Bv9ARM.ch03.html revision 010a51c427bfb6ab658fc0056955a1a5b69810be
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<!--
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - Copyright (C) 2004-2015 Internet Systems Consortium, Inc. ("ISC")
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - Copyright (C) 2000-2003 Internet Software Consortium.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin -
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - Permission to use, copy, modify, and/or distribute this software for any
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - purpose with or without fee is hereby granted, provided that the above
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - copyright notice and this permission notice appear in all copies.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin -
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin - PERFORMANCE OF THIS SOFTWARE.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin-->
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<html>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<head>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<title>Chapter�3.�Name Server Configuration</title>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<meta name="generator" content="DocBook XSL Stylesheets V1.76.1">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<link rel="home" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<link rel="up" href="Bv9ARM.html" title="BIND 9 Administrator Reference Manual">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<link rel="prev" href="Bv9ARM.ch02.html" title="Chapter�2.�BIND Resource Requirements">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<link rel="next" href="Bv9ARM.ch04.html" title="Chapter�4.�Advanced DNS Features">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</head>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<div class="navheader">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<table width="100%" summary="Navigation header">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<tr><th colspan="3" align="center">Chapter�3.�Name Server Configuration</th></tr>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<tr>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<td width="20%" align="left">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<a accesskey="p" href="Bv9ARM.ch02.html">Prev</a>�</td>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<th width="60%" align="center">�</th>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<td width="20%" align="right">�<a accesskey="n" href="Bv9ARM.ch04.html">Next</a>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</td>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</tr>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</table>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<hr>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</div>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<div class="chapter" title="Chapter�3.�Name Server Configuration">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<div class="titlepage"><div><div><h2 class="title">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<a name="Bv9ARM.ch03"></a>Chapter�3.�Name Server Configuration</h2></div></div></div>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<div class="toc">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<p><b>Table of Contents</b></p>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dl>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#sample_configuration">Sample Configurations</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dd><dl>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#idp71738576">A Caching-only Name Server</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#idp71740752">An Authoritative-only Name Server</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</dl></dd>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#idp71743568">Load Balancing</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#idp71787728">Name Server Operations</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dd><dl>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#idp71788624">Tools for Use With the Name Server Daemon</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<dt><span class="section"><a href="Bv9ARM.ch03.html#idp71886416">Signals</a></span></dt>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</dl></dd>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</dl>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</div>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin <p>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin In this chapter we provide some suggested configurations along
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin with guidelines for their use. We suggest reasonable values for
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin certain option settings.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin </p>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin <div class="section" title="Sample Configurations">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<div class="titlepage"><div><div><h2 class="title" style="clear: both">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<a name="sample_configuration"></a>Sample Configurations</h2></div></div></div>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin <div class="section" title="A Caching-only Name Server">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<div class="titlepage"><div><div><h3 class="title">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<a name="idp71738576"></a>A Caching-only Name Server</h3></div></div></div>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin <p>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin The following sample configuration is appropriate for a caching-only
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin name server for use by clients internal to a corporation. All
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin queries
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin from outside clients are refused using the <span class="command"><strong>allow-query</strong></span>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin option. Alternatively, the same effect could be achieved using
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin suitable
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin firewall rules.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin </p>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin<pre class="programlisting">
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin// Two corporate subnets we wish to allow queries from.
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinacl corpnets { 192.168.4.0/24; 192.168.7.0/24; };
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinoptions {
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin // Working directory
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin directory "/etc/namedb";
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin allow-query { corpnets; };
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin};
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin// Provide a reverse mapping for the loopback
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin// address 127.0.0.1
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chinzone "0.0.127.in-addr.arpa" {
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin type master;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin file "localhost.rev";
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin notify no;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin};
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin</pre>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin </div>
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin <div class="section" title="An Authoritative-only Name Server">
<div class="titlepage"><div><div><h3 class="title">
<a name="idp71740752"></a>An Authoritative-only Name Server</h3></div></div></div>
<p>
This sample configuration is for an authoritative-only server
that is the master server for "<code class="filename">example.com</code>"
and a slave for the subdomain "<code class="filename">eng.example.com</code>".
