Abstract: “Due to the rapid growth in number of different protocols over the internet, internet protocols have become an ideal vehicle for covert communications. They represent a high bandwidth for such communications. Moreover, new high-speed network technology has significantly amplified the network’s covert channel capacity. Certainly, a covert channel bandwidth of only one bit size can easily allow transmission of a system bin code which can lead to tremendous risk. This paper presents a brief overview of network protocols-based covert channels, and surveys some recent and relevant work on covert channels detection and elimination techniques along with their achievements and limitations. In sum, the covert channel countermeasures—detection, elimination, mitigation, and capacity reduction—are still real challenges and lag behind an acceptable level of network security. Therefore, the research door is wide open for more contributions in this field.”

Keywords: covert channel, security; detection, prevention, elimination, capacity reduction, network protocols.