VPN

A technique that allows two or more LANs to be extended over public communication channels by creating private communication subchannels (tunnels). Effectively, these LANs can use a WAN as a single large "virtually private" LAN. This removes the need to use leased lines for WAN communications through secure use of a publicly available WAN (such as the Internet). Examples of VPN technology are: PPTP (Point to Point Tunneling Protocol), L2TP (Layer 2 Tunneling Protocol), and IPSec (Internet Protocol Security).