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<center><h1>pdnsd Documentation</h1></center>
This is the "official" pdnsd documentation and reference written by
<a href="index.html#authors">Thomas Moestl</a> with revisions by
<a href="index.html#authors">Paul A. Rombouts</a>.<br>
This manual is a part of the pdnsd package, and may be distributed in
original or modified form under terms of the GNU General Public
License, as published by the Free Software Foundation; either version
3, or (at your option) any later version.<br>
You can find a copy of the GNU GPL in the file <code>COPYING</code> in the source or documentation directory.<br>
This manual is up-to-date for version 1.2.9. For older documentation, please refer to the doc
directory of the respective pdnsd package.<br>
If you want a quicker introduction to pdnsd, you can try some of the
<a href="http://www.google.com/search?q=pdnsd+howto">HOWTOs available on the web</a>.
For Apple Mac users, Brian Wells has published a good HOWTO at
<a href="http://web.mac.com/brianwells/main/pdnsd.html">http://web.mac.com/brianwells/main/pdnsd.html</a>.
<h2>0. Installation</h2>
<h3>0.1 Installing binary RPM's</h3>
To install a binary RPM, just do<br>
<p class="indented"><code>rpm -i pdnsd-<<i>version</i>>.rpm</code></p>
This should install pretty much everything automatically. The only thing left
for you to do is adapt your configuration file (stored in <code>/etc/pdnsd.conf</code>)
according to your needs (see below).
In the Red Hat and SuSE RPMs, a start script is also installed; read the section
<i>0.4, Start at Boot Time</i> about that.
<br>
<h3>0.2 Building RPM's</h3>
It is possible to build a binary RPM from a source package using the command<br>
<p class="indented"><code>rpmbuild --rebuild pdnsd-<<i>version</i>>.src.rpm</code></p>
or alternatively from a tarball using the command<br>
<p class="indented"><code>rpmbuild -tb pdnsd-<<i>version</i>>.tar.gz</code></p>
You can do this as root, but it is safer to build a binary package first as a normal user,
and then, when all has gone well, install the resulting binary package as root as in the previous section.
How to build an RPM package without being root is described at
<a href="http://www.ibm.com/developerworks/linux/library/l-rpm1/">
http://www.ibm.com/developerworks/linux/library/l-rpm1/</a>.<br><br>
Several pdnsd-specific options are available when building RPM packages:
<table cellpadding=7>
<tr>
<td class="nowrap">
<code>--with isdn</code>
</td>
<td>
Has the same effect as <code>--enable-isdn</code> (<a href="#enableisdn">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--without poll</code>
</td>
<td>
Has the same effect as <code>--disable-poll</code> (<a href="#disablepoll">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--without nptl</code>
</td>
<td>
Has the same effect as <code>--with-thread-lib=linuxthreads</code> (<a href="#threadlib">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with ipv6</code>
</td>
<td>
Has the same effect as <code>--enable-ipv6</code> (<a href="#enableipv6">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--without tcpqueries</code>
</td>
<td>
Has the same effect as <code>--disable-tcp-queries</code> (<a href="#disabletcpqueries">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--without debug</code>
</td>
<td>
Has the same effect as <code>--with-debug=0</code> (<a href="#withdebug">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--define "distro <<i>distro</i>>"</code>
</td>
<td>
Has the same effect as <code>--with-distribution=<<i>distro</i>></code> (<a href="#withdistro">see below</a>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--define "run_as_user <<i>user</i>>"</code>
</td>
<td>
Has the same effect as <code>--with-default-id=<<i>user</i>></code> (<a href="#defaultid">see below</a>).<br>
For RPMs the default <code><<i>user</i>></code> is <code>"pdnsd"</code>.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--define "run_as_uid <<i>uid</i>>"</code>
</td>
<td>
If the user defined by the previous option does not exist when the RPM is installed,
the pre-install script will try to create a new user with numerical id <code><<i>uid</i>></code>.
The default is to let the system choose the numerical id at install time.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--define "cachedir <<i>dir</i>>"</code>
</td>
<td>
Has the same effect as <code>--with-cachedir=<<i>dir</i>></code> (<a href="#withcachedir">see below</a>).
</td>
</tr>
</table>
You can also configure which compiler flags will be used by setting the environment variable
<code>CFLAGS</code>.
Using a bash shell, you can do that on the command line like this:
<code> CFLAGS="-O1 -Wall" rpmbuild ...</code><br>
This is useful if you prefer a different level of optimization, for instance.
<br>
<h3>0.3 Installing from pure sources (tar archives or git repositories)</h3>
<h4>0.3.1 Setting up the source code tree</h4>
Source code is available in the form of snapshots (tarballs) or a git repository
with the very latest development code and a (nearly) complete history of all the revisions.
Cloning a git repository is useful if you need a recent fix or feature
that is not yet contained in a main release or you want to participate in pdnsd development.
Otherwise you will probably find the tarballs more convenient because they are much more compact.
<h5>0.3.1.1 Unpacking a tar archive</h5>
The pdsnsd snapshot releases come in the form of a gzip'ed tar archive.
To decompress it (using a modern tar) do<br>
<p class="indented"><code>tar -xzf pdnsd-<version>.tar.gz</code></p>
If your tar doesn't do this, use:<br>
<p class="indented"><code>gzip -dc pdnsd-<version>.tar.gz | tar -xf -</code></p>
<h5>0.3.1.2 Cloning a git repository</h5>
To clone a git repository you need to install, if not already installed,
the git version control system, which is available as a package in most modern Linux distributions.
Then run the command:<br>
<p class="indented"><code>git clone git://gitorious.org/pdnsd/pdnsd.git pdnsd</code></p>
In rare cases, if you are behind some kind of firewall, the special git protocol can't be used
and you will need to fall back to the http protocol.
See the <a href="http://gitorious.org/pdnsd">gitorious.org</a> website or git documentation for more information.
<h4>0.3.2 Configuring the source</h4>
Change into the pdnsd source directory and run configure. It takes the following command line
options (if you do not specify an option, defaults will be used):<br>
<table bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td class="nowrap">
<code>--prefix=<i>dir</i></code>
</td>
<td>
Specify the prefix directory. The pdnsd files are installed in subdirectories
of the prefix, the pdnsd and pdnsd-ctl executables are for example installed
in the sbin subdirectory of the prefix. The default for this is /usr/local;
you might want to set this to /usr (using <code>--prefix=/usr</code>).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--sysconfdir=<i>dir</i></code>
</td>
<td>
Specify the config directory. pdnsd expects its pdnsd.conf file to reside
there if the <code>-c</code> option is not given at startup.
The default for this is the <code>etc</code> subdirectory of your prefix, e.g. <code>/usr/local/etc</code>
if you did not specify a prefix. To set this e.g. to <code>/etc</code>, use <code>--sysconfdir=/etc</code>.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="withdistro">--with-distribution=<i>distro</i></a></code>
</td>
<td>
Specify target distribution (default=Generic; others: RedHat, SuSE, Debian)<br>
See below for the effect of these settings.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-target=<i>platform</i></code>
</td>
<td>
Change compilation target platform (default: autodetect; others: Linux, BSD, Cygwin).<br>
autodetect will attempt to detect whether you are using Linux, *BSD or Cygwin and
should normally be sufficient. If this does not work, try specifying
your system manually (for the Darwin platform (Apple Mac OS X) specify BSD here).
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="withcachedir">--with-cachedir=<i>dir</i></a></code>
</td>
<td>
Default directory for pdnsd cache (default=/var/cache/pdnsd)<br>
This setting can be changed via config file settings when pdnsd has been built.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-hash-buckets=<i>num</i></code>
</td>
<td>
Number of hash buckets to use (default=1024). The default should be
sufficient for most purposes, but if you want to store a large number of names
in the cache, cache lookups may be faster if the number of hash buckets
is comparable to the number of names stored in the cache.
The number actually used is the smallest power of two
greater or equal to the number specified here.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="enableisdn">--enable-isdn</a></code>
</td>
<td>
Enable ISDN support<br>
This option will work only on Linux and may cause problems with 2.0.x or
old 2.2.x kernels. You will need it for a proper <code>if</code> uptest
under Linux for ISDN ppp devices.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--disable-ipv4</code>
</td>
<td>
Disable IPv4 networking support (default=enabled)
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="enableipv6">--enable-ipv6</a></code>
</td>
<td>
Enable IPv6 networking support.<br>
If your OS does support IPv6 properly, you should be able to serve also
IPv4 queries using this. Normally, this is disabled and you won't need
it.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--disable-ipv4-startup</code>
</td>
<td>
Disable IPv4 on pdnsd startup by default (default=enabled)
</td>
</tr>
<tr>
<td class="nowrap">
<code>--enable-ipv6-startup</code>
</td>
<td>
Enable IPV6 on pdnsd startup by default (default=IPv4).
These options are only defaults, you can specify on
the command line or in the config files which IP version
will really be used.
Normally, you won't need to change these.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--disable-udp-queries</code>
</td>
<td>
Disable UDP as query method. You shouldn't need to change
this.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="disabletcpqueries">--disable-tcp-queries</a></code>
</td>
<td>
Disable TCP as query method. This only effects the querying of
name servers by pdnsd, not the ability of pdnsd to answer
TCP queries from clients.
TCP queries are slower than UDP queries, but can be more secure
against certain types of attacks and are able to handle large answers.
For normal use this can be disabled.
(Note that the default has changed: TCP-query support
is now compiled in by default, but it still depends on the run-time
options whether it is actually used.)
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-query-method=<i>qm</i></code>
</td>
<td>
Specify the query method (default=udponly, others: tcponly, tcpudp, udptcp).
If you have enabled both UDP and TCP queries, this lets you control
which query method pdnsd will use by default. tcpudp will try TCP
first and fall back to UDP if TCP is not supported by the server;
udptcp will try UDP first and, if the answer was truncated, will repeat
the query using TCP.
udponly and tcponly should be clear. Note that this only effects
the compiled-in default; the query method can still be changed using
command-line options or options in the configuration file.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--disable-tcp-server</code>
</td>
<td>
Disable the TCP server.
In this case pdnsd will not be able to respond to TCP queries from clients.
This may cause problems with very large answers.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--disable-src-addr-disc</code>
</td>
<td>
Disable the UDP source address discovery.<br>
You need this only if you have trouble with messages saying
"could not discover udp source address".<br>
For the Cygwin target, this option is disabled by default.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="disablepoll">--disable-poll</a></code>
</td>
<td>
Disable poll(2) and use select(2) (default=enabled)<br>
You will normally not need this.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--disable-new-rrs</code>
</td>
<td>
Since version 1.2.9 this option is obsolete and ignored.
It is now possible to configure for each RR type separately whether it is
cacheable by pdnsd by editing the file <code>src/rr_types.in</code>.
The comments in this file explain how to do this.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--enable-strict-rfc2181</code>
</td>
<td>
Enforce strict RFC 2181 compliance.<br>
This will cause pdnsd to reject DNS answers with incorrect
timestamp settings (multiple RRs of the same type and for the same domain with
different TTLs). Normally not needed.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="enableunderscores">--enable-underscores</a></code>
</td>
<td>
This option is obsolete. Since version 1.2, pdnsd places no restrictions
on the types of characters in domain names (there are still a few restrictions
for locally defined names, though).
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-random-device=<i>device</i></code>
</td>
<td>
Specify random device; default: C Library <code>random()</code> PRNG<br>
pdnsd uses (pseudo-) random numbers as query IDs for security reasons
(this makes forging DNS answers more difficult). This option
controls where pdnsd gets these from. The default is the C library
<code>random()</code> function, which is relatively weak.
You can specify a device like /dev/urandom here if you like; pdnsd will read
random numbers from it 16-bit-wise. /dev/urandom is present under Linux and
most BSD derivates. You should not use /dev/random - it is more secure, but
may block and delay pdnsd's answers for a long time.<br>
You can specify <code>arc4random</code> to use the BSD <code>arc4random()</code>
library function (default for FreeBSD target), which is considered safe.<br>
You can also specify <code>random</code> as device to use the C Library
<code>random()</code> function (described above).
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="defaultid">--with-default-id=<i>user</i></a></code>
</td>
<td>
Specify default user for pdnsd (default=nobody).
This is the user that will be entered for the <code>run_as</code>
option in the config file (see <a href="#runas">below</a>) that will be installed during <code>make install</code>.
You can change this any time in your config file.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="withdebug">--with-debug=<i>level</i></a></code>
</td>
<td>
Specify debugging level. Normally you can safely switch debugging off
by setting the level to 0. This will increase speed (although only
marginally) and save space in the executable (only about 12kB).
However, more significant may be the savings in stack space, especially
if pdnsd is put under heavy load and there are many simultaneous
running threads.<br>
Presently the only defined debug levels are in the range 0 - 9.
Setting the level to 9 enables hex dumps of the queries and replies
pdnsd receives and should normally not be needed. Debug output will only
be generated if you turn on special switches; it might be useful for
debugging your config files, so I recommend using the default (1).
However, if you use pdnsd under heavy load, a better strategy may be
to compile one version of pdnsd without debug support (configured with
<code>--with-debug=0</code>) for production use, and one version with
with debug support (e.g. <code>--with-debug=9</code>)
for diagnostic purposes.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-verbosity=<i>level</i></code>
</td>
<td>
Specify default message verbosity. The default should be ok.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--enable-rcsids</code>
</td>
<td>
Enable RCS IDs in executables (default=disabled).<br>
For personal use, there is no need to do this. If you build rpm's, it
might have advantages.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--enable-tcp-subseq</code>
</td>
<td>
Enable subsequent tcp queries. The DNS protocol standard
requires that servers must be capable of answering multiple
subsequent queries that are sent over the same tcp connection, and that
the server may only close the connection by himself after a certain
timeout. This feature is rarely used, but may make denial-of-service
attacks easier, as it allows for an attacker to hold a connection open
a long time (although the attacker's IP is most likely revealed then).
