psyBNC is an easy-to-use, multi-user, permanent IRC-Bouncer with many features. Some of its features include symmetric ciphering of talk and connections (Blowfish and IDEA) It compiles on Linux, FreeBSD, SunOs and Solaris.
A Port Knocking C-based server & client. Stealth mode by closed ports, strong encryption (ARC4 & BlowFish), Daemon mode, compresed sequence, MD5 digest log check, user passwords and user privelege system, action triggers... GPL license.