Abstract. Modern wireless devices, such as those that implement the 802.11b standard, utilize multiple transmission rates in order to accommodate a wide range of channel conditions. Traditional ad hoc routing protocols typically use minimum hop paths. These paths tend to contain long range links that have low effective throughput and reduced reliability in multi-rate networks. In this work, we present the Medium Time Metric (MTM), which is derived from a general theoretical model of the attainable throughput in multi-rate ad hoc wireless networks. MTM avoids using the long range links favored by shortest path routing in favor of shorter, higher throughput, more reliable links. We present NS2 simulations that show that using MTM yields an average total network throughput increase of 20% to 60%, depending on network density. In addition, by combining the MTM with a medium time fair MAC protocol, average total network throughput increases of 100% to 200% are obtained over traditional route selection and packet fairness techniques.
Survivable routing protocols are able to provide service in the presence of attacks and failures. The strongest attacks that protocols can experience are attacks where adversaries have full control of a number of authenticated nodes that behave arbitrarily to disrupt the network, also referred to as Byzantine attacks. This work examines the survivability of ad hoc wireless routing protocols in the presence of several Byzantine attacks: black holes, flood rushing, wormholes and overlay network wormholes. Traditional secure routing protocols that assume authenticated nodes can always be trusted, fail to defend against such attacks. Our protocol, ODSBR, is an on-demand wireless routing protocol able to provide correct service in the presence of failures and Byzantine attacks. We demonstrate through simulations its effectiveness in mitigating such attacks. Our analysis of the impact of these attacks versus the adversary's effort gives insights into their relative strengths, their interaction and their importance when designing wireless routing protocols.
Abstract-An ad hoc wireless network is an autonomous selforganizing system of mobile nodes connected by wireless links where nodes not in direct range communicate via intermediary nodes. Routing in ad hoc networks is a challenging problem as a result of highly dynamic topology as well as bandwidth and energy constraints. In addition, security is critical in these networks due to the accessibility of the shared wireless medium and the cooperative nature of ad hoc networks. However, none of the existing routing algorithms can withstand a dynamic proactive adversarial attack. The routing protocol presented in this work attempts to provide throughput-competitive route selection against an adaptive adversary. A proof of the convergence time of our algorithm is presented as well as preliminary simulation results. I. BACKGROUNDThe basic service offered by every node in an ad-hoc network is that of routing packets from their source to their ultimate destination. In general, routing protocols are susceptible to a wide variety of attacks. For example, a malicious node may perform a denial of service attack by selectively jamming some areas of the network.A great deal of work has been done in terms of guaranteeing practical security considerations in existing network protocols. In practice, adversarial attacks observed and documented in ad hoc networks might not be overly sophisticated. The ease of access to the medium has allowed extremely basic attacks to cause a great deal of damage. Consequently, such attacks can be thwarted by simple yet effective methods.Existing work in the literature considered a number of strong adversary models. For example, [1] considers a random fault pattern; [2] deals with a static fault pattern and [3] deals with an oblivious (non-adaptive) pattern.Our goal is to design routing protocols for networks that are provably tolerant of arbitrary adaptive DOS attacks. The adversary that we will consider selectively attacks packets on a given node or link. This adversary benefits from knowledge of the traffic pattern (including packet contents); this includes all current traffic and all past traffic history.As a result, the algorithms and analysis techniques used in the previous work will not apply. Existing methods that do not ignore sophisticated adaptive attacks either use brute force (flooding) or assume the existence of some trusted servers or routers. We do not wish to make such restrictive assumptions. As a result, the task of designing a throughput-competitive routing algorithm is much harder.It may appear that our adversarial routing model may lead to impractical algorithms in benign (non-adversarial) settings. However, routing algorithms similar to the one studied here were developed and tested in real network environments by British Telecomm and NTT for both wired and wireless networks with superior results Our contribution: We propose a new algorithm for adaptively selecting routing paths in a network with dynamic adversarial edge failures, and we give a rigorous mathematical analysis of...
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