For full standard compliance, you should use this option.
If you do not use <code>--enable-tcp-server</code>, is option is not honored.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-tcp-qtimeout=<i>secs</i></code>
</td>
<td>
Specify default tcp query timeout after which the connection is closed
if no full query has been received. The default is 30s.
You can also change this option at run time using the tcp_qtimeout
config file option.
If you do not use <code>--enable-tcp-server</code>, is option is not honored.
</td>
</tr>
<tr>
<td class="nowrap">
<code>--with-par-queries=<i>num</i></code>
</td>
<td>
Specify the default number of queries that can be executed in parallel.
You can also change this option at run time using the par_queries
config file option. See the description of that option for an explanation
of what it really does.<br>
The default for this option is 2.
</td>
</tr>
<tr>
<td class="nowrap">
<code><a name="threadlib">--with-thread-lib=<i>lib</i></a></code>
</td>
<td>
<em>Added by Paul Rombouts</em>: Use this option if you experience problems with
signal handling under Linux. The usual symptom is that pdnsd fails to save
the cache to disk, and <code>/var/cache/pdnsd/pdnsd.cache</code> remains empty.
If you experience this kind of trouble, try reconfiguring with different values
for the <code>--with-thread-lib</code> option. The allowable values are
<code>linuxthreads</code> (or <code>lt</code> for short), <code>linuxthreads2</code>
(or <code>lt2</code> for short), and <code>nptl</code>.
By default the configure script tries to detect automatically whether
<code>linuxthreads</code> or <code>nptl</code> is more appropriate for your system,
but the method used is not foolproof. Look for the line:
<code>checking if this is an NPTL-based system...</code><br>
If the automatic test mistakenly indentifies the thread library on your system as
NPTL based, you should reconfigure with <code>--with-thread-lib=lt</code> and recompile.
If the result of the automatic test is "<code>no</code>" or if
<code>--with-thread-lib=lt</code> does not have the desired effect, try again using
<code>--with-thread-lib=lt2</code> .
</td>
</tr>
</table>
Normally, you will need only <code>--prefix</code>, <code>--sysconfdir</code> and
<code>--with-distribution</code>.
If you specify your distribution using <code>--with-distribution</code>, this has the
following effects:
<ul>
<li> An rc script is copied in the appropriate localtion, which enables pdnsd to start
at machine boot time (see 0.4)
<li> Distribution-specific portions might be included in the generated pdnsd.spec
file (only important if you want to build rpm archives yourself).
</ul>
If you choose <code>Generic</code>, no rc script is installed, and a generic spec
file is generated.<br>
Further instructions are in the INSTALL document in the pdnsd source directory.
<code>./configure --help</code> will give you a list of all supported command line
options.<br><br>
<em>Note added by Paul Rombouts</em>: Some people may want change the compiler optimization flag.
I use the <code>-O2</code> flag, but it might be safer to use a lower level of
optimization or no optimization at all. In that case prefix the
<code>configure</code> command with the desired compiler flags like this
(assuming you're using a bash shell):
<p class="indented"><code>CFLAGS="-O1 -Wall" ./configure ...</code></p>
<br>
<h4>0.3.3 Building & installing </h4>
Type <code>make</code> in the source directory. <i>Should</i> work by now.<br>
To install, type <code>make install</code> or do the installation by hand (see <i>0.3.4</i>).<br>
<code>make install</code> will do the following ($prefix is the prefix directory; see above):<br>
<ol>
<li> copies pdnsd to <code>$(prefix)/sbin/</code>
<li> copies pdnsd-ctl to <code>$(prefix)/sbin/</code>
<li> copies docs/pdnsd.conf.sample (a sample configuration) to the pdnsd config directory.
<li> creates your cache directory if it is not there.
After installation, you should check the file permissions and create or edit
<code>/etc/pdnsd.conf</code> to fit your needs (see below).
If you use the <a href="#runas"><code>run_as</code></a> option, please make sure that your
cache directory is owned by the user you specified with this option!
</ol>
You must be root for this installation!<br>
<b>Security notes:</b> <b><i>never</i></b> make the pdnsd cache directory
writeable for untrusted users, or you will get several security holes:
the users might modify the cache contents, or plant dangerous links.<br>
If you use a pidfile, you should be aware that you introduce security
problems if you place the pidfile in a directory in a NFS filesystem that
is writeable for untrusted users. Generally, the pidfile directory
(typically /var/run) should not be writeable for untrusted users.
<br>
<h4>0.3.4 Manual installation </h4>
For a manual installation, you need to do the following steps:
<ol>
<li> Copy pdnsd and pdnsd-ctl from your build directory to an appropriate location (e.g. <code>/usr/sbin</code>).
<li> Copy <code>docs/pdnsd.conf</code> into the directory you want it to reside (<code>/etc</code> by default,
and change it according to your needs (see below).
<li> Create your caching directory; default is <code>/var/cache/pdnsd</code> (you may change this
in your <code>pdnsd.conf</code>); Permissions should be at max <code>rwxr-xr-x</code> (if you want to
protect your cache and status socket, make it <code>rwx------</code>).
</ol>
Thats it!
<br>
<h3>0.4 Start at boot time</h3>
In the <code>src/rc</code> folder of the pdnsd distribution are start scripts
for pdnsd designed for different Linux distros. There are scripts
for SuSE, Redhat, Debian, Arch Linux and Slackware now.<br>
The start scripts are automatically installed during RPM install, and also during <code>make install</code>
if you specified your distro.<br>
For Slackware Linux there is a start-up script contributed by Nikola Kotur, but presently
it must be installed manually.
See <code>src/rc/README</code> and <code>src/rc/Slackware/rc.pdnsd</code> for details.
<h4>0.4.1 SuSE Linux startup</h4>
<code>rc/SuSE/pdnsd</code> is a start script for SuSE Linux. It was tested for 6.? but should run on some
versions below. You can do <code>make install</code> as root in the <code>rc/SuSE</code>
directory to install it, or you can install manually:<br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=5>
<tr>
<td>
<b>manual installation</b>
</td>
</tr>
<tr>
<td>
For manual installation, copy <code>rc/SuSE/pdnsd</code> into <code>/sbin/init.d/</code>, go to
<code>/sbin/init.d/rc2.d/</code> and create there the following two symlinks:<br>
S11pdnsd to ../pdnsd (do <code>ln -s ../pdnsd S11pdnsd</code> in that dir) <br>
K34pdnsd to ../pdnsd (do <code>ln -s ../pdnsd K34pdnsd</code> in that dir) <br>
The numbers dictate the order different services are started and
might need to be modified. Then edit your <code>/etc/rc.config</code> file and
add the line <code>START_PDNSD=yes</code> to start pdnsd at boot time.
</td>
</tr>
</table>
<p>
If you used the <code>make install</code> command, <code>START_PDNSD=yes</code> has been
appended to your <code>/etc/rc.config</code> file, causing pdnsd to be started
at boot time. If you don't want that, change the <code>yes</code> into <code>no</code>.
</p>
This start script was created from <code>/sbin/init.d/skeleton</code> by me, so the
most is copyrighted by SuSE. They put it under the GPL, however, so
the license stated in <a href="../../COPYING">COPYING</a> also applies to this script.
There is NO WARRANTY OF ANY KIND on these scripts.
This is no official SuSE script, and SuSE naturally does NO support
for it.
<h4>0.4.2 Red Hat Linux startup</h4>
<code>rc/Redhat/pdnsd</code> is a start script for Red Hat Linux. It was contibuted by Torben
Janssen. <br>
This was tested for 6.1 but should run on 5.0+. You can do <code>make install</code> as root in the
<code>rc/Redhat</code> directory to install it, or you can install manually:<br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=5>
<tr>
<td>
<b>manual installation</b>
</td>
</tr>
<tr>
<td>
For manual installation, copy <code>rc/Redhat/pdnsd</code> into <code>/etc/rc.d/init.d/</code><br>
Then go to <code>/etc/rc.d/rc3.d</code> and create there the following symlink:<br>
S78pdnsd -> ../init.d/pdnsd
(do <code>ln -f -s ../init.d/pdnsd S78pdnsd</code> in that dir)<br>
Then go to <code>/etc/rc.d/rc0.d</code> and create there the following symlink:<br>
K78pdnsd -> ../init.d/pdnsd
(do <code>ln -f -s ../init.d/pdnsd K78pdnsd</code> in that dir)<br>
Then go to /etc/rc.d/rc6.d and create there the following symlink:<br>
K78pdnsd -> ../init.d/pdnsd
(do <code>ln -f -s ../init.d/pdnsd K78pdnsd</code> in that dir)
</td>
</tr>
</table>
This script is also covered by license stated in <a href="../../COPYING">COPYING</a>.
Again, there is NO WARRANTY OF ANY KIND on these scripts.
This is no offical Redhat script, and Redhat naturally does NO support
for it
<br>
<h3>0.5 Notes for FreeBSD users</h3>
The special handling of ISDN ppp devices is only supported on Linux. It is not needed in FreeBSD, the normal
device handling also works fine with isdn4bsd devices.<br>
When compiled for FreeBSD, pdnsd as a small RFC compatability issue: RFC2181 demands answers on dns querys
to be sent with the same source address the query packet went to. In seldom cases, this will not be the case,
because the kernel selects the source address depending on the interface that was used for sending the answer.<br>
Setting the source address currently does not work for IPv4. I have written a kernel patch that will provide an easy way
to program this. We'll see if or when it gets commited.<br>
<br>
<br>
<h2>1 Invocation</h2>
When invoking pdnsd, you can specify various options at the command line. Command line options
always override config file options. The various <b>--noX</b> options are present to override
config file options.
<p>
pdnsd <b>--help</b> (or <b>-h</b>) gives you an overview of the pdnsd command line options.
</p>
<p>
pdnsd <b>--version</b> (or <b>-V</b> for short) prints licence and version information.
</p>
<p>
To start pdnsd as background daemon, specifiy <b>--daemon</b> (or <b>-d</b> for short) on
the command line. Diagnostic and error messages after the actual daemon start
will be printed to the syslog instead of the console. <b>--nodaemon</b> will disable this.
</p>
<p>
When starting pdnsd as a daemon, the <b>-p</b> option may be helpful: It writes the pid
of the server process to the file of the name given as argument to this option. <br>
Example: <code>pdnsd -d -p /var/run/pdnsd.pid</code>
</p>
<p>
If you want to specify a configuration file other than <code>/etc/pdnsd.conf</code>, specify
<b>-c</b> or <b>--config-file</b> on the command line, followed by a filename.
</p>
<p>
If pdnsd was compiled with debugging support, you may specify <b>-g</b> or
<b>--debug</b> on the command line. This will cause extra diagnostic messages to be
printed. When pdnsd runs in daemon mode, the messages will be written to the <code>pdnsd.debug</code>
file in your cache directory. <b>--nodebug</b> disables debugging.
</p>
<p>
pdnsd <b>-v</b><i>n</i> sets the verbosity level of pdnsd. <i>n</i> is normally a digit from 0 to 3,
where 0 means normal operation, while 3 will most verbose.
Level 9 can be used in combination with the <code>--debug</code> option for very
extensive debug information.<br>
<i>Note</i>: The current implementation mostly ignores the verbosity level,
so you may not notice much difference between the various levels.
</p>
<p>
The option <b>-s</b> or <b>--status</b> enables the status control socket. This is a named socket in
the cache directory called <code>pdnsd.status</code>. This socket allows run-time configuration of pdnsd
using the utility <code>pdnsd-ctl</code>. See <a href="#pdnsdctl">below</a> for more details about <code>pdnsd-ctl</code>.
<b>--nostatus</b> disables status control.
See also the configuration option <a href="#statusctl"><code>status_ctl</code></a> in the global section.
</p>
<p>
The option <b>--notcp</b> disables the seldom needed TCP server thread, which may
save you some resources. <b>-t</b> or <b>--tcp</b> will enable it.
See also the <a href="#tcpserver"><code>tcp_server</code></a> configuration option.
</p>
<p>
Using the <a name="querymethodcommandlineoption"><b>-m</b></a> option, you can select the method pdnsd uses to query other name servers.
Following methods are supported (see also the <a href="#querymethod"><code>query_method</code></a>
configuration option):<br>
<b>-muo</b>: pdnsd will use UDP only. This is the fastest method, and should be supported by all name servers
on the Internet. <br>
<b>-mto</b>: pdnsd will use TCP only. TCP queries usually take longer time than UDP queries, but are more secure
against certain attacks, where an attacker tries to guess your query id and to send forged answers. TCP queries
are not supported by some name servers.<br>
<b>-mtu</b>: pdnsd will try to use TCP, and will fall back to UDP if its connection is refused or times out.<br>
<b>-mut</b>: <em>New in version 1.2.5:</em> pdnsd will try to use UDP, and will repeat the query using TCP if the UDP reply was truncated
(i.e. the <code>tc</code> bit is set). This is the behaviour recommended by the DNS standards.<br>
</p>
<p>
The <b>-4</b> option switches to IPv4 mode, providing pdnsd was compiled with IPv4 support.<br>
The <b>-6</b> option switches to IPv6 mode, providing pdnsd was compiled with IPv6 support.<br>
The <b>-a</b> option is only available when pdnsd was compiled with both IPv4 and IPv6 support.
With this option, pdnsd will try to detect automatically if a system supports IPv6, and fall back to IPv4 otherwise.<br>
</p>
<p>
With <b>-i</b> <em>prefix</em> or <b>--ipv4_6_prefix=</b><em>prefix</em> you can set the prefix pdnsd uses (when running in IPv6
mode) to map IPv4 addresses in the configuration file to IPv6 addresses.
