external/bsd/bind/dist/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="man.nsupdate"></a><div class="titlepage"></div>
  26 <div class="refnamediv">
  27 <h2>Name</h2>
  28 <p><span class="application">nsupdate</span> &#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">-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>
  33 </div>
  34 <div class="refsect1" lang="en">
  35 <a name="id2543453"></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 RFC 2136
  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       The <code class="option">-D</code> option makes <span><strong class="command">nsupdate</strong></span>
  70       report additional debugging information to <code class="option">-d</code>.
  71     </p>
  72 <p>
  73       The <code class="option">-L</code> option with an integer argument of zero or
  74       higher sets the logging debug level.  If zero, logging is disabled.
  75     </p>
  76 <p>
  77       Transaction signatures can be used to authenticate the Dynamic
  78       DNS updates.  These use the TSIG resource record type described
  79       in RFC 2845 or the SIG(0) record described in RFC 2535 and
  80       RFC 2931 or GSS-TSIG as described in RFC 3645.  TSIG relies on
  81       a shared secret that should only be known to
  82       <span><strong class="command">nsupdate</strong></span> and the name server.  Currently,
  83       the only supported encryption algorithm for TSIG is HMAC-MD5,
  84       which is defined in RFC 2104.  Once other algorithms are
  85       defined for TSIG, applications will need to ensure they select
  86       the appropriate algorithm as well as the key when authenticating
  87       each other.  For instance, suitable <span class="type">key</span> and
  88       <span class="type">server</span> statements would be added to
  89       <code class="filename">/etc/named.conf</code> so that the name server
  90       can associate the appropriate secret key and algorithm with
  91       the IP address of the client application that will be using
  92       TSIG authentication.  SIG(0) uses public key cryptography.
  93       To use a SIG(0) key, the public key must be stored in a KEY
  94       record in a zone served by the name server.
  95       <span><strong class="command">nsupdate</strong></span> does not read
  96       <code class="filename">/etc/named.conf</code>.
  97     </p>
  98 <p>
  99       GSS-TSIG uses Kerberos credentials.  Standard GSS-TSIG mode
 100       is switched on with the <code class="option">-g</code> flag.  A
 101       non-standards-compliant variant of GSS-TSIG used by Windows
 102       2000 can be switched on with the <code class="option">-o</code> flag.
 103     </p>
 104 <p><span><strong class="command">nsupdate</strong></span>
 105       uses the <code class="option">-y</code> or <code class="option">-k</code> option
 106       to provide the shared secret needed to generate a TSIG record
 107       for authenticating Dynamic DNS update requests, default type
 108       HMAC-MD5.  These options are mutually exclusive.
 109     </p>
 110 <p>
 111       When the <code class="option">-y</code> option is used, a signature is
 112       generated from
 113       [<span class="optional"><em class="parameter"><code>hmac:</code></em></span>]<em class="parameter"><code>keyname:secret.</code></em>
 114       <em class="parameter"><code>keyname</code></em> is the name of the key, and
 115       <em class="parameter"><code>secret</code></em> is the base64 encoded shared secret.
 116       Use of the <code class="option">-y</code> option is discouraged because the
 117       shared secret is supplied as a command line argument in clear text.
 118       This may be visible in the output from
 119       <span class="citerefentry"><span class="refentrytitle">ps</span>(1)</span>
 120       or in a history file maintained by the user's shell.
 121     </p>
 122 <p>
 123       With the
 124       <code class="option">-k</code> option, <span><strong class="command">nsupdate</strong></span> reads
 125       the shared secret from the file <em class="parameter"><code>keyfile</code></em>.
 126       Keyfiles may be in two formats: a single file containing
 127       a <code class="filename">named.conf</code>-format <span><strong class="command">key</strong></span>
 128       statement, which may be generated automatically by
 129       <span><strong class="command">ddns-confgen</strong></span>, or a pair of files whose names are
 130       of the format <code class="filename">K{name}.+157.+{random}.key</code> and
 131       <code class="filename">K{name}.+157.+{random}.private</code>, which can be
 132       generated by <span><strong class="command">dnssec-keygen</strong></span>.
