Bv9ARM.ch04.html revision 4a14ce5ba00ab7bc55c99ffdcf59c7a4ab902721
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<!--
33d0a7767d53cb366039fd0ac4f63cf8a9c351b0Tinderbox User - Copyright (C) 2004-2009 Internet Systems Consortium, Inc. ("ISC")
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - Copyright (C) 2000-2003 Internet Software Consortium.
5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User -
5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User - Permission to use, copy, modify, and/or distribute this software for any
5347c0fcb04eaea19d9f39795646239f487c6207Tinderbox User - purpose with or without fee is hereby granted, provided that the above
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - copyright notice and this permission notice appear in all copies.
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont -
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont - PERFORMANCE OF THIS SOFTWARE.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User-->
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<!-- $Id: Bv9ARM.ch04.html,v 1.98 2009/07/11 01:12:47 tbox Exp $ -->
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<html>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<head>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<title>Chapter�4.�Advanced DNS Features</title>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<meta name="generator" content="DocBook XSL Stylesheets V1.71.1">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<link rel="start" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<link rel="up" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<link rel="prev" href="Bv9ARM.ch03.html" title="Chapter�3.�Name Server Configuration">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<link rel="next" href="Bv9ARM.ch05.html" title="Chapter�5.�The BIND 9 Lightweight Resolver">
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User</head>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<div class="navheader">
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User<table width="100%" summary="Navigation header">
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<tr><th colspan="3" align="center">Chapter�4.�Advanced DNS Features</th></tr>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<tr>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<td width="20%" align="left">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<a accesskey="p" href="Bv9ARM.ch03.html">Prev</a>�</td>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<th width="60%" align="center">�</th>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<td width="20%" align="right">�<a accesskey="n" href="Bv9ARM.ch05.html">Next</a>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater</td>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater</tr>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User</table>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<hr>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User</div>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<div class="chapter" lang="en">
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<div class="titlepage"><div><div><h2 class="title">
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<a name="Bv9ARM.ch04"></a>Chapter�4.�Advanced DNS Features</h2></div></div></div>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<div class="toc">
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p><b>Table of Contents</b></p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dl>
aaaf8d4f4873d21e55c3ffb4f656203d08339865Mark Andrews<dt><span class="sect1"><a href="Bv9ARM.ch04.html#notify">Notify</a></span></dt>
aaaf8d4f4873d21e55c3ffb4f656203d08339865Mark Andrews<dt><span class="sect1"><a href="Bv9ARM.ch04.html#dynamic_update">Dynamic Update</a></span></dt>
731cc132f22dbc9e0ecd7035dce314a61076d31bAutomatic Updater<dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch04.html#journal">The journal file</a></span></dt></dl></dd>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<dt><span class="sect1"><a href="Bv9ARM.ch04.html#incremental_zone_transfers">Incremental Zone Transfers (IXFR)</a></span></dt>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<dt><span class="sect1"><a href="Bv9ARM.ch04.html#id2570510">Split DNS</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2570529">Example split DNS setup</a></span></dt></dl></dd>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect1"><a href="Bv9ARM.ch04.html#tsig">TSIG</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dd><dl>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571030">Generate Shared Keys for Each Pair of Hosts</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571104">Copying the Shared Secret to Both Machines</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571114">Informing the Servers of the Key's Existence</a></span></dt>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2563989">Instructing the Server to Use the Key</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2564115">TSIG Key Based Access Control</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2564163">Errors</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User</dl></dd>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<dt><span class="sect1"><a href="Bv9ARM.ch04.html#id2571549">TKEY</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect1"><a href="Bv9ARM.ch04.html#id2571598">SIG(0)</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect1"><a href="Bv9ARM.ch04.html#DNSSEC">DNSSEC</a></span></dt>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<dd><dl>
2a6d4c9948b3f4f31311bd799d114585a30419a9Automatic Updater<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571803">Generating Keys</a></span></dt>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571950">Signing the Zone</a></span></dt>
2a6d4c9948b3f4f31311bd799d114585a30419a9Automatic Updater<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2572032">Configuring Servers</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User</dl></dd>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect1"><a href="Bv9ARM.ch04.html#id2572201">IPv6 Support in <acronym class="acronym">BIND</acronym> 9</a></span></dt>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dd><dl>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2572400">Address Lookups Using AAAA Records</a></span></dt>
8ec3c085233cedb22b05da36e2773c8f357a7e45Automatic Updater<dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2572421">Address to Name Lookups Using Nibble Format</a></span></dt>
6ea2385360e9e2167e65f9286447da9eea189457Tinderbox User</dl></dd>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User</dl>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User</div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<div class="sect1" lang="en">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<div class="titlepage"><div><div><h2 class="title" style="clear: both">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<a name="notify"></a>Notify</h2></div></div></div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User <acronym class="acronym">DNS</acronym> NOTIFY is a mechanism that allows master
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User servers to notify their slave servers of changes to a zone's data. In
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User response to a <span><strong class="command">NOTIFY</strong></span> from a master server, the
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User slave will check to see that its version of the zone is the
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User current version and, if not, initiate a zone transfer.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p>
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User For more information about <acronym class="acronym">DNS</acronym>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <span><strong class="command">NOTIFY</strong></span>, see the description of the
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User <span><strong class="command">notify</strong></span> option in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called &#8220;Boolean Options&#8221;</a> and
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User the description of the zone option <span><strong class="command">also-notify</strong></span> in
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called &#8220;Zone Transfers&#8221;</a>. The <span><strong class="command">NOTIFY</strong></span>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User protocol is specified in RFC 1996.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<h3 class="title">Note</h3>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User As a slave zone can also be a master to other slaves, <span><strong class="command">named</strong></span>,
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User by default, sends <span><strong class="command">NOTIFY</strong></span> messages for every zone
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User it loads. Specifying <span><strong class="command">notify master-only;</strong></span> will
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User cause <span><strong class="command">named</strong></span> to only send <span><strong class="command">NOTIFY</strong></span> for master
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User zones that it loads.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User</div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<div class="sect1" lang="en">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<div class="titlepage"><div><div><h2 class="title" style="clear: both">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<a name="dynamic_update"></a>Dynamic Update</h2></div></div></div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Dynamic Update is a method for adding, replacing or deleting
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User records in a master server by sending it a special form of DNS
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User messages. The format and meaning of these messages is specified
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User in RFC 2136.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User Dynamic update is enabled by including an
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User <span><strong class="command">allow-update</strong></span>, <span><strong class="command">update-policy</strong></span>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User clause in the <span><strong class="command">zone</strong></span> statement, or by setting the
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <span><strong class="command">ddns-autconf</strong></span> option to <strong class="userinput"><code>yes</code></strong>.