There is also a corresponding option for the config file, <a href="#ipv46prefix">see below</a>.
Must be a valid IPv6 address.
The default is <code>::ffff:0.0.0.0</code>
</p>
<h2>2 The configuration file</h2>
This section describes the layout of the configuration file and the available
configuration options.
The default location of the file is <code>/etc/pdnsd.conf</code>. This may be changed
with the -c command line option.
An example pdnsd.conf comes with the pdnsd distribution in the docs directory
and will be installed to <code>/etc/</code> by <code>make install</code>.
<br>
<h3>2.1 Layout</h3>
The configuration file is divided into sections. Each section is prefixed with
the section name and opening curlies ({) and closed with closing curlies (}).
In each section, configuration options can be given in the form
<br><code>
<i>option_name</i>=<i>option_value</i>;
</code><br>
Option value may be a string literal, a number, a time specification or a constant.
In previous versions of pdnsd strings had to be enclosed
in quotes ("), but since version 1.1.10 this is no longer necessary, unless
a string contains a special character such as whitespace, a token that normally starts
a comment, or one of "<code>,;{}\</code>".
Since version 1.2.9 a backslash (\) inside a string is interpreted as an escape character,
so it is possible to include special characters in strings (both quoted or unquoted)
by preceding them with a backslash. Some escape sequences are in interpreted as in the C
programming language, e.g. <code>\t</code> becomes a tab,
<code>\n</code> becomes a new-line control char.<br>
A time specification consists a sequence of digits followed by a one-letter suffix.
The following suffixes are recognized:
<code>s</code> (seconds), <code>m</code> (minutes), <code>h</code> (hours),
<code>d</code> (days) and <code>w</code> (weeks).
If the suffix is missing, seconds are assumed.
If several time specifications are concatenated, their values are added together;
e.g. <code>2h30m</code> is interpreted as 2*60*60 + 30*60 = 9000 seconds.<br>
Some options take more than one value; in this case, the values are separated with commas.<br>
If you may supply one of a set of possible values to an option, this is noted
in the documentation as
<code>(option1|option2|option3|...)</code><br>
The constants <code>true|false</code> and <code>yes|no</code>
are accepted as synonyms for the constants <code>on|off</code>.<br>
Comments may be enclosed in /* and */, nested comments are possible. If the
# sign or two slashes (//) appear in the configuration file, everything from
these signs to the end of the current line is regarded as a comment and ignored.<br>
There are examples for nearly all options in the sample config file.
<br>
<h3>2.1.1 <a name="globalsection"><code>global</code> Section</a></h3>
The global section specifies parameters that affect the overall behaviour of the
server. If you specify multiple global sections, the settings of those later in
the file will overwrite the earlier given values.<br>
These are the possible options:<br><br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td>
<b><code>perm_cache=(<i>number</i>|off);</code></b><br>
Switch the disk cache off or supply a maximum cache size in kB. If the disk
cache is switched off, 8 bytes will still be written to disk.
The memory cache is always 10kB larger than the file cache.
This value is 2048 (2 MB) by default.
</td>
</tr>
<tr>
<td>
<b><code>cache_dir=<i>string</i>;</code></b><br>
Set the directory you want to keep the cache in.
The default is <code>"/var/cache/pdnsd"</code>
(unless pdnsd was compiled with a different default).
</td>
</tr>
<tr>
<td>
<b><code>server_port=<i>number</i>;</code></b><br>
Set the server port. This is especially useful when you want to start the
server and are not root. Note that you may also not specify uptest=ping in
the server section as non-root.<br>
The default port is 53, the RFC-standard one. Note that you should only use
non-standard ports when you only need clients on your machine to communicate
with the server; others will probably fail if the try to contact the server
on the basis of an NS record, since the A record that supplies the address for
(among others) name servers does not have a port number specification.
</td>
</tr>
<tr>
<td>
<b><code>server_ip=<i>string</i>;</code></b><br>
or<br>
<b><code>interface=<i>string</i>;</code></b><br>
Set the IP address pdnsd listens on for requests. This can be useful
when the host has several interfaces and you want pdnsd not to listen on
all interfaces. For example, it is possible to bind pdnsd to listen on
127.0.0.2 to allow pdnsd to be a forwarder for BIND.
The default setting for this option is <code>server_ip=any</code>, which means that
pdnsd will listen on all of your local interfaces.
Presently you can only specify one address here; if you want pdnsd to listen on multiple
interfaces but not all you will have to specify <code>server_ip=any</code>
and use firewall rules to restrict access.<br>
The IP address used to need quotation marks around it, but since version 1.1.10
this is no longer necessary.<br>
If pdnsd has been compiled with both IPv4 and IPv6 support, and you want to
specify an IPv6 address here, then unless pdnsd was compiled to start up in IPv6 mode
by default, you will need to use the <code>-6</code> command-line option or
set <code>run_ipv4=off</code> first (see <a href="#runipv4">below</a>) in order to ensure that the
IPv6 address is parsed correctly.<br>
If pdnsd is running in IPv6 mode and you specify an IPv4 address here,
it will automatically be mapped to an IPv6 address.<br>
<em>New in version 1.2:</em> You may also give the name of an interface
such as <code>"lo"</code> or <code>"eth0"</code> here, instead of an IP address
(this has been tested on Linux, and may or may not work on other platforms).
pdnsd will not bind to the interface name, but will look up the address of the
interface at start-up and listen on that address. If the address of the interface
changes while pdnsd is running, pdnsd will not notice that. You will need to
restart pdnsd in that case.
</td>
</tr>
<tr>
<td>
<b><code>outgoing_ip=<i>string</i>;</code></b><br>
or<br>
<b><code>outside_interface=<i>string</i>;</code></b><br>
<em>New in version 1.2.9:</em>
Set the IP address of the interface used by pdnsd for outgoing queries.
This can be useful when the host has several interfaces and you want pdnsd
to send outgoing queries via only one of them.
For example, if pdnsd is running on a host with one interface with IP address
192.168.1.1 connected to the local network, and another with IP address 123.xxx.yyy.zzz
connected to the internet, you may specify <code>server_ip=192.168.1.1</code>
and <code>outgoing_ip=123.xxx.yyy.zzz</code> to enforce that pdnsd only responds
to queries received from the local network, and only sends outgoing queries via
the interface connected to the internet.<br>
The default setting for this option is <code>any</code>, which means that
the kernel is free to decide which interface to use.
Like with the <code>server_ip</code> option, you may also give the name of an
interface here, instead of an IP address.
</td>
</tr>
<tr>
<td>
<b><code>linkdown_kluge=(on|off);</code></b><br>
This option enables a kluge that some people might need: when all servers are
marked down, with this option set the cache is not even used when a query is
received, and a DNS error is returned in any case. The only exception from this
is that local records (as specified in <code>rr</code> and <code>source</code>
sections are still served normally.
In general, you probably want to get cached entries even when the network is down,
so this defaults to off.
</td>
</tr>
<tr>
<td>
<b><code>max_ttl=<i>timespec</i>;</code></b><br>
This option sets the maximum time a record is held in cache. All dns
resource records have a time to live field that says for what period of time the
record may be cached before it needs to be requeried. If this is more than the
value given with <code>max_ttl</code>, this time to live value is set to <code>max_ttl</code>.
This is done to prevent records from being cached an inappropriate long period of time, because
that is almost never a good thing to do. Default is 604800s (one week).
</td>
</tr>
<tr>
<td>
<b><code>min_ttl=<i>timespec</i>;</code></b><br>
This option sets the minimum time a record is held in cache. All dns
resource records have a time to live field that says for what period of time the
record may be cached before it needs to be requeried. If this is less than the
value given with <code>min_ttl</code>, this time to live value is set to <code>min_ttl</code>.
Default is 120 seconds.
</td>
</tr>
<tr>
<td>
<b><code>neg_ttl=<i>timespec</i>;</code></b><br>
This option sets the time that negatively cached records will remain valid in the
cache if no time to live can be determined. This is always the case when whole
domains are being cached negatively, and additionally when record types are cached
negatively for a domain for which no SOA record is known to pdnsd. If a SOA is present,
the ttl of the SOA is taken.
</td>
</tr>
<tr>
<td>
<b><code>neg_rrs_pol=(on|off|auth|default);</code></b><br>
This sets the RR set policy for negative caching; this tells pdnsd under which circumstances
it should cache a record type negatively for a certain domain. <code>off</code> will
turn the negative caching of record types off, <code>on</code> will always add a negative
cache entry when a name server did not return a record type we asked it for, and <code>auth</code>
will only add such entries if the answer came from an authoritative name server for that
domain.<br>
<em>New in version 1.2.8:</em> The <code>default</code> setting will add a negatively cached record
if either the answer was authoritive or the answer indicated the name server had "recursion available"
while the query explicitly requested such recursion.<br>
The preset is "<code>default</code>" (used to be <code>auth</code>).
</td>
</tr>
<tr>
<td>
<b><code>neg_domain_pol=(on|off|auth);</code></b><br>
This is analogue to <code>neg_rrs_pol</code> for whole domain negative caching. It should be safe
to set this <code>on</code>, because I have not seen a caching server that will falsely claim that a
domain does not exist.<br>
The default is <code>auth</code>.
</td>
</tr>
<tr>
<td>
<b><code><a name="runas">run_as=<i>string</i>;</a></code></b><br>
This option allows you to let pdnsd change its user and group id after operations that needed
privileges have been done. This helps minimize security risks and is therefore recommended. The
supplied string gives a user name whose user id and primary group id are taken. <br>
A little more details: after reading the config file, becoming a daemon (if specified) and starting
the server status thread, the main thread changes its gid and uid, as do all newly created threads
thereafter. By taking another uid and gid, those threads run with the privileges of the
specified user.
Under Linux and FreeBSD, the server status thread runs with the original privileges only when the strict_setuid option
is set to <code>off</code> (see below, <code>on</code> by default), because these may be needed
for exec uptests. The manager thread also retains its original privileges in this case.
You should take care that the user you specify has write permissions on your cache file and
status pipe (if you need a status pipe). You should look out for error messages like "permission denied"
and "operation not permitted" to discover permission problems.<br>
</td>
</tr>
<tr>
<td>
<b><code>strict_setuid=(on|off);</code></b><br>
When used together with the <code>run_as</code> option, this option lets you specify that all threads of the
program will run with the privileges of the <code>run_as</code> user. This provides higher security than
the normal <code>run_as</code>
option, but is not always possible. See the <a href="#runas"><code>run_as</code></a> option for further discussion.<br>
This option is on by default.<br>
Note that this option has no effect on Non-Linux systems.
</td>
</tr>
<tr>
<td>
<b><code>paranoid=(on|off);</code></b><br>
Normally, pdnsd queries all servers in recursive mode (i.e. instructs servers to query other servers themselves
if possible,
and to give back answers for domains that may not be in its authority), and accepts additional records with information
for servers that are not in the authority of the queried server. This opens the possibility of so-called cache poisoning:
a malicious attacker might set up a dns server that, when queried, returns forged additional records. This way, he might
replace trusted servers with his own ones by making your dns server return bad IP addresses. This option protects
you from cache poisoning by rejecting additional records
that do not describe domains in the queried servers authority space and not doing recursive queries any more.
An exception
to this rule are the servers you specify in your config file, which are trusted.<br>
The penalty is a possible performance decrease, in particular, more queries might be necessary for the same
operation.<br>
You should also notice that there may be other similar security problems, which are essentially problems of
the DNS, i.e.
any "traditional" server has them (the DNS security extensions solve these problems, but are not widely
supported).
One of this vulnerabilities is that an attacker may bombard you with forged answers in hopes that one may match a
query
you have done. If you have done such a query, one in 65536 forged packets will be succesful (i.e. an average packet
count of 32768 is needed for that attack). pdnsd can use TCP for queries,
which has a slightly higher overhead, but is much less vulnerable to such attacks on sane operating systems. Also, pdnsd
chooses random query ids, so that an attacker cannot take a shortcut. If the attacker is able to listen to your network
traffic, this attack is relatively easy, though.<br>
This vulnerability is not pdnsd's fault, and is possible using any conventional
name server (pdnsd is perhaps a little more secured against this type of attacks if you make it use TCP).<br>
The <code>paranoid</code> option is off by default.<br>
</td>
</tr>
<tr>
<td>
<b><code>ignore_cd=(on|off);</code></b><br>
<em>New in version 1.2.8:</em> This option lets you specify that the CD bit of a DNS query will be ignored.
Otherwise pdnsd will reply FORMERR to clients that set this bit in a query.
It is safe to enable this option, as the CD bit refers to 'Checking Disabled'
which means that the client will accept non-authenticated data.<br>
This option is on by default. Turn it off if you want the old behaviour (before version 1.2.8).
</td>
</tr>
<tr>
<td>
<b><code>scheme_file=<i>string</i>;</code></b><br>
In addition to normal uptests, you may specify that some servers shall only be queried when a certain
pcmcia-cs scheme is active (only under linux). For that, pdnsd needs to know where the file resides that
holds the pcmcia scheme information. Normally, this is either <code>/var/lib/pcmcia/scheme</code> or
<code>/var/state/pcmcia/scheme</code>.
</td>
</tr>
<tr>
<td>
<b><code><a name="statusctl">status_ctl=(on|off);</a></code></b><br>
This has the same effect as the <code>-s</code> command line option: the status control is enabled when
<code>on</code> is specified.<br>
<em>Added by Paul Rombouts</em>: Note that <code>pdnsd-ctl</code> allows run-time configuration of pdnsd,
even the IP addesses of the name servers can be changed. If you're not using <code>pdnsd-ctl</code> and
you want maximum security, you should not enable this option. It is disabled by default.
