mod_ifier is an Apache2 module which allows you to filter each incoming HTTP request to your webserver - allowing you to drop Referer-spam, exploit attempts, and more.

Using this module you can define a collection of rules which will be processed for each incoming request. If a rule matches then you can respond in several different ways:

• Return a specific HTTP status code.
• Redirect the visitor to a different URL
• Execute a local program.

The available rule-types allow you to perform matching on many aspects of the incoming request - and new rules will be added if you suggest them to the author.

For example you may:

• Deny requests based upon arbitary incoming HTTP headers.
  • e.g. Drop Referer-spam
  • e.g. Drop badly behaved user-agents.
• Deny requests based upon the request method
  • GET, POST, TRACE, SEARCH, OPTIONS, PROPFIND & etc.
• Deny requests based upon submitted CGI parameters.
  • Both GET & POST requests are supported
• Deny requests based upon the file/path requested.
• Blacklist/Whitelist IP addresses.
• Log which clients were dropped.
• Execute commands when clients are dropped.
  • (To add them to a firewall, for example.)

You may download the source code for this module from the following URL:

• mod-ifier-0.8.tar.gz (GPG Signature) [19k]
  • The freshmeat project page allows you to subscribe and be notified of new releases.

The module is licensed under the terms of the GNU General Public License, with an exception allowing linking with both Apache & libssl/mod_ssl.

If you are interested in following the development of the module you may be interested in the mod_ifier mercurial repository. Please feel free to get in touch if you have any suggestions or comments.