# A Novel Anomaly Behavior Detection Scheme for Mobile Ad Hoc Networks
## 1 Introduction  
Mobile Ad Hoc Networks (MANETs) are prospective communication systems for all devices. Unlike wired infrastructure networks, MANETs functionalities are independent of sophisticated architecture, i.e., they are infrastructure-less and decentralized. In addition to the infrastructure-less and decentralized characteristics of MANETs, the dynamic nature of nodes poses diverse research issues associated with security, quality of service (QoS), anomaly/outlier/abnormal behavior detection, and clustering, etc. QoS is the most challenging job for developers due to continuous variation in the topology of MANETs. To attain a certain QoS, and sustain it, is difficult when the settings of the network frequently change. Moreover, because of multi hop routing in MANETs, each node is a router that enables information sharing by forwarding packets to other nodes. Hence, the default route is unavailable, and the solution to routing issues is complicated as there is seamless connectivity to other devices in its zone. Maintaining security in the wireless link is difficult as it is more vulnerable when compared to a wired link. Since the first encryption was carried out, issues such as eavesdropping, encryption cracking, etc. have increased along with the user's input of spurious information, extended timeouts, and updates for the old routing table. There areseveral unresolved issues concerning security that require significant solutions for secure communication in ad hoc networks. In traditional wired networks, the nodes are static; however, MANETs are capable of connecting any devices at a particular time in the network to communicate with one another. Researchers tend to focus on novel communication methods, i.e., wireless technology for data transmission, in which nodes are unrestricted in movement in the network; this is a restraint in wired networks. MANETs are widely employed in many applications due to the ease with which nodes can travel without restrictions and set up at a fast rate in such a network. Hence, MANETs have been used to establish a large set of applications. The nodes in the network communicate with one another by forwarding packets, consuming battery energy due to multi hopping in routes, and for transmission/reception of nodes in the network. The energy used by nodes i.e., battery power--means limited bandwidth and limited range of transmission; these are the most important concerns related to MANETs. To construct and manage MANETs that are secure, efficient, and lightweight, mechanisms that involve reduced hardware resources are required; however, there is a lack of resources. Additional challenges include limited bandwidth, small subnets, traffic overhead, and high processing costs. The security primitives of confidentiality, authentication, authorization availability, and integrity need to work together for resource-constrained mobile devices. In the present study, resource-constrained key management networks are observed for the detection of outliers, and in addition, a lightweight key management network is built to ensure the stated security primitives through outlier detection. Also, we extend [PERSON] and [PERSON]'s model [1] by incorporating outlier detection methods to build a secure key management network. [PERSON] and [PERSON] [1] proposed a method for key management in hierarchical MANETs that lacks energy efficiency due to the escalation of key messages because of dynamic topology and distant nodes that are considered to be constituents of a cluster in the hierarchy. Moreover, they have not considered the traits of network and routing security in their entirety. Another methodology, proposed by [PERSON] et al. [2], is centered on a social event using the Bayesian location interference framework to enable the detection of nodes in the event; they also propose a scheme of event detection in their imminent activities. Nevertheless, this approach does not include performance parameters when sensing futuristic activities.