Virtual Private Network

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A VPN (Virtual Private Network) is a computer network that is implemented in an additional software layer (overlay) on top of an existing larger network for the purpose of creating a private scope of computer communications or providing a secure extension of a private network into an insecure network such as the Internet. The links between nodes of a virtual private network are formed over logical connections or virtual circuits between hosts of the larger network. The Link Layer protocols of the virtual network are said to be tunneled through the underlying transport network. One common application is to secure communications through the public Internet, but a VPN does not need to have explicit security features such as authentication or traffic encryption. For example, VPNs can also be used to separate the traffic of different user communities over an underlying network with strong security features, or to provide access to a network via customized or private routing mechanisms.