</td>
</tr>
<tr>
<td>
<b><code>daemon=(on|off);</code></b><br>
This has the same effect as the <code>-d</code> command line option: the daemon mode is enabled when
<code>on</code> is specified.<br>
Default is <code>off</code>.
</td>
</tr>
<tr>
<td>
<b><code><a name="tcpserver">tcp_server=(on|off);</a></code></b><br>
<code>tcp_server=on</code> has the same effect as the <code>-t</code> or <code>--tcp</code>
command-line option: it enables TCP serving.
Similarly, <code>tcp_server=off</code> is like the <code>--notcp</code> command-line option.<br>
Default is <code>on</code>.
</td>
</tr>
<tr>
<td>
<b><code>pid_file=<i>string</i>;</code></b><br>
This has the same effect as the <code>-p</code> command line option: you can specify a file that pdnsd
will write its pid into when it starts in daemon mode.
</td>
</tr>
<tr>
<td>
<b><code>verbosity=<i>number</i>;</code></b><br>
This has the same effect as the <code>-v</code> command line option: you can set the verbosity of pdnsd's
messages with it. The argument is a number between 0 (few messages) to 3 (most messages).
</td>
</tr>
<tr>
<td>
<b><code><a name="querymethod">query_method=(tcp_only|udp_only|tcp_udp|udp_tcp);</a></code></b><br>
This has the same effect as the <code>-m</code> command line option.
Read the documentation for the <a href="#querymethodcommandlineoption">command line option</a> on this.
<code>tcp_only</code> corresponds to the <code>to</code>, <code>udp_only</code> to the <code>uo</code>,
<code>tcp_udp</code> to the <code>tu</code> and <code>udp_tcp</code> to the <code>ut</code>
argument of the command line option.<br>
If you use <code>query_method=tcp_udp</code>, it is recommended that you also set the <a href="#globaltimeout">global timeout option</a> to at least twice the longest server timeout.
</td>
</tr>
<tr>
<td>
<b><code><a name="runipv4">run_ipv4=(on|off);</a></code></b><br>
This has the same effect as the <code>-4</code> or <code>-6</code> command line option:
if on is specified, IPv4 support is enabled, and IPv6 support is disabled (if available).
If off is specified, IPv4 will be disabled and IPv6 will be enabled.
For this option to be meaningful, pdnsd needs to be compiled with support for the protocol you choose.
If pdnsd was compiled with both IPv4 and IPv6 support, and you want to include IPv6 addresses
in the configuration file, you will probably need to specify <code>run_ipv4=off</code> first to
ensure that the IPv6 addresses are parsed correctly.
</td>
</tr>
<tr>
<td>
<b><code>debug=(on|off);</code></b><br>
This has the same effect as the <code>-g</code> command line option: the debugging messages are enabled when
<code>on</code> is specified.
</td>
</tr>
<tr>
<td>
<b><code>ctl_perms=<i>number</i>;</code></b><br>
This option allows you to set the file permissions that the pdnsd status control socket will have. These
are the same as file permissions. The owner of the file will be the run_as user, or, if none is specified,
the user who started pdnsd. If you want to specify the permissions in octal (as usual), don't forget
the leading zero (0600 instead of 600!). To use the status control, write access is needed. The default
is 0600 (only the owner may read or write).<br>
Please note that the socket is kept in the cache directory, and that the cache directory permissions
might also need to be adjusted. Please ensure that the cache directory is not writeable for untrusted
users.
</td>
</tr>
<tr>
<td>
<b><code>proc_limit=<i>number</i>;</code></b><br>
With this option, you can set a limit on the pdnsd threads that will be active simultaneously. If
this number is exceeded, queries are queued and may be delayed some time.
See also the <code>procq_limit</code> option.<br>
The default for this option is 40.
</td>
</tr>
<tr>
<td>
<b><code>procq_limit=<i>number</i>;</code></b><br>
When the query thread limit <code>proc_limit</code> is exceeded, connection attempts to pdnsd will be queued.
With this option, you can set the maximum queue length.
If this length is also exceeded, the incoming queries will be dropped.
That means that tcp connections will be closed and udp queries will just be dropped, which
will probably cause the querying resolver to wait for an answer until it times out.<br>
See also the <code>proc_limit</code> option. A maximum of <code>proc_limit+procq_limit</code>
query threads will exist at any one time (plus 3 to 6 threads that will always
be present depending on your configuration).<br>
The default for this option is 60.
</td>
</tr>
<tr>
<td>
<b><code>tcp_qtimeout=<i>timespec</i>;</code></b><br>
This option sets a timeout for tcp queries. If no full query has been received on a tcp connection
after that time has passed, the connection will be closed. The default is set using the
<code>--with-tcp-qtimeout</code> option to <code>configure</code>.
</td>
</tr>
<tr>
<td>
<b><code>par_queries=<i>number</i>;</code></b><br>
This option used to set the maximum number of remote servers that would be queried simultaneously,
for every query that pdnsd receives.<br>
Since version 1.1.11, the meaning of this option has changed slightly.
It is now the increment with which the number of parallel queries is
increased when the previous set of servers has timed out.
For example, if we have a list <i>server1, server2, server3,</i> etc. of available servers
and <code>par_queries=2</code>, then pdnsd will first send queries to <i>server1</i> and <i>server2</i>,
and listen for responses from these servers.<br>
If these servers do not send a reply within their timeout period, pdnsd will send additional
queries to <i>server3</i> and <i>server4</i>, and listen for responses from
<i>server1, server2, server3</i> and <i>server4</i>, and so on until a useful reply is
received or the list is exhausted.<br>
In the worst case there will be pending queries to all the servers in the list of available servers.
We may be using more system resources this way (but only if the first servers in the list
are slow or unresponsive), but the advantage is that we have a greater chance of catching a reply.
After all, if we wait longer anyway, why not for more servers.<br>
See also the explanation of the global timeout option below.<br>
1 or 2 are good values for this option.
The default is set at compile time using the <code>--with-par-queries</code> option to <code>configure</code>.
</td>
</tr>
<tr>
<td>
<b><code><a name="globaltimeout">timeout=<i>timespec</i>;</a></code></b><br>
This is the global timeout parameter for dns queries.
This specifies the minimum period of time pdnsd will wait after sending the
first query to a remote server before giving up without having
received a reply. The timeout options in the configuration file are
now only minimum timeout intervals. Setting the global timeout option
makes it possible to specify quite short timeout intervals in the
server sections (see below). This will have the effect that pdnsd will start
querying additional servers fairly quickly if the first servers are
slow to respond (but will still continue to listen for responses from
the first ones). This may allow pdnsd to get an answer more quickly in
certain situations.<br>
If you use <code>query_method=tcp_udp</code> it is recommended that
you make the global timeout at least twice as large as the largest
server timeout, otherwise pdnsd may not have time to try a UDP query
if a TCP connection times out.<br>
Default value is 0.
</td>
</tr>
<tr>
<td>
<b><code>randomize_recs=(on|off);</code></b><br>
If this option is turned on, pdnsd will randomly reorder the cached records of one type
when creating an answer. This supports round-robin DNS schemes and increases fail
safety for hosts with multiple IP addresses, so this is usually a good idea.<br>
On by default.
</td>
</tr>
<tr>
<td>
<b><code><a name="queryportstart">query_port_start=(<i>number</i>|none);</a></code></b><br>
If a number is given, this defines the start of the port range used for queries of pdnsd. The
value given must be >= 1024. The purpose of this option is to aid certain firewall
configurations that are based on the source port. Please keep in mind that another application
may bind a port in that range, so a stateful firewall using target port and/or process uid may
be more effective. In case a query start port is given pdnsd uses this port as the first port of a
specified port range (see <a href="#queryportend"><code>query_port_end</code></a>) used for queries.
pdnsd will try to randomly select a free port from this range as local port for the query.<br>
To ensure that there are enough ports for pdnsd to use, the range between <code>query_port_start</code> and
<code>query_port_end</code> should be adjusted to at least (<code>par_queries</code> * <code>proc_limit</code>).
A larger range is highly recommended for security reasons, and also because other applications may
allocate ports in that range. If possible, this range should be kept out of the space
that other applications usually use.<br>
The default for this option is 1024. Together with the default value of <code>query_port_end</code>,
this makes it the hardest for an attacker to guess the source port used by the pdnsd resolver.
If you specify <code>none</code> here, pdnsd will let the kernel choose the source port, but
this may leave pdnsd more vulnerable to an attack.
</td>
</tr>
<tr>
<td>
<b><code><a name="queryportend">query_port_end=<i>number</i>;</a></code></b><br>
Used if <code>query_port_start</code> is not <code>none</code>. Defines the last port of the range started by query_port_start
used for querys by pdnsd. The default is 65535, which is also the maximum legal value for this option.
For details see the description of <a href="#queryportstart"><code>query_port_start</code></a>.
</td>
</tr>
<tr>
<td>
<b><code><a name="delegationonly">delegation_only=<i>string</i>;</a></code></b><br>
<em>Added by Paul Rombouts</em>: This option specifies a "delegation-only" zone.
This means that if pdnsd receives a query for a name that is in a
subdomain of a "delegation-only" zone but the remote name server
returns an answer with an authority section lacking any NS RRs for
subdomains of that zone, pdnsd will answer NXDOMAIN (unknown domain).
This feature can be used for undoing the undesired effects of DNS
"wildcards". Several "delegation-only" zones may be specified together.
If you specify root servers in a <a href="#serversection"><code>server</code></a> section it is
important that you set <code><a href="#rootserver">root_server</a>=on</code> in such a section.<br>
Example:
<p class="indented"><code>delegation_only="com","net";</code></p>
This feature is off by default. It is recommended that you only use
this feature if you actually need it, because there is a risk that
some legitimate names will be blocked, especially if the remote
name servers queried by pdnsd return answers with empty authority
sections.
</td>
</tr>
<tr>
<td>
<b><code><a name="ipv46prefix">ipv4_6_prefix=<i>string</i>;</a></code></b><br>
This option has the same effect as the <code>-i</code> command-line option.
When pdnsd runs in IPv6 mode, this option specifies the prefix pdnsd uses to convert IPv4 addresses in
the configuration file (or addresses specified with <a href="#pdnsdctl"><code>pdnsd-ctl</code></a>)
to IPv6-mapped addresses.
The string must be a valid IPv6 address. Only the first 96 bits are used.
Note that this only effects the parsing of IPv4 addresses listed after this option.<br>
The default is <code>"::ffff.0.0.0.0"</code>.
</td>
</tr>
<tr>
<td>
<b><code>use_nss=(on|off);</code></b><br>
If this option is turned on, pdnsd will call <code>initgroups()</code> to set up the group access list,
whenever pdnsd changes its user and group id (see <a href="#runas"><code>run_as</code></a> option).
There is a possible snag, though, if <code>initgroups()</code> uses NSS (Name Service Switch) and
NSS in turn uses DNS. In such a case you may experience lengthy timeouts and stalls.
By setting <code>use_nss=off</code>, you can disable the <code>initgroups()</code> call
(only possible in versions 1.2.5 and later).<br>
This option was contributed by Jan-Marek Glogowski.<br>
On by default.
</td>
</tr>
<tr>
<td>
<b><code><a name="udpbufsize">udpbufsize=<i>number</i>;</a></code></b><br>
<em>New in version 1.2.9:</em>
This option sets the upper limit on the size of UDP DNS messages. The default is 1024.<br>
See also the <code><a href="#ednsquery">edns_query</a></code> server option below.
</td>
</tr>
</table>
<br>
<h3>2.1.2 <a name="serversection"><code>server</code> Section</a></h3>
Each server section specifies a set of name servers that pdnsd should try to get
resource records or authoritative name server information from. The servers are
queried in the order of their appearance (or parallel to a limited extend).
If one fails, the next one is taken and so on.<br>
You probably want to specify the dns server in your LAN, the caching dns servers
of your internet provider or even a list of root servers in one or more server sections.<br>
The supported options in this section are:<br><br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td>
<b><code>label=<i>string</i>;</code></b><br>
Specify a label for the server section. This can be used to refer to this section
when using <a href="#pdnsdctl"><code>pdnsd-ctl</code></a>, the pdnsd control utility.<br>
You can give several server sections the same label, but if you want to change the addresses
of a server section (see <b><code>ip</code></b> option below) during run-time with
<code>"pdnsd-ctl server <i>label</i> up <i>dns1</i>,<i>dns2</i>,..."</code>,
the label must be unique.
</td>
</tr>
<tr>
<td>
<b><code>ip=<i>string</i>;</code></b><br>
Give the IP (the address, <em>not</em> the host name) of the server.<br>
Multiple IP addresses can be given per server section.
This can be done by entering multiple lines of the form <code>ip=<i>string</i>;</code>
or a single line like this:
<p class="indented"><code>ip=<i>string</i>,<i>string</i>,<i>string</i>;</code></p>
IP addresses do not have to be specified in the configuration file.
A server section without IP addresses will remain inactive until it is assigned
one or more addresses with <a href="#pdnsdctl"><code>pdnsd-ctl</code></a>,
the pdnsd control utility.<br>
If pdnsd has been compiled with both IPv4 and IPv6 support, any IPv6 addresses you specify
here will be skipped with a warning message, unless pdnsd is running in IPv6 mode.
Thus, unless pdnsd was compiled to startup in IPv6 mode by default, you need to use the
command-line option <code>-6</code> or set <code>run_ipv4=off</code>
first (see <a href="#runipv4"><code>global</code></a> section) in order to ensure
that IPv6 addresses are parsed correctly.<br>
If pdnsd is running in IPv6 mode and you specify an IPv4 address here,
it will automatically be mapped to an IPv6 address.
</td>
</tr>
<tr>
<td>
<b><code><a name="resolvfile">file=<i>string</i>;</a></code></b><br>
<em>New in version 1.2:</em> This option allows you to give the name of a <code>resolv.conf</code>-style file.