 133       The <code class="option">-k</code> may also be used to specify a SIG(0) key used
 134       to authenticate Dynamic DNS update requests.  In this case, the key
 135       specified is not an HMAC-MD5 key.
 136     </p>
 137 <p>
 138       <span><strong class="command">nsupdate</strong></span> can be run in a local-host only mode
 139       using the <code class="option">-l</code> flag.  This sets the server address to
 140       localhost (disabling the <span><strong class="command">server</strong></span> so that the server
 141       address cannot be overridden).  Connections to the local server will
 142       use a TSIG key found in <code class="filename">/var/run/named/ddns.key</code>,
 143       which is automatically generated by <span><strong class="command">named</strong></span> if any
 144       local master zone has set <span><strong class="command">update-policy</strong></span> to
 145       <span><strong class="command">local</strong></span>.  The location of this key file can be
 146       overridden with the <code class="option">-k</code> option.
 147     </p>
 148 <p>
 149       By default, <span><strong class="command">nsupdate</strong></span>
 150       uses UDP to send update requests to the name server unless they are too
 151       large to fit in a UDP request in which case TCP will be used.
 152       The
 153       <code class="option">-v</code>
 154       option makes
 155       <span><strong class="command">nsupdate</strong></span>
 156       use a TCP connection.
 157       This may be preferable when a batch of update requests is made.
 158     </p>
 159 <p>
 160       The <code class="option">-p</code> sets the default port number to use for
 161       connections to a name server.  The default is 53.
 162     </p>
 163 <p>
 164       The <code class="option">-t</code> option sets the maximum time an update request
 165       can
 166       take before it is aborted.  The default is 300 seconds.  Zero can be
 167       used
 168       to disable the timeout.
 169     </p>
 170 <p>
 171       The <code class="option">-u</code> option sets the UDP retry interval.  The default
 172       is
 173       3 seconds.  If zero, the interval will be computed from the timeout
 174       interval
 175       and number of UDP retries.
 176     </p>
 177 <p>
 178       The <code class="option">-r</code> option sets the number of UDP retries. The
 179       default is
 180       3.  If zero, only one update request will be made.
 181     </p>
 182 <p>
 183       The <code class="option">-R <em class="replaceable"><code>randomdev</code></em></code> option
 184       specifies a source of randomness.  If the operating system
 185       does not provide a <code class="filename">/dev/random</code> or
 186       equivalent device, the default source of randomness is keyboard
 187       input.  <code class="filename">randomdev</code> specifies the name of
 188       a character device or file containing random data to be used
 189       instead of the default.  The special value
 190       <code class="filename">keyboard</code> indicates that keyboard input
 191       should be used.  This option may be specified multiple times.
 192     </p>
 193 </div>
 194 <div class="refsect1" lang="en">
 195 <a name="id2543785"></a><h2>INPUT FORMAT</h2>
 196 <p><span><strong class="command">nsupdate</strong></span>
 197       reads input from
 198       <em class="parameter"><code>filename</code></em>
 199       or standard input.
 200       Each command is supplied on exactly one line of input.
 201       Some commands are for administrative purposes.
 202       The others are either update instructions or prerequisite checks on the
 203       contents of the zone.
 204       These checks set conditions that some name or set of
 205       resource records (RRset) either exists or is absent from the zone.
 206       These conditions must be met if the entire update request is to succeed.
 207       Updates will be rejected if the tests for the prerequisite conditions
 208       fail.
 209     </p>
 210 <p>
 211       Every update request consists of zero or more prerequisites
 212       and zero or more updates.
 213       This allows a suitably authenticated update request to proceed if some
 214       specified resource records are present or missing from the zone.
 215       A blank input line (or the <span><strong class="command">send</strong></span> command)
 216       causes the
 217       accumulated commands to be sent as one Dynamic DNS update request to the
 218       name server.
 219     </p>
 220 <p>
 221       The command formats and their meaning are as follows:
 222       </p>
 223 <div class="variablelist"><dl>
 224 <dt><span class="term">
 225               <span><strong class="command">server</strong></span>
 226                {servername}
 227                [port]
 228             </span></dt>
 229 <dd><p>
 230               Sends all dynamic update requests to the name server
 231               <em class="parameter"><code>servername</code></em>.
