http://ubuntuforums.org/showthread.php?t=826815&highlight=set+vpn
http://ubuntuforums.org/showthread.php?t=854660&highlight=pptp+server+install
http://ubuntuforums.org/showthread.php?t=487480&highlight=pptp+server+install
http://forums.bit-tech.net/showthread.php?t=132029