3. The problem of a hidden channel on a network

Implementing such a channel via the TCP/IP protocol is a tricky business. Indeed, any generation of superfluous traffic is (potentially) immediately detected by network supervision tools.

Let's assume that any abnormal traffic on the network is either listened in on or detected, and therefore cannot be used as a channel. This requires various countermeasures to be in place on the network, essentially IDSs that will attempt to detect suspicious traffic. The other constraint not to be overlooked concerns the network on which the channel will exist: its equipment and architecture also come into play, as they can bring modifications...