Securing DSR against wormhole attacks in multirate ad hoc networks

A packet traversal time per hop based adaptive wormhole detection algorithm for MANETs

“…RTT-based approaches offer low overhead solutions in terms of hardware, computation, and throughput, but have the limitation that variations in a node's packet processing time must be small. In a real MANET, nodes can exhibit high packet processing time variations resulting in low wormhole detection rates and high false positive (FP) rates for RTT-based solutions, as is theoretically proven in [9] and in [10].…”

“…While various detection strategies have been proposed in [3] [5][6][7][8][9][10][11][12][13], most solutions have some recurring limitations including the inability to detect all wormhole types, the requirement for dedicated hardware, reliance on particular MANET environments, and imposing high computational overheads and/or bandwidth loads upon the network.…”

“…Another approach [9,10,13] for improving the distance estimation accuracy between nodes is to subtract the packet processing times from RTT measurements, resulting in the air packet traversal time (PTT). The PTT of a route reflects better than RTT the route distance between two nodes.…”

“…The PTT of a route reflects better than RTT the route distance between two nodes. In [9], a modified version of TTM (M-TTM) was proposed where every node on a route measures the RTT between itself and the next hop. The measured RTT is then compared with the expected RTT, which is estimated by measuring the packet processing times of the route request (RREQ) and route reply (RREP) packets at the next hop and thereafter adding the maximum PTT (PTTMAX).…”

“…Firstly, each node along a route must add four different timestamps to every routing packet to reflect the specific times incurred in receiving and forwarding RREQ and RREP packets. The assumptions underpinning how the expected RTT is determined are also unrealistic since in [9] PTTMAX is presumed to be 1µs which corresponds to a distance of about 300m. In a real network, the PTTMAX of a node will be dependent on both its hardware and surroundings, since in a line-of-sight (LOS) link PTTMAX will be much higher than when there are obstacles between nodes.…”