mod_info

Apache Module mod_info

Description: Provides a comprehensive overview of the server configuration
Status: Extension
ModuleIdentifier: info_module
SourceFile: mod_info.c

Summary

To configure mod_info, add the following to your httpd.conf file.

<Location "/server-info">
    SetHandler server-info
</Location>

You may wish to use mod_authz_host inside the <Location> directive to limit access to your server configuration information:

<Location "/server-info">
    SetHandler server-info
    Require host example.com
</Location>

Once configured, the server information is obtained by accessing http://your.host.example.com/server-info

Security Issues

Once mod_info is loaded into the server, its handler capability is available in all configuration files, including per-directory files (e.g., .htaccess). This may have security-related ramifications for your site.

In particular, this module can leak sensitive information from the configuration directives of other Apache modules such as system paths, usernames/passwords, database names, etc. Therefore, this module should only be used in a controlled environment and always with caution.

You will probably want to use mod_authz_host to limit access to your server configuration information.

Access control

<Location "/server-info">
    SetHandler server-info
    # Allow access from server itself
    Require ip 127.0.0.1

    # Additionally, allow access from local workstation
    Require ip 192.168.1.17
</Location>

Selecting the information shown

By default, the server information includes a list of all enabled modules, and for each module, a description of the directives understood by that module, the hooks implemented by that module, and the relevant directives from the current configuration.

Other views of the configuration information are available by appending a query to the server-info request. For example, http://your.host.example.com/server-info?config will show all configuration directives.

?<module-name>
Only information relevant to the named module
?config
Just the configuration directives, not sorted by module
?hooks
Only the list of Hooks each module is attached to
?list
Only a simple list of enabled modules
?server
Only the basic server information

Dumping the configuration on startup

If the config define -DDUMP_CONFIG is set, mod_info will dump the pre-parsed configuration to stdout during server startup. Pre-parsed means that directives like <IfDefine> and <IfModule> are evaluated and environment varialbles are replaced. However it does not represent the final state of the configuration. In particular, it does not represent the merging or overriding that may happen for repeated directives.

This is roughly equivalent to the ?config query.

Known Limitations

mod_info provides its information by reading the parsed configuration, rather than reading the original configuration file. There are a few limitations as a result of the way the parsed configuration tree is created:

  • Directives which are executed immediately rather than being stored in the parsed configuration are not listed. These include ServerRoot, LoadModule, and LoadFile.
  • Directives which control the configuration file itself, such as Include, <IfModule> and <IfDefine> are not listed, but the included configuration directives are.
  • Comments are not listed. (This may be considered a feature.)
  • Configuration directives from .htaccess files are not listed (since they do not form part of the permanent server configuration).
  • Container directives such as <Directory> are listed normally, but mod_info cannot figure out the line number for the closing </Directory>.
  • Directives generated by third party modules such as mod_perl might not be listed.

AddModuleInfo Directive

Description: Adds additional information to the module information displayed by the server-info handler
Syntax:
AddModuleInfo module-name string
Context: server config, virtual host
Status: Extension
Module: mod_info

This allows the content of string to be shown as HTML interpreted, Additional Information for the module module-name. Example:

AddModuleInfo mod_deflate.c 'See <a \
    href="http://httpd.apache.org/docs/2.4/mod/mod_deflate.html">\
    http://httpd.apache.org/docs/2.4/mod/mod_deflate.html</a>'
doc_apache_http_server
2017-02-05 05:02:40
Comments
Leave a Comment

Please login to continue.