Packet Drop Attack Detection Techniques in Wireless Ad hoc Networks: A Review <s> PathRater <s> This paper describes two techniques that improve throughput in an ad hoc network in the presence of nodes that agree to forward packets but fail to do so. To mitigate this problem, we propose categorizing nodes based upon their dynamically measured behavior. We use a watchdog that identifies misbehaving nodes and a pathrater that helps routing protocols avoid these nodes. Through simulation we evaluate watchdog and pathrater using packet throughput, percentage of overhead (routing) transmissions, and the accuracy of misbehaving node detection. When used together in a network with moderate mobility, the two techniques increase throughput by 17% in the presence of 40% misbehaving nodes, while increasing the percentage of overhead transmissions from the standard routing protocol's 9% to 17%. During extreme mobility, watchdog and pathrater can increase network throughput by 27%, while increasing the overhead transmissions from the standard routing protocol's 12% to 24%. <s> BIB001 </s> Packet Drop Attack Detection Techniques in Wireless Ad hoc Networks: A Review <s> PathRater <s> Mobile ad hoc networks (MANETs) turn out to be very useful in the current application areas for networks that require ad hoc connectivity as well as mobility. While the MANET routing protocols were designed it was assumed that there is no chance to have a malicious node in the network that does not co operate with each other to transmit data. Because of this fact, the network layer of MANETs is vulnerable to attacks of several kinds. Here in this paper, different kinds of attacks on MANETs are discussed first and then some protection mechanisms against those attacks are discussed. Comparisons of these mechanisms are also included. <s> BIB002
PathRater is run by every node in the network BIB001 BIB002 . A node maintains ratings for every other node it knows in the network basing on the knowledge of misbehaving nodes and link reliability data in order to choose the most suitable path. A path metric is calculated by averaging the ratings for nodes in the path. In case there is more than one path to the destination, the path with the highest metric is chosen. A pathrater node assigns a neutral rating of 0.5 to nodes known to it. It normally assigns itself a rating of 1. The ratings are updated in intervals of 200ms. The ratings for nodes in active path are increased by 0.01 and the maximum rating a node can attain is 0.8. A node's rating is decreased by 0.05 when a link break is detected and the node becomes unreachable. A negative path metric value indicates presence of misbehaving nodes in the path. Due to faults or false accusations, a node may be marked as a misbehaving node. It is generally better not to permanently mark it as misbehaving node. Therefore, the marked misbehaving nodes' rating should be increased slowly or set back to 0.0 after a long time period. When a pathrater detects a misbehaving node in a path it is using and fails to get an alternative path free of misbehaving nodes, it sends out a route request message called Send Route Request (SRR) BIB001 . This way, a new metric can be constructed from which a new path can be determined.