</p>
<pre class="programlisting">
options {
// Working directory
directory "/etc/namedb";
// Do not allow access to cache
allow-query-cache { none; };
// This is the default
allow-query { any; };
// Do not provide recursive service
recursion no;
};
// Provide a reverse mapping for the loopback
// address 127.0.0.1
zone "0.0.127.in-addr.arpa" {
type master;
file "localhost.rev";
notify no;
};
// We are the master server for example.com
zone "example.com" {
type master;
file "example.com.db";
// IP addresses of slave servers allowed to
// transfer example.com
allow-transfer {
192.168.4.14;
192.168.5.53;
};
};
// We are a slave server for eng.example.com
zone "eng.example.com" {
type slave;
file "eng.example.com.bk";
// IP address of eng.example.com master server
masters { 192.168.4.12; };
};
</pre>
</div>
</div>
<div class="section" title="Load Balancing">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="idp71743568"></a>Load Balancing</h2></div></div></div>
<p>
A primitive form of load balancing can be achieved in
the <acronym class="acronym">DNS</acronym> by using multiple records
(such as multiple A records) for one name.
</p>
<p>
For example, if you have three WWW servers with network addresses
of 10.0.0.1, 10.0.0.2 and 10.0.0.3, a set of records such as the
following means that clients will connect to each machine one third
of the time:
</p>
<div class="informaltable">
<table border="1">
<colgroup>
<col width="0.875in" class="1">
<col width="0.500in" class="2">
<col width="0.750in" class="3">
<col width="0.750in" class="4">
<col width="2.028in" class="5">
</colgroup>
<tbody>
<tr>
<td>
<p>
Name
</p>
</td>
<td>
<p>
TTL
</p>
</td>
<td>
<p>
CLASS
</p>
</td>
<td>
<p>
TYPE
</p>
</td>
<td>
<p>
Resource Record (RR) Data
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="literal">www</code>
</p>
</td>
<td>
<p>
<code class="literal">600</code>
</p>
</td>
<td>
<p>
<code class="literal">IN</code>
</p>
</td>
<td>
<p>
<code class="literal">A</code>
</p>
</td>
<td>
<p>
<code class="literal">10.0.0.1</code>
</p>
</td>
</tr>
<tr>
<td>
<p></p>
</td>
<td>
<p>
<code class="literal">600</code>
</p>
</td>
<td>
<p>
<code class="literal">IN</code>
</p>
</td>
<td>
<p>
<code class="literal">A</code>
</p>
</td>
<td>
<p>
<code class="literal">10.0.0.2</code>
</p>
</td>
</tr>
<tr>
<td>
<p></p>
</td>
<td>
<p>
<code class="literal">600</code>
</p>
</td>
<td>
<p>
<code class="literal">IN</code>
</p>
</td>
<td>
<p>
<code class="literal">A</code>
</p>
</td>
<td>
<p>
<code class="literal">10.0.0.3</code>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<p>
When a resolver queries for these records, <acronym class="acronym">BIND</acronym> will rotate
them and respond to the query with the records in a different
order. In the example above, clients will randomly receive
records in the order 1, 2, 3; 2, 3, 1; and 3, 1, 2. Most clients
will use the first record returned and discard the rest.
</p>
<p>
For more detail on ordering responses, check the
<span class="command"><strong>rrset-order</strong></span> sub-statement in the
<span class="command"><strong>options</strong></span> statement, see
<a class="xref" href="Bv9ARM.ch06.html#rrset_ordering" title="RRset Ordering">RRset Ordering</a>.
