Strategy based proxy to secure user agent from flooding attack in SIP

Voice over IP (VoIP) technology has proven to be an immensely useful technology during the last decade. Not only it provides various services to users (e.g. calls, instant messaging, internet conferencing etc), but it is also in a process of extending services (e.g. fax service). Due to the open environment of packet switched network, the signaling protocols (such as SIP and H.323) and the transport protocols (e.g. RTP and SRTP) used by VoIP, it is prone to unwanted accesses and does not comply with the security standards. VoIP is also vulnerable to threats from TCP/IP and UDP. Furthermore, the malicious users can exhaust proxy and end users with INIVTE flooding in SIP. In order to overcome these challenging issues, we propose a simple and robust method to detect INVITE flooding on the SIP proxy server by a strategic proxy model that is based on a user-specified threshold. This model is based on the traffic pattern of normal VoIP traffic and the attacked traffic pattern. Unlike considering only stateful proxies, our model is works for both stateless and stateful proxies.