 232               When no server statement is provided,
 233               <span><strong class="command">nsupdate</strong></span>
 234               will send updates to the master server of the correct zone.
 235               The MNAME field of that zone's SOA record will identify the
 236               master
 237               server for that zone.
 238               <em class="parameter"><code>port</code></em>
 239               is the port number on
 240               <em class="parameter"><code>servername</code></em>
 241               where the dynamic update requests get sent.
 242               If no port number is specified, the default DNS port number of
 243               53 is
 244               used.
 245             </p></dd>
 246 <dt><span class="term">
 247               <span><strong class="command">local</strong></span>
 248                {address}
 249                [port]
 250             </span></dt>
 251 <dd><p>
 252               Sends all dynamic update requests using the local
 253               <em class="parameter"><code>address</code></em>.
 254
 255               When no local statement is provided,
 256               <span><strong class="command">nsupdate</strong></span>
 257               will send updates using an address and port chosen by the
 258               system.
 259               <em class="parameter"><code>port</code></em>
 260               can additionally be used to make requests come from a specific
 261               port.
 262               If no port number is specified, the system will assign one.
 263             </p></dd>
 264 <dt><span class="term">
 265               <span><strong class="command">zone</strong></span>
 266                {zonename}
 267             </span></dt>
 268 <dd><p>
 269               Specifies that all updates are to be made to the zone
 270               <em class="parameter"><code>zonename</code></em>.
 271               If no
 272               <em class="parameter"><code>zone</code></em>
 273               statement is provided,
 274               <span><strong class="command">nsupdate</strong></span>
 275               will attempt determine the correct zone to update based on the
 276               rest of the input.
 277             </p></dd>
 278 <dt><span class="term">
 279               <span><strong class="command">class</strong></span>
 280                {classname}
 281             </span></dt>
 282 <dd><p>
 283               Specify the default class.
 284               If no <em class="parameter"><code>class</code></em> is specified, the
 285               default class is
 286               <em class="parameter"><code>IN</code></em>.
 287             </p></dd>
 288 <dt><span class="term">
 289               <span><strong class="command">ttl</strong></span>
 290                {seconds}
 291             </span></dt>
 292 <dd><p>
 293               Specify the default time to live for records to be added.
 294               The value <em class="parameter"><code>none</code></em> will clear the default
 295               ttl.
 296             </p></dd>
 297 <dt><span class="term">
 298               <span><strong class="command">key</strong></span>
 299                {name}
 300                {secret}
 301             </span></dt>
 302 <dd><p>
 303               Specifies that all updates are to be TSIG-signed using the
 304               <em class="parameter"><code>keyname</code></em> <em class="parameter"><code>keysecret</code></em> pair.
 305               The <span><strong class="command">key</strong></span> command
 306               overrides any key specified on the command line via
 307               <code class="option">-y</code> or <code class="option">-k</code>.
 308             </p></dd>
 309 <dt><span class="term">
 310               <span><strong class="command">prereq nxdomain</strong></span>
 311                {domain-name}
 312             </span></dt>
 313 <dd><p>
 314               Requires that no resource record of any type exists with name
 315               <em class="parameter"><code>domain-name</code></em>.
 316             </p></dd>
 317 <dt><span class="term">
 318               <span><strong class="command">prereq yxdomain</strong></span>
 319                {domain-name}
 320             </span></dt>
 321 <dd><p>
 322               Requires that
 323               <em class="parameter"><code>domain-name</code></em>
 324               exists (has as at least one resource record, of any type).
 325             </p></dd>
 326 <dt><span class="term">
 327               <span><strong class="command">prereq nxrrset</strong></span>
 328                {domain-name}
 329                [class]
 330                {type}
 331             </span></dt>
 332 <dd><p>
 333               Requires that no resource record exists of the specified
 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               If
 339               <em class="parameter"><code>class</code></em>
 340               is omitted, IN (internet) is assumed.
