VPN or in other words Virtual Private Network is a technology that allows computer users or companies to create a secure connection over the public network, for example the Internet, and connect to their destination.

VPN allows two private networks to communicate securely over the Internet through the establishment of a virtual network.

In other words a VPN is a virtual computer network that allows remote users and remote offices connectivity to their organizations network securely.

Symmetric encryption is used between the two or more VPN enabled networking devices that are communicating.

There are 3 types of VPN that can be established:

• Client to Sever (Roadwarrior Connection).

These types of connection allow remote users specially the users that are travelling to access their data which is resident on their company’s network. The users can either use PPTP (Point to Point Tunneling Protocol) or L2TP (Layer 2 Tunneling Protocol) or IPSec VPN Client to connect to their company’s network.

• Site to Site (Between two private networks).

This connection is between two remote sites. For example, the VPN connection between a branch office and a head office can be called a Site to Site connection. The VPN enabled networking devices at both ends would establish a secure tunnel over the internet and the users on either side can access the data that is resident on the opposite network.

• Host to Host (Between two end systems in private networks across the Internet).

This type of connection is not used extensively expect in cases where there are a few servers that hold critical data and need to communicate among themselves for transfer of application data. Example would be a VPN tunnel between an application server and a database server.