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Ad-hoc wireless networks are being deployed in critical applications that require protection against sophisticated adversaries. However, wireless routing protocols, such as the widely-used AODV, are often designed with the assumption that nodes are benign. Cryptographic extensions such as Secure AODV (SAODV) protect against some attacks but are still vulnerable to easily-performed attacks using colluding adversaries, such as the wormhole attack. In this paper, we make two contributions to securing routing protocols. First, we present a protocol called route verification (RV) that can detect and isolate malicious nodes involved in routing-based attacks with very high likelihood. However, RV is expensive in terms of energy consumption due to its radio communications. To remedy the high energy cost of RV, we make our second contribution. We propose a multigrade monitoring (MGM) approach. The MGM approach employs a previously developed lightweight local monitoring technique to detect any necessary condition for an attack to succeed. However, local monitoring suffers from false positives due to collisions on the wireless channel. When a necessary condition is detected, the heavy-weight RV protocol is triggered. We show through simulation that MGM applied to AODV generally requires little extra energy compared to baseline AODV, under the common case where there is no attack present. It is also more resource-efficient and powerful than SAODV in detecting attacks. Our work, for the first time, lays out the framework of multigrade monitoring, which we believe fundamentally addresses the tension between security and resource consumption in ad-hoc wireless networks.
Date of Conference: 12-15 Oct. 2009