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<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
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Copyright 2004-2006 The Apache Software Foundation or its licensors, as
applicable.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
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<modulesynopsis metafile="mod_log_forensic.xml.meta">
<name>mod_log_forensic</name>
<description>Forensic Logging of the requests made to the server</description>
<status>Extension</status>
<sourcefile>mod_log_forensic.c</sourcefile>
<identifier>log_forensic_module</identifier>
<compatibility><module>mod_unique_id</module> is no longer required since
version 2.1</compatibility>
<summary>
<p>This module provides for forensic logging of client
requests. Logging is done before and after processing a request, so the
forensic log contains two log lines for each request.
The forensic logger is very strict, which means:</p>
<ul>
<li>The format is fixed. You cannot modify the logging format at
runtime.</li>
<li>If it cannot write its data, the child process
exits immediately and may dump core (depending on your
<directive module="mpm_common">CoreDumpDirectory</directive>
configuration).</li>
</ul>
<p>The <code>check_forensic</code> script, which can be found in the
distribution's support directory, may be helpful in evaluating the
forensic log output.</p>
</summary>
<seealso><a href="../logs.html">Apache Log Files</a></seealso>
<seealso><module>mod_log_config</module></seealso>
<section id="formats"><title>Forensic Log Format</title>
<p>Each request is logged two times. The first time is <em>before</em> it's
processed further (that is, after receiving the headers). The second log
entry is written <em>after</em> the request processing at the same time
where normal logging occurs.</p>
<p>In order to identify each request, a unique request ID is assigned.
This forensic ID can be cross logged in the normal transfer log using the
<code>%{forensic-id}n</code> format string. If you're using
<module>mod_unique_id</module>, its generated ID will be used.</p>
<p>The first line logs the forensic ID, the request line and all received
headers, separated by pipe characters (<code>|</code>). A sample line
looks like the following (all on one line):</p>
<example>
+yQtJf8CoAB4AAFNXBIEAAAAA|GET /manual/de/images/down.gif
HTTP/1.1|Host:localhost%3a8080|User-Agent:Mozilla/5.0 (X11;
U; Linux i686; en-US; rv%3a1.6) Gecko/20040216
Firefox/0.8|Accept:image/png, <var>etc...</var>
</example>
<p>The plus character at the beginning indicates that this is the first log
line of this request. The second line just contains a minus character and
the ID again:</p>
<example>
-yQtJf8CoAB4AAFNXBIEAAAAA
</example>
<p>The <code>check_forensic</code> script takes as its argument the name
of the logfile. It looks for those <code>+</code>/<code>-</code> ID pairs
and complains if a request was not completed.</p>
</section>
<section id="security"><title>Security Considerations</title>
<p>See the <a
href="../misc/security_tips.html#serverroot">security tips</a>
document for details on why your security could be compromised
if the directory where logfiles are stored is writable by
anyone other than the user that starts the server.</p>
</section>
<directivesynopsis>
<name>ForensicLog</name>
<description>Sets filename of the forensic log</description>
<syntax>ForensicLog <var>filename</var>|<var>pipe</var></syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<usage>
<p>The <directive>ForensicLog</directive> directive is used to
log requests to the server for forensic analysis. Each log entry
is assigned a unique ID which can be associated with the request
using the normal <directive module="mod_log_config">CustomLog</directive>
directive. <module>mod_log_forensic</module> creates a token called
<code>forensic-id</code>, which can be added to the transfer log
using the <code>%{forensic-id}n</code> format string.</p>
<p>The argument, which specifies the location to which
the logs will be written, can take one of the following two
types of values:</p>
<dl>
<dt><var>filename</var></dt>
<dd>A filename, relative to the <directive module="core"
>ServerRoot</directive>.</dd>
<dt><var>pipe</var></dt>
<dd>The pipe character "<code>|</code>", followed by the path
to a program to receive the log information on its standard
input. The program name can be specified relative to the <directive
module="core">ServerRoot</directive> directive.
<note type="warning"><title>Security:</title>
<p>If a program is used, then it will be run as the user who
started <program>httpd</program>. This will be root if the server was
started by root; be sure that the program is secure or switches to a
less privileged user.</p>
</note>
<note><title>Note</title>
<p>When entering a file path on non-Unix platforms, care should be taken
to make sure that only forward slashed are used even though the platform
may allow the use of back slashes. In general it is a good idea to always
use forward slashes throughout the configuration files.</p>
</note></dd>
</dl>
</usage>
</directivesynopsis>
</modulesynopsis>
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