ABSTRACT
Conventional networks use dedicated nodes to carry out basic functions such as packet forwarding, routing, and network management. In ad hoc networks, these are carried out collaboratively by all nodes available. Nodes on MANETs use multihop communication: nodes that are within each other’s radio range can communicate directly through wireless links, whereas those that are far apart must rely on intermediate nodes to act as routers to relay messages. Mobile nodes can move, leave, and join the network, and routes need to be updated frequently due to the dynamic network topology. For example, node S can communicate with node D by using the shortest path S-A-B-D as shown in Figure 6.1 (the dashed lines show the direct links between the nodes). If node A moves out of range of node S, it has to find an alternative route to node D (S-C-E-BD). A variety of new protocols have been developed for finding/updating the routes and generally providing communication between end points (but no proposed protocol has yet been accepted as standard). However, these new routing protocols, based on cooperation between nodes, are vulnerable to new forms of attacks. Unfortunately, many proposed routing protocols for MANETs do not consider security. Moreover, their specific features such as the lack of central points, the dynamic topology, and the existence of highly constrained nodes presents a particular challenge for security.
