History Of The Virtual Private NetworkA VPN supplies virtual network connectivity over a possibly long physical distance. The key feature of a VPN, however, is its ability to use public networks like the Internet rather than rely on private leased lines which consume valuable recourse and extra cost . VPN technologies implement restricted-access networks that utilize the same cabling and routers as a public network, and they do so without sacrificing features or basic security , a simple cooperation office and remote branched VPN shown in below diagram .Sonicwall_VpnA VPN supports at least three different modes of use as shown above:Remote access client connections.LAN-to-LAN internetworking .Controlled access within an intranet .A several network protocols have become popular as a result of VPN developments state as following :PPTPL2TPIPsecThese protocols emphasize authentication and encryption in VPNs. Authentication allows VPN clients and servers to correctly establish the identity of people on the network.