</p>
</div>
<div class="section" title="Name Server Operations">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="idp71787728"></a>Name Server Operations</h2></div></div></div>
<div class="section" title="Tools for Use With the Name Server Daemon">
<div class="titlepage"><div><div><h3 class="title">
<a name="idp71788624"></a>Tools for Use With the Name Server Daemon</h3></div></div></div>
<p>
This section describes several indispensable diagnostic,
administrative and monitoring tools available to the system
administrator for controlling and debugging the name server
daemon.
</p>
<div class="section" title="Diagnostic Tools">
<div class="titlepage"><div><div><h4 class="title">
<a name="diagnostic_tools"></a>Diagnostic Tools</h4></div></div></div>
<p>
The <span class="command"><strong>dig</strong></span>, <span class="command"><strong>host</strong></span>, and
<span class="command"><strong>nslookup</strong></span> programs are all command
line tools
for manually querying name servers. They differ in style and
output format.
</p>
<div class="variablelist"><dl>
<dt><span class="term"><a name="dig"></a><span class="command"><strong>dig</strong></span></span></dt>
<dd>
<p>
The domain information groper (<span class="command"><strong>dig</strong></span>)
is the most versatile and complete of these lookup tools.
It has two modes: simple interactive
mode for a single query, and batch mode which executes a
query for
each in a list of several query lines. All query options are
accessible
from the command line.
</p>
<div class="cmdsynopsis"><p>
<code class="command">dig</code>
[@<em class="replaceable"><code>server</code></em>]
<em class="replaceable"><code>domain</code></em>
[<em class="replaceable"><code>query-type</code></em>]
[<em class="replaceable"><code>query-class</code></em>]
[+<em class="replaceable"><code>query-option</code></em>]
[-<em class="replaceable"><code>dig-option</code></em>]
[%<em class="replaceable"><code>comment</code></em>]
</p></div>
<p>
The usual simple use of <span class="command"><strong>dig</strong></span> will take the form
</p>
<p class="simpara">
<span class="command"><strong>dig @server domain query-type query-class</strong></span>
</p>
<p>
For more information and a list of available commands and
options, see the <span class="command"><strong>dig</strong></span> man
page.
</p>
</dd>
<dt><span class="term"><span class="command"><strong>host</strong></span></span></dt>
<dd>
<p>
The <span class="command"><strong>host</strong></span> utility emphasizes
simplicity
and ease of use. By default, it converts
between host names and Internet addresses, but its
functionality
can be extended with the use of options.
</p>
<div class="cmdsynopsis"><p>
<code class="command">host</code>
[-aCdlnrsTwv]
[-c <em class="replaceable"><code>class</code></em>]
[-N <em class="replaceable"><code>ndots</code></em>]
[-t <em class="replaceable"><code>type</code></em>]
[-W <em class="replaceable"><code>timeout</code></em>]
[-R <em class="replaceable"><code>retries</code></em>]
[-m <em class="replaceable"><code>flag</code></em>]
[-4]
[-6]
<em class="replaceable"><code>hostname</code></em>
[<em class="replaceable"><code>server</code></em>]
</p></div>
<p>
For more information and a list of available commands and
options, see the <span class="command"><strong>host</strong></span> man
page.
</p>
</dd>
<dt><span class="term"><span class="command"><strong>nslookup</strong></span></span></dt>
<dd>
<p><span class="command"><strong>nslookup</strong></span>
has two modes: interactive and
non-interactive. Interactive mode allows the user to
query name servers for information about various
hosts and domains or to print a list of hosts in a
domain. Non-interactive mode is used to print just
the name and requested information for a host or
domain.
</p>
<div class="cmdsynopsis"><p>
<code class="command">nslookup</code>
[-option...]
[
[<em class="replaceable"><code>host-to-find</code></em>]
| [- [server]]
]
</p></div>
<p>
Interactive mode is entered when no arguments are given (the
default name server will be used) or when the first argument
is a
hyphen (`-') and the second argument is the host name or
Internet address
of a name server.
