Peer to Peer (P2P) file sharing systems have been introduced in business networks yet they are causing certain security problems in the network infrastructure. Securing P2P networks can be challenging as data traffic in such networks is difficult to manage and peers may have very different security settings and configurations. For example, P2P applications can use different port numbers as a configuration parameter, or simply use a random port number. Furthermore, not every P2P application supports encryption and decryption. This paper summarizes the existing solutions for detecting and stopping unwanted data traffic in P2P networks.