If you are not hip to pfSense I suggest you check it out. It is an open source firewall that is making waves in InfoSec. The pfSense guys have a great howto for configuring IPSec VPN on the pfSense firewall as well as making connections via a freeware Windows IPSec VPN client called Shrew Soft which can be read by clicking here. The only item lacking in the article is a recommendation for a Mac OSX client as well as configuration tips for a Mac OSX client which is the sole point of this article. Below is information about where to download a freeware Mac OSX IPSec VPN client and then the necessary configuration to make a connection to the suggested settings noted in the howto of the pfSense web site.