Different organizations use different VPN connection options such as SSL, PPTP or IPSEC. When you need to access corporate network and its services, you need to login using VPN. The Point-to-Point Tunneling Protocol (PPTP) is a method for implementing virtual private networks. It works on Data link layer (#2 layer) on TCP/IP model. That being said, I was unable to set up my laptop to connect to a PPTP VPN server. I have Ubuntu 8.10 installed on my laptop.