A Survey: MAC Misbehaviour in Wireless Mesh Networks Anil Kumar Gankotiya 1 , Sahil Seth 2 , Gurdit Singh 3 Department of Computer Science, PEC University of Technology, Chandigarh, India 1 anilgankotiya@ieee.org 2 sahilseth@ieee.org 3 gurditsingh@ieee.org Abstract— Wireless Mesh Networks (WMNs) have attracted significant interest as a cost-effective wireless network infrastructure. Security is a fundamental prerequisite for network survivability and reliability in wireless mesh networks (WMN). One of the major challenges in WMNs is to ensure nodal collaboration. Nevertheless, collaboration may lead to undesired results when nodes can exploit their siblings for their own benefits. In the presence of selfish nodes that disobey the standard, the performance of well-behaved nodes will significantly degrade. In this paper, we focus on identifying potential threats in medium access control (MAC) layer introduced by misbehaving nodes. Keywords— MA; RTS&CTS; misbehavior; NAV; back-off I. INTRODUCTION Reliable communication in wireless mesh networks depends on the inherent trust among nodes. Clearly, trust means nodes need to fully cooperate with each other to ensure correct routing establishment mechanisms, also the protection of routing information and the security of packet forwarding. However, this trust might be abused by adversaries to carry out security breaches through compromised nodes. The traditional approach to provide network security is built on cryptography based authentication. However, this is not sufficient to solve the problems arising from new node misbehaviors in wireless mesh networks (WMNs). Hence, securing WMN against MAC layer misbehavior has become a major challenge in the research community. Host misbehaviors in WMN can be classified into two categories as in ad hoc networks; namely, selfish misbehavior [8], [10] and malicious misbehavior [9]. A selfish host can deliberately misuse the MAC protocol to gain more network resources than well behaved hosts. The node can benefit from this behavior by: (1) obtaining a large portion of channel capacity (hence improved throughput); (2) reduced power consumption; (3) improved quality of service, i.e. low network latency. For example, hosts competing for the channel to wait for back-off interval [10] before any transmissions. A selfish host may choose to wait for a smaller back-off interval, thereby increasing its chance of accessing the channel and hence reducing the throughput share received by well-behaved stations. Such selfish misbehavior can seriously degrade the performance of the network and accordingly they proposed some modifications for the protocol (e.g., by allowing the receiver to assign back-off values rather than the sender) to detect and penalize misbehaving nodes. Similarly, the authors of [3] addressed the same problem and proposed a system, DOMINO, to detect greedy misbehavior such as back-off manipulations in IEEE 802.11. Alternatively, malicious misbehavior aims primarily at disrupting the normal operation of the network. This includes colluding adversaries that continuously send data to each other in order to deplete the channel capacity in their vicinity (i.e., causing a denial of service attack) and hence prevent other legitimate users from communicating [11]. A new class of vulnerabilities was presented in [1] where a host could maliciously modify the protocol timeout mechanism (e.g. by changing SIFS parameter in IEEE 802.11) and force MAC frames to be dropped at well-behaved nodes. A host exploiting this vulnerability will completely cooperate in forwarding data packets but maliciously forces the forwarding operation to fail. Moreover, the attack also targets crossing flows (flows that traverse through a malicious node) by disrupting their communication and forcing the routing protocol to reroute packets around the misbehaved node. In this paper, we present a series of new selfish attack strategies against the existing detection and reaction systems as well as IEEE 802.11 standard; we also concentrated on multichannel communication. OUTLINES The rest of this paper is organized as follows: The selfishness and greediness is introduced in Section II. Then we discuss MAC protocols and its vulnerabilities in Section III. Then we discuss MAC misbehavior in cognitive radios in Section IV, and we conclude the approaches in Section V. II. SELFISHNESS AND GREEDINESS Misbehaving among nodes is a primary requirement for the network functioning that cannot directly be assumed. Providing