Mobile Ad hoc Network (MANET) is an autonomous collection of mobile nodes that form a temporary network without of any existing network infrastructure or central access point. The popularity of these networks created security challenges as an important issue. The traditional routing protocols perform well with dynamically changing topology but are not designed to defense against security challenges. In this paper we discuss about current challenges in an ad hoc environment which includes the different types of potential attacks that are possible in the Mobile Ad hoc Networks that can harm its working and operation. We have done literature study and gathered information relating to various types of attacks. In our study, we have found that there is no general algorithm that suits well against the most commonly known attacks. But the complete security solution requires the prevention, detection and reaction mechanisms applied in MANET. To develop suitable security solutions for such environments, we must first understand how MANETs can be attacked. This paper provides a comprehensive study of attacks against mobile ad hoc networks. We present a detailed classification of the attacks against MANETs.

Wireless networks, in particular Mobile Ad hoc Networks (MANETs) have revolutionized the field of networking with increasing number of their commercial and military applications. Security on the other hand, is now an essential requirement for these applications. However, the limitations of the dynamic, infrastructure-less nature of MANETs impose major difficulties in establishing a secure framework suitable for such services. Security for MANETs is a dynamic area of research. Most of the traditional routing protocols proposed for MANETs are focused on routing only not on the security aspects. As in traditional wired networks, wireless networks also require security. Unlike the wired networks, where dedicated routers, servers control the network, in MANETs nodes act both as terminals and also as routers for other nodes. A popular mechanism to satisfy the security requirements is the Group Key Management in which the group key is to be shared by each group communication participant. But to establish and manage the group key efficiently imposes new challenges – especially in infrastructure less MANETs. The basic needs of such networks require that the group key schemes must demonstrate not only high performance but also fault-tolerance.

A Mobile Ad hoc Network (MANET) is a collection of autonomous self-organized nodes. They use wireless medium for communication, thus two nodes can communicate directly if and only if they are within each other’s transmission radius in a multi-hop fashion. Many conventional routing algorithms have been proposed for MANETs. An emerging area that has recently captured much attention in network routing researches is Swarm Intelligence (SI). Besides conventional approaches, many new researches have proposed the adoption of Swarm Intelligence for MANET routing. Swarm Intelligence (SI) refers to complex behaviors that arise from very simple individual behaviors and interactions, which is often observed in nature, especially among social insects such as ants, bees, fishes etc. Although each individual has little intelligence and simply follows basic rules using local information obtained from the environment. Ants routing resembles basic mechanisms from distributed Swarm Intelligence (SI) in biological systems and turns out to become an interesting solution where routing is a problem. Ants based routing is gaining more popularity because of its adaptive and dynamic nature. A number of Swarm Intelligence (SI) based algorithms were proposed by researchers. In this paper, we study bio-inspired routing protocols for MANETs.

The traditional notion of a Adhoc wireless network is one in which there are a few Base Stations or Access Points and a number of Mobile Stations or Nodes. Security has become a primary concern in order to provide protected communication between mobile nodes in a hostile environment. The Adhoc networks pose a number of nontrivial challenges to security design, such as open peer-to-peer network architecture, shared wireless medium and network topology. These challenges clearly make a case for building multifence security solutions that achieve both road protection and desirable network performance. The general security objectives like authentication, confidentiality, integrity, availability and non-repudiation, the ad hoc routing protocols should also address location confidentiality, cooperation fairness and absence of traffic diversion. In this paper we attempt to analyze Challenges, Overview of Security, attacks, threats faced by the Adhoc network environment and provide a classification of the various security mechanisms.