G. I. Papadimitriou, Aristotle University
M. S. Obaidat, Monmouth University
C. Papazoglou and A.S. Pomportsis, Aristotle University
The best way to come up with a definition of the term virtual private network (VPN) is to analyze each word separately. Having done that, Ferguson and Huston (1998) came up with the following definition: A VPN is a communications environment in which access is controlled to permit peer connections only within a defined community of interest and is constructed through some form of partitioning of a common underlying communications medium, where this underlying communications medium provides services to the network on a nonexclusive basis. Ferguson and Huston also provided a simpler and less formal description. A VPN is a private network constructed within a public network infrastructure, such as the global Internet. Others define a VPN as a network that allows two or more private networks to be connected over a publicly accessed network. It is similar to wide area networks ...