TUKAB: An Efficient NAT Traversal Scheme on Security of VoIP Network System Based on Session Initiation Protocol

Voice over Internet Protocol (VoIP) is subject to many security threats unique to both telephony and traditional Internet data transmission. As adoption of Session Initiation Protocol (SIP)-based telephony increases, concerns are rising over risks to system confidentiality, integrity and availability. Currently, several VoIP security tools are available to detect vulnerabilities and protect against attacks. In this paper we present various issues concerning the security of VoIP. A brief discussion of the SIP protocol is presented based on its operating principle. Finally, we proposed a solution for the Network Address Translation (NAT) traversal problem of SIP-based networks. This solution supports all types of NAT and maintains the current VoIP architecture. Based on our experiment, we examined the latency, buffer size and voice packet loss under various network conditions. We found that it is possible to establish a call from outside the NAT to inside, maintaining the quality issues of VoIP call. With this approach, it is possible to use the current network architecture by making some minor changes of the Register Server. Hence we evaluate our model, showing the QoS conditions that achieve both high efficiency and secure voice transmission. Sufficient simulation results are presented to verify our model.