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In mobile ad hoc networks (MANETs), the nodes need to cooperate each other to establish multi-hop routes for out-of-range wireless communication. However, some of them may not always behave normally, either behaving selfishly for saving computational resource or maliciously for compromising communication protocols. Regardless of intents, such misbehavior would lead to the degradation of network performance. It is therefore important to design appropriate mechanisms to ensure that network performance could be maintained at an acceptable level in the presence of misbehaving nodes. But the open nature of MANETs makes such designs challenging. Reputation system has been widely recognized as an effective approach, which associates the behavior of nodes with its reputation, which is calculated by specifying and quantifying the observations of interest with respect to predefined performance metrics. More interestingly, the observations can be obtained and integrated from multiple layers, facilitating cross-layer analysis. This paper intends to take a deep look into several well-studied reputation systems and examine their operational characteristics in terms of modeling approaches and redemption techniques, with an objective to identify their capabilities in terms of misbehavior detection coverage and blind spots. Furthermore, such an anatomy allows us to better understand the failure curses of the deployment and operation of reputation systems in MANETs, so as to improve their performance by adopting effective countermeasures.Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A particularly severe attack on routing protocols in ad hoc networks is the so-called worm- hole attack in which two or more colluding attackers record packets at one location, and tunnel them to another location for replay at that remote location. When this attack targets specifically routing control packets, the nodes that are close to the attackers are shielded from any alternative routes with more than one or two hops to the remote location. All routes are thus directed to the wormhole established by the attackers. In the optimized link state routing protocol, if a wormhole attack is launched during the propagation of link state packets, the wrong link information percolates throughout the network, leading to routing disruption. In this article we devise an efficient method to detect and avoid wormhole attacks in the OLSR protocol. This method first attempts to pinpoint links that may potentially be part of a wormhole tunnel. Then a proper wormhole detection mechanism is applied to suspicious links by means of an exchange of encrypted probing packets between the two supposed neighbors (endpoints of the wormhole). The proposed solution exhibits several advantages, among which are its nonreliance on any time synchronization or location information, and its high detection rate under various scenarios. [ABSTRACT FROM AUTHOR]