Chris McDonald

Performance comparison of trust-based reactive routing protocols

Ad hoc networks, due to their improvised nature, are frequently established in insecure environments and hence become susceptible to attacks. These attacks are launched by participating malicious nodes against different network services. Routing protocols, which act as the binding force in these networks, are a common target of these nodes. A number of secure routing protocols have recently been proposed, which make use of cryptographic algorithms to secure the routes. However, in doing so, these protocols entail a number of prerequisites during both the network establishment and operation phases. In contrast, trust-based routing protocols locate trusted rather than secure routes in the network by observing the sincerity in participation by other nodes. These protocols thus permit rapid deployment along with a dynamically adaptive operation, which conforms with the current network situation. In this paper, we evaluate the performance of three trust-based reactive routing protocols in a network with varying number of malicious nodes. With the help of exhaustive simulations, we demonstrate that the performance of the three protocols varies significantly even under similar attack, traffic, and mobility conditions. However, each trust-based routing protocol has its own peculiar advantage making it suitable for application in a particular extemporized environment.

Trust Establishment In Pure Ad-hoc Networks

An ad-hoc network is a set of limited range wireless nodes that function in a cooperative manner so as to increase the overall range of the network. Each node in the network pledges to help its neighbours by passing packets to and fro, in return of a similar assurance from them. All is well if all participating nodes uphold such an altruistic behaviour. However, this is not always the case and often nodes are subjected to a variety of attacks by other nodes. These attacks range from naive passive eavesdropping to vicious battery draining attacks. Routing protocols, data, battery power and bandwidth are the common targets of these attacks. In order to overcome such attacks a number of routing protocols have been devised that use cryptographic algorithms to secure the routing mechanism, which in turn protects the other likely targets. A limiting requirement regarding these protocols is the reliance on an omnipresent, and often omniscient, trust authority. In our opinion, this reliance on a central entity is against the very nature of ad-hoc networks, which are supposed to be improvised and spontaneous. We present in this paper, a trust-based model for communication in ad-hoc networks that is based on individual experience rather than on a third party advocating trust levels. The model introduces the notion of belief and provides a dynamic measure of reliability and trustworthiness in pure ad-hoc networks.

Trust-based routing for ad-hoc wireless networks

An ad-hoc wireless network is formed by a number of mobile nodes having limited communication range. The dynamic source routing (DSR) protocol is frequently used to extend the effective range of these nodes through mutual cooperation. The accurate execution of the DSR protocol demands sustained benevolent behaviour by all participating nodes. However, as ad-hoc networks are created in improvised environments, the realization of such altruistic behaviour is virtually impossible to achieve. In fixed networks, trust infrastructures like certification authorities and key distribution centres are generally used to provide default trust relationships. However, the creation of such an entity in an ad-hoc network is considered neither feasible nor pragmatic. In this paper, we propose a novel mechanism for establishing trust based routing in ad-hoc networks without necessitating a trust infrastructure. We accentuate, that the proposed mechanism is most suitable for ad-hoc networks that can be created on the fly without making any suppositions or imposing pre-configuration requirements.

Propagating trust in ad-hoc networks for reliable routing

Ad-hoc networks emerge when a number of mobile wireless nodes agree to mutually cooperate with each other in order to establish communication over a wide region. All nodes in the network execute a pre-agreed routing protocol to pass packets for other nodes. The dynamic source routing (DSR) protocol is one of the unique routing protocols for ad-hoc wireless networks, where each transmitted data packet contains the complete route that it has to traverse. This is due to the fact that during route discovery, all intermediate nodes contribute faithfully to the route generation process. Such an altruistic behaviour is though difficult to realize in realistic environments and so a number of malicious nodes may also participate in the route discovery process only to sabotage the network. In this paper we present a unique mechanism for establishing trusted routes in a DSR based ad-hoc network. The proposed mechanism is specifically designed for improvised networks where the establishment of a fixed or mobile trust infrastructure is considered impractical.

A Critique of Mobility Models for Wireless Network Simulation

Simulation is universally considered the most effective method of designing and evaluating new network protocols. When developing protocols for mobile networking, the chosen mobility model is one of the key determinants in the success of an accurate simulation. The main role of a mobility model is to mimic the movement behaviors of actual users. Several mobility models, with widely differing characteristics, are employed in contemporary simulation-supported research. Some are simple but far from representative of real user movement patterns, while others provide more complex and realistic modeling. Given the critical role of the mobility model in supporting realistic and accurate protocol simulations, its correct design and selection is essential. In this paper we critique a number of recent mobility models.

