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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>3. Operational logging using syslog</title><link rel="stylesheet" href="docbook.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="PowerDNS manual" /><link rel="up" href="monitoring.html" title="Chapter 6. Logging & Monitoring Authoritative Server performance" /><link rel="prev" href="init-d-commands.html" title="2. Via init.d commands" /><link rel="next" href="security.html" title="Chapter 7. Security settings & considerations" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">3. Operational logging using syslog</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="init-d-commands.html">Prev</a> </td><th width="60%" align="center">Chapter 6. Logging & Monitoring Authoritative Server performance</th><td width="20%" align="right"> <a accesskey="n" href="security.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="3. Operational logging using syslog"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="syslog"></a>3. Operational logging using syslog</h2></div></div></div><p>(<span class="command"><strong>logging-facility</strong></span> is available from 1.99.10 and onwards)</p><p>
This chapter assumes familiarity with syslog, the unix logging device. PDNS logs messages with different levels. The more urgent the
message, the lower the 'priority'. By default, PDNS will only log messages with an urgency of 3 or lower, but this can be changed
using the <span class="command"><strong>loglevel</strong></span> setting in the configuration file. Setting it to 0 will eliminate all logging, 9 will log
everything.
</p><p>
By default, logging is performed under the 'DAEMON' facility which is shared with lots of other programs. If you regard nameserving
as important, you may want to have it under a dedicated facility so PDNS can log to its own files, and not clutter generic files.
</p><p>
For this purpose, syslog knows about 'local' facilities, numbered from LOCAL0 to LOCAL7. To move PDNS logging to LOCAL0, add
<span class="command"><strong>logging-facility=0</strong></span> to your configuration.
</p><p>
Furthermore, you may want to have separate files for the differing priorities - preventing lower priority messages from obscuring
important ones.
</p><p>
A sample syslog.conf might be:
</p><pre class="programlisting">
local0.info -/var/log/pdns.info
local0.warn -/var/log/pdns.warn
local0.err /var/log/pdns.err
</pre><p>
</p><p>
Where local0.err would store the really important messages. For performance and disk space reasons, it is advised
to audit your syslog.conf for statements also logging PDNS activities. Many syslog.confs have a '*.*' statement to
/var/log/syslog, which you may want to remove.
</p><p>
For performance reasons, be especially certain that no large amounts of synchronous logging take place. Under Linux, this
is indicated by file names not starting with a '-' - indicating a synchronous log, which hurts performance.
</p><p>
Be aware that syslog by default logs messages at the configured priority and higher! To log only info messages, use
<span class="command"><strong>local0.=info</strong></span>.
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