OpenVPN is a robust and highly flexible tunneling application that uses all of the encryption, authentication, and certification features of the OpenSSL library to securely tunnel IP networks over a single TCP/UDP port.
Discussion forums and project wiki can be found here:
https://forums.openvpn.net/
http://community.openvpn.net/openvpn
VTun is the easiest way to create Virtual Tunnels over TCP/IP networks with traffic shaping, compression, and encryption.
It supports IP, Ethernet, PPP and other tunnel types. VTun is easily and highly configurable.
VPN, Mobile IP, Shaping, etc