Section 8.7 Virtual Private Networks

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8.7 Virtual Private Networks

Virtual Private Networks (VPNs) are an excellent way for two systems that trust each other to have their packets tunnel through any number of systems that these two do not trust. They give all the security of private networks (that tend to be trustworthy but very expensive) with the cost effectiveness of public networks. Another advantage of private networks, guaranteed bandwidth, now is becoming available through some ISPs.

There are a number of commercial VPN products and this is what IPsec is intended for. However, the secure shell (SSH) provides this too and is an excellent solution for most people. SSH allows protected shell and X sessions as well as generic TCP connections. See "Protecting User Sessions with SSH" on page 409.

Even the coveted NFS using UDP could be made to run over SSH with the use of a simple home-grown client/server system, where each side listens on the appropriate UDP ports to the "real" NFS client and server and then conveys this information between the home-grown client and server using TCP over the SSH-secured TCP connection. This should be a few days' effort for an experienced network programmer.

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