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont </p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User If the zone's <span><strong class="command">ddns-autoconf</strong></span> option is set to
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User <strong class="userinput"><code>yes</code></strong>, then updates to the zone
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User will be permitted for the key <code class="filename">ddns.key</code>,
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User which will be generated by <span><strong class="command">named</strong></span> at startup.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User The <span><strong class="command">tkey-gssapi-credential</strong></span> and
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater <span><strong class="command">tkey-domain</strong></span> clauses in the
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <span><strong class="command">options</strong></span> statement enable the
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater server to negotiate keys that can be matched against those
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User in <span><strong class="command">update-policy</strong></span> or
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater <span><strong class="command">allow-update</strong></span>.
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater </p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater Updating of secure zones (zones using DNSSEC) follows RFC
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater 3007: RRSIG, NSEC and NSEC3 records affected by updates are
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User automatically regenerated by the server using an online
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont zone key. Update authorization is based on transaction
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User signatures and an explicit server policy.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<div class="sect2" lang="en">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<div class="titlepage"><div><div><h3 class="title">
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<a name="journal"></a>The journal file</h3></div></div></div>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User All changes made to a zone using dynamic update are stored
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User in the zone's journal file. This file is automatically created
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User by the server when the first dynamic update takes place.
f8e3e03cacd16ffb923a9603fca23a9e1a1fee07Automatic Updater The name of the journal file is formed by appending the extension
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <code class="filename">.jnl</code> to the name of the
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User corresponding zone
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User file unless specifically overridden. The journal file is in a
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User binary format and should not be edited manually.
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont </p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User The server will also occasionally write ("dump")
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User the complete contents of the updated zone to its zone file.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User This is not done immediately after
0a7ed88633a680bb881868b75ded4d09a7bbbc50Automatic Updater each dynamic update, because that would be too slow when a large
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User zone is updated frequently. Instead, the dump is delayed by
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User up to 15 minutes, allowing additional updates to take place.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User When a server is restarted after a shutdown or crash, it will replay
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User the journal file to incorporate into the zone any updates that
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User took
a3f8c8e20780e488141d200acdfea6c5f3303513Automatic Updater place after the last zone dump.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User Changes that result from incoming incremental zone transfers are
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User also
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User journalled in a similar way.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User The zone files of dynamic zones cannot normally be edited by
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont hand because they are not guaranteed to contain the most recent
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User dynamic changes &#8212; those are only in the journal file.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User The only way to ensure that the zone file of a dynamic zone
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User is up to date is to run <span><strong class="command">rndc stop</strong></span>.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User If you have to make changes to a dynamic zone
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User manually, the following procedure will work: Disable dynamic updates
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User to the zone using
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User <span><strong class="command">rndc freeze <em class="replaceable"><code>zone</code></em></strong></span>.
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User This will also remove the zone's <code class="filename">.jnl</code> file
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User and update the master file. Edit the zone file. Run
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User <span><strong class="command">rndc thaw <em class="replaceable"><code>zone</code></em></strong></span>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User to reload the changed zone and re-enable dynamic updates.
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User </p>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User</div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User</div>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<div class="sect1" lang="en">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<div class="titlepage"><div><div><h2 class="title" style="clear: both">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<a name="incremental_zone_transfers"></a>Incremental Zone Transfers (IXFR)</h2></div></div></div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User The incremental zone transfer (IXFR) protocol is a way for
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User slave servers to transfer only changed data, instead of having to
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User transfer the entire zone. The IXFR protocol is specified in RFC
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont 1995. See <a href="Bv9ARM.ch09.html#proposed_standards">Proposed Standards</a>.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User When acting as a master, <acronym class="acronym">BIND</acronym> 9
6f1205897504b8f50b1785975482c995888dd630Tinderbox User supports IXFR for those zones
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User where the necessary change history information is available. These
6f1205897504b8f50b1785975482c995888dd630Tinderbox User include master zones maintained by dynamic update and slave zones
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User whose data was obtained by IXFR. For manually maintained master
a3416b0a1b5482b6df32839445ca98c016945570Automatic Updater zones, and for slave zones obtained by performing a full zone
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User transfer (AXFR), IXFR is supported only if the option
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User <span><strong class="command">ixfr-from-differences</strong></span> is set
a3416b0a1b5482b6df32839445ca98c016945570Automatic Updater to <strong class="userinput"><code>yes</code></strong>.
