Sanewall is a firewall builder for Linux that uses an elegant language abstracted to just the right level. This makes it powerful and easy to use, audit, and understand. It allows you to create very readable configurations even for complex stateful firewalls. Sanewall can be used for almost any purpose, including control of any number of internal/external/virtual interfaces, control of any combination of routed traffic, setting up DMZ routers and servers, all kinds of NAT, providing strong protection (flooding, spoofing, etc.), transparent caches, source MAC verification, blacklists, and whitelists. Newer versions abstract the differences between IPv4 and IPv6, allowing you to define a common set of rules for both, while permitting specific rules for each as you need. Sanewall is a fork of FireHOL and can make use of existing FireHOL configurations.
conntrack-tools is a set of userspace tools for Linux that allow system administrators to interact with the Connection Tracking System, the module which provides stateful packet inspection for iptables. It includes the userspace daemon conntrackd and the commandline interface conntrack.
Flac2All is a multi-threaded script that will convert your collection of FLAC files into either Ogg Vorbis, MP3 (with the Lame encoder), or FLAC, complete with any tags and identical file/folder structure. The script has been stable for about a year now, and it has been known to saturate 8-core machines with parallel conversions. It is useful for people with with large FLAC collections who also want a lossy version for portable media players. If wanted, the script can perform updates by skipping already converted files. It has only been tested on Linux, but it should work without alteration on the other Unix systems with bash and the required dependencies.
The ROHC library provides an easy and robust way for applications to reduce their bandwidth usage on network links with limited capacity or expensive costs. Headers of network packets are compressed with the ROHC protocol and algorithms. The ROHC protocol is very efficient for compressing VoIP streams which use RTP as a transport protocol. ROHC is also suitable for compressing IP-only (IPv4 or IPv6) flows, UDP flows, and many others.
StressItOut is a hardware stressing and testing program for GNU/Linux. Its main purpose is to strain the computer to ensure the hardware is in good state. There are several test modules: CPU load, memory test, 2D OpenGL painting, 3D OpenGL rendering, hard drives, optical drives, serial ports transmission, and parallel ports. Support for lm-sensors is in the works. This software, when ready for release, will mainly be aimed at the QA departments of hardware manufacturing companies, who need to ensure their newly produced machines perform correctly under heavy workloads, and that all their components work as expected.