摘要：Voice over internet protocol (VoIP) service has been a very popular and important application over the internet. Wireless VoIP also becomes more and more popular due to its features of low cost and convenience. Wireless mesh networks (WMNs) have emerged as a key technology for the next-generation wireless networks and have been considered as a good solution for VoIP services due to deployment and wide coverage. However, there have been raised relevant security concerns referred to integrating IP Telephony into existing applications and system infrastructure. One of the critical concerns is how to enhance the security of session initiation protocol (SIP) and security among the nodes by blocking identity spoofing and preventing various attacks in the convergent communication systems in WMNs, which are usually deployed under the assumption that participating nodes cooperate with each other. In this paper, we propose a subjective logic based dynamic trust mechanism for securing the SIP-based VoIP over WMNs. The dynamic trust mechanism incorporates uncertainty in association with subjective logic into the reputation computation to detect and isolate the existing malicious nodes. Also, it considers the quality of wireless links which can differentiate intentional packet drop from packet drop due to poor link quality and give accurate detection even in presence of poor wireless links. We demonstrate the performance of the dynamic trust mechanism through network simulator (NS) 2 simulations.
