Virtual Private Network
Definition:Virtual Private Network(VPN)
A Virtual Private Network (VPN) is a network technology that creates a secure network connection over a public network such as the Internet or a private network owned by a service provider. Large corporations, educational institutions, and government agencies use VPN technology to enable remote users to securely connect to a private network.
A VPN can connect multiple sites over a large distance just like a Wide Area Network (WAN). VPNs are often used to extend intranets worldwide to disseminate information and news to a wide user base. Educational institutions use VPNs to connect campuses that can be distributed across the country or around the world.
Protocols of VPN
There are a number of VPN protocols in use that secure the transport of data traffic over a public network infrastructure. Each protocol varies slightly in the way that data is kept secure. Those protocols include: IP security (IPSec),Secure Sockets Layer (SSL) and Transport Layer Security (TLS),Point-To-Point Tunneling Protocol (PPTP),Layer 2 Tunneling Protocol (L2TP).
Types of VPN
There are three important VPN technologies: trusted VPNs, secure VPNs, and hybrid VPNs. It is important to note that secure VPNs and trusted VPNs are not technically related, and can co-exist in a single service package.
VPNs can be either remote-access (connecting an individual computer to a network) or site-to-site (connecting two networks together). In a corporate setting, remote-access VPNs allow employees to access their company's intranet from home or while traveling outside the office, and site-to-site VPNs allow employees in geographically separated offices to share one cohesive virtual network. A VPN can also be used to interconnect two similar networks over a dissimilar middle network; for example, two IPv6 networks over an IPv4 network.
VPN systems can be classified by: the protocols used to tunnel the traffic the tunnel's termination point, i.e., customer edge or network-provider edge whether they offer site-to-site or remote-access connectivity the levels of security provided the OSI layer they present to the connecting network, such as Layer 2 circuits or Layer 3 network connectivity