a3416b0a1b5482b6df32839445ca98c016945570Automatic Updater </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User When acting as a slave, <acronym class="acronym">BIND</acronym> 9 will
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User attempt to use IXFR unless
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont it is explicitly disabled. For more information about disabling
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User IXFR, see the description of the <span><strong class="command">request-ixfr</strong></span> clause
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User of the <span><strong class="command">server</strong></span> statement.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User</div>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<div class="sect1" lang="en">
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<div class="titlepage"><div><div><h2 class="title" style="clear: both">
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<a name="id2570510"></a>Split DNS</h2></div></div></div>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater Setting up different views, or visibility, of the DNS space to
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater internal and external resolvers is usually referred to as a
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater <span class="emphasis"><em>Split DNS</em></span> setup. There are several
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User reasons an organization would want to set up its DNS this way.
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User </p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User One common reason for setting up a DNS system this way is
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater to hide "internal" DNS information from "external" clients on the
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Internet. There is some debate as to whether or not this is actually
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User useful.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User Internal DNS information leaks out in many ways (via email headers,
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User for example) and most savvy "attackers" can find the information
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User they need using other means.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User However, since listing addresses of internal servers that
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User external clients cannot possibly reach can result in
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User connection delays and other annoyances, an organization may
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User choose to use a Split DNS to present a consistent view of itself
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User to the outside world.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Another common reason for setting up a Split DNS system is
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User to allow internal networks that are behind filters or in RFC 1918
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User space (reserved IP space, as documented in RFC 1918) to resolve DNS
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User on the Internet. Split DNS can also be used to allow mail from outside
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User back in to the internal network.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater<div class="sect2" lang="en">
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<div class="titlepage"><div><div><h3 class="title">
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<a name="id2570529"></a>Example split DNS setup</h3></div></div></div>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User Let's say a company named <span class="emphasis"><em>Example, Inc.</em></span>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User (<code class="literal">example.com</code>)
79cf9524b15ca65f55fd6913e6cf01b5581c588aAutomatic Updater has several corporate sites that have an internal network with
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User reserved
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User Internet Protocol (IP) space and an external demilitarized zone (DMZ),
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User or "outside" section of a network, that is available to the public.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater <span class="emphasis"><em>Example, Inc.</em></span> wants its internal clients
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User to be able to resolve external hostnames and to exchange mail with
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User people on the outside. The company also wants its internal resolvers
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User to have access to certain internal-only zones that are not available
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User at all outside of the internal network.
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User In order to accomplish this, the company will set up two sets
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User of name servers. One set will be on the inside network (in the
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User reserved
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User IP space) and the other set will be on bastion hosts, which are
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User "proxy"
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User hosts that can talk to both sides of its network, in the DMZ.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<p>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User The internal servers will be configured to forward all queries,
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User except queries for <code class="filename">site1.internal</code>, <code class="filename">site2.internal</code>, <code class="filename">site1.example.com</code>,
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User and <code class="filename">site2.example.com</code>, to the servers
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User in the
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User DMZ. These internal servers will have complete sets of information
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User for <code class="filename">site1.example.com</code>, <code class="filename">site2.example.com</code>, <code class="filename">site1.internal</code>,
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User and <code class="filename">site2.internal</code>.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<p>
9d557856c2a19ec95ee73245f60a92f8675cf5baTinderbox User To protect the <code class="filename">site1.internal</code> and <code class="filename">site2.internal</code> domains,
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User the internal name servers must be configured to disallow all queries
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User to these domains from any external hosts, including the bastion
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User hosts.
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User </p>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User<p>
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User The external servers, which are on the bastion hosts, will
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User be configured to serve the "public" version of the <code class="filename">site1</code> and <code class="filename">site2.example.com</code> zones.
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User This could include things such as the host records for public servers
794b79e6bbc3f5db1ea6ae154d739b9f1ef1a375Tinderbox User (<code class="filename">www.example.com</code> and <code class="filename">ftp.example.com</code>),
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User and mail exchange (MX) records (<code class="filename">a.mx.example.com</code> and <code class="filename">b.mx.example.com</code>).
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater </p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User In addition, the public <code class="filename">site1</code> and <code class="filename">site2.example.com</code> zones
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User should have special MX records that contain wildcard (`*') records
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User pointing to the bastion hosts. This is needed because external mail
2eeb74d1cf5355dd98f6d507a10086e16bb08c4bTinderbox User servers do not have any other way of looking up how to deliver mail
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont to those internal hosts. With the wildcard records, the mail will
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont be delivered to the bastion host, which can then forward it on to
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont internal hosts.
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont </p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Here's an example of a wildcard MX record:
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User<pre class="programlisting">* IN MX 10 external1.example.com.</pre>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p>
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User Now that they accept mail on behalf of anything in the internal
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User network, the bastion hosts will need to know how to deliver mail
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User to internal hosts. In order for this to work properly, the resolvers
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User on
e62b9c9ce6413fb183c8116381e75dcd07ca5517Tinderbox User the bastion hosts will need to be configured to point to the internal
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont name servers for DNS resolution.
9d557856c2a19ec95ee73245f60a92f8675cf5baTinderbox User </p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont Queries for internal hostnames will be answered by the internal
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont servers, and queries for external hostnames will be forwarded back
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont out to the DNS servers on the bastion hosts.
