Detection and Mitigation of Blackhole Attack Effect in Opportunistic Networks

Blackhole attack is one of the major security concerns in mobile ad-hoc networks that are hard to detect. In this type of attack, the malicious node attracts message packets by advertising itself as a cooperating node but eventually drops them, thus heavily degrading the network performance. This attack becomes a more serious threat in Opportunistic Networks due to the absence of any predefined path of trustworthy nodes between source and destination. In this paper, we have proposed a technique to identify the potential Blackhole nodes present in the network. With the knowledge of such a list and minor modification of the traditional Spray-and-Wait Routing protocol, we were able to mitigate the effect of Blackhole attack on the network performance. Simulation results show improvement in the network performance in terms of delivery ratio and the number of dropped messages, even in the presence of Blackhole nodes. It has also been observed that traditional routing protocols like Epidemic, Prophet and Spray-and-Wait routing, perform better if the paths containing the suspected nodes detected by our proposed method are avoided.