VPN - Virtual private Networks - DEFINITION

Keywords: VPN GUIDE, VPN DEFINITION
TOPIC: WHAT IS VPN

A VPN is a secure, private tunnel between two or more devices across a public network such as the internet. A VPN device can be anything from a standard PC with VPN software installed on it to a dedicated hardware device called a VPN router.

At the very basic VPN allows computers at different locations to communicate with each other in a safe and secure environment. This can be two computers at different offices or thousands of computers on different networks around the world.

VPN is secure because it employs very strong encryption to protect your data as it travels across the internet. Even if a hacker or snooper were to try to eavesdrop on the communication they wouldn't be able to understand it because all the data is so highly encrypted. Another important security aspect of VPN technology is that VPN devices continuously monitor their data traffic in very sophisticated ways that ensure information is never altered while traveling across the public network.

It is this encryption and continuous data verification that is very resource intensive and it puts a lot of strain on the CPU. This is why it is not recommended to install VPN software on you PC's or servers, but instead invest in a reliable dedicated VPN router as these have their own onboard VPN CPU.

Clients and Servers

A VPN server is the piece of hardware or software acting as the gateway into an entire network or just a single computer. In most scenarios it is always on and listening for VPN clients to connect to it and authenticate.

A VPN Client is most often a software programme but can also be hardware as well (usually another VPN router). The client initiates a conversation with the server and attempts to authenticate and log on. If authentication is successful then the VPN client and VPN server are able to communicate as if they were on the same network. At this point they are on the same virtual network.

VPN Software

VPN server software is still very rare. Windows 2000 Server and Windows Server 2003 have a VPN server built in but as VPN encryption is so CPU intensive we do not advise using your existing Windows server as a VPN gateway unless you can afford to dedicate it to doing just that.

VPN client software, however, is much more readily available but relatively expensive. When installed on your PC VPN software creates a secure VPN tunnel across the Internet and into another network which has a VPN server.

VPN Protocols

There are two major protocols (or languages) that VPN technology employs to communicate. Microsoft uses PPTP or Point to Point Tunneling Protocol whereas almost everyone else uses IPSec - Internet Protocol Security. Microsoft have however, recently bowed to the pressure and updated Windows 2000 professional and XP to support Ipsec. Similar updates are also available for Microsoft's non business systems such as Windows 98 and ME.

PPTP has good encryption and also features authentication for verifying a user ID and password. IPSec is purely an encryption model and is much safer but does not include authentication routines. A third standard, L2TP is IPSec with authentication built in. Microsoft operating systems now also support L2TP.