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater </p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User In order for all this to work properly, internal clients will
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont need to be configured to query <span class="emphasis"><em>only</em></span> the internal
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont name servers for DNS queries. This could also be enforced via
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont selective
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont filtering on the network.
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont </p>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<p>
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater If everything has been set properly, <span class="emphasis"><em>Example, Inc.</em></span>'s
c7d32c0b0ff4c01f0d4479af3410d3c06044d48aAutomatic Updater internal clients will now be able to:
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont </p>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<div class="itemizedlist"><ul type="disc">
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<li>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User Look up any hostnames in the <code class="literal">site1</code>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User and
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User <code class="literal">site2.example.com</code> zones.
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User </li>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<li>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont Look up any hostnames in the <code class="literal">site1.internal</code> and
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User <code class="literal">site2.internal</code> domains.
bbbf2e27d3a981163dab139497d6b2dc85449db0Tinderbox User </li>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<li>Look up any hostnames on the Internet.</li>
fd2597f75693a2279fdf588bd40dfe2407c42028Tinderbox User<li>Exchange mail with both internal and external people.</li>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont</ul></div>
90f35c2f2a1c660f3b96eec413036d238df395f6Francis Dupont<p>
Hosts on the Internet will be able to:
</p>
<div class="itemizedlist"><ul type="disc">
<li>
Look up any hostnames in the <code class="literal">site1</code>
and
<code class="literal">site2.example.com</code> zones.
</li>
<li>
Exchange mail with anyone in the <code class="literal">site1</code> and
<code class="literal">site2.example.com</code> zones.
</li>
</ul></div>
<p>
Here is an example configuration for the setup we just
described above. Note that this is only configuration information;
for information on how to configure your zone files, see <a href="Bv9ARM.ch03.html#sample_configuration" title="Sample Configurations">the section called &#8220;Sample Configurations&#8221;</a>.
</p>
<p>
Internal DNS server config:
</p>
<pre class="programlisting">
acl internals { 172.16.72.0/24; 192.168.1.0/24; };
acl externals { <code class="varname">bastion-ips-go-here</code>; };
options {
...
...
forward only;
// forward to external servers
forwarders {
<code class="varname">bastion-ips-go-here</code>;
};
// sample allow-transfer (no one)
allow-transfer { none; };
// restrict query access
allow-query { internals; externals; };
// restrict recursion
allow-recursion { internals; };
...
...
};
// sample master zone
zone "site1.example.com" {
type master;
file "m/site1.example.com";
// do normal iterative resolution (do not forward)
forwarders { };
allow-query { internals; externals; };
allow-transfer { internals; };
};
// sample slave zone
zone "site2.example.com" {
type slave;
file "s/site2.example.com";
masters { 172.16.72.3; };
forwarders { };
allow-query { internals; externals; };
allow-transfer { internals; };
};
zone "site1.internal" {
type master;
file "m/site1.internal";
forwarders { };
allow-query { internals; };
allow-transfer { internals; }
};
zone "site2.internal" {
type slave;
file "s/site2.internal";
masters { 172.16.72.3; };
forwarders { };
allow-query { internals };
allow-transfer { internals; }
};
</pre>
<p>
External (bastion host) DNS server config:
</p>
<pre class="programlisting">
acl internals { 172.16.72.0/24; 192.168.1.0/24; };
acl externals { bastion-ips-go-here; };
options {
...
...
// sample allow-transfer (no one)
allow-transfer { none; };
// default query access
allow-query { any; };
// restrict cache access
allow-query-cache { internals; externals; };
// restrict recursion
allow-recursion { internals; externals; };
...
...
};
// sample slave zone
zone "site1.example.com" {
type master;
file "m/site1.foo.com";
allow-transfer { internals; externals; };
};
zone "site2.example.com" {
type slave;
file "s/site2.foo.com";
masters { another_bastion_host_maybe; };
allow-transfer { internals; externals; }
};
</pre>
<p>
In the <code class="filename">resolv.conf</code> (or equivalent) on
the bastion host(s):
</p>
<pre class="programlisting">
search ...
nameserver 172.16.72.2
nameserver 172.16.72.3
nameserver 172.16.72.4
</pre>
</div>
</div>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="tsig"></a>TSIG</h2></div></div></div>
<p>
This is a short guide to setting up Transaction SIGnatures
(TSIG) based transaction security in <acronym class="acronym">BIND</acronym>. It describes changes
to the configuration file as well as what changes are required for
different features, including the process of creating transaction
keys and using transaction signatures with <acronym class="acronym">BIND</acronym>.
</p>
<p>
<acronym class="acronym">BIND</acronym> primarily supports TSIG for server
to server communication.
This includes zone transfer, notify, and recursive query messages.
Resolvers based on newer versions of <acronym class="acronym">BIND</acronym> 8 have limited support
for TSIG.
</p>
<p>
TSIG can also be useful for dynamic update. A primary
server for a dynamic zone should control access to the dynamic
update service, but IP-based access control is insufficient.
The cryptographic access control provided by TSIG
is far superior. The <span><strong class="command">nsupdate</strong></span>
program supports TSIG via the <code class="option">-k</code> and
<code class="option">-y</code> command line options or inline by use
of the <span><strong class="command">key</strong></span>.
</p>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2571030"></a>Generate Shared Keys for Each Pair of Hosts</h3></div></div></div>
<p>
A shared secret is generated to be shared between <span class="emphasis"><em>host1</em></span> and <span class="emphasis"><em>host2</em></span>.
An arbitrary key name is chosen: "host1-host2.". The key name must
be the same on both hosts.
