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16 <p class="apache">Apache HTTP Server Version 2.3</p>
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21 <div id="page-content">
22 <div id="preamble"><h1>Apache Module mod_log_forensic</h1>
24 <p><span>Available Languages: </span><a href="../en/mod/mod_log_forensic.html" title="English"> en </a> |
25 <a href="../ja/mod/mod_log_forensic.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
27 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Forensic Logging of the requests made to the server</td></tr>
28 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
29 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>log_forensic_module</td></tr>
30 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_log_forensic.c</td></tr>
31 <tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td><code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code> is no longer required since
32 version 2.1</td></tr></table>
35 <p>This module provides for forensic logging of client
36 requests. Logging is done before and after processing a request, so the
37 forensic log contains two log lines for each request.
38 The forensic logger is very strict, which means:</p>
41 <li>The format is fixed. You cannot modify the logging format at
43 <li>If it cannot write its data, the child process
44 exits immediately and may dump core (depending on your
45 <code class="directive"><a href="../mod/mpm_common.html#coredumpdirectory">CoreDumpDirectory</a></code>
49 <p>The <code>check_forensic</code> script, which can be found in the
50 distribution's support directory, may be helpful in evaluating the
51 forensic log output.</p>
53 <div id="quickview"><h3 class="directives">Directives</h3>
55 <li><img alt="" src="../images/down.gif" /> <a href="#forensiclog">ForensicLog</a></li>
59 <li><img alt="" src="../images/down.gif" /> <a href="#formats">Forensic Log Format</a></li>
60 <li><img alt="" src="../images/down.gif" /> <a href="#security">Security Considerations</a></li>
61 </ul><h3>See also</h3>
63 <li><a href="../logs.html">Apache Log Files</a></li>
64 <li><code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code></li>
66 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
68 <h2><a name="formats" id="formats">Forensic Log Format</a></h2>
69 <p>Each request is logged two times. The first time is <em>before</em> it's
70 processed further (that is, after receiving the headers). The second log
71 entry is written <em>after</em> the request processing at the same time
72 where normal logging occurs.</p>
74 <p>In order to identify each request, a unique request ID is assigned.
75 This forensic ID can be cross logged in the normal transfer log using the
76 <code>%{forensic-id}n</code> format string. If you're using
77 <code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code>, its generated ID will be used.</p>
79 <p>The first line logs the forensic ID, the request line and all received
80 headers, separated by pipe characters (<code>|</code>). A sample line
81 looks like the following (all on one line):</p>
83 <div class="example"><p><code>
84 +yQtJf8CoAB4AAFNXBIEAAAAA|GET /manual/de/images/down.gif
85 HTTP/1.1|Host:localhost%3a8080|User-Agent:Mozilla/5.0 (X11;
86 U; Linux i686; en-US; rv%3a1.6) Gecko/20040216
87 Firefox/0.8|Accept:image/png, <var>etc...</var>
90 <p>The plus character at the beginning indicates that this is the first log
91 line of this request. The second line just contains a minus character and
94 <div class="example"><p><code>
95 -yQtJf8CoAB4AAFNXBIEAAAAA
98 <p>The <code>check_forensic</code> script takes as its argument the name
99 of the logfile. It looks for those <code>+</code>/<code>-</code> ID pairs
100 and complains if a request was not completed.</p>
101 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
102 <div class="section">
103 <h2><a name="security" id="security">Security Considerations</a></h2>
104 <p>See the <a href="../misc/security_tips.html#serverroot">security tips</a>
105 document for details on why your security could be compromised
106 if the directory where logfiles are stored is writable by
107 anyone other than the user that starts the server.</p>
109 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
110 <div class="directive-section"><h2><a name="ForensicLog" id="ForensicLog">ForensicLog</a> <a name="forensiclog" id="forensiclog">Directive</a></h2>
111 <table class="directive">
112 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets filename of the forensic log</td></tr>
113 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForensicLog <var>filename</var>|<var>pipe</var></code></td></tr>
114 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
115 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
116 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_log_forensic</td></tr>
118 <p>The <code class="directive">ForensicLog</code> directive is used to
119 log requests to the server for forensic analysis. Each log entry
120 is assigned a unique ID which can be associated with the request
121 using the normal <code class="directive"><a href="../mod/mod_log_config.html#customlog">CustomLog</a></code>
122 directive. <code class="module"><a href="../mod/mod_log_forensic.html">mod_log_forensic</a></code> creates a token called
123 <code>forensic-id</code>, which can be added to the transfer log
124 using the <code>%{forensic-id}n</code> format string.</p>
126 <p>The argument, which specifies the location to which
127 the logs will be written, can take one of the following two
131 <dt><var>filename</var></dt>
132 <dd>A filename, relative to the <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code>.</dd>
134 <dt><var>pipe</var></dt>
135 <dd>The pipe character "<code>|</code>", followed by the path
136 to a program to receive the log information on its standard
137 input. The program name can be specified relative to the <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code> directive.
139 <div class="warning"><h3>Security:</h3>
140 <p>If a program is used, then it will be run as the user who
141 started <code class="program"><a href="../programs/httpd.html">httpd</a></code>. This will be root if the server was
142 started by root; be sure that the program is secure or switches to a
143 less privileged user.</p>
146 <div class="note"><h3>Note</h3>
147 <p>When entering a file path on non-Unix platforms, care should be taken
148 to make sure that only forward slashes are used even though the platform
149 may allow the use of back slashes. In general it is a good idea to always
150 use forward slashes throughout the configuration files.</p>
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157 <p><span>Available Languages: </span><a href="../en/mod/mod_log_forensic.html" title="English"> en </a> |
158 <a href="../ja/mod/mod_log_forensic.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
159 </div><div id="footer">
160 <p class="apache">Copyright 2007 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
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