Research Of Network Covert Channel Based On Time Delay

With the increasing information being shared and transmitted through network, network security is becoming more and more crucial. The high capacity of a network covert timing channel makes it an ideal way to exfiltrate information from the compromised computer. Due to the covert feature of a network covert timing channel and the defections of traditional network security products, the communication process in the channel is hard to be detected. Customers, such as financial organization, government, and research institutes, demonstrate the determination to protect their information resources. The research of network covert timing channel is then presented to fulfill this requirement.The thesis takes Network Covert Timing Channel as its object, and mainly discusses the communication process on it. Firstly, it demonstrates the possibility, necessity and non-eras ability of a network covert timing channel based on the information transmission framework. Then, the channel capacity is analyzed and the related algorithm is implemented, from both the information theorem and the security point. Secondly, the sending and receiving methods, as well as the self-adaptation of a binary channel is studied. Based on this, a communication system is analyzed and designed. Thirdly, the conclusions and design methods are verified based on experiments. Then, the experimental results are presented and analyzed. Finally, the thesis evaluates and comments on the research domain of the network covert timing channel, giving an illustrative description of the ideology that leads the way.Based on this thesis, a covert communication system is developed, which works on the Linux environment. The related conclusions and techniques have been deployed in development and research of the Next Generation Security Access and Violation System.