 341             </p></dd>
 342 <dt><span class="term">
 343               <span><strong class="command">prereq yxrrset</strong></span>
 344                {domain-name}
 345                [class]
 346                {type}
 347             </span></dt>
 348 <dd><p>
 349               This requires that a resource record of the specified
 350               <em class="parameter"><code>type</code></em>,
 351               <em class="parameter"><code>class</code></em>
 352               and
 353               <em class="parameter"><code>domain-name</code></em>
 354               must exist.
 355               If
 356               <em class="parameter"><code>class</code></em>
 357               is omitted, IN (internet) is assumed.
 358             </p></dd>
 359 <dt><span class="term">
 360               <span><strong class="command">prereq yxrrset</strong></span>
 361                {domain-name}
 362                [class]
 363                {type}
 364                {data...}
 365             </span></dt>
 366 <dd><p>
 367               The
 368               <em class="parameter"><code>data</code></em>
 369               from each set of prerequisites of this form
 370               sharing a common
 371               <em class="parameter"><code>type</code></em>,
 372               <em class="parameter"><code>class</code></em>,
 373               and
 374               <em class="parameter"><code>domain-name</code></em>
 375               are combined to form a set of RRs.  This set of RRs must
 376               exactly match the set of RRs existing in the zone at the
 377               given
 378               <em class="parameter"><code>type</code></em>,
 379               <em class="parameter"><code>class</code></em>,
 380               and
 381               <em class="parameter"><code>domain-name</code></em>.
 382               The
 383               <em class="parameter"><code>data</code></em>
 384               are written in the standard text representation of the resource
 385               record's
 386               RDATA.
 387             </p></dd>
 388 <dt><span class="term">
 389               <span><strong class="command">update delete</strong></span>
 390                {domain-name}
 391                [ttl]
 392                [class]
 393                [type [data...]]
 394             </span></dt>
 395 <dd><p>
 396               Deletes any resource records named
 397               <em class="parameter"><code>domain-name</code></em>.
 398               If
 399               <em class="parameter"><code>type</code></em>
 400               and
 401               <em class="parameter"><code>data</code></em>
 402               is provided, only matching resource records will be removed.
 403               The internet class is assumed if
 404               <em class="parameter"><code>class</code></em>
 405               is not supplied.  The
 406               <em class="parameter"><code>ttl</code></em>
 407               is ignored, and is only allowed for compatibility.
 408             </p></dd>
 409 <dt><span class="term">
 410               <span><strong class="command">update add</strong></span>
 411                {domain-name}
 412                {ttl}
 413                [class]
 414                {type}
 415                {data...}
 416             </span></dt>
 417 <dd><p>
 418               Adds a new resource record with the specified
 419               <em class="parameter"><code>ttl</code></em>,
 420               <em class="parameter"><code>class</code></em>
 421               and
 422               <em class="parameter"><code>data</code></em>.
 423             </p></dd>
 424 <dt><span class="term">
 425               <span><strong class="command">show</strong></span>
 426             </span></dt>
 427 <dd><p>
 428               Displays the current message, containing all of the
 429               prerequisites and
 430               updates specified since the last send.
 431             </p></dd>
 432 <dt><span class="term">
 433               <span><strong class="command">send</strong></span>
 434             </span></dt>
 435 <dd><p>
 436               Sends the current message.  This is equivalent to entering a
 437               blank line.
 438             </p></dd>
 439 <dt><span class="term">
 440               <span><strong class="command">answer</strong></span>
 441             </span></dt>
 442 <dd><p>
 443               Displays the answer.
 444             </p></dd>
 445 <dt><span class="term">
 446               <span><strong class="command">debug</strong></span>
 447             </span></dt>
 448 <dd><p>
 449               Turn on debugging.
 450             </p></dd>
 451 </dl></div>
 452 <p>
 453     </p>
 454 <p>
 455       Lines beginning with a semicolon are comments and are ignored.
 456     </p>
 457 </div>
 458 <div class="refsect1" lang="en">
 459 <a name="id2544626"></a><h2>EXAMPLES</h2>
 460 <p>
 461       The examples below show how
 462       <span><strong class="command">nsupdate</strong></span>
 463       could be used to insert and delete resource records from the
 464       <span class="type">example.com</span>
 465       zone.
