Research On Countermeasures Against Wormhole Attack In Ad Hoc Network

Ad Hoc network consists of a set of mobile wireless nodes that can communicate with each other without fixed networking infrastructure. Because of the dynamic changes of network topology, limited bandwidth and energy, and distributed architecture, Ad Hoc network is more susceptible to various kinds of attacks.Wormhole is a kind of serious attack against Ad Hoc network. In a wormhole attack, an attacker receives packets at one point in the network, "tunnels" them to another point in the network, and then replays them from that point. For tunneled distances longer than the normal wireless transmission range of a single hop, it is simple for the attacker to make the tunneled packet arrive with better metric than a normal multi-hop route, and then the attacker can drop or modify the packets, or even damage the network topology.Ad hoc on demand distance vector (AODV) protocol and the optimized link state routing (OLSR) are two typical routing protocols in ad hoc networks. Nodes find routes only when required in the AODV, and obtain routes by periodic exchange of topology information in the OLSR. Based on the features of the two routing protocols and the position technology in ad hoc, countermeasures against the wormhole attack are proposed. The key of the method is to enhance the relationship of the neighboring nodes. The distance between two neighbors can be calculated according the transmission time difference for the same packet transferred in two different media. And then the distance is compared with the covered range of one hop. Usually, in wormhole attack, the distance between the two far nodes (much larger than one hop range) can consider that they are neighbors within one hop range. Then the hidden wormhole attack can be exposed by the contradiction of distance.At the same time, nodes can check the legitimacy of the nodes that send their packets to them by encryption and authentication technologies. Only those who locate within one hop range and pass the identity authentication can be regarded as the one hop neighbors, thus avoiding the visible wormhole attack.Five implementation scenarios are presented, followed by the analysis of their feasibility and the surveys of pros and cons individually.