Microsoft® Exchange Server 2003 Unleashed

Examining Virtual Private Networks

A virtual private network (VPN) is the extension of a private network that encompasses links across shared or public networks, such as the Internet. A VPN enables data to be sent between two computers across the Internet in a manner that emulates a point-to-point private link. With a virtual private network, illustrated in Figure 9.1, a point-to-point link, or “tunnel,” is created by encapsulating or wrapping the data with a header that provides routing information, enabling the data to travel through the Internet. A private link is created by encrypting the data for confidentiality; data packets that are intercepted while traveling through the Internet are unreadable without the proper encryption keys.

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