Using non-deterministic finite automaton to research intrusion tolerant system

Intrusion Tolerant is a new network information security technology after firewall, access control and intrusion detection. When a network system is attacked by illegal intrusion, intrusion tolerant system is capable of self-diagnosing, recovering, reconstruction and continuing to provide service to legitimate clients in the presence of intrusions. It is the last defense line of system after the intruder successfully bypassed firewall, intrusion detection or access permission control. Based on non-deterministic finite automaton, the working method after attacked is described, and a different way to develope intrusion tolerant technology is provided.