[ Thanks to Matthew Casperson for this
link. ]
“Tunneling through the internet has become all the rage ever
since people could get faster and cheaper connections to remote
networks using VPNs than they could with direct dial in modem
connections. Tunneling basically involves wrapping the packets sent
between two computers inside additional packets that can be easily
passed around on the internet. This can be done for security (the
inner packets can be encrypted), routing (with the inner packets
targeting PC’s that don’t have a public IP address), or, as is the
case with the example that will be presented here, working around
the limitations of a firewall or proxy.”