Contents I. Introduction
Now these days the working principle of mobile ad-hoc network is similar according to the above reason. In a wireless ad-hoc network, the devices are interconnected with each other using a wireless physical medium without be dependent on pre-existing wired infrastructure. Because of this an ad-hoc network is also known as infrastructure less network or mobile ad-hoc networks (MANETs). MANETs can form individual groups of wireless terminals, and some of these may be connected to some fixed wire network. An important characteristic of ad-hoc networks is that they should be able to configure themselves on-the-fly without inter mediation of a centralized administration. Hence there is no central entity. The mobile stations in the ad-hoc network can not only act as end-system but also as an intermediate router system Even though mobile ad-hoc network are predictable to work in the lack of any fixed infrastructure network, mobile ad-hoc networks (MANETs) [8] are finding ever growing applications in both military and civilian systems due to their self-configuration and self-maintenance capabilities. MANETS are the self healing networks. Many of these applications are security sensitive, such as military battleground missions, home security scenarios, law enforcement, and rescue operations. So security aspects plays a vital role in the MANETs. As a result, security in MANETs has drawn intensive attention. Since their appearance in the 1970s, wireless networks have become increasingly popular in the computing industry. This is particularly true within the past decade, which has seen wireless networks being adapted to enable mobility. There are currently two variations of mobile wireless networks [18]. The first is known as the infra structured network (i.e., a network with fixed and wired gateways) and the second type of mobile wireless network is the infrastructure less mobile network. In infrastructure network, the bridges for these networks are known as base stations. In other words there is a central entity known as base station. A mobile unit within these networks connects to, and communicates with, the nearest base station that is within its communication radius. As the mobile travels out of range of one base station and into the range of another a “hand” off occurs from the old base station to the new, and the mobile is able to continue communication seamlessly throughout the network. Hence the hand off process reduces the signal drop effect in the network by connecting one terminal in case of weak signal strength due to long distance between entity and base station. Typical applications of this type of network include office wireless local area networks (WLANs). The second type of mobile wireless network is the infra structure less mobile network, commonly known as an ad-hoc network. Infra structure less networks has no fixed routers; all nodes are capable of movement and can be connected dynamically in an arbitrary manner. Nodes of these networks function as routers which discover and maintain routes to other nodes in the network. Example applications of ad-hoc networks are emergency search-and-rescue operations, meetings or conventions in which persons wish to quickly share information, and data acquisition operations in hospitable terrain. A mobile ad-hoc network can be quickly deployed to designated areas while consisting of available nodes of which two nodes can directly communicate with each other wirelessly, as long as they are within wireless radio communication range, without any fixed infrastructure (Mal-Sarkar et al., 2009)[20]. Moreover, available nodes must both act as routers for themselves and also rely on other nodes to relay communication data. As a result, the communication between two nodes is usually forwarded through a number of intermediate nodes, while the transmission range of a node is assumed to be limited. It follows a multihop transmission approach. Traditional wired networks are well-protected by several lines of defense, such as firewalls and centralized administration. However, wireless ad-hoc networks do lack these defenses because there are no particular firewalls are activated. So security attacks may come from any direction and could target all available nodes. Various attacks have been proposed, such as passive eavesdropping, active tampering, interfering, and spamming. Therefore, in order to ensure the security of two communication nodes, a protocol must enable a destination node to identify the source of a given message, and the source node must be able to authenticate the legal destination node. The work presented in this thesis have emphasize on the improvement of security in mobile ad-hoc network. AODV has no security mechanisms, so malicious nodes can perform many attacks just by not behaving according to the AODV rule.