Of the lines beginning with the <code>nameserver</code> keyword, the second field will be parsed as an
IP address, as if it were specified with the <code>ip=</code> option. The remaining lines will be ignored.
If the contents of the file changes while pdnsd is running, you can make pdnsd aware of the changes through the
use of <a href="#pdnsdctl"><code>pdnsd-ctl</code></a>, the pdnsd control utility.
This is usually most conveniently done by placing the command <code>"pdnsd-ctl config"</code> in a script
that is automatically run whenever the DNS configuration changes.<br>
For example, suppose you have a ppp client that writes the DNS configuration for your ISP to the file
<code>/etc/ppp/resolv.conf</code> and runs the script <code>/etc/ppp/ip-up</code> when a new
connection is established. One way of ensuring that pdnsd is automatically reconfigured is to
add a <code>server</code> section in the config file with <code>file=/etc/ppp/resolv.conf</code> and to
add the command <code>"pdnsd-ctl config"</code> to <code>/etc/ppp/ip-up</code>.
</td>
</tr>
<tr>
<td>
<b><code>port=<i>number</i>;</code></b><br>
Give the port the remote name server listens on. Default is 53 (the official
dns port)
</td>
</tr>
<tr>
<td>
<b><code>uptest=(ping|none|if|dev|diald|exec|query);</code></b><br>
Determine the method to check whether the server is available. Currently
defined methods are:
<ul>
<li><b><code>ping</code></b>: Send an ICMP_ECHO request to the server. If it doesn't respond
within the timeout, it is regarded to be unavailable until the next probe.
<li><b><code>none</code></b>: The availability status is not changed, only the time stamp is updated.
<li><b><code>if</code></b>: Check whether the interface (specified in the <code>interface=</code> option) is
existent, up and running. This currently works for all "ordinary"
network interfaces, interfaces that disappear when down (e.g. ppp?),
and additionally for Linux isdn interfaces (as of kernel 2.2). Note that
you need a <code>/dev/isdninfo</code> device file (major#45, minor#255), or the
isdn uptest will always fail.
<li><b><code>dev</code></b> and <b><code>diald</code></b>: Perform an <code>if</code> uptest, and, if that
was succesful, additionally check whether a program is running that
has locked a given (modem-) device. The needed parameters are an interface (specified as for the <code>if</code>
uptest, e.g. <code>"ppp0"</code>) and a device relative to <code>/dev</code> (e.g.
<code>"modem"</code> for <code>/dev/modem</code> specified using the <code>device=</code> option.
pdnsd will then look for a pid file for the given interface in <code>/var/lock</code> (e.g.
<code>/var/run/ppp0.pid</code>) and for a lockfile for the given device (e.g. <code>/var/lock/LCK..modem</code>),
and then test whether the locking process is the process that created the pid file and this process is still
alive. If this is the case, the normal <code>if</code> uptest is executed for the given interface.<br>
The <code>dev</code> option is for pppd dial-on-demand, <code>diald</code> is the same for diald users.
<li><b><code>exec</code></b>: Executes a given command in the <code>/bin/sh</code> shell
(as <code>/bin/sh -c <command></code>)
and evaluates the result (the return code of the last command) in the shell's way of handling return codes,
i.e. 0 indicates success, all other indicate failure. The shell's process name will be
<code>uptest_sh</code>. The command is given with the <code>uptest_cmd</code> option (see below).
For secuity issues, also see that entry.
<li><b><code>query</code></b>: <em>New in version 1.2:</em>
This works like the ping test, except it sends an (empty) DNS query to the remote server.
If the server sends a well-formed response back within the timeout period (except SERVFAIL),
it will be regarded as available.
This test is useful if a remote server does not respond to ICMP_ECHO requests at all,
which unfortunately is quite common these days.
It can also happen that a remote server is online but ignores empty DNS queries.
Then you will need the set the <code><a href="#querytestname">query_test_name</a></code> option (see below).
In many cases this test will be a more reliable indicator of availability
than the ones mentioned before.
</ul>
<p>
The default value is <b><code>none</code></b>.
<br><br>
<b>NOTE</b>: If you use on-demand dialing, use <code>none</code>, <code>if</code>,
<code>dev</code>, <code>diald</code> or <code>exec</code>,
since <code>ping</code> or <code>query</code> will send packets
in the specified interval and the interface will thus frequently dial!
</td>
</tr>
<tr>
<td>
<b><code>ping_timeout=<i>number</i>;</code></b><br>
Sets the timeout for the ping test in tenths of seconds
(this unit is used for legacy reasons; actually the current implementation is
only accurate to a second).<br>
The default is 600 (one minute).
</td>
</tr>
<tr>
<td>
<b><code>ping_ip=<i>string</i>;</code></b><br>
The IP address for the ping test. The default is the IP of the name server.
</td>
</tr>
<tr>
<td>
<b><code><a name="querytestname">query_test_name=<i>string</i>;</a></code></b><br>
<em>New in version 1.2.9:</em>
Sets the name to be queried when using <code>uptest=query</code> availability test.
If the string is the unquoted constant <code>none</code>,
an empty query is used (this the default), otherwise a query of type A will be
sent for the domain name specified here. It is not necessary for the domain name
to exist or have a record of type A in order for the uptest to succeed.<br>
If the the remote server ignores empty queries, you will probably want to set
<code>query_test_name="."</code> (the root domain).
</td>
</tr>
<tr>
<td>
<b><code>uptest_cmd=<i>string</i>,<i>string</i>;</code></b><br>
or<br>
<b><code>uptest_cmd=<i>string</i>;</code></b><br>
Sets the command for the uptest=exec function to the first string.
If the second string is given, it specifies a user with whose user
id and primary group id the command is executed.<br>
This is especially useful if you are executing the server as root,
but do not want the uptest to be performed with root privileges.
In fact, you should never execute the uptest as root if you can help
it.<br>
If the server is running setuid or setgid, the privileges thus gained
are attempted to be dropped even before changing identity to the
specified user to prevent setuid/gid security holes (otherwise, any
user might execute commands as root if you setuid the executable).<br>
<b>Note that this is not always possible, and that pdnsd should never
be installed as setuid or setgid.</b>
The command is executed using <code>/bin/sh</code>, so you should be able to use
shell builtin commands.
</td>
</tr>
<tr>
<td>
<b><code>interval=(<i>timespec</i>|onquery|ontimeout);</code></b><br>
Sets the interval for the server up-test. The default is 900 seconds;
however, a test is forced when a query times out and the timestamp is reset then.<br>
If you specify <code>onquery</code> instead of a timeout, the interface will be
tested before every query. This is to prevent automatically dialing
interfaces (diald/pppd or ippp) to dial on dns queries. It is intended to be
used in connection with an interface-testing uptest ;-) <br>
Note that using uptest=exec, you might run into performance problems
on slow machines when you use that option.
DON'T use <code>onquery</code> with <code>uptest=ping</code> or
<code>uptest=query</code>, as it may cause delays if the server does not answer
(btw, it doesn't make sense anyway).
Note also that using <code>onquery</code> is no guarantee that the interface
will not be used. When another (reachable) dns server tells pdnsd
to query a third dns server for data, pdnsd will do that and has
no means of checking whether this will dial up the interface or not.
This however should be a rare situation.<br>
<em>New in version 1.2.3:</em>
A third possibility is to specify <code>interval=ontimeout</code>.
In this case the server is not tested at startup/reconfiguration, nor at regular intervals,
but only after a DNS query to a server times out. Certain types of network problems
such as a refused connection will also cause the server to be considered unavailable.
However, once a server is declared dead it is never considered again unless it is revived using a
<code><a href="#pdnsdctl">pdnsd-ctl</a> config</code> or <code>server</code> command.
The idea behind this option is to minimize uptests by assuming all
servers are available until there is reason to believe otherwise.
</td>
</tr>
<tr>
<td>
<b><code>interface=<i>string</i>;</code></b><br>
The network interface (or network device, e.g. <code>"eth0"</code>) for the <code>uptest=if</code> option.
Must be specified if <code>uptest=if</code> is given.
</td>
</tr>
<tr>
<td>
<b><code>device=<i>string</i>;</code></b><br>
The (modem-) device that is used for the <code>dev</code> uptest. If you use this for a dial-on-demand
ppp uptest (together with <code>uptest=dev</code>), you need to enter the device you are using for your
pppd here, e.g. <code>modem</code> for <code>/dev/modem</code>.<br>
Must be specified if <code>uptest=dev</code> is given.
</td>
</tr>
<tr>
<td>
<b><code>timeout=<i>timespec</i>;</code></b><br>
Set the timeout for the dns query. The default is 120 seconds. You probably want to set this lower.<br>
Timeouts specified in the configuration file are only treated as the
minimum period of time to wait for a reply. A queries to a remote
server are not canceled until a useful reply has been received, or all
the other queries have timed out or failed.<br>
If you have also set the global timeout option, you may consider setting a fairly small value here.
See the explanation of the timeout option in the <a href="#globaltimeout"><code>global</code></a>
section for what that means.
</td>
</tr>
<tr>
<td>
<b><code>purge_cache=(on|off);</code></b><br>
In every fetched dns record, there is a cache timeout given, which
specifies how long the fetched data may be cached until it needs to be
reloaded. If <code>purge_cache</code> is set to <code>off</code>, the stale records are not purged
(unless the cache size would be exceeded, in this case the oldest records are purged).
Instead, they are still served if they cannot succesfully be
updated (e.g. because all servers are down).<br>
Default is <code>off</code>.
</td>
</tr>
<tr>
<td>
<b><code>caching=(on|off);</code></b><br>
Specifies if caching shall be performed for this server at all. Default is
<code>on</code>.
</td>
</tr>
<tr>
<td>
<b><code>lean_query=(on|off);</code></b><br>
Specifies whether to use the "lean" query mode. In this mode, only the
information actually queried from pdnsd is resolved and cached. This has
the advantage that usually less cache space is used and the query is
usually faster. In 90% of the cases, only address (A) records are needed
anyway. If switched off, pdnsd will always cache all data about a host
it can find and will specifically ask for all available records
(well, at least it is a good approximation for what it really does ;-)
This will of course increase the answer packet sizes.<br>
Some buggy name servers may not deliver CNAME records when not asked for
all records. I do not know if such servers are around, but if you have
trouble resolving certain host names, try turning this option off.<br>
A last note: If you use multiple pdnsd's that access each other, turning
this option on is probably a big win.<br>
This on by default.
</td>
</tr>
<tr>
<td>
<b><code><a name="ednsquery">edns_query=(on|off);</a></code></b><br>
<em>New in version 1.2.9:</em>
Specifies whether to use EDNS (Extension mechanisms for DNS) for outgoing queries.
Currently this is only useful for allowing UDP message sizes larger than 512 bytes.
Note that setting this option on can give problems in combination with some legacy
systems or software, including, embarrassingly enough, previous versions of pdnsd.<br>
The default is <code>off</code>, but if your network can handle UDP payloads
significantly larger than 512 bytes, the recommended value is <code>on</code>.<br>
Note that this option only effects outgoing queries. If pdnsd receives a query using
EDNS, it will reply using EDNS regardless of the value of this option.
<br>
See also the <code><a href="#udpbufsize">udpbufsize</a></code> option above.
</td>
</tr>
<tr>
<td>
<b><code>scheme=<i>string</i>;</code></b><br>
You can specify a pcmcia-cs scheme that is used in addition to the uptests. If you specify
a scheme here, the server this section is for will only be queries if the given scheme
is active. Shell wildcards (* and ?) are allowed in the string under their special
meanings. You need to use the <code>scheme_file</code> option on the <code>global</code>
section to make this option work.
</td>
</tr>
<tr>
<td>
<b><code>preset=(on|off);</code></b><br>
This allows you to specify the initial state of a server before any uptest is performed.
<code>on</code> specifies that the server is regarded available. The default is <code>on</code>.
This is especially useful when you set <code>uptest=none;</code> and want to change
the status of a server only via pdnsd-ctl.
</td>
</tr>
<tr>
<td>
<b><code><a name="proxyonly">proxy_only=(on|off);</a></code></b><br>
When this option is set to <code>on</code>, answers given by the servers are always accepted, and no
other servers (as, for example, specified in the NS records of the query domain) are
queried. If you do not turn this option on, pdnsd will do such queries in some cases
(in particular when processing ANY queries).<br>
This option is useful when you do not want pdnsd to make connections to outside servers
for some reasons (e.g. when a firewall is blocking such queries).<br>
I recommend that you turn on <code>lean_query</code> when using this option.<br>
Default is <code>off</code>.
</td>
</tr>
<tr>
<td>
<b><code><a name="rootserver">root_server=(on|off|discover);</a></code></b><br>
Set this option to <code>on</code> if the servers specified in a section are root servers.
A root server will typically only give the name servers for the top-level domain in its reply.
Setting <code>root_server=on</code> will cause pdnsd to try to use cached information about
top-level domains to reduce to number of queries to root servers, making the resolving of
new names more efficient.
You can get a list of available root servers by running the command
<code>"dig . ns"</code>.<br>
This option is also necessary if you use the <a href="#delegationonly"><code>delegation_only</code></a> option.<br>
<em>New in version 1.2.8:</em> This option may also be set to "<code>discover</code>".
This will cause pdnsd to query the servers provided with the <code>ip=</code> option
to obtain the full list of root servers. The root-server addresses will replace the addresses
specified with the <code>ip=</code> option.
This will only be done once on startup, or after a "<code>pdnsd-ctl config</code>" command.
In this case the name servers specified with the <code>ip=</code> option don't have to be
root servers, they just have to know the names and addresses of the root servers.
After root-server discovery pdnsd will behave just as if <code>root_server=on</code>
had been specified.<br>
Default is <code>off</code>.
