International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 09 | Sep 2020 www.irjet.net p-ISSN: 2395-0072 © 2020, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 3034 Defending Malicious Nodes against Collaborative Black-Hole and Gray- Hole Attacks in Mobile Ad Hoc Networks Dr. Madugundu Neelakantappa 1 , Dr. Amjan Shaik 2 1 Associate Professor of Information Technology, B.V.Raju Institute of Technology, Narsapur, Telangana State, India 2 Professor of Computer Science & Engineering, B.V.Raju Institute of Technology, Narsapur, Telangana State, India -----------------------------------------------------------------------***------------------------------------------------------------------------ Abstract: Mobile Ad hoc Network (MANET) is an infrastructure-less self-containing and ubiquitous wireless network. In MANETs, mobile nodes forms an ad hoc network without any physical infrastructure. In these networks, each node plays a role of host and a router as well and hence communication will be established on demand without need of any fixed equipment of network. This network faces major security concern, in case of presence of malicious node, as these nodes can distracts the routing process. In this context, the major challenge is the detection and prevention of malicious nodes, launching collaborative gray-hole or black- hole attacks. In this paper, a novel secured routing protocol known as “Malevolent Node Detection Protocol by Collaborative Bait (MNDPCB)”. This technique acts as hybrid protocol as it have the advantages of defending architectures of both reactive and proactive. This MNDPCB protocol is processed with a reverse tracking technique for detecting the malevolent nodes and there by defend their attacks of collaborative nature. Simulation results demonstrates that in the presence of malicious node attacks, the MNDPCB provides better performance when compared with base-DSR, 2-ACK and best-effort-fault tolerant (BFTR) routing protocols in-terms of performance metrics: packet-delivery-ratio, throughput and routing overhead. Keywords: MANET, Black hole attack, Gray hole attack, malevolent nodes, MANET security, proactive and reactive defend architecture 1. INTRODUCTION Due to wide availability of mobile devices, Mobile Ad hoc Networks MANETs [1][2] have been extensively used in large set of applications like disaster-recovery, military-operations and commercial applications. The major cause for its wide spread applications is its Infrastructure less nature. In MANETs, each node will play a role of a host and a router as well. In absence of base-stations, each node requires to forward the other nodes packets, resulting the formation of wireless network on ad hoc basis [1]. However, this nature invite serious security threats to the network, in presence of malicious nodes. The ad hoc network applications will apply specific rigid constraints on the routing security, data-traffic and topology of the network. For instance, the presence of malicious nodes and their collaboration will lead to disturb the process of routing, which results in mal functioning of all the defined operations of the network. In the recent past, elaborative research has been carried out on the security of the MANETs. This research work mainly focused on techniques for defending the malicious node attacks by detection and prevention approaches to face individual malicious nodes. In this scenario, these methods have no use in dealing collaborative attacks posed by multiple malevolent nodes working together. In these situations, more disaster may result to the network, resulting the failure in its functioning of the application. The infrastructure less feature along with the dynamic topology of MANET will makes it highly vulnerable to attacks on routing process such as black-hole and gray-hole. In Figure-1, black-hole attack scenario is illustrated. A malevolent node broadcasts a false packet, which have the shorter path to the destination-node, with the intention of misguide the source nodes. With this approach, a black-hole node, known as malicious (malevolent) node can get majority of the packets to route, by claiming “fake” shortest-path to its destination. All these received packets will be discarded, avoiding the forwarding the packets towards the destination. As a variation for this technique, to avoid the detection of malevolent node, it selectively discards the packets rather than discarding every packet. In this paper, we mainly concentrate on the process of identification and combating gray-hole and collaborative black-hole attacks using a basic-Dynamic Source Routing (DSR) routing protocol.