With the growing use of protocols obfuscation techniques, protocol identification for Q.O.S enforcement,traffic prohibition, and intrusion detection has became a complex task. This paper addresses this issue with a probabilistic identification analysis that combines multiples advanced identification techniques and returns an ordered list of probable protocols. It combines a payload analysis with a classifier based on several discriminators, including packet entropy and size. We show with its implementation, that it overcomes the limitations of traditional port-based protocol identification when dealing with hard to classify protocol such as peer to peer protocols. We also detail how it deals with tunneled session and covert channel.