Network Covert Channel Interference

With the rapid development of computer and network, network covert channel becomes hot in the field of network security. Network covert channel includes network covert storage channel and network covert timing channel. Network covert timing channel transmits covert information by interval time between packets' sending, and thus leaks information. Network covert timing channel has become a serious threat, so that the system and network which deal with the confidential information must limit network covert timing channel strictly. This paper did research on network covert timing channel and finished the following work.(1) The article described the development, classification and reference model of covert channel. The study defined network covert timing channel and reviewed some classical network covert timing channels, also summed up a few models and designed a udp covert timing channel. After that, the research focused on the discussion about disrete-time queues with single or multiple arrivals based on the network covert timing channel, and then analyzed delay jammers with a maximum delay constraint and a maximum buffer size constraint for discrete-time packet waveforms.(2) Based on those, the paper presented an adaptive random delay based on the maximum delay constraint, and anaylzed the channel capacity.(3) In order to evaluate the performance of the strategy, the paper achieved a network covert timing channel. The jamming of the network covert timing channel was implemented on a Linux system by modifying the kernel codes. The paper described the actual implementation's technical points.(4) The paper assessed the performance of the jamming strategy. After disturbing the channel, the receiver almost decoded wrong and the channel capacity reduced by 60.5%. The paper tested the network delay and throughout on the normal network traffic and compared with the existing jamming strategy. The result indicated that the network delay increased obviously and the network throughout decreased obviously.Because of the limitations about the research of the channel, the paper illustrated research's prospects of the network covert timing channel and proposed a few more reasonable research directions about design and jamming of the channel.