Abstract
Secret communication via network has always been an area of interest for many. It has not only attracted the trusted parties to communicate with each other secretly but has also attracted the hackers/attackers to find ways to discover and leak the information and use the network in a manner that violate security policies. Steganography and covert channels are most widely used approaches for secret communication. Number of detecting techniques has been proposed for steganography and covert channel detection. This paper covers detecting techniques of covert channel only as the covert channel is a modern way of leaking information and it is difficult to detect such channels. Covert channel falls into two categories: storage covert channel and timing covert channel. Storage covert channel is created by manipulating the header fields of packets whereas timing covert channel is created by timing of event i.e. arrival pattern of packets. In this paper different techniques for detecting storage and timing covert has been surveyed and analysis of these techniques is done.