How Does a VPN Work?

By Alex Burke

Virtual Private Networks

Virtual private networks (VPN) are a secure way for businesses and companies to communicate via the Internet. They assure the tightest of security and are not open to traffic from the public. Remote users and multiple sites of users can be connected through a direct private pathway. The installation of a VPN alters the need for a WAN (wide area network), simplifies the companies' network needs, provides extended telecommute opportunities and opens up the possibility for global networking. Building a secure VPN requires reliability, scalability and management of the network and policies designed to run the network. VPN's can be managed by the company or contracted to a VPN provider.

The Language Of VPNs

Virtual private networks use a special vocabulary that describes its components. Nodes are the points at which connections or lines intersect. Nodes generally have a server or router to monitor traffic. Network access servers (NAS) allow entry into and out of the network. Protocols are standards that control a connection. A tunneling protocol describes the act of encapsulating one protocol within a second protocol. This provides secure pathways through questionable networks and makes a VPN work. Service-level agreements define what a VPN provider, also called an enterprise service provider or ESP, will supply the customer with. VPNs are usually more complex than just a point-to-point connection. Their topology can be very complex, and it is important that the provider outline how delivery of a customer's traffic will be achieved.

Remote-Access VPN

VPNs come in two common types: remote-access and site-to-site access. A remote-access VPN is also called a virtual private dial-up network. This type of VPN is used by companies with a large number of remote users that need to call in to go to work. Since they are calling from all over the nation or from international locations, their connections need to be secure. Software that is loaded onto their computers allows them to use a toll-free number that connects them to their network access server, then verifies them and allows them into their corporate network. Encryption is often used to secure the connection further.

Site-To-Site VPN's

Site-to-site connections allude to multiple fixed locations that need to be connected securely. Sometimes, companies wish to connect to other companies due to contractual obligations or shared projects. This VPN is called a site-to-site extranet. Site-to-site VPNs for a company's internal connections are referred to as an intranet. Neither are open to the public and both require permission, user names and passwords to enter.