</p>
<p>
Non-interactive mode is used when the name or Internet
address
of the host to be looked up is given as the first argument.
The
optional second argument specifies the host name or address
of a name server.
</p>
<p>
Due to its arcane user interface and frequently inconsistent
behavior, we do not recommend the use of <span class="command"><strong>nslookup</strong></span>.
Use <span class="command"><strong>dig</strong></span> instead.
</p>
</dd>
</dl></div>
</div>
<div class="section" title="Administrative Tools">
<div class="titlepage"><div><div><h4 class="title">
<a name="admin_tools"></a>Administrative Tools</h4></div></div></div>
<p>
Administrative tools play an integral part in the management
of a server.
</p>
<div class="variablelist"><dl>
<dt>
<a name="named-checkconf"></a><span class="term"><span class="command"><strong>named-checkconf</strong></span></span>
</dt>
<dd>
<p>
The <span class="command"><strong>named-checkconf</strong></span> program
checks the syntax of a <code class="filename">named.conf</code> file.
</p>
<div class="cmdsynopsis"><p>
<code class="command">named-checkconf</code>
[-jvz]
[-t <em class="replaceable"><code>directory</code></em>]
[<em class="replaceable"><code>filename</code></em>]
</p></div>
</dd>
<dt>
<a name="named-checkzone"></a><span class="term"><span class="command"><strong>named-checkzone</strong></span></span>
</dt>
<dd>
<p>
The <span class="command"><strong>named-checkzone</strong></span> program
checks a master file for
syntax and consistency.
</p>
<div class="cmdsynopsis"><p>
<code class="command">named-checkzone</code>
[-djqvD]
[-c <em class="replaceable"><code>class</code></em>]
[-o <em class="replaceable"><code>output</code></em>]
[-t <em class="replaceable"><code>directory</code></em>]
[-w <em class="replaceable"><code>directory</code></em>]
[-k <em class="replaceable"><code>(ignore|warn|fail)</code></em>]
[-n <em class="replaceable"><code>(ignore|warn|fail)</code></em>]
[-W <em class="replaceable"><code>(ignore|warn)</code></em>]
<em class="replaceable"><code>zone</code></em>
[<em class="replaceable"><code>filename</code></em>]
</p></div>
</dd>
<dt>
<a name="named-compilezone"></a><span class="term"><span class="command"><strong>named-compilezone</strong></span></span>
</dt>
<dd>
<p>
Similar to <span class="command"><strong>named-checkzone,</strong></span> but
it always dumps the zone content to a specified file
(typically in a different format).
</p>
</dd>
<dt>
<a name="rndc"></a><span class="term"><span class="command"><strong>rndc</strong></span></span>
</dt>
<dd>
<p>
The remote name daemon control
(<span class="command"><strong>rndc</strong></span>) program allows the
system
administrator to control the operation of a name server.
Since <acronym class="acronym">BIND</acronym> 9.2, <span class="command"><strong>rndc</strong></span>
supports all the commands of the BIND 8 <span class="command"><strong>ndc</strong></span>
utility except <span class="command"><strong>ndc start</strong></span> and
<span class="command"><strong>ndc restart</strong></span>, which were also
not supported in <span class="command"><strong>ndc</strong></span>'s
channel mode.
If you run <span class="command"><strong>rndc</strong></span> without any
options
it will display a usage message as follows:
</p>
<div class="cmdsynopsis"><p>
<code class="command">rndc</code>
[-c <em class="replaceable"><code>config</code></em>]
[-s <em class="replaceable"><code>server</code></em>]
[-p <em class="replaceable"><code>port</code></em>]
[-y <em class="replaceable"><code>key</code></em>]
<em class="replaceable"><code>command</code></em>
[<em class="replaceable"><code>command</code></em>...]
</p></div>
<p>See <a class="xref" href="man.rndc.html" title="rndc"><span class="refentrytitle"><span class="application">rndc</span></span>(8)</a> for details of
the available <span class="command"><strong>rndc</strong></span> commands.
