—Because of the enormous growth in the number of peer-to-peer (P2P) applications in recent years, P2P traffic now constitutes a substantial proportion of Internet traffic. The ability to accurately identify different P2P applications from the network traffic is essential for managing a number of network traffic issues, such as service differentiation and capacity planning. However, modern P2P applications often use proprietary protocols, dynamic port numbers, and packet encryptions, which make traditional identification approaches like port-based or signaturebased identification less effective. In this paper, we propose an approach for accurately recognizing P2P applications running on monitored hosts based on signaling behavior, which is regulated by the underlying P2P protocol; therefore, each application possesses a distinguishing characteristic. We consider that the signaling behavior of each P2P application can serve as a unique signature for application identification. O...