IPSec VPN Using FreeBSD

This paper will demonstrate a way to setup an IPSec VPN that will allow for NAT'ing using FreeBSD boxes as the gateway machines. It also has the bonus of being a fairly easy method for connecting WANs across public networks. The information and examples provided here should be compatible with other open-source unixes. The items covered in this paper are: setting up the tunnel using gif interfaces, IPSec to encrypt the traffic, racoon for automatic key exchange, setting up some simple firewalling and setting up some simple NAT.