Screaming Penguin - Source Does Matter

Oreilly has a great article on IPSec and FreeBSD. Since FreeBSD is one of the most (if not the) secure operating systems there is it makes a great firewall and or tunnel endpoint for a VPN. Using isakmpd or raccoon with FreeBSD is explained in detail in the article, good stuff.   Cryptosystems: Configuring IPSec: Oreilly