How to install and configure vpn client on your Ubuntu 14.04

Before following this procedure please get VPNClient password visiting VPN Group password page.
Due to security reasons, the VPN password page is readable outside the SISSA network inserting your SISSA username and your SISSA password. There are no restriction inside the SISSA network.
If you have any problem about vpn password, please contact helpesk service by phone or personally.