How Virtual Private Networks Work

How Virtual Private Networks Work

Virtual private networks (VPNs) are being increasingly adopted by information technology companies. In this article, the working of such a network has been succinctly explained.
One technology that has had a huge impact on the working of businesses all over the world, is computer networking. Setting up of these networks has helped bring down the usage of paper and made collaboration of work and data sharing simpler. Of the many types of computer networks, which might be set up, one is a virtual private network (VPN).


The need to establish secure and cost-effective long distance links between two or more computing networks, led to the development of VPN. A virtual private network is a special type of wide area network (WAN), which achieves connectivity without using leased private lines and makes use of the Internet. It uses the established Internet network, for remote connectivity between physically distant workstations or networks. It has its own set of software programs, protocols, and security constructs, which make secure connectivity possible. The USP of these networks over conventional ones lies in the fact that this technology is a significantly low-cost alternative.


Depending on the scale and location of networks connected via VPN, there can be different types. There are three primary ways in which this network type might be implemented. One of the most commonly used ones is remote client access via VPN, that can let employees of a company access the intranet. Another type can let two separate local area networks, to be linked together. The third type is simply a private intranet of a company, that allows enabling of access control for each user.


Of the many types of VPNs, most common is the one which provides remote access to the intranet of any company. It is based on a conventional server-client model. The company's private network has a VPN server connected to the Internet. Client programs are installed on the machines which need remote access.

Using the Internet connectivity provided by an ISP, the client program establishes a connection with the company server, which grants access to the program, after verification of username and password. Once the VPN connection has been established, the remote computer can access the private network, like all other terminals, which are internally connected in the network.

There is no need for the establishment of a separate leased line for such a connection, which brings down connectivity costs substantially. To create a connection, a secure tunnel is established between server and client.

How VPN Tunnels Work

This tunnel is a special type of link between a server and a client. The data transported through the link follows different protocol rules, that encapsulate the data or even encrypt it over its journey to the server.

On reception at the server, the data is again removed from its encapsulation and decrypted. It is a dedicated and secure connection, maintained between the server and remote computer. A tunnel could be voluntary or compulsory. Some of the protocols used for tunneling are Layer Two Tunneling Protocol (L2TP), Point-to-Point Tunneling Protocol (PPTP), and Internet Protocol Security (Ipsec).


One of the obvious advantages of VPN connectivity is that it's substantially easy and inexpensive to set up. It can provide long distance connectivity, between multiple branches of a company office, by providing secure data transfer and encryption, to enable video conferencing, as well as data transfer. It reduces the costs involved in maintaining long distance networks. Overall, it brings reduction in costs of operation.

Most industry Intranets use VPN technology to establish internal connectivity. The cost-effectiveness, efficiency, and security features of these networks, make them attractive and preferred choices, over conventional leased line based networks.