Covert Channels In Network

A covert channel is different from the open channel. The open channel is used to transmit legitimate information. And the covert channel can be used to leak illegal and confidential information across a network under the cover of open channels. The idea of the network covert channel comes of the research of monolithic systems. Network covert channel can resist examination, result in network vulnerability and compromise sensitive information. In this paper, the phylogeny, principle, detecting technology and the implement of network covert channel on Linux platform are researched.Firstly, this thesis investigates the phylogeny of the covert channels existing in computer networks by analyzing protocol suite. The models, taxonomy and the characteristics are summarized.Secondly, a new type of network covert channel based on HTTP was proposed.Then, the implement of network covert channels on Linux platform was analyzed. Methods to design network covert channel are discussed by the framework Netfilter.Finally, a mathematics model was proposed to evaluate the negative impact on network. Also a detect model was created to efficient detecting process.