[Bauer88] D. S. Bauer, M. E. Koblentz, NIDX: An Expert System for Real-Time Intrusion Detection IEEE Proceedings -- Computer Networking Symposium, April, 1988, pp98-106 New York. [This paper describes a prototype real-time network-based intrusion detection system based on using an expert system to detect known attack patterns and deviations from known user behavioral patterns.]