 466       Notice that the input in each example contains a trailing blank line so
 467       that
 468       a group of commands are sent as one dynamic update request to the
 469       master name server for
 470       <span class="type">example.com</span>.
 471
 472       </p>
 473 <pre class="programlisting">
 474 # nsupdate
 475 &gt; update delete oldhost.example.com A
 476 &gt; update add newhost.example.com 86400 A 172.16.1.1
 477 &gt; send
 478 </pre>
 479 <p>
 480     </p>
 481 <p>
 482       Any A records for
 483       <span class="type">oldhost.example.com</span>
 484       are deleted.
 485       And an A record for
 486       <span class="type">newhost.example.com</span>
 487       with IP address 172.16.1.1 is added.
 488       The newly-added record has a 1 day TTL (86400 seconds).
 489       </p>
 490 <pre class="programlisting">
 491 # nsupdate
 492 &gt; prereq nxdomain nickname.example.com
 493 &gt; update add nickname.example.com 86400 CNAME somehost.example.com
 494 &gt; send
 495 </pre>
 496 <p>
 497     </p>
 498 <p>
 499       The prerequisite condition gets the name server to check that there
 500       are no resource records of any type for
 501       <span class="type">nickname.example.com</span>.
 502
 503       If there are, the update request fails.
 504       If this name does not exist, a CNAME for it is added.
 505       This ensures that when the CNAME is added, it cannot conflict with the
 506       long-standing rule in RFC 1034 that a name must not exist as any other
 507       record type if it exists as a CNAME.
 508       (The rule has been updated for DNSSEC in RFC 2535 to allow CNAMEs to have
 509       RRSIG, DNSKEY and NSEC records.)
 510     </p>
 511 </div>
 512 <div class="refsect1" lang="en">
 513 <a name="id2544669"></a><h2>FILES</h2>
 514 <div class="variablelist"><dl>
 515 <dt><span class="term"><code class="constant">/etc/resolv.conf</code></span></dt>
 516 <dd><p>
 517             used to identify default name server
 518           </p></dd>
 519 <dt><span class="term"><code class="constant">/var/run/named/ddns.key</code></span></dt>
 520 <dd><p>
 521             sets the default TSIG key for use in local-only mode
 522           </p></dd>
 523 <dt><span class="term"><code class="constant">K{name}.+157.+{random}.key</code></span></dt>
 524 <dd><p>
 525             base-64 encoding of HMAC-MD5 key created by
 526             <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
 527           </p></dd>
 528 <dt><span class="term"><code class="constant">K{name}.+157.+{random}.private</code></span></dt>
 529 <dd><p>
 530             base-64 encoding of HMAC-MD5 key created by
 531             <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
 532           </p></dd>
 533 </dl></div>
 534 </div>
 535 <div class="refsect1" lang="en">
 536 <a name="id2544753"></a><h2>SEE ALSO</h2>
 537 <p>
 538       <em class="citetitle">RFC 2136</em>,
 539       <em class="citetitle">RFC 3007</em>,
 540       <em class="citetitle">RFC 2104</em>,
 541       <em class="citetitle">RFC 2845</em>,
 542       <em class="citetitle">RFC 1034</em>,
 543       <em class="citetitle">RFC 2535</em>,
 544       <em class="citetitle">RFC 2931</em>,
 545       <span class="citerefentry"><span class="refentrytitle">named</span>(8)</span>,
 546       <span class="citerefentry"><span class="refentrytitle">ddns-confgen</span>(8)</span>,
 547       <span class="citerefentry"><span class="refentrytitle">dnssec-keygen</span>(8)</span>.
 548     </p>
 549 </div>
 550 <div class="refsect1" lang="en">
 551 <a name="id2542148"></a><h2>BUGS</h2>
 552 <p>
 553       The TSIG key is redundantly stored in two separate files.
 554       This is a consequence of nsupdate using the DST library
 555       for its cryptographic operations, and may change in future
 556       releases.
 557     </p>
 558 </div>
 559 </div></body>
 560 </html>