http://www.monkeedev.co.uk/blog/2009/03/06/setting-up-openvpn-in-debianubuntu/
https://help.ubuntu.com/11.04/serverguide/C/openvpn.html
https://help.ubuntu.com/community/OpenVPN
http://www.openvpn.net/index.php/open-source/documentation/howto.html#examples