FK

FK is a free software alternative to the TIS fwtk firewall kit. Its main aim is to provide a proxy firewall kit that operates on a free software model. The idea for this project stemmed from dissatisfaction with the TIS fwtk firewall kit, and due to the lack of a suitable alternative, FK was developed. However, one of the collaborators, Ian Lynagh, is no longer on the project.

Some of the key features of FK include: A simple TCP plug, POP-3 gateway, an RFC 1413 (ident) server, FTP gateway, a simple HTTP server, an HTTP proxy, a userspace ping server, log file monitoring tools, and an ACL facility for network/host. Currently, there is no support for proxy authentication.

In the latest version, there are a few notable upgrades such as new documentation including a status document and configuration guide, a userspace ping server (currently only works on Linux), improved HTTP proxy features, and significant performance improvements. The HTTP proxy now understands "GET," HEAD," and "POST" syntax, and keepalives can be configured. The "--wait" option has also been added. Moreover, there is a fix for a QUIT bug in the POP-3 proxy and updates to IDSA support.

Overall, FK is an excellent option for those looking for a free and open-source firewall kit with various features. The addition of new enhancements in the latest version has made it even more compelling.