</p>
<p>
<span class="command"><strong>rndc</strong></span> requires a configuration file,
since all
communication with the server is authenticated with
digital signatures that rely on a shared secret, and
there is no way to provide that secret other than with a
configuration file. The default location for the
<span class="command"><strong>rndc</strong></span> configuration file is
<code class="filename">/etc/rndc.conf</code>, but an
alternate
location can be specified with the <code class="option">-c</code>
option. If the configuration file is not found,
<span class="command"><strong>rndc</strong></span> will also look in
<code class="filename">/etc/rndc.key</code> (or whatever
<code class="varname">sysconfdir</code> was defined when
the <acronym class="acronym">BIND</acronym> build was
configured).
The <code class="filename">rndc.key</code> file is
generated by
running <span class="command"><strong>rndc-confgen -a</strong></span> as
described in
<a class="xref" href="Bv9ARM.ch06.html#controls_statement_definition_and_usage" title="controls Statement Definition and Usage">the section called &#8220;<span class="command"><strong>controls</strong></span> Statement Definition and
Usage&#8221;</a>.
</p>
<p>
The format of the configuration file is similar to
that of <code class="filename">named.conf</code>, but
limited to
only four statements, the <span class="command"><strong>options</strong></span>,
<span class="command"><strong>key</strong></span>, <span class="command"><strong>server</strong></span> and
<span class="command"><strong>include</strong></span>
statements. These statements are what associate the
secret keys to the servers with which they are meant to
be shared. The order of statements is not
significant.
</p>
<p>
The <span class="command"><strong>options</strong></span> statement has
three clauses:
<span class="command"><strong>default-server</strong></span>, <span class="command"><strong>default-key</strong></span>,
and <span class="command"><strong>default-port</strong></span>.
<span class="command"><strong>default-server</strong></span> takes a
host name or address argument and represents the server
that will
be contacted if no <code class="option">-s</code>
option is provided on the command line.
<span class="command"><strong>default-key</strong></span> takes
the name of a key as its argument, as defined by a <span class="command"><strong>key</strong></span> statement.
<span class="command"><strong>default-port</strong></span> specifies the
port to which
<span class="command"><strong>rndc</strong></span> should connect if no
port is given on the command line or in a
<span class="command"><strong>server</strong></span> statement.
</p>
<p>
The <span class="command"><strong>key</strong></span> statement defines a
key to be used
by <span class="command"><strong>rndc</strong></span> when authenticating
with
<span class="command"><strong>named</strong></span>. Its syntax is
identical to the
<span class="command"><strong>key</strong></span> statement in <code class="filename">named.conf</code>.
The keyword <strong class="userinput"><code>key</code></strong> is
followed by a key name, which must be a valid
domain name, though it need not actually be hierarchical;
thus,
a string like "<strong class="userinput"><code>rndc_key</code></strong>" is a valid
name.
The <span class="command"><strong>key</strong></span> statement has two
clauses:
<span class="command"><strong>algorithm</strong></span> and <span class="command"><strong>secret</strong></span>.
While the configuration parser will accept any string as the
argument
to algorithm, currently only the strings
"<strong class="userinput"><code>hmac-md5</code></strong>",
"<strong class="userinput"><code>hmac-sha1</code></strong>",
"<strong class="userinput"><code>hmac-sha224</code></strong>",
"<strong class="userinput"><code>hmac-sha256</code></strong>",
"<strong class="userinput"><code>hmac-sha384</code></strong>"
and "<strong class="userinput"><code>hmac-sha512</code></strong>"
have any meaning. The secret is a base-64 encoded string
as specified in RFC 3548.
</p>
<p>
The <span class="command"><strong>server</strong></span> statement
associates a key
defined using the <span class="command"><strong>key</strong></span>
statement with a server.
