Cope with a Malicious Host in Mobile Adhoc Networks (MANET)

Abstract

From a security perspective, a jamming attack is easy to launch and relatively hard to detect. Jamming attacks are generally directed towards seizing the medium completely by transmitting fake packets violating the medium access protocol, either constantly or periodically. This work analyzes the effects of different types of jammers using Conservation of Flow (CoF), which has been useful for detecting other attacks in wired networks. Additionally, simulation results are presented in justification of proposed methodology. With the miniaturization of wireless devices, the popularity and usage has increased in recent past, especially due to portability. Since the design of such devices does not primarily emphasize heavy computation and secure communication, these are treated as add-ons. In setting up an ad hoc network rather than choosing all or more than the channels offered by 802.11 standard, only a single channel is generally utilized to minimize delay and synchronization issues. However, by using additional available multiple channels, significant gain in terms of overall system performance can be achieved. This, and other limitations like a shared medium which is open to all, attracts intruders in wireless networks. Mainly, the use of a lone channel can become single point of failure in case of an attack, especially a jamming attack. In contrast to other security attacks, no special hardware and computation is required in launching jamming attacks. Additionally, even if the attacker does not get hold of the communication, he can emit radio signals periodically to jam legitimate conversation. Thus, legitimate nodes escape physically or logically to avoid a jammer at the cost of additional overhead involving coordination amongst nodes to resume communication. The overhead involved in either of the methods is considered worthy in terms of regaining the performance of the network. In this thesis, a couple of MAC layer-based algorithms are proposed to mitigate the effects of jamming attacks efficiently; the first is a reactive mechanism and the second is a proactive proposal. The work starts with an investigation of different jamming types and their effects on wireless communication. For this purpose, a simulation model was developed and the resulting data set was verified using AI algorithms, which predicted 98% accuracy. Next, a reactive technique namely packet-feed is proposed to keep the jammer busy on the jammed channel. Once the nodes detect the existence of the jammer and hop to another channel, they alternatively visit the earlier channel to feed the jammer with valid packets. This way, the nodes pretend to the jammer that the earlier channel is still in use. Finally, a proactive channel hopping protocol is proposed where each node has a separate and dynamically selected control channel. Additionally, rather than each of them feeding the other its channel hopping sequence, both parties coordinate to come up with a new channel where data transfer can take place. Thus, provision of redundant channels is provided to each node. Following on from this, the proposed idea is analyzed with the existence of a jammer.