Abstract: The rapid increase of P2P traffic worsens the congestion of network while P2P traffic identification becomes the basic technical support for network management．The heuristic method for identifying P2P application was studied．Firstly,the behaviors that are inherent to P2P host were explored．The behaviors were translated to metrics:remote hosts’ IP address entropy．An algorithm based on remote hosts’ IP address entropy characteristics was proposed．The algorithm showed low false positive in experiment.

Key words: P2P,IP address entropy,Heuristic method