</p>
<div class="sect3" lang="en">
<div class="titlepage"><div><div><h4 class="title">
<a name="id2571047"></a>Automatic Generation</h4></div></div></div>
<p>
The following command will generate a 128-bit (16 byte) HMAC-MD5
key as described above. Longer keys are better, but shorter keys
are easier to read. Note that the maximum key length is 512 bits;
keys longer than that will be digested with MD5 to produce a
128-bit key.
</p>
<p>
<strong class="userinput"><code>dnssec-keygen -a hmac-md5 -b 128 -n HOST host1-host2.</code></strong>
</p>
<p>
The key is in the file <code class="filename">Khost1-host2.+157+00000.private</code>.
Nothing directly uses this file, but the base-64 encoded string
following "<code class="literal">Key:</code>"
can be extracted from the file and used as a shared secret:
</p>
<pre class="programlisting">Key: La/E5CjG9O+os1jq0a2jdA==</pre>
<p>
The string "<code class="literal">La/E5CjG9O+os1jq0a2jdA==</code>" can
be used as the shared secret.
</p>
</div>
<div class="sect3" lang="en">
<div class="titlepage"><div><div><h4 class="title">
<a name="id2571085"></a>Manual Generation</h4></div></div></div>
<p>
The shared secret is simply a random sequence of bits, encoded
in base-64. Most ASCII strings are valid base-64 strings (assuming
the length is a multiple of 4 and only valid characters are used),
so the shared secret can be manually generated.
</p>
<p>
Also, a known string can be run through <span><strong class="command">mmencode</strong></span> or
a similar program to generate base-64 encoded data.
</p>
</div>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2571104"></a>Copying the Shared Secret to Both Machines</h3></div></div></div>
<p>
This is beyond the scope of DNS. A secure transport mechanism
should be used. This could be secure FTP, ssh, telephone, etc.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2571114"></a>Informing the Servers of the Key's Existence</h3></div></div></div>
<p>
Imagine <span class="emphasis"><em>host1</em></span> and <span class="emphasis"><em>host 2</em></span>
are
both servers. The following is added to each server's <code class="filename">named.conf</code> file:
</p>
<pre class="programlisting">
key host1-host2. {
algorithm hmac-md5;
secret "La/E5CjG9O+os1jq0a2jdA==";
};
</pre>
<p>
The algorithm, <code class="literal">hmac-md5</code>, is the only one supported by <acronym class="acronym">BIND</acronym>.
The secret is the one generated above. Since this is a secret, it
is recommended that either <code class="filename">named.conf</code> be non-world
readable, or the key directive be added to a non-world readable
file that is included by
<code class="filename">named.conf</code>.
</p>
<p>
At this point, the key is recognized. This means that if the
server receives a message signed by this key, it can verify the
signature. If the signature is successfully verified, the
response is signed by the same key.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2563989"></a>Instructing the Server to Use the Key</h3></div></div></div>
<p>
Since keys are shared between two hosts only, the server must
be told when keys are to be used. The following is added to the <code class="filename">named.conf</code> file
for <span class="emphasis"><em>host1</em></span>, if the IP address of <span class="emphasis"><em>host2</em></span> is
10.1.2.3:
</p>
<pre class="programlisting">
server 10.1.2.3 {
keys { host1-host2. ;};
};
</pre>
<p>
Multiple keys may be present, but only the first is used.
This directive does not contain any secrets, so it may be in a
world-readable
file.
</p>
<p>
If <span class="emphasis"><em>host1</em></span> sends a message that is a request
to that address, the message will be signed with the specified key. <span class="emphasis"><em>host1</em></span> will
expect any responses to signed messages to be signed with the same
key.
</p>
<p>
A similar statement must be present in <span class="emphasis"><em>host2</em></span>'s
configuration file (with <span class="emphasis"><em>host1</em></span>'s address) for <span class="emphasis"><em>host2</em></span> to
sign request messages to <span class="emphasis"><em>host1</em></span>.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2564115"></a>TSIG Key Based Access Control</h3></div></div></div>
<p>
<acronym class="acronym">BIND</acronym> allows IP addresses and ranges
to be specified in ACL
definitions and
<span><strong class="command">allow-{ query | transfer | update }</strong></span>
directives.
This has been extended to allow TSIG keys also. The above key would
be denoted <span><strong class="command">key host1-host2.</strong></span>
</p>
<p>
An example of an <span><strong class="command">allow-update</strong></span> directive would be:
</p>
<pre class="programlisting">
allow-update { key host1-host2. ;};
</pre>
<p>
This allows dynamic updates to succeed only if the request
was signed by a key named "<span><strong class="command">host1-host2.</strong></span>".
</p>
<p>
You may want to read about the more powerful
<span><strong class="command">update-policy</strong></span> statement in
<a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called &#8220;Dynamic Update Policies&#8221;</a>.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2564163"></a>Errors</h3></div></div></div>
<p>
The processing of TSIG signed messages can result in
several errors. If a signed message is sent to a non-TSIG aware
server, a FORMERR (format error) will be returned, since the server will not
understand the record. This is a result of misconfiguration,
since the server must be explicitly configured to send a TSIG
signed message to a specific server.
</p>
<p>
If a TSIG aware server receives a message signed by an
unknown key, the response will be unsigned with the TSIG
extended error code set to BADKEY. If a TSIG aware server
receives a message with a signature that does not validate, the
response will be unsigned with the TSIG extended error code set
to BADSIG. If a TSIG aware server receives a message with a time
outside of the allowed range, the response will be signed with
the TSIG extended error code set to BADTIME, and the time values
will be adjusted so that the response can be successfully
verified. In any of these cases, the message's rcode (response code) is set to
NOTAUTH (not authenticated).