</td>
</tr>
<tr>
<td>
<b><code>randomize_servers=(on|off);</code></b><br>
<em>New in version 1.2.6:</em> Set this option to <code>on</code> to give each name server
in this section an equal chance of being queried. If this option is off, the name servers
are always queried starting with the first one specified. Even with this option on, the
query order is not truly random. Only the first server is selected randomly; the following
ones are queried in consecutive order, wrapping around to the beginning of the list when
the end is reached. Note that this option only effects the order within a section. The
servers in the first (active) section are always queried before those in the second one,
etc.<br> The default is off, but if you are resolving from root servers setting this
option on is highly recommended. If <code>root_server=on</code> this option also effects
the query order of the name servers for the top-level domains.
</td>
</tr>
<tr>
<td>
<b><code>reject=<i>string</i>;</code></b><br>
<em>New in version 1.2.6:</em> This option can be used to make pdnsd reject replies that
contain certain IP addresses. You can specify a single IP address, which will be matched
exactly, or a range of addresses using an address/mask pair.
The mask can be specified as a simple integer, indicating the number of initial 1 bits in
the mask, or in the usual IP address notation. IP addresses may be either IPv4 or IPv6
(provided there is sufficient support in the C libraries and support for AAAA records was
not disabled).
When addresses in the reject list are compared with those in a reply, only the bits
corresponding to those set in the netmask are significant, the rest are ignored.<br>
Multiple addresses or address/mask pairs may be specified; this can be done by entering
multiple lines of the form <code>reject=<i>string</i>;</code>
or a single line like this:
<p class="indented"><code>reject=<i>string</i>,<i>string</i>,<i>string</i>;</code></p>
How pdnsd reacts when an address in the reply matches one in the <code>reject</code> list,
depends on the <code>reject_policy</code> option, see below.
</td>
</tr>
<tr>
<td>
<b><code>reject_policy=(fail|negate);</code></b><br>
<em>New in version 1.2.6:</em>
This option determines what pdnsd does when an address in the reply from a name server
matches the <code>reject</code> list (see above). If this option is set to
<code>fail</code>, pdnsd will try another server, or, if there no more servers to try,
return the answer SERVFAIL. If this option is set to <code>negate</code>, pdnsd will
immediately return the answer NXDOMAIN (unknown domain) without querying additional
servers. The <code>fail</code> setting is useful if you don't always trust the servers in
this section, but do trust the servers in the following section. The <code>negate</code>
setting can be used to completely censor certain IP addresses. In this case you should put
the same <code>reject</code> list in every server section, and also set the
<code>reject_recursively</code> option (see below) to true.<br>
The default is <code>fail</code>.
</td>
</tr>
<tr>
<td>
<b><code>reject_recursively=(on|off);</code></b><br>
<em>New in version 1.2.6:</em> Normally pdnsd checks for addresses in the
<code>reject</code> list (see above) only when the reply comes directly from a name server
listed in the configuration file. With this option set to <code>on</code>, pdnsd will
also do this check for name servers that where obtained from NS records in the authority
section of a previous reply (which was incomplete and non-authoritative).<br>
Default is <code>off</code>.
</td>
</tr>
<tr>
<td>
<b><code>policy=(included|excluded|simple_only|fqdn_only);</code></b><br>
pdnsd supports inclusion/exclusion lists for server sections: with <code>include=</code>
and <code>exclude=</code> (see below) you can specify domain names for which this server
will be used or will not be used. The first match counts (i.e., the first include or
exclude rule in a server section that matches a domain name is applied, and the
search for other rules is terminated). If no rule matched a given domain name,
the <code>policy=</code> option determines whether this server is used for the
lookup for that domain name; when <code>included</code> is given, the server will
be asked, and when <code>excluded</code> is given, it will not.
If <code>simple_only</code> is given the server will be used if the name to lookup
is a simple (single-label) domain name, on the other hand if <code>fqdn_only</code>
is given the server will be used only for names consisting of two or more labels
(i.e. the name has at least one dot in-between).<br>
If no server is available for a queried domain, pdnsd will return an error message
to the client that usually will stop the client's attempts to resolve a specific
domain from this server (the libc resolver will e.g. return an error to the application that
tried to resolve the domain if no other servers are available in the <code>resolv.conf</code>).
This may be of use sometimes.<br>
<em>Note</em>: the <code>simple_only</code> and <code>fqdn_only</code> constants
were added by Paul Rombouts.
They are useful for controlling which name servers (if any) will be used by
pdnsd for resolving simple (single-label) host names.
<code>fqdn_only</code> used to stand for "fully qualified domain name only", but this is
actually a misnomer. The names in queries received by pdnsd are always considered to be
fully qualified. If you do not exactly understand what the options <code>simple_only</code> and
<code>fqdn_only</code> are good for, you are probably better off not using them.<br>
The default for this option is <code>included</code>.
</td>
</tr>
<tr>
<td>
<b><code>include=<i>string</i>;</code></b><br>
This option adds an entry to the exclusion/inclusion list. If a domain matches
the name given as string, the server is queried if this was the first matching rule
(see also the entry for <code>policy</code>).<br>
If the given name starts with a dot, the whole subdomain
of the given name including the one of that name is matched, e.g. <code>".foo.bar."</code>
will match the domain names a.foo.bar., a.b.c.foo.bar. and foo.bar.<br>
If it does not start in a dot, only exactly the given name (ignoring the case, of course)
will be matched (hint: if you want to include all subdomains, but not the domain of the given
name itself, place an exact-match exclude rule before the include rule, e.g:
<code>exclude="foo.bar."; include=".foo.bar.";</code><br>
Previous versions of pdnsd
required that names given with this and the next option ended in a dot, but since
version 1.1.8b1-par8, pdnsd automatically adds a dot at the end if it
is missing.<br>
pdnsd now also accepts a more compact notation for adding several <code>"include"</code> entries in
one line, e.g.:
<p class="indented"><code>include=".foo",".bar",".my.dom";</code></p>
</td>
</tr>
<tr>
<td>
<b><code>exclude=<i>string</i>;</code></b><br>
This option adds an entry to the exclusion/inclusion list. If a domain matches
the name given as string, the server is not queried if this was the first matching rule
(see also the entry for <code>policy</code>).<br>
If the given name starts with a dot, the whole subdomain
of the given name including the one of that name is matched, e.g. <code>".foo.bar."</code>
will match the domain names a.foo.bar., a.b.c.foo.bar. and foo.bar.<br>
If it does not start in a dot, only exactly the given name (ignoring the case, of course)
will be matched (hint: if you want to exclude all subdomains, but not the domain of the given
name itself, place an exact-match include rule before the exclude rule, e.g:
<code>include="foo.bar."; exclude=".foo.bar.";</code><br>
pdnsd now also accepts a more compact notation for adding several <code>"exclude"</code> entries in
one line, e.g.:
<p class="indented"><code>exclude=".foo",".bar",".my.dom";</code></p>
</td>
</tr>
</table>
<br>
<h3>2.1.3 <a name="rrsection"><code>rr</code> Section</a></h3>
Every <code>rr</code> section specifies a dns resource record that is stored locally. It
allows you to specify own dns records that are served by pdnsd in a limited way.
Only A, PTR, CNAME, MX, NS and SOA records are implemented.<br>
This option is intended to allow you to define RRs for 1.0.0.127.in-addr.arpa.
and localhost. (and perhaps even one or two hosts) without having to start an
extra named if your cached name servers do not serve those records.
It is <b>NOT</b> intended and not capable to work as a full-featured name server.
<br><br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td>
<b><code>name=<i>string</i>;</code></b><br>
Specifies the name of the resource records, i.e. the domain name of
the resource the record describes. This option must be specified
before any <code>a</code>, <code>ptr</code>, <code>cname</code>,
<code>mx</code>, <code>ns</code> or <code>soa</code> records.
Names are interpreted as absolute domain names
(i.e. pdnsd assumes they end in the root domain).
For this and all following arguments that take domain names, you need to
specify domain names in dotted notation (example venera.isi.edu.).<br>
Previous versions of pdnsd
required that domain names given in the configuration file ended in a
dot, but since version 1.1.8b1-par8, pdnsd automatically assumes a
dot at the end if it is missing.<br>
<em>New in version 1.2:</em> It is also possible to specify a name starting
with the label *. Such a name is called a wildcard. The * in a wildcard
can match one or more labels in a queried name, but only whole labels.
Any other * characters in a wildcard, apart from the leading one,
will only match a literal *.<br>
For example, *.mydomain will match a.mydomain or www.a.mydomain, but not
mydomain. *.a*.mydomain will match www.a*.mydomain, but not www.ab.mydomain.
*a.mydomain will only match itself.<br>
Before you can specify an <code>rr</code> section with <code>name=*.mydomain</code>
you must define some records for mydomain, typically NS and/or SOA records.
Example:
<pre>
rr {
name = mydomain;
ns = localhost;
soa = localhost, root.localhost, 42, 86400, 900, 86400, 86400;
}
rr {
name = *.mydomain;
a = 192.168.1.10;
}</pre>
In this example, www.mydomain and ftp.mydomain will resolve to the numeric
address 192.168.1.10 (unless you add <code>rr</code> sections explicitly
specifying different addresses for www.mydomain or ftp.mydomain).
If you want mydomain also to resolve to a numeric address,
add an A record to the first <code>rr</code> section.
</td>
</tr>
<tr>
<td>
<b><code>ttl=<i>timespec</i>;</code></b><br>
Specifies the ttl (time to live) for all resource records in this section after this entry.
This may be redefined. The default is 86400 seconds (=1 day).
</td>
</tr>
<tr>
<td>
<b><code>authrec=(on|off);</code></b><br>
If this is turned on, pdnsd will create authoritative local records for this <code>rr</code> section.
This means that pdnsd flags the domain record so that records of this domain that are not
present in the cache are treated as non-existent, i.e. no other servers are queried for
that record type, and an response containing none of those records is returned. This is
most time what people want: if you add an A record for a host, and it has no AAAA record
(thus no IPv6 address), you normally don't want other name servers to be queried for it.<br>
This is on by default.<br>
Please note that this only has an effect if it precedes the <code>name</code> option!
</td>
</tr>
<tr>
<td>
<b><code>reverse=(on|off);</code></b><br>
<em>New in version 1.2:</em> If you want a locally defined name to resolve to a numeric address
and vice versa, you can achieve this by setting reverse=on before defining the A record
(see below). The alternative is to define a separate PTR record, but you will
probably find this option much more convenient.<br>
The default is <code>off</code>.
</td>
</tr>
<tr>
<td>
<b><code>a=<i>string</i>;</code></b><br>
Defines an A (host address) record. The argument is an IPv4 address in dotted notation.
pdnsd will serve this address for the host name given in the <code>name</code> option.<br>
Provided there is sufficient support in the C libraries and support for AAAA records was not
disabled, the argument string may also be an IPv6 address, in which case an AAAA record
will be defined.<br>
This option be may used multiple times within an <code>rr</code> section, causing
multiple addresses to be defined for the name. However, if you put the different addresses
in different <code>rr</code> sections for the same name, the definition in the last
<code>rr</code> section will cancel the definitions in the previous ones.
</td>
</tr>
<tr>
<td>
<b><code>ptr=<i>string</i>;</code></b><br>
Defines a PTR (domain name pointer) record. The argument is a host name in
dotted notation (see name). The ptr record is for resolving adresses into names. For example, if
you want the adress 127.0.0.1 to resolve into localhost, and localhost into 127.0.0.1, you need something
like the following sections:<br>
<pre>
rr {
name = localhost;
a = 127.0.0.1;
owner = localhost;
soa = localhost, root.localhost, 42, 86400, 900, 86400, 86400;
}
rr {
name = 1.0.0.127.in-addr.arpa;
ptr = localhost;
owner = localhost;
soa = localhost, root.localhost, 42, 86400, 900, 86400, 86400;
}</pre>
The second section is for reverse resolving and uses the <code>ptr</code> option.
Note that you can get the same effect by specifying only the first <code>rr</code> section
with <code>reverse=on</code>.<br>
There is something special about the name in the second section:
when a resolver wants to get a host name from an internet address,
it composes an address that is built of the IP address in reverse byte order
(<code>1.0.0.127</code> instead of <code>127.0.0.1</code>) where each byte of the adress written
as number constitutes a sub-domain under the domain <code>in-addr.arpa.</code> <br>
So, if you want to compose an adress for reverse resolving, take your ip in dotted notation (e.g. <code>1.2.3.4</code>),
reverse the byte order (<code>4.3.2.1</code>) and append in-addr.arpa. (<code>4.3.2.1.in-addr.arpa.</code>)
Then, define an <code>rr</code> section giving this address as <code>name</code> and the domain name corresponding to
that ip in the <code>ptr</code> option.
</td>
</tr>
<tr>
<td>
<b><code>cname=<i>string</i>;</code></b><br>
Defines a CNAME (canonical name) record.
The argument should be a fully-qualified host name in dotted notation (see name).
A CNAME is the DNS equivalent of an alias or symbolic link.<br>
A useful application for CNAMEs is giving short, easy to remember nicknames to hosts with complicated names.
For example, you might want the name "<tt>news</tt>" to refer to your ISP's news server "<tt>nntp2.myisp.com</tt>".
Instead of adding an A record for "<tt>news</tt>" with the same address as "<tt>nntp2.myisp.com</tt>", you could
put in a CNAME pointing to "<tt>nntp2.myisp.com</tt>", so that if the IP address of the news server changes,
there is no need to update the record for "<tt>news</tt>".<br>
To implement this with pdnsd, you could add the following section to your configuration file:<br>
<pre>
rr {
name = news;
cname = nntp2.myisp.com;
owner = localhost;
}</pre>
</td>
</tr>
<tr>
<td>
<b><code>mx=<i>string</i>,<i>number</i>;</code></b><br>
Defines an MX (mail exchange) record. The string is the host name of the mail server in dotted notation (see name).