The keyword <strong class="userinput"><code>server</code></strong> is followed by a
host name or address. The <span class="command"><strong>server</strong></span> statement
has two clauses: <span class="command"><strong>key</strong></span> and <span class="command"><strong>port</strong></span>.
The <span class="command"><strong>key</strong></span> clause specifies the
name of the key
to be used when communicating with this server, and the
<span class="command"><strong>port</strong></span> clause can be used to
specify the port <span class="command"><strong>rndc</strong></span> should
connect
to on the server.
</p>
<p>
A sample minimal configuration file is as follows:
</p>
<pre class="programlisting">
key rndc_key {
algorithm "hmac-sha256";
secret
"c3Ryb25nIGVub3VnaCBmb3IgYSBtYW4gYnV0IG1hZGUgZm9yIGEgd29tYW4K";
};
options {
default-server 127.0.0.1;
default-key rndc_key;
};
</pre>
<p>
This file, if installed as <code class="filename">/etc/rndc.conf</code>,
would allow the command:
</p>
<p>
<code class="prompt">$ </code><strong class="userinput"><code>rndc reload</code></strong>
</p>
<p>
to connect to 127.0.0.1 port 953 and cause the name server
to reload, if a name server on the local machine were
running with
following controls statements:
</p>
<pre class="programlisting">
controls {
inet 127.0.0.1
allow { localhost; } keys { rndc_key; };
};
</pre>
<p>
and it had an identical key statement for
<code class="literal">rndc_key</code>.
</p>
<p>
Running the <span class="command"><strong>rndc-confgen</strong></span>
program will
conveniently create a <code class="filename">rndc.conf</code>
file for you, and also display the
corresponding <span class="command"><strong>controls</strong></span>
statement that you need to
add to <code class="filename">named.conf</code>.
Alternatively,
you can run <span class="command"><strong>rndc-confgen -a</strong></span>
to set up
a <code class="filename">rndc.key</code> file and not
modify
<code class="filename">named.conf</code> at all.
</p>
</dd>
</dl></div>
</div>
</div>
<div class="section" title="Signals">
<div class="titlepage"><div><div><h3 class="title">
<a name="idp71886416"></a>Signals</h3></div></div></div>
<p>
Certain UNIX signals cause the name server to take specific
actions, as described in the following table. These signals can
be sent using the <span class="command"><strong>kill</strong></span> command.
</p>
<div class="informaltable">
<table border="1">
<colgroup>
<col width="1.125in" class="1">
<col width="4.000in" class="2">
</colgroup>
<tbody>
<tr>
<td>
<p><span class="command"><strong>SIGHUP</strong></span></p>
</td>
<td>
<p>
Causes the server to read <code class="filename">named.conf</code> and
reload the database.
</p>
</td>
</tr>
<tr>
<td>
<p><span class="command"><strong>SIGTERM</strong></span></p>
</td>
<td>
<p>
Causes the server to clean up and exit.
</p>
</td>
</tr>
<tr>
<td>
<p><span class="command"><strong>SIGINT</strong></span></p>
</td>
<td>
<p>
Causes the server to clean up and exit.
</p>
</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</div>
<div class="navfooter">
<hr>
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left">
<a accesskey="p" href="Bv9ARM.ch02.html">Prev</a>�</td>
<td width="20%" align="center">�</td>
<td width="40%" align="right">�<a accesskey="n" href="Bv9ARM.ch04.html">Next</a>
</td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Chapter�2.�<acronym class="acronym">BIND</acronym> Resource Requirements�</td>
<td width="20%" align="center"><a accesskey="h" href="Bv9ARM.html">Home</a></td>
<td width="40%" align="right" valign="top">�Chapter�4.�Advanced DNS Features</td>
</tr>
</table>
</div>
<p xmlns:db="http://docbook.org/ns/docbook" style="text-align: center;">BIND 9.11.0pre-alpha</p>
</body>
</html>