With no cooperation from a firewall operator, the FEP allows ANY application to traverse a Firewall. Our methodology is to layer any application layer Transmission Control Protocol/User Datagram Protocol (TCP/UDP) packets over the HyperText Transfer Protocol (HTTP) protocol, since HTTP packets are typically able to transit Firewalls.

This scheme does not violate the actual security usefulness of a Firewall, since Firewalls are designed to thwart attacks from the outside and to ignore threats from within. The use of FEP is compatible with the current Firewall security model because it requires cooperation from a host inside the Firewall. FEP allows the best of both worlds: the security of a firewall, and transparent tunneling thought the firewall.

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said by Killer Maxx :

If "Firewalls are designed to thwart attacks from the outside and to ignore threats from within" then what circumstances would require you to "encapsulate" your outbound TCP/IP packets to get out ? Also, HTTP rides over TCP, so putting TCP inside HTTP is like sticking your head up your ass and expecting to breathe some fresh air from your inside-out nose. I smell more than one rat in this one.

But, by employing a little-known implementation of TCP/IP, they can use simple HTTP to encapsulate TCP connection requests.