I use both actually, where the best tool is applicable. Some commenters have mentioned StrongSwan (or OpenSwan which is more known to me). I've actually seen

I use both actually, where the best tool is applicable. Some commenters have mentioned StrongSwan (or OpenSwan which is more known to me). I've actually seen OpenSwan perform better than Cisco VPN tunnels. And I love pointing that out to our networking guys since we pay nothing for OpenSwan.