Tunneling, Crypto and VPNs
By Dawid Czagan
The idea of Virtual Private Network (VPN) is to simulate a private network over a public network. A VPN tunnel can be used to securely connect LANs of the company over an insecure Internet (VPN gateways are responsible for making the connection secure). This article describes how tunneling and cryptography can be used to build VPN tunnels without going into the details of existing VPN protocols.