What Is a VPN?

Corporate networks are protected from prying public eyes through various methods, many of which you have already seen in this book. Arguably the most common situation is for a company’s network to be situated behind a firewall device that performs Network Address Translation (NAT) of IP addresses within the company to a single “masked” address visible from the outside. The idea behind this configuration is that machines within the network can access resources out on the Internet, but machines on the Internet cannot contact the “masked” corporate machines directly.


Network Address Translation is an Internet connection technique that enables multiple hosts to connect to the Internet using a single IP address. NAT is fully described ...

Get FreeBSD6 Unleashed now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.