Virtual Private Networks (VPNs)
The huge increase in the number of VPN clients and companies wanting to use VPNs requires administrators to understand the special security considerations necessary when dealing with VPNs. Because most VPNs are used over a connection to the Internet, any security gap has the potential to be exploited by hundreds of hackers.
VPNs are built by using tunneling protocols, which are protocols that are encapsulated within another protocol. Examples of tunneling protocols used in VPNs are General Routing Encapsulation (GRE), Layer 2 Tunneling Protocol (L2TP), Encapsulation Security Protocol (ESP), Cisco Encryption Technology (CET), and the Layer 2 Forwarding (L2F) protocols. This section covers some of the more commonly ...
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