In many security problems, service providers are basically unaware of the type of their clients. The client can potentially be an attacker who will launch an attack at any time during their connections to service providers. Our main goal is to provide a general framework for modeling security problems subject to different types of clients connected to service providers. We develop an incomplete information two-player game, to capture the interaction between the service provider (i.e., the server) and an unknown client. In particular, we consider two types of clients, i.e., attacker and benign clients. We analyze the game using perfect Bayesian Nash equilibrium (PBNE) with different conditions. We finally design an algorithm using the computed PBNE strategy profiles to find the best defense strategy.
