Abstract: Intrusion prevention system (IPS) is a crucial defensive measure against malicious attacks to information system. However, the improper IPS configuration can have a negative impact on network performances in terms of end-to-end delay or packets loss. Most researchers mainly focus on putting forward new IPS and analyzing the different methodologies, but ignoring the research of quantitative analysis on IPS. By analyzing the system as a quasi-birth-and -death process, this paper obtains the steady probabilities distribution to compute some important indices by establishing a two-dimensional Markov chain model. The experimental results prove that the general analytical method can effectively evaluate the performances of IPS, and also testify the correctness of the model indirectly.

Key words: intrusion prevention system, Markov chain mode, performance analysis