Analysis and Protection of SIP based Services

Multimedia communications over IP are booming as they offer higher flexibility and more features than traditional voice and video services. IP telephony known as Voice over IP (VoIP) is one of the commercially most important emerging trends in multimedia communications over IP. Due to the flexibility and descriptive power, the Session Initiation Protocol (SIP) is becoming the root of many sessions-based applications such as VoIP and media streaming that are used by a growing number of users and organizations. The increase of the availability and use of such applications calls for careful attention to the possibility of transferring malformed, incorrect, or malicious SIP messages as they can cause problems ranging from relatively innocuous disturbances to full blown attacks and frauds. Given this scenario, a deep knowledge of the normal behavior of the network and users is essential to problem diagnosis and security protection of IP Telephony. Moreover, analysis tools taking into account service semantics and troubleshooting VoIP systems based on SIP are of paramount importance for network administrators. However, efficient design and deployment of robust and high performance security controlling systems remain a high challenge, in particular due to the open architecture of the Internet, heterogeneous environment and real time communication constraint. This thesis deals with the analysis and protection of services based on the SIP protocol with a special focus on SIP based VoIP applications. The first part of the work is dedicated to the conformance and security analysis