</p>
</div>
</div>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="id2571549"></a>TKEY</h2></div></div></div>
<p><span><strong class="command">TKEY</strong></span>
is a mechanism for automatically generating a shared secret
between two hosts. There are several "modes" of
<span><strong class="command">TKEY</strong></span> that specify how the key is generated
or assigned. <acronym class="acronym">BIND</acronym> 9 implements only one of
these modes, the Diffie-Hellman key exchange. Both hosts are
required to have a Diffie-Hellman KEY record (although this
record is not required to be present in a zone). The
<span><strong class="command">TKEY</strong></span> process must use signed messages,
signed either by TSIG or SIG(0). The result of
<span><strong class="command">TKEY</strong></span> is a shared secret that can be used to
sign messages with TSIG. <span><strong class="command">TKEY</strong></span> can also be
used to delete shared secrets that it had previously
generated.
</p>
<p>
The <span><strong class="command">TKEY</strong></span> process is initiated by a
client
or server by sending a signed <span><strong class="command">TKEY</strong></span>
query
(including any appropriate KEYs) to a TKEY-aware server. The
server response, if it indicates success, will contain a
<span><strong class="command">TKEY</strong></span> record and any appropriate keys.
After
this exchange, both participants have enough information to
determine the shared secret; the exact process depends on the
<span><strong class="command">TKEY</strong></span> mode. When using the
Diffie-Hellman
<span><strong class="command">TKEY</strong></span> mode, Diffie-Hellman keys are
exchanged,
and the shared secret is derived by both participants.
</p>
</div>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="id2571598"></a>SIG(0)</h2></div></div></div>
<p>
<acronym class="acronym">BIND</acronym> 9 partially supports DNSSEC SIG(0)
transaction signatures as specified in RFC 2535 and RFC 2931.
SIG(0)
uses public/private keys to authenticate messages. Access control
is performed in the same manner as TSIG keys; privileges can be
granted or denied based on the key name.
</p>
<p>
When a SIG(0) signed message is received, it will only be
verified if the key is known and trusted by the server; the server
will not attempt to locate and/or validate the key.
</p>
<p>
SIG(0) signing of multiple-message TCP streams is not
supported.
</p>
<p>
The only tool shipped with <acronym class="acronym">BIND</acronym> 9 that
generates SIG(0) signed messages is <span><strong class="command">nsupdate</strong></span>.
</p>
</div>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="DNSSEC"></a>DNSSEC</h2></div></div></div>
<p>
Cryptographic authentication of DNS information is possible
through the DNS Security (<span class="emphasis"><em>DNSSEC-bis</em></span>) extensions,
defined in RFC 4033, RFC 4034, and RFC 4035.
This section describes the creation and use of DNSSEC signed zones.
</p>
<p>
In order to set up a DNSSEC secure zone, there are a series
of steps which must be followed. <acronym class="acronym">BIND</acronym>
9 ships
with several tools
that are used in this process, which are explained in more detail
below. In all cases, the <code class="option">-h</code> option prints a
full list of parameters. Note that the DNSSEC tools require the
keyset files to be in the working directory or the
directory specified by the <code class="option">-d</code> option, and
that the tools shipped with BIND 9.2.x and earlier are not compatible
with the current ones.
</p>
<p>
There must also be communication with the administrators of
the parent and/or child zone to transmit keys. A zone's security
status must be indicated by the parent zone for a DNSSEC capable
resolver to trust its data. This is done through the presence
or absence of a <code class="literal">DS</code> record at the
delegation
point.
</p>
<p>
For other servers to trust data in this zone, they must
either be statically configured with this zone's zone key or the
zone key of another zone above this one in the DNS tree.
</p>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2571803"></a>Generating Keys</h3></div></div></div>
<p>
The <span><strong class="command">dnssec-keygen</strong></span> program is used to
generate keys.
</p>
<p>
A secure zone must contain one or more zone keys. The
zone keys will sign all other records in the zone, as well as
the zone keys of any secure delegated zones. Zone keys must
have the same name as the zone, a name type of
<span><strong class="command">ZONE</strong></span>, and must be usable for
authentication.
It is recommended that zone keys use a cryptographic algorithm
designated as "mandatory to implement" by the IETF; currently
the only one is RSASHA1.
</p>
<p>
The following command will generate a 768-bit RSASHA1 key for
the <code class="filename">child.example</code> zone:
</p>
<p>
<strong class="userinput"><code>dnssec-keygen -a RSASHA1 -b 768 -n ZONE child.example.</code></strong>
</p>
<p>
Two output files will be produced:
<code class="filename">Kchild.example.+005+12345.key</code> and
<code class="filename">Kchild.example.+005+12345.private</code>
(where
12345 is an example of a key tag). The key filenames contain
the key name (<code class="filename">child.example.</code>),
algorithm (3
is DSA, 1 is RSAMD5, 5 is RSASHA1, etc.), and the key tag (12345 in
this case).
The private key (in the <code class="filename">.private</code>
file) is
used to generate signatures, and the public key (in the
<code class="filename">.key</code> file) is used for signature
verification.
</p>
<p>
To generate another key with the same properties (but with
a different key tag), repeat the above command.
</p>
<p>
The <span><strong class="command">dnssec-keyfromlabel</strong></span> program is used
to get a key pair from a crypto hardware and build the key
files. Its usage is similar to <span><strong class="command">dnssec-keygen</strong></span>.
