The article compares modelling techniques for network security, including the theory of probability, Markov processes, Petri networks and application of stochastic activity networks. The paper introduces the advantages and disadvantages of the above proposed methods and accepts the method of modelling the network of stochastic activity as one of the most relevant. The stochastic activity network allows modelling the behaviour of the dynamic system where the theory of probability is inappropriate. A real network distributes incidents referring to various distribution methods (exponential, gama, Veibul, etc.). A real system should evaluate time value when the stochastic activity network allows such activity.

Article in Lithuanian