Stateful Packet Filter for Linux – constantly adjust an inbound packet filter to deal with allowing traffic in based on what was sent out. Now with RealAudio support.
You can download it from the following link: https://packetstormsecurity.com/files/download/10764/spf-2.0.3.tar.gz
Source: https://packetstormsecurity.com/files/10764/spf-2.0.3.tar.gz.html