The number specifies the preference level.<br>
When you send mail to someone, your mail typically goes from your E-mail client to an SMTP server.
The SMTP server then checks for the MX record of the domain in the E-mail address.
For example, with <tt>joe@example.com</tt>, it would look for the MX record for <tt>example.com</tt> and find
that the name of mail server for that domain is, say, <tt>mail.example.com</tt>.
The SMTP server then gets the A record for <tt>mail.example.com</tt>, and connects to the mail server.<br>
If there are multiple MX records, the SMTP server will pick one based on the preference level
(starting with the lowest preference number, working its way up).<br>
Don't define MX records with pdnsd unless you know what you're doing.
</td>
</tr>
<tr>
<td>
<b><code>owner=<i>string</i>;</code></b><br>
or<br>
<b><code>ns=<i>string</i>;</code></b><br>
Defines an NS (name server) record. Specifies the name of the host which should be authoritative for the records
you defined in the <code>rr</code> section. This is typically the host pdnsd runs on.<br>
<em>Note:</em> In previous versions of pdnsd this option had to be specified before
any <code>a</code>, <code>ptr</code>, <code>cname</code>, <code>mx</code> or <code>soa</code> entries.
In version 1.2, the restrictions on this option are same as the options just mentioned,
and it must listed after the <code>name=</code> option.
This can be a pain if you want to use an old config file which specifies <code>owner=</code>
before <code>name=</code> (sorry about that).
Apart from greater consistency, the advantage is that you can now specify as many NS records as you like (including zero).
</td>
</tr>
<tr>
<td>
<b><code>soa=<i>string</i>,<i>string</i>,<i>number</i>,<i>timespec</i>,<i>timespec</i>,<i>timespec</i>,<i>timespec</i>;</code></b><br>
This defines a soa (start of authority) record. The first string is the
domain name of the server and should be equal to the name you specified as
owner. <br>
The second string specifies the email address of the maintainer of the name
server. It is also specified as a domain name, so you will have to replace the
@ sign in the name with a dot (.) to get the name you have to specify here.
The next parameter (the first number) is the serial number of the record. You
should increment this number if you change the record.<br>
The 4th parameter is the refresh timeout. It specifies after what amount
of time a caching server should attempt to refresh the cached record.<br>
The 5th parameter specifies a time after which a caching server should attempt
to refresh the record after a refresh failure.<br>
The 6th parameter defines the timeout after which a cached record expires if it
has not been refreshed.<br>
The 7th parameter is the ttl that is specified in every rr and should be the
same as given with the ttl option (if you do not specify a ttl, use the default 86400).
</td>
</tr>
<tr>
<td>
<b><code>txt=<i>string</i>,...,<i>string</i>;</code></b><br>
<em>New in version 1.2.9:</em>
Defines an TXT record. You can specify one or more strings here.
</td>
</tr>
</table>
<br>
<h3>2.1.4 <a name="negsection"><code>neg</code> Section</a></h3>
Every <code>neg</code> section specifies a dns resource record or a dns domain that should be
cached negatively locally. Queries for negatively cached records are always answered
immediatley with an error or an empty answer without querying other hosts as long
as the record is valid. The records defined with <code>neg</code> sections remain
valid until they are explicitely invalidated or deleted by the user using
<a href="#pdnsdctl"><code>pdnsd-ctl</code></a>.<br>
This is useful if a certain application asks periodically for nonexisting hosts or
RR types and you do not want a query to go out every time the cached record has
timed out. Example: Netscape Communicator will ask for the servers news and mail
on startup if unconfigured. If you do not have a dns search list for your network,
you can inhibit outgoing queries for these by specifying<br>
<pre>
neg {
name = news;
types = domain;
}
neg {
name = mail;
types = domain;
}</pre>
in your config file. If you have a search list, you have to repeat that for any
entry in your search list in addition to the entries given above!<br>
In versions 1.1.11 and later, if you negate whole domains this way, all subdomains
will be negated as well. Thus if you specify<br>
<code>neg {name=example.com; types=domain;}</code> in the
config file, this will also negate www.example.com, xxx.adserver.example.com, etc.
<br><br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td>
<b><code>name=<i>string</i>;</code></b><br>
Specifies the name of the domain for which negative cache entries are created.
This option must be specified before the types option.
Names are interpreted as absolute domain names (i.e. pdnsd
assumes they end in the root domain).
You need to specify domain names in dotted notation (example venera.isi.edu.).<br>
Previous versions of pdnsd
required that domain names given in the configuration file ended in a
dot, but since version 1.1.8b1-par8, pdnsd automatically assumes a
dot at the end if it is missing.
</td>
</tr>
<tr>
<td>
<b><code>ttl=<i>timespec</i>;</code></b><br>
Specifies the ttl (time to live) for all resource records in this section after this entry.
This may be redefined. The default is 86400 seconds (=1 day).
</td>
</tr>
<tr>
<td>
<b><code>types=(domain|<i>rr_type</i>[,<i>rr_type</i>[,<i>rr_type</i>[,...]]]);</code></b><br>
Specifies what is to be cached negatively: <code>domain</code> will cache the whole
domain negatively; alternatively, you can specify a comma-separated list of RR types
which are to be cached negatively. You may specify multiple types options, but
<code>domain</code> and the RR types are mutually exclusive.<br>
The RR types are specified using their official names from the RFC's in capitals,
e.g. <code>A</code>, <code>CNAME</code>, <code>NS</code>, <code>PTR</code>, <code>MX</code>,
<code>AAAA</code>, ...<br>
The command <code>pdnsd-ctl list-rrtypes</code> will give you a complete list
of those types. <a href="#pdnsdctl"><code>pdnsd-ctl</code></a> is built along with pdnsd
and will be installed in the same directory as the pdnsd binary during <code>make install</code>.
</td>
</tr>
</table>
<br>
<h3>2.1.5 <a name="sourcesection"><code>source</code> Section</a></h3>
Every source section allows you to let pdnsd read the records from a file in an
<code>/etc/hosts</code>-like format. pdnsd will generate records to resolve the entries
address from its host name and vice versa for every entry in the file. This is
normally easier than defining an rr for every of your addresses, since localhost
and your other FQDNs are normally given in <code>/etc/hosts</code>.<br>
The accepted format is as follows: The #-sign initiates a comment, the rest of
the line from the first occurence of this character on is ignored. Empty lines
are tolerated.<br>
The first entry on a line (predeceded by an arbitrary number of tabs and spaces)
is the IP in dotted notation, the second entry on one line (separated by the
first by an arbitrary number of tabs and spaces) is the FQDN (fully qualified
domain name) for that ip. The rest of the line is ignored by default (in the original
<code>/etc/hosts</code>, it may contain information not needed by pdnsd).
<br><br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td>
<b><code>owner=<i>string</i>;</code></b><br>
Specifies the name of the host pdnsd runs on and that are specified in dns
answers (specifically, nameserver records).
Must be specified before any file entries.<br>
Names are interpreted as absolute domain names (i.e. pdnsd
assumes they end in the root domain).
You need to specify domain names in dotted notation (example venera.isi.edu.).<br>
Previous versions of pdnsd
required that domain names given in the configuration file ended in a
dot, but since version 1.1.8b1-par8, pdnsd automatically assumes a
dot at the end if it is missing.
</td>
</tr>
<tr>
<td>
<b><code>ttl=<i>timespec</i>;</code></b><br>
Specifies the ttl (time to live) for all resource records in this section after
this entry. This may be redefined. The default is 86400 seconds (=1 day).
</td>
</tr>
<tr>
<td>
<b><code>file=<i>string</i>;</code></b><br>
The string specifies a file name. For every file entry in a source section,
pdnsd will try to load the given file as described above. Failure is indicated
only when the file cannot be opened, malformed entries will be ignored.
</td>
</tr>
<tr>
<td>
<b><code>serve_aliases=(on|off);</code></b><br>
If this is turned on pdnsd will serve the aliases given in a <code>hosts</code>-style file.
These are the third entry in a line of a hosts-style file, which usually give a "short name" for the host.
This may be used to support broken clients without a proper domain-search option.
If no aliases are given in a line of the file, pdnsd behaves as without this option for this line.<br>
This feature was suggested by Bert Frederiks.<br>
It is off by default.
</td>
</tr>
<tr>
<td>
<b><code>authrec=(on|off);</code></b><br>
If this is turned on, pdnsd will create authoritative local records with the data from the hosts file.
Please see the description of the option of the same name in the rr section for a closer description of
what this means. Please note that this only has an effect for files sourced with <code>file</code> options
subsequent to this option.<br>
This is on by default.
</td>
</tr>
</table>
<br>
<h3>2.1.6 <a name="includesection"><code>include</code> Section</a></h3>
A configuration file may include other configuration files.
However, only the top-level configuration file may contain <a href="#globalsection"><code>global</code></a>
and <a href="#serversection"><code>server</code></a> sections,
thus include files are effectively limited to sections that add local definitions to the cache.<br>
Include sections currently only have one type of option, which may be given multiple times within a single section.
<br><br>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td>
<b><code>file=<i>string</i>;</code></b><br>
The string specifies a file name. For every <code>file</code> option in an include section,
pdnsd will parse the given file as described above. The file may contain include sections itself,
but as a precaution pdnsd checks that a certain maximum depth is not exceeded to guard against
the possibility of infinite recursion.
</td>
</tr>
</table>
<br>
<h2>3 <a name="pdnsdctl">pdnsd-ctl</a></h2>
<p>
pdnsd-ctl allows you to configure pdnsd at run time. To make this work, you have to start pdnsd with the <code>-s</code>
option (or use the <code><a href="#statusctl">status_ctl</a></code> option in the config file). You also should make sure that you
have appropriate permissions on the control socket (use the <code>ctl_perms</code> option to make this sure) and of your pdnsd
cache directory (pdnsd keeps its socket there). Please make sure the pdnsd cache directory is not writeable for untrusted users!</p>
<p>
pdnsd-ctl accepts two command-line options starting with a dash.<br>
<code>-c</code> may be used to specify the cache directory (and takes this as argument).
The default for this setting is the pdnsd default cache directory (specified at compile time).
The cache directory for pdnsd-ctl must be the same pdnsd uses!<br>
<code>-q</code> can be used to make the output of pdnsd-ctl less verbose.</p>
<p>
The following table lists the commands that pdnsd-ctl supports. The command must always be
the first command-line option (not starting with a dash), the arguments to the command must follow in the given order.<br>
In the following table, keywords are in a normal font, while placeholders are in italics.<br>
Alternatives are specified like (alt1|alt2|alt3).
Optional arguments are placed between square brackets [].</p>
<table width="100%" bgcolor="#CCCCCC" cellpadding=10>
<tr>
<td><b>Command</b></td>
<td><b>Arguments</b></td>
<td><b>Description</b></td>
</tr>
<tr>
<td class="nowrap">help</td>
<td></td>
<td>Print a command summary.</td>
</tr>
<tr>
<td class="nowrap">version</td>
<td></td>
<td>Print version and license info.</td>
</tr>
<tr>
<td class="nowrap" valign=top>status</td>
<td></td>
<td>
Print a description of pdnsd's cache status, thread status and configuration.
Also shows which remote name servers are assumed to be available.
</td>
</tr>
<tr>
<td class="nowrap" valign=top>server</td>
<td valign=top>(<i>index</i>|<i>label</i>) (up|down|retest) [<i>dns1</i>[,<i>dns2</i>[,...]]]</td>
<td>
Set the status of the server with the given <i>index</i> or <i>label</i> (where the given label
matches the one given with the label option in the respective server section in the config file)
to up or down, or force a retest. The index is assigned in the order of definition in
<code>pdnsd.conf</code> starting with 0. Use the status command to view the indices and labels.
You can specify <code>all</code> instead of an index or label to perform the action for all
servers registered with pdnsd. Example:<br>
<code>pdnsd-ctl server 0 retest</code><br>
An optional third argument consisting of a list of IP addresses (separated by commas or
white-space characters) can be given.
This list will replace the previous list of addresses of name servers used by pdnsd in the
specified section of the config file.
For example in the <code>/etc/ppp/ip-up</code> script called by <code>pppd</code> you could
place the following line:<br>
<code>pdnsd-ctl server isplabel up $DNS1,$DNS2</code><br>
If white space is used to separate addresses the list will have to be quoted.
Spurious commas and white-space characters are ignored.
The last argument may also be an empty string, in which case the existing IP addresses are
removed and the corresponding server section becomes inactive.
</td>
</tr>
<tr>
<td class="nowrap" valign=top>record</td>
<td valign=top><i>name</i> (delete|invalidate)</td>
<td>
Delete or invalidate the records of the given domain <i>name</i> if it is in the
cache. Invalidation means that the records are marked as timed out, and
will be reloaded if possible (if purge_cache is set to on, they will
be deleted in any case).<br>
For local records (i.e., records that were given in the config file
using a <code>rr</code> section, records read from a hosts-style file
and records added using pdnsd-ctl), invalidation has no effect. Deletion
will work, though. Example:<br>
<code>pdnsd-ctl record localhost. delete</code>
</td>
</tr>
<tr>
<td class="nowrap" valign=top>source</td>
<td valign=top><i>fn</i> <i>owner</i> [<i>ttl</i>] [(on|off)] [noauth]</td>
<td>
Load a hosts-style file. Works like using the pdnsd
<a href="#sourcesection">source configuration section</a>.
<i>owner</i> and <i>ttl</i> are used as in the source section. <i>ttl</i> has a default
of 900 (it does not need to be specified). The next to last argument corresponds
to the serve_aliases option, and is off by default (i.e. if it is not specified).
