What is a VPN (Virtual Private Network)?

[VelMurugan]

What is a VPN (Virtual Private Network)?

A traditional private network consists of leased lines connecting multiple sites together. An example would be two offices connected by a point-to-point T-1 line.

Connecting multiple sites together over the Internet is usually less expensive than leasing dedicated circuits. One risk in using the Internet as a transport medium is the risk of data interception by unauthorized parties. When data is moved across the Internet, it should be considered public knowledge.

A VPN (Virtual Private Network) solves that problem. A VPN is an encrypted tunnel between two endpoints.

VPN tunnels are created using a tunneling protocol such as L2TP and secured using a protocol such as IPsec.

L2TP is described in RFC 2661: Layer Two Tunneling Protocol "L2TP". IPsec is described in RFC 3193: Securing L2TP using IPsec.