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Apache HTTP Server Version 1.3
Module mod_log_forensic
This module provides for forensic logging of the requests made to the
server
Status: Extension
Source File:
mod_log_forensic.c
Module Identifier:
log_forensic_module
Compatibility: Available in
Version 1.3.30 and later.
Summary
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:
- The format is fixed. You cannot modify the logging format at
runtime.
- If it cannot write its data, the child process exits immediately
and may dump core (depends on your
CoreDumpDirectory
configuration).
The check_forensic script, which can be found in the
distribution's support directory, may be helpful in evaluating the
forensic log output.
See also: Apache Log Files.
Directives
Each request is logged two times. The first time before it's
processed further (that is, after receiving the headers). The second log
entry is written after the request processing at the same time
where normal logging occurs.
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
%{forensic-id}n format string. If you're using
mod_unique_id, its generated
ID will be used.
The first line logs the forensic ID, the request line and all received
headers, separated by pipe characters (|). A sample line
looks like the following (all on one line):
+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, etc...
The plus character at the beginning indicates that this is first log
line of this request. The second line just contains a minus character and
the id again:
-yQtJf8CoAB4AAFNXBIEAAAAA
The check_forensic script takes as its argument the name
of the logfile. It looks for those +/- ID pairs
and complains if a request was not completed.
Security Considerations
See the security tips
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.
Syntax: ForensicLog
filename|pipe
Context: server config, virtual
host
Module: mod_log_forensic
Compatibility: Available
in Version 1.3.30 and above
The ForensicLog directive is used to
log requests to the server for forensic analysis. Each log entry
is assigned unique ID which can be associated with the request
using the normal CustomLog
directive. mod_log_forensic creates a token called
forensic-id, which can be added to the transfer log
using the %{forensic-id}n format string.
The argument, which specifies the location to which
the logs will be written, can take one of the following two
types of values:
- filename
- A filename, relative to the
ServerRoot.
- pipe
- The pipe character "
|", followed by the path
to a program to receive the log information on its standard
input. Security: if a program is used, then
it will be run as the user who started httpd. This will be
root if the server was started by root; be sure that the
program is secure.
Apache HTTP Server Version 1.3
