Narrow Results

As the Internet technology has developed, the demands for the improvement of the reliability and security of the system connected with the Internet have increased. Although various services are performed on the Internet, illegal access on the Internet has become a problem in recent years. This paper formulates stochastic models for a system with illegal access. The server has the function of IDS, and illegal access is checked in multiple stages which consist of simple check, detailed check and dynamic check. We apply the theory of Markov renewal processes to a system with illegal access, and derive the mean time and the expected checking number until a server system becomes faulty. Further, optimal policies which minimize the expected cost are discussed. Finally, numerical examples are given.

This paper formulates a stochastic model for a system with illegal access. The server has the function of IDS, and illegal access is checked in multiple stages which consist of simple check and detailed check. In this model, we consider type I and II errors of simple check and a type I error of detailed check. There are two cases where IDS judges the occurrence of illegal access erroneously. One is when illegal access does not occur, and the other is when illegal access occurs. We apply the theory of Markov renewal processes to a system with illegal access, and derive the mean time and the expected checking number until a server system becomes faulty. Further, an optimal policy which minimizes the expected cost is discussed. Finally, numerical examples are given.