VPN stands for a virtual private network. If you want to dial in a secure network extraneously, that is to say at home or anywhere else on the campus using wireless LAN, the VPN-client on your computer “pretends” that your are part of this network. This means that your computer gets a certain IP address which will be accepted from the secure network. For this VPN requires an authentication with username and password as well as the desired security certificates, which are set by the network provider. In this way it is guaranteed that no unauthorised person gains access to the network.