Abstract:

With the rapid development of the Internet, the network security issue based on Trojan invasion has been more attention. Covert transmission is important technology used by Trojans and other malicious. Network covert channel brings us harm, but also brings forward for our use. We can transmit information covertly and safely by network covert channel, also can test the performance of protection facilities of the existing system. So research covert channel has great significance for network protection. This paper researches network protocol, network protection technology, the principle and working mechanism of hidden transmission network, some technical flaws of network protocol and elements of the communication system, proposes a network covert transmission method based on the TCP protocol, in order to build a network covert channel. The channel can bypass firewalls and intrusion detection systems to transmit hidden information. This paper designs and implements the method and the method is tested and verified. The experiments prove that the channel has a high concealment and transmission speed. The method provides a theoretical basis and technical support for protection Trojans and other malicious attacks. It has certain significance for network security.

Key words: network security, TCP, covert transmission