INTRODUCTIONSecure Ad-Hoc Routing Protocols 1 Secure Ad-Hoc Routing Protocols Mehul K Revankar Abstract—An Ad-Hoc network is a collection of mobile nodes dynamically forming a temporary network without the presence of existing network infrastructure. A lot of research has taken place in developing efficient routing protocols for the Ad-Hoc Network, but very little has been done to incorporate security feature into the protocol. In this paper I have done a detailed study of three protocols namely SEAD (Secure Efficient Distance Vector Routing Protocol for Ad-Hoc Network), ARAIDNE (A secure on demand Routing protocol for Ad-Hoc Networks) and ARAN (A Routing protocol for Ad-hoc Networks) and I have tried to examine the mechanisms that have been implemented to defend against well known attacks. I have also tried to evaluate the performance overhead within the respective protocols due to inclusion of the security feature. I. INTRODUCTION In a mobile wireless ad hoc network, computers (nodes) in the network cooperate to forward packets for each other, due to the limited wireless transmission range of each individual node. The network route from some sender node to a destination node may require a number of intermediate nodes to forward packets to create a “multihop” path from this sender to this destination. The role of the routing protocol in an ad hoc network is to allow nodes to learn such multihop paths. Since the nodes in the network may move at any time, or may even move continuously, and since sources of wireless interference and wireless transmission propagation conditions may change frequently, the routing protocol must also be able to react to these changes and to learn new routes to maintain connectivity. Ad hoc networks require no centralized administration or fixed network infrastructure such as base stations or access points, and can be quickly and inexpensively set up as needed. They can thus be used in scenarios where no infrastructure exists, or where the existing infrastructure does not meet application requirements for reasons such as security, cost, or quality. Examples of applications for ad hoc networks range from military operations and emergency disaster relief, to community networking and interaction between attendees at a meeting or students during a lecture. In these and other applications of ad hoc networking, security in the routing protocol is necessary in order to guard against attacks such as malicious routing misdirection, but relatively little previous work has been done in securing ad hoc network routing protocols. This paper is a part of term project for ECE 646 Cryptography and network security under Dr. Kris Gaj and the author is a Masters student in Computer Engineering. Secure ad hoc network routing protocols are not easy to design, due to the generally highly dynamic nature of an ad hoc network and due to the need to operate efficiently with resources, including network bandwidth and the CPU processing capacity, memory, and battery power (energy) of each individual node in the network. Existing insecure ad hoc network routing protocols are often highly optimized to spread new routing information quickly as conditions change, requiring more rapid and often more frequent routing protocol interaction between nodes than is typical in a traditional (e.g., wired and stationary) network. Expensive and cumbersome security mechanisms can delay or prevent such exchanges of routing information, leading to reduced routing effectiveness, and may consume excessive network or node resources, leading to many new opportunities for possible Denial-of-Service (DoS) attacks through the routing protocol. In this paper I have tried to examine the security mechanisms that have been implemented in SEAD [1], ARIADNE [2] and ARAN [3] to guard against well-known attacks in Ad-Hoc Routing Protocols. I have also tried to evaluate their security and performance with the existing protocols. 2. Routing Protocols Routing involves transfer of information over the network from a source router and destination router. In Ad-hoc networks mobile nodes acts as a router as well as a host. Mobile nodes use routing algorithms to find the best route to a destination. When we say "best route," we consider parameters like the number of hops (the trip a packet takes from one router or intermediate point to 1Secure Ad-Hoc Routing Protocols 2another in the network), time delay and communication cost of packet transmission. Routing protocols historically have been divided in to two kinds of protocols Distance Vector Protocol and Link State Routing Protocol. Distance Vector Protocol [8l: This type of routing protocol requires that each router simply inform its neighbors of its routing table. For each network path, the receiving routers pick the neighbor advertising the lowest cost, then add this entry into its routing table for re-advertisement Link State Routing Protocol [9]: This type of routing protocol requires each router to maintain at least a partial map of the network. When a network link changes state (up to down, or vice versa), a notification, called a link state advertisement (LSA) is flooded throughout the network. All the routers note the change, and recompute their routes accordingly. This method is more reliable, easier to debug and less bandwidth-intensive than Distance-Vector. It is also more complex and more compute- and memory-intensive. 2.1 Ad-Hoc Routing Protocols The drawback of the above mentioned protocols is that they require periodic updates of the network topology from all the nodes in the network. This kind of behavior is extremely expensive on a resource constrained mobile ad-hoc network node. This has given rise to a new breed of protocols called as on-demand protocols. In an on-demand protocol, nodes exchange routing information only when needed, with a node attempting to discover a route to some destination only when it has a packet to send to that destination. Given below is a list of on-demand routing protocols. DSR [6]: Dynamic Source Routing – is based on source routing and the sender knows the complete hop-by-hop route to the destination. When the mobile station in network has a packet to send to some destination and does not know the route, it initiates route discovery process to determine the route. It locally broadcasts a route request packet and the destination or any node with
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