Virtual Private Network (VPN)

A virtual private network is a logical network that is established, at the application layer of the Open Systems Interconnection (OSI) model, over an existing physical network and typically does not include every node present on the physical network.

[A] protected information-system (IS) link utilizing tunneling, security controls (see information assurance), and end-point address translation giving the user the impression a dedicated line exists between nodes. [INFOSEC-99]