Trusted Greedy Perimeter Stateless Routing

Ad-hoc networks generally comprise of mobile wireless nodes having limited communication and computation resources. These nodes execute special routing protocols, which help to establish multi-hop communication despite a dynamic topology. The greedy perimeter stateless routing (GPSR) protocol is one such routing protocol that is frequently used to establish routes in an ad-hoc or sensor network. However, for its precise execution, it is imperative that all nodes depict sustained benevolent behaviour. However, such an altruistic setting would never work in a wireless environment, which is intrinsically physically insecure. Consequently, participating malicious nodes may launch an array of attacks against the routing protocol leading to route severing, elongation or loop creation. In this paper, we present an improved variant of the GPSR protocol that uses the inherent characteristics of the routing process to assess the trust in the network nodes. These trust levels are then used to influence the routing decisions so as to circumvent malevolent nodes in the network. Extensive simulations indicate that the packet delivery ratio of the trusted GPSR protocol surpasses that of the standard GPSR by as much as 30% when as many as 50% of the nodes are acting maliciously in the network.

Secure Routing with the AODV Protocol

Ad-hoc networks, due to their improvised nature, are frequently established in insecure environments, which makes them susceptible to attacks. These attacks are launched by participating malicious nodes against different network services. Routing protocols, which act as the binding force in these networks, are a common target of these nodes. Ad-hoc on-demand distance vector (AODV) is one of the widely used routing protocols that is currently undergoing extensive research and development. AODV is based on distance vector routing, but the updates are shared not on a periodic basis but on an as per requirement basis. The control packets contain a hop-count and sequence number field that identifies the freshness of routing updates. As these fields are mutable, it creates a potential vulnerability that is frequently exploited by malicious nodes to advertise better routes. Similarly, transmission of routing updates in clear text also discloses vital information about the network topology, which is again a potential security hazard. In this paper we present a novel and pragmatic scheme for securing the ad-hoc on-demand distance vector routing protocol that protects against a number of attacks carried out against mobile ad-hoc wireless networks

Incorporating trust and reputation in the DSR protocol for dependable routing

An ad-hoc network is formed when two or more wireless nodes agree to forward packets on behalf of each other. As the wireless range of such nodes is severely limited, the nodes mutually cooperate with their neighbours in order to extend the overall communication range of the network. Dynamic Source Routing (DSR) is one of the commonly used protocols used in establishing ad-hoc networks. The network keeps on functioning smoothly when each node executes the routing protocol in the correct manner. However, along with benevolent nodes, there may always be some malicious and selfish nodes present in the network that try to disrupt, distort or disturb the network traffic. In this paper, we propose a novel and pragmatic scheme for establishing and sustaining trustworthy routes in the network. Each node maintains trust levels for its immediate neighbours based upon their current actions. Nodes also share these trust levels (reputations) to get ancillary information about other nodes in the network. In order to minimise control packet overhead, we have integrated the trust sharing mechanism with the DSR route discovery process in a unique manner that augments the protocols performance in the presence of malicious nodes.

Map: a scalable monitoring system for dependable 802.11 wireless networks

Many enterprises deploy 802.11 wireless networks for mission-critical operations; these networks must be protected for dependable access. This article introduces the MAP project, which includes a scalable 802.11 measurement system that can provide continuous monitoring of wireless traffic to quickly identify threats and attacks. We discuss the MAP system architecture, design decisions, and evaluation results from a real testbed.

Secure Routing Protocols for Mobile Ad-Hoc Wireless Networks

An ad-hoc network comprises of limited range wireless nodes that function in a cooperative manner so as to increase the overall range of the network. Each node in the network pledges to help its neighbours by passing packets to and fro in return of a similar assurance from them. All is well if the participating nodes uphold such an altruistic behaviour. However, this is not always the case and often nodes are subjected to a variety of attacks by other nodes. These attacks range from naive eavesdropping to vicious battery draining attacks. Routing protocols, data, bandwidth and battery power are the common targets of these attacks. In order to overcome such attacks a number of routing protocols have been devised that use cryptographic algorithms to secure the routing mechanism, which in turn protects the other likely targets. This chapter gives an overview of seven such secure routing protocols by presenting their characteristics and functionality, and then provides a comparison and discussion of their respective merits and drawbacks.