</p>
<p>
The public keys should be inserted into the zone file by
including the <code class="filename">.key</code> files using
<span><strong class="command">$INCLUDE</strong></span> statements.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2571950"></a>Signing the Zone</h3></div></div></div>
<p>
The <span><strong class="command">dnssec-signzone</strong></span> program is used
to sign a zone.
</p>
<p>
Any <code class="filename">keyset</code> files corresponding to
secure subzones should be present. The zone signer will
generate <code class="literal">NSEC</code>, <code class="literal">NSEC3</code>
and <code class="literal">RRSIG</code> records for the zone, as
well as <code class="literal">DS</code> for the child zones if
<code class="literal">'-g'</code> is specified. If <code class="literal">'-g'</code>
is not specified, then DS RRsets for the secure child
zones need to be added manually.
</p>
<p>
The following command signs the zone, assuming it is in a
file called <code class="filename">zone.child.example</code>. By
default, all zone keys which have an available private key are
used to generate signatures.
</p>
<p>
<strong class="userinput"><code>dnssec-signzone -o child.example zone.child.example</code></strong>
</p>
<p>
One output file is produced:
<code class="filename">zone.child.example.signed</code>. This
file
should be referenced by <code class="filename">named.conf</code>
as the
input file for the zone.
</p>
<p><span><strong class="command">dnssec-signzone</strong></span>
will also produce a keyset and dsset files and optionally a
dlvset file. These are used to provide the parent zone
administrators with the <code class="literal">DNSKEYs</code> (or their
corresponding <code class="literal">DS</code> records) that are the
secure entry point to the zone.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2572032"></a>Configuring Servers</h3></div></div></div>
<p>
To enable <span><strong class="command">named</strong></span> to respond appropriately
to DNS requests from DNSSEC aware clients,
<span><strong class="command">dnssec-enable</strong></span> must be set to yes.
(This is the default setting.)
</p>
<p>
To enable <span><strong class="command">named</strong></span> to validate answers from
other servers, the <span><strong class="command">dnssec-enable</strong></span> and
<span><strong class="command">dnssec-validation</strong></span> options must both be
set to yes (the default setting in <acronym class="acronym">BIND</acronym> 9.5
and later), and at least one trust anchor must be configured
with a <span><strong class="command">trusted-keys</strong></span> statement in
<code class="filename">named.conf</code>.
</p>
<p>
<span><strong class="command">trusted-keys</strong></span> are copies of DNSKEY RRs
for zones that are used to form the first link in the
cryptographic chain of trust. All keys listed in
<span><strong class="command">trusted-keys</strong></span> (and corresponding zones)
are deemed to exist and only the listed keys will be used
to validated the DNSKEY RRset that they are from.
</p>
<p>
<span><strong class="command">trusted-keys</strong></span> are described in more detail
later in this document.
</p>
<p>
Unlike <acronym class="acronym">BIND</acronym> 8, <acronym class="acronym">BIND</acronym>
9 does not verify signatures on load, so zone keys for
authoritative zones do not need to be specified in the
configuration file.
</p>
<p>
After DNSSEC gets established, a typical DNSSEC configuration
will look something like the following. It has one or
more public keys for the root. This allows answers from
outside the organization to be validated. It will also
have several keys for parts of the namespace the organization
controls. These are here to ensure that <span><strong class="command">named</strong></span> is immune
to compromises in the DNSSEC components of the security
of parent zones.
</p>
<pre class="programlisting">
trusted-keys {
/* Root Key */
"." 257 3 3 "BNY4wrWM1nCfJ+CXd0rVXyYmobt7sEEfK3clRbGaTwS
JxrGkxJWoZu6I7PzJu/E9gx4UC1zGAHlXKdE4zYIpRh
aBKnvcC2U9mZhkdUpd1Vso/HAdjNe8LmMlnzY3zy2Xy
4klWOADTPzSv9eamj8V18PHGjBLaVtYvk/ln5ZApjYg
hf+6fElrmLkdaz MQ2OCnACR817DF4BBa7UR/beDHyp
5iWTXWSi6XmoJLbG9Scqc7l70KDqlvXR3M/lUUVRbke
g1IPJSidmK3ZyCllh4XSKbje/45SKucHgnwU5jefMtq
66gKodQj+MiA21AfUVe7u99WzTLzY3qlxDhxYQQ20FQ
97S+LKUTpQcq27R7AT3/V5hRQxScINqwcz4jYqZD2fQ
dgxbcDTClU0CRBdiieyLMNzXG3";
/* Key for our organization's forward zone */
example.com. 257 3 5 "AwEAAaxPMcR2x0HbQV4WeZB6oEDX+r0QM6
5KbhTjrW1ZaARmPhEZZe3Y9ifgEuq7vZ/z
GZUdEGNWy+JZzus0lUptwgjGwhUS1558Hb
4JKUbbOTcM8pwXlj0EiX3oDFVmjHO444gL
kBOUKUf/mC7HvfwYH/Be22GnClrinKJp1O
g4ywzO9WglMk7jbfW33gUKvirTHr25GL7S
TQUzBb5Usxt8lgnyTUHs1t3JwCY5hKZ6Cq
FxmAVZP20igTixin/1LcrgX/KMEGd/biuv
F4qJCyduieHukuY3H4XMAcR+xia2nIUPvm
/oyWR8BW/hWdzOvnSCThlHf3xiYleDbt/o
1OTQ09A0=";
/* Key for our reverse zone. */
2.0.192.IN-ADDRPA.NET. 257 3 5 "AQOnS4xn/IgOUpBPJ3bogzwc
xOdNax071L18QqZnQQQAVVr+i
LhGTnNGp3HoWQLUIzKrJVZ3zg
gy3WwNT6kZo6c0tszYqbtvchm
gQC8CzKojM/W16i6MG/eafGU3
siaOdS0yOI6BgPsw+YZdzlYMa
IJGf4M4dyoKIhzdZyQ2bYQrjy
Q4LB0lC7aOnsMyYKHHYeRvPxj
IQXmdqgOJGq+vsevG06zW+1xg
YJh9rCIfnm1GX/KMgxLPG2vXT
D/RnLX+D3T3UL7HJYHJhAZD5L
59VvjSPsZJHeDCUyWYrvPZesZ
DIRvhDD52SKvbheeTJUm6Ehkz
ytNN2SN96QRk8j/iI8ib";
};
options {
...
