A virtual private network (VPN) is the extension of a private network that encompasses links across shared or public networks like the Internet. A VPN enables you to send data between two computers across a shared or public internetwork in a manner that emulates the properties of a point-to-point private link. The act of configuring and creating a virtual private network is known as virtual private networking.
VPN connections allow users working at home or on the road to connect in a secure fashion to a remote organisation server using the routing infrastructure provided by a public internetwork (such as the Internet). From the user’s perspective, the VPN connection is a point-to-point connection between the user’s computer and an organisation’s server. The nature of the intermediate internetwork is irrelevant to the
user because it appears as if the data is being sent over a dedicated private link.
VPN technology also allows a corporation to connect to branch offices or to other companies over a public internetwork (such as the Internet), while maintaining secure communications. The VPN connection across the Internet logically operates as a wide area network (WAN) link between the sites.
In both of these cases, the secure connection across the internetwork appears to the user as a private network communication - despite the fact that this communication occurs over a public internetwork - hence the name virtual private network.
VPN technology is designed to address issues surrounding the current business trend toward increased telecommuting and widely distributed global operations, where workers must be able to connect to central resources and must be able to communicate with one another.
To provide employees with the ability to connect to an organisation’s computing resources, regardless of their location, a corporation must deploy a scalable remote access solution. Typically, corporations choose either a departmental solution, where an internal information systems department is charged with buying, installing, and maintaining organisation modem pools and a private network infrastructure; or they choose a value-added network (VAN) solution, where they pay an outsourced company to buy, install, and maintain modem pools and a telecommunications infrastructure.
Connecting Computers over an Intranet
In some organisational internetworks, the departmental data is so sensitive that the department’s LAN is physically disconnected from the rest of the organisation’s internetwork. Although this protects the department’s confidential information, it creates information accessibility problems for those users not physically connected to the separate LAN.
Using a VPN connection to connect to a secured or hidden network
VPNs allow the department’s LAN to be physically connected to the organisation’s internetwork but separated by a VPN server. The VPN server is not acting as a router between the organisation’s internetwork and the department LAN. A router would connect the two networks, allowing everyone access to the sensitive LAN. By using a VPN server, the network administrator can ensure that only those users on the organisation’s internetwork who have appropriate credentials (based on a need-to-know policy within the company) can establish a VPN connection with the VPN server and gain access to the protected resources of the department. Additionally, all communication across the VPN can be encrypted for data confidentiality. Those users who do not have the proper credentials cannot view the department LAN.
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