mod_log_forensic - Apache HTTP Server Version 2.4









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Apache HTTP Server Version 2.4



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Apache Module mod_log_forensic

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Description:Forensic Logging of the requests made to the server
Status:Extension
Module Identifier:log_forensic_module
Source File:mod_log_forensic.c
Compatibility:mod_unique_id is no longer required since
version 2.1
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 (depending 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.

Topics

 Forensic Log Format
 Security Considerations
Directives

 ForensicLog

Bugfix checklisthttpd changelogKnown issuesReport a bugSee also

Apache Log Files
mod_log_config
Comments


Forensic Log Format
    Each request is logged two times. The first time is 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 the 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.
    The log files may contain sensitive data such as the contents of 
    Authorization: headers (which can contain passwords), so
    they should not be readable by anyone except the user that starts the
    server.


ForensicLog Directive

Description:Sets filename of the forensic log
Syntax:ForensicLog filename|pipe
Context:server config, virtual host
Status:Extension
Module:mod_log_forensic

    The ForensicLog 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 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. The program name can be specified relative to the ServerRoot directive.

      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 or switches to a
      less privileged user.
      

      Note
        When entering a file path on non-Unix platforms, care should be taken
        to make sure that only forward slashes 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.
      
    




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