<code>noauth</code> is used to make the domains non-authoritative - please see
the description of the <code>authrec</code> config file options for a description of what
that means.
<i>fn</i> is the filename. The file must be readable by pdnsd! Example:<br>
<code>pdnsd-ctl source /etc/hosts localhost. 900 off</code>
</td>
</tr>
<tr>
<td class="nowrap" valign=top>add</td>
<td valign=top>a <i>addr</i> <i>name</i> [<i>ttl</i>] [noauth]</td>
<td rowspan=6>
Add a record of the given type to the pdnsd cache, replacing existing
records for the same <i>name</i> and type. The 2nd argument corresponds
to the value of the option in the rr section that is named like
the first argument: a is a record for hostname-to-address mapping,
aaaa is the same thing for IPv6 addresses, and ptr is for address-to-hostname
mapping. See the documentation for the <code>rr</code> section for more details.
In case of A and AAAA records, the <i>addr</i> argument may be a list of IP addresses,
separated by commas or white space, causing multiple addresses to be defined
for the same <i>name</i>.
The <i>ttl</i> is optional, the default is 900 seconds.
<code>noauth</code> is used to make the domains non-authoritative - please see
the description of the <code>authrec</code> config file options for a description of what
that means.
If you want no other record than the newly added in the cache, do<br>
<code>pdnsd-ctl record <i>name</i> delete</code>
before adding records. This is also better when overwriting local records. Example:<br>
<code>pdnsd-ctl add a 127.0.0.1 localhost. 900</code>
</td>
</tr>
<tr>
<td class="nowrap" valign=top>add</td>
<td valign=top>aaaa <i>addr</i> <i>name</i> [<i>ttl</i>] [noauth]</td>
</tr>
<tr>
<td class="nowrap" valign=top>add</td>
<td valign=top>ptr <i>host</i> <i>name</i> [<i>ttl</i>] [noauth]</td>
</tr>
<tr>
<td class="nowrap" valign=top>add</td>
<td valign=top>cname <i>host</i> <i>name</i> [<i>ttl</i>] [noauth]</td>
</tr>
<tr>
<td class="nowrap" valign=top>add</td>
<td valign=top>mx <i>host</i> <i>name</i> <i>pref</i> [<i>ttl</i>] [noauth]</td>
</tr>
<tr>
<td class="nowrap" valign=top>add</td>
<td valign=top>ns <i>host</i> <i>name</i> [<i>ttl</i>] [noauth]</td>
</tr>
<tr>
<td class="nowrap" valign=top>neg</td>
<td valign=top><i>name</i> [<i>type</i>] [<i>ttl</i>]</td>
<td>
Add a negatively cached record to pdnsd's cache, replacing existing
records for the same <i>name</i> and <i>type</i>. If no type is given, the whole
domain is cached negatively. For negatively cached records, errors are
immediately returned on a query, without querying other servers first.
The <i>ttl</i> is optional, the default is 900 seconds.<br>
You can get a list of all types you can pass to this command using
<code>pdnsd-ctl list-rrtypes</code>. The type is treated case-sensitive!
Example:<br>
<code>pdnsd-ctl neg foo.bar A 900</code><br>
<code>pdnsd-ctl neg foo.baz 900</code><br>
</td>
</tr>
<tr>
<td class="nowrap" valign=top>config</td>
<td valign=top>[<i>filename</i>]</td>
<td>
Reload pdnsd's configuration file.<br>
The config file must be owned by the uid that pdnsd had when it was
started, and be readable by pdnsd's <a href="#runas"><code>run_as</code></a> uid. If no file name is
specified, the config file used at start-up is reloaded.<br>
Note that some configuration changes, like the port or IP address pdnsd listens on,
cannot be made this way and you will receive an error message.
In these cases, you will have to restart pdnsd instead.
</td>
</tr>
<tr>
<td class="nowrap" valign=top>include</td>
<td valign=top><i>filename</i></td>
<td>
Parse the given file as an include file, see the documentation on
<a href="#includesection">include sections</a> for a description
what this file may contain.<br>
This command is useful for adding definitions to the cache without reconfiguring pdnsd.
</td>
</tr>
<tr>
<td class="nowrap" valign=top>eval</td>
<td valign=top><i>string</i></td>
<td>
Parse the given string as if it were part of pdnsd's configuration file.
The string should hold one or more complete configuration sections.
However, <a href="#globalsection"><code>global</code></a> and
<a href="#serversection"><code>server</code></a> sections are not allowed,
just as in <a href="#includesection">include files</a>.
If multiple strings are given, they will be joined using newline chars
and parsed together.<br>
This command is useful for adding records interactively to the cache
that cannot be defined using the "<code>pdnsd-ctl add</code>" command,
(e.g. soa records).
</td>
</tr>
<tr>
<td class="nowrap" valign=top>empty-cache</td>
<td valign=top>[[+|-]<i>name</i> ...]</td>
<td>
If no arguments are provided, the cache will be completely emptied,
freeing all existing entries.
Note that this also removes local records, as defined by the config file.
To restore local records, run <code>"pdnsd-ctl config"</code> or
<code>"pdnsd-ctl include <i>filename</i>"</code> immediately afterwards.<br>
The <code>"pdnsd-ctl empty-cache"</code> command now accepts additional arguments;
these are interpreted as include/exclude names. If an argument starts with a '+'
the name will be included. If an argument starts with a '-' it will be
excluded. If an argument does not begin with '+' or '-', a '+' is
assumed. If the domain name of a cache entry ends in one of the names in
the list, the first match will determine what happens. If the matching
name is to be included, the cache entry is deleted, otherwise not.
If there are no matches, the default action is not to delete.
Note that if you want to delete exactly one name and no others, you should
use <code>"pdnsd-ctl record <i>name</i> delete"</code>,
this is also much more efficient.<br>
Examples:<br>
<code>pdnsd-ctl empty-cache</code><br>
This command will remove all cache entries.<br>
<br>
<code>pdnsd-ctl empty-cache microsoft.com msft.net</code><br>
This will remove all entries ending in microsoft.com or msft.net.<br>
<br>
<code>pdnsd-ctl empty-cache -localdomain -168.192.in-addr.arpa .</code><br>
This will remove all entries except those ending in localdomain or
168.192.in-addr.arpa. Note that '.' is the root domain which matches any
domain name.
</td>
</tr>
<tr>
<td class="nowrap" valign=top>dump</td>
<td valign=top>[<i>name</i>]</td>
<td>
Print information stored in the cache about <i>name</i>.
If <i>name</i> begins with a dot and is not the root domain, information about
the names in the cache ending in <i>name</i> (including <i>name</i> without
the leading dot) will be printed.
If <i>name</i> is not specified, information about all the names in the cache will
be printed.<br>
For each RR record the time and date that this record has been added to the cache
will be printed in the form mm/dd HH:MM:SS (locally defined records are printed without a time stamp).
After that the type of record is printed with the data. For the more common types
of RR records the data will be printed in human readable form, the remaining ones in a
hexadecimal representation.<br>
This command is mainly useful for diagnostic purposes.<br>
Note that if you pipe the output of this command through an application that
reads only part of the output and then blocks (such as <code>more</code> or <code>less</code>),
pdnsd will not be able to add new entries to the cache until the pipe is closed.
It is preferable to capture the output in a file in such a case.
</td>
</tr>
<tr>
<td class="nowrap" valign=top>list-rrtypes</td>
<td></td>
<td>
List available rr types for the neg command.
Note that those are only used for the neg command, not for add!
</td>
</tr>
</table>
<br>
<br>
<h2>4 contrib/</h2>
The contrib directory in the pdnsd distribution contains useful user-contributed scripts.<br>
So far, there are scripts contributed by Marko Stolle and Paul Rombouts that make pdnsd
usable in a DHCP setup.
Please take a look into the README file in the contrib directory for further information.
<br>
<br>
<h2>5 Problems...</h2>
If you have problems with configuring or running pdnsd, be sure to read the <a href="faq.html">FAQ</a>.
If this does not help you, pdnsd crashes or you find bugs, please mail one of the authors.<br>
<em>Note added by <a href="mailto:p.a.rombouts@home.nl">Paul A. Rombouts</a></em>:
Thomas Moestl no longer maintains the code. I have revised the code and added new features.
See <a href="../../README.par"><code>README.par</code></a> and the
<a href="../../ChangeLog"><code>ChangeLog</code></a> in the source directory
(or <code>/usr/share/doc/pdnsd-<version></code> if you have installed a binary package)
for more details.
If you have questions about my modifications, you can find my email address at the end of
<a href="../../README.par"><code>README.par</code></a>.
<br>
<br>
<h2>6 Hacking</h2>
Here comes some information you might find useful for hacking pdnsd.
<br>
<h3>6.1 Source files</h3>
<table width="100%" cellspacing=1 cellpadding=7>
<tr>
<td bgcolor="#FFCCFF" width="20%">Makefile.am, configure.in, acconfig.h</td>
<td bgcolor="#CCFFFF" width="80%">
autoconf/automake/autoheader scripts. Makefile.am's are in most subdirectories.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">pdnsd.spec.in</td>
<td bgcolor="#CCFFFF" width="80%">
A template from which configure generates a spec file for building rpm's for various
distributions.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">version</td>
<td bgcolor="#CCFFFF" width="80%">
Contains only the program version string. Needed for several templates.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/rc/*</td>
<td bgcolor="#CCFFFF" width="80%">
rc (start-up) scripts for various linux distributions.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/cache.c</td>
<td bgcolor="#CCFFFF" width="80%">
The pdnsd cache subsystem(s) as defined in src/cache.h.
This is the "traditional" pdnsd system which keeps the cache in memory and uses hash tables for accesses.
Sourav K. Mandal is working on a system using gdbm.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/pdnsd-ctl/*</td>
<td bgcolor="#CCFFFF" width="80%">
Contains the code for pdnsd-ctl, a program that allows you to control pdnsd at run time.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/conf-lex.l.in</td>
<td bgcolor="#CCFFFF" width="80%">
The lex/flex source file for the config file lexer. This is a template because there might be
inserted "%option yylineno" for proper flex support.
<font color="#990000">(obsolete, superseded by src/conf-parser.c)</font>
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/conf-lex.l</td>
<td bgcolor="#CCFFFF" width="80%">
This is automatically generated by configure from conf-lex.l.in. It may be overwritten
in any make, so never modify this, but conf-lex.l.in instead!
<font color="#990000">(obsolete, superseded by src/conf-parser.c)</font>
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/conf-parse.y</td>
<td bgcolor="#CCFFFF" width="80%">
The yacc/bison source of the config file parser.
<font color="#990000">(obsolete, superseded by src/conf-parser.c)</font>
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/conf-parser.c, src/conf-parser.h, src/conf-keywords.h</td>
<td bgcolor="#CCFFFF" width="80%">
The config file parser written purely in C (versions 1.1.10-par and later).
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/conff.c, src/conff.h</td>
<td bgcolor="#CCFFFF" width="80%">
The configuration handler functions and their prototypes. The parser is called from here.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/consts.h</td>
<td bgcolor="#CCFFFF" width="80%">
Some constants used by the parser, config file handler functions and in the server status thread,
among others.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/dns.c, src/dns.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define dns message structures, constants, and some common dns data handlers. dns.h contains gcc-specific
code (in praticular, "__attribute__((packed))").
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/dns_answer.c, src/dns_answer.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define functions that answer incoming dns queries.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/dns_query.c, src/dns_query.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define functions to manage outgoing dns queries.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/error.c, src/error.h</td>
<td bgcolor="#CCFFFF" width="80%">
Functions for error output to stderr or the syslog, and debug output to stderr or <code>pdnsd.debug</code>.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/hash.c, src/hash.h</td>
<td bgcolor="#CCFFFF" width="80%">
Contains the code for storing and looking up cache entries in the hash table.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/helpers.c, src/helpers.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define miscellaneous helper functions.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/icmp.c, src/icmp.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define a function for performing a ping test. This contains OS-specific code.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/main.c</td>
<td bgcolor="#CCFFFF" width="80%">
Contains main(), which holds the command line parser, performs initialisations and signal handling.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/make_hashconvtable.c</td>
<td bgcolor="#CCFFFF" width="80%">
Contains the code for the executable <code>make_hashconvtable</code>, which is only run once, during build time, to generate the file <code>hashconvtable.h</code>, used by <code>src/hash.c</code> (versions 1.1.10-par and later).
<font color="#990000">(obsolete since version 1.2)</font>
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/make_rr_types_h.pl</td>
<td bgcolor="#CCFFFF" width="80%">
A perl script for generating src/rr_types.h,
a C header file containing macro definitions and tables needed for handling the
RR types known to pdnsd, from the text file src/rr_types.in.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/rr_types.c, src/rr_types.h, src/rr_types.in</td>
<td bgcolor="#CCFFFF" width="80%">
These define tables and macros needed for handling the RR types known to pdnsd.
Since version 1.2.9, rr_types.h is an automatically generated file,
see make_rr_types_h.pl.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/netdev.c, src/netdev.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define functions for network device handling. OS-specific.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/servers.c, src/servers.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define functions for the server status thread that performs the periodical uptests.
</td>
</tr>
<tr>
<td bgcolor="#FFCCFF" width="20%">src/status.c, src/status.h</td>
<td bgcolor="#CCFFFF" width="80%">
Define functions for the status control thread. This is pdnsd's interface to pdnsd-ctl.
</td>
</tr>
</table>
<br>
<hr>
<address>
Copyright (C) 2000, 2001 <a href="mailto:tmoestl@gmx.net">Thomas Moestl</a><br>
Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2012 <a href="mailto:p.a.rombouts@home.nl">Paul A. Rombouts</a>
</address>
<p>
<i>Last revised: 27 February 2012 by Paul A. Rombouts</i>
</p>
</body>
</html>
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