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Recent advances in wireless networking technologies have made it possible to construct a Mobile Ad hoc Network (MANET) which can be applied in infrastructureless situations. However, due to their inherent characteristics, they are much more vulnerable to malicious attacks than a conventinal wired network. In MANET, routing plays an important role in providing connectivity for mobile nodes who are not within the same radio range. Existing routing protocols in MANET assume a trusted and reliable environment. However, in hostile environment mobile nodes are susceptible to various types of routing attacks. This paper identifies a new routing attack, called Node Isolation attack, against Optimized Link State Routing (OLSR) protocol, one of the four standard routing protocols for MANETs. We analyze in detail and demonstrate the impact of this attack in order to show the necessity for a countermeasure to guard against the attack. As a first step to defend against the attack, we present a simple technique to detect the attack and identify the source of the attack.

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SUMMARYA mobile ad hoc network (MANET) is a collection of mobile nodes which are able to communicate with each other without relying on predefined infrastructures or central administration. Due to their flexibilities and easy deployment, MANET can be applied in situation where network infrastructures are not available. However, due to their unique characteristics such as open medium and the lack of central administration, they are much more vulnerable to malicious attacks than a conventional infrastructured wireless network. MANET employs routing to provide connectivity for mobile nodes that are not within direct wireless transmission range. Existing routing protocols in MANET assume a trusted and cooperative environment. However, in hostile environment, mobile nodes are susceptible to various kinds of routing attacks. In this paper, we show that an OLSR MANET node is prone to be isolated by malicious attack called Node Isolation attack. After analysing the attack in detail, we present a technique to mitigate the impact of the attack and improve the performance of the network when the attack is launched. The results of our implementations illustrate that the proposed solution can mitigate the attack efficiently.

Currently, Mobile Ad Hoc Network (MANET) has drawn great attention for being part of the ubiquitous network. Unlike the conventional network, MANETs have many unique features such as node resource constraint. That is why several efficient routing protocols have been proposed specifically for MANETs. Among these protocols, Optimized Link State Routing (OLSR) is one of the four important routing protocol identified by IETF. The current OLSR protocol assumes that all nodes are trusted. However, in hostile environment, the OLSR is known to be vulnerable to various kinds of malicious attacks. In this paper, we propose a new Security Aware Optimized Link State Routing (SA-OLSR) which is a secured version of current OLSR. Our approach is based on exchanging acknowledgement between 2-hop neighbors when the control traffic is successfullyreceived. The main advantage of our approach is that it can protect against many sophisticated attacks such as link spoofing, colluding misrelay attack, and wormhole attack without requiring any location information as well as the knowledge of complete network topology. Our simulation results show that the proposed solution can achieve higher packet delivery ratio compared to the network using the standard OLSR in the presence of malicious nodes.