="refentrytitle">RFC2535</span></span>,
 496       <span class="citerefentry"><span class="refentrytitle">RFC2931</span></span>,
 497       <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
 498       <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
 499     </p>
 500 </div>
 501 <div class="refsect1" lang="en">
 502 <a name="id2544867"></a><h2>BUGS</h2>
 503 <p>
 504       The TSIG key is redundantly stored in two separate files.
 505       This is a consequence of nsupdate using the DST library
 506       for its cryptographic operations, and may change in future
 507       releases.
 508     </p>
 509 </div>
 510 </div></body>
 511 </html>