dnssec-enable yes;
dnssec-validation yes;
};
</pre>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
None of the keys listed in this example are valid. In particular,
the root key is not valid.
</div>
<p>
When DNSSEC validation is enabled and properly configured,
the resolver will reject any answers from signed, secure zones
which fail to validate, and will return SERVFAIL to the client.
</p>
<p>
Responses may fail to validate for any of several reasons,
including missing, expired, or invalid signatures, a key which
does not match the DS RRset in the parent zone, or an insecure
response from a zone which, according to its parent, should have
been secure.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
When the validator receives a response from an unsigned zone
that has a signed parent, it must confirm with the parent
that the zone was intentionally left unsigned. It does
this by verifying, via signed and validated NSEC/NSEC3 records,
that the parent zone contains no DS records for the child.
</p>
<p>
If the validator <span class="emphasis"><em>can</em></span> prove that the zone
is insecure, then the response is accepted. However, if it
cannot, then it must assume an insecure response to be a
forgery; it rejects the response and logs an error.
</p>
<p>
The logged error reads "insecurity proof failed" and
"got insecure response; parent indicates it should be secure".
(Prior to BIND 9.7, the logged error was "not insecure".
This referred to the zone, not the response.)
</p>
</div>
</div>
</div>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="id2572201"></a>IPv6 Support in <acronym class="acronym">BIND</acronym> 9</h2></div></div></div>
<p>
<acronym class="acronym">BIND</acronym> 9 fully supports all currently
defined forms of IPv6 name to address and address to name
lookups. It will also use IPv6 addresses to make queries when
running on an IPv6 capable system.
</p>
<p>
For forward lookups, <acronym class="acronym">BIND</acronym> 9 supports
only AAAA records. RFC 3363 deprecated the use of A6 records,
and client-side support for A6 records was accordingly removed
from <acronym class="acronym">BIND</acronym> 9.
However, authoritative <acronym class="acronym">BIND</acronym> 9 name servers still
load zone files containing A6 records correctly, answer queries
for A6 records, and accept zone transfer for a zone containing A6
records.
</p>
<p>
For IPv6 reverse lookups, <acronym class="acronym">BIND</acronym> 9 supports
the traditional "nibble" format used in the
<span class="emphasis"><em>ip6.arpa</em></span> domain, as well as the older, deprecated
<span class="emphasis"><em>ip6.int</em></span> domain.
Older versions of <acronym class="acronym">BIND</acronym> 9
supported the "binary label" (also known as "bitstring") format,
but support of binary labels has been completely removed per
RFC 3363.
Many applications in <acronym class="acronym">BIND</acronym> 9 do not understand
the binary label format at all any more, and will return an
error if given.
In particular, an authoritative <acronym class="acronym">BIND</acronym> 9
name server will not load a zone file containing binary labels.
</p>
<p>
For an overview of the format and structure of IPv6 addresses,
see <a href="Bv9ARM.ch09.html#ipv6addresses" title="IPv6 addresses (AAAA)">the section called &#8220;IPv6 addresses (AAAA)&#8221;</a>.
</p>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2572400"></a>Address Lookups Using AAAA Records</h3></div></div></div>
<p>
The IPv6 AAAA record is a parallel to the IPv4 A record,
and, unlike the deprecated A6 record, specifies the entire
IPv6 address in a single record. For example,
</p>
<pre class="programlisting">
$ORIGIN example.com.
host 3600 IN AAAA 2001:db8::1
</pre>
<p>
Use of IPv4-in-IPv6 mapped addresses is not recommended.
If a host has an IPv4 address, use an A record, not
a AAAA, with <code class="literal">::ffff:192.168.42.1</code> as
the address.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2572421"></a>Address to Name Lookups Using Nibble Format</h3></div></div></div>
<p>
When looking up an address in nibble format, the address
components are simply reversed, just as in IPv4, and
<code class="literal">ip6.arpa.</code> is appended to the
resulting name.
For example, the following would provide reverse name lookup for
a host with address
<code class="literal">2001:db8::1</code>.
</p>
<pre class="programlisting">
$ORIGIN 0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0 14400 IN PTR (
host.example.com. )
</pre>
</div>
</div>
</div>
<div class="navfooter">
<hr>
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left">
<a accesskey="p" href="Bv9ARM.ch03.html">Prev</a>�</td>
<td width="20%" align="center">�</td>
<td width="40%" align="right">�<a accesskey="n" href="Bv9ARM.ch05.html">Next</a>
</td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Chapter�3.�Name Server Configuration�</td>
<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
<td width="40%" align="right" valign="top">�Chapter�5.�The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver</td>
</tr>
</table>
</div>
</body>
</html>