OpenFWTK is an application proxy toolkit which inherits the ideology of TIS fwtk and maintains API backwards compatibility. The design goal is to make it simple yet powerful; no performance hacks are allowed in the code and library dependencies are reduced to a minimum. It is a true application layer filter. It features unified pluggable content inspection for the most frequently used protocols, NAC (Network Admission Control), and the ability to define fine-grained Internet access policy based on browser identification.
Rxpd plugin for XChat is a plugin for the XChat IRC client which lets users filter the incoming conversation with the RegexPolicyDaemon. This is used to ignore spam, trolls, and other abusive content (at the user's option). People can publish their ignore rules and then filter or merge published rules from friends into their own rules, thus providing a distributed peer to peer system.
PottyMouth transforms completely unstructured and untrusted text to valid, nice-looking, completely safe XHTML. PottyMouth is designed to handle input text from non-technical, potentially careless, or malicious users. It produces HTML that is completely safe, programmatically and visually, to include on any Web page. You don't need to make your users read any instructions before they start typing. They don't even need to know that PottyMouth is being used.
mailprocd is a standalone mail classification and delivery daemon for massive multiuser servers, designed to extend the capabilities of MTAs such as Postfix and sendmail. It embeds perl in C in order to use SpamAssassin efficiently. It implements a process manager with persistent spam checker processes running under users' own UIDs.
BarricadeMX provides very accurate, high performance spam and virus protection for Enterprise and ISP sites. Features include simple installation and administration, little if any end user interaction required, no quarrantine required, and an optional custom non-delivery receipt for all rejected messages. It uses a custom version of SpamAssassin along with many proprietary anti-spam techniques to achieve a guaranteed level of over 99% accurate spam detection with fewer than 0.1% false positives.
xtee (cross-tee/expanded tee) is a program for building complex pipelines. It resembles the tee command, except that instead of copying stdin to stdout, it copies an input file to stdout and stdin to an output file. You can use xtee for building things like a bidirectional HTTP filter (using netcat and sed).