Network administrators are more and more concerned about scrutinizing the traffic that comes in and out of their networks, but applications and attackers know that they won’t block HTTP traffic over port 80.
So if you can't beat'em, join'em. Applications and attacks have quickly learned that they can evade firewalls and other security devices via HTTP tunneling. HTTP tunneling is a method of evading network firewalls and access control policies by encapsulating traffic in HTTP headers and sending it over the most open port in the network – port 80. To learn about how applications and attackers are using this method to bypass firewall and router access control policies, click on the link below.