and defending against privacy attacks on user data are critical requirements for most of the real-world applications in WMNs [5,6]. Some security and privacy protection protocols for wireless networks are based on the computation and the use of the trust and reputation values of the nodes [7,8]. However, most of these schemes are primarily designed for deployment in mobile ad hoc networks (MANETs) [9,10], and hence these mechanisms do not fit well into the network architecture and the requirements of the applications in WMNs. Fig 1. The three-tier architecture of a wireless mesh network (WMN)Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defence mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.The chapter is organized as follows. Section 2 presents various possible attacks on different layers on the communication protocol stack of the WMNs. Section 3 discusses various security mechanisms at different layers for defending the attacks mentioned in Section 2. Section 4 provides a brief discussion on various trust management schemes for enforcing security and collaboration among the nodes in wireless networks with particular focus on WMNs. Section 5 highlights some future research trends on security and privacy issues in WMNs. Finally, Section 6 concludes the chapter.
Security Vulnerabilities in WMNsDifferent protocols for various layers of WMN communication stack have several vulnerabilities. These vulnerabilities can be exploited by potential attackers to degrade or disrupt the network services. Since many of the protocols assume a pre-existing cooperative relation among the nodes, for successful working of these protocols, the participating nodes need to be honest and well-behaving with no malicious or dishonest intentions. In practice, however, some nodes may behave in a malicious or selfish manner ...
