The it does not tamper with the normal

The chances of getting attacks in the MANET’s will be increased due to lack of infrastructure and wireless medium in the networks which are established in ad-hoc basis. This chapter will discuss some popular attacks frequently encountered. Attacks in MANETs can be classi?ed on the basis of their effects on the network, behavior of attacking node, the origin or, the method of performing attack using vulnerabilities and exposures in the network. On the basis of effect on the network, attacks can be classi?ed as active or passive. The passive attacker will get the information to be exchange between two parties without modifying it. This leads to attack on the con?dentiality of the data. Detection of passive attacks is dif?cult as it does not tamper with the normal functions of the network. In active attacks the attacker is more active to disturb the general functionality of the network. An attacker may jam the network completely or partially by making some part or some subnetwork unreachable from the other network. It may modify, spoof or replay packets. An attacker may be classi?ed as internal or external depending upon whether the attacker is a compromised node within the network or outside of the network. Internal attacks are dif?cult to detect as the compromised nodes are the authorized nodes of the network and hence possess the secret keys required to authenticate the messages. On the other side, internal attacks are dif?cult to launch. As external attacks are easier to launch they occur more frequently and hence they need attention.

Attacks can be classi?ed in various ways on the basis of methods used by an attacker to perform the attack. Modi?cation is a method in which an unauthorized party tampers an asset. For example a node which was attacked can redirect the network traf?c and conduct denial-of-service (DoS) attack by modifying message ?elds or by forwarding routing message with false values. Spoo?ng or masquerading as some good node is another weapon used by malicious nodes to launch different types of attacks. In MANETs, the attacks will be launched by producing false routing messages.

An attack in a network may be at application layer, medium access layer (MAC), transport layer, network layer or physical layer. The well-known physical layer attacks in MANETs are eavesdropping, interference and jamming. The wireless radio signal can be interrupted in many ways. More over an attacker will connect to the wireless medium and over hear the transmission. MAC misbehaving is one of the common attacks at the MAC layer. In this attack, an attacked node does not consider the rules and procedure specified by the MAC protocol. The MAC layer in ad-hoc networks is typically based on CSMA/CA (carrier sense multiple access / collision avoidance) protocol. In this protocol a node senses the channel, waits for some time using back off exponential algorithm if the channel is busy and transmits only if the communication channel is free. A affected node may start transmitting without waiting causing other nodes to continually back-off. In MANETs, the individual node can act as a router to establish and maintain the routes to other nodes with in the network. Establishing an optimal and ef?cient route between the communicating parties is the primary concern of routing protocols in MANETs. An attack on routing may decrease the overall performance of the network and hence paralyze the entire network. Network layer vulnerabilities fall into two categories: routing attacks and packet forwarding attacks. The family of routing attacks refers to any action of advertising routing updates that do not follow the speci?cations of the routing protocols. The speci?c attack behaviors are related to the routing protocol used by the MANET. These attacks are discussed in detail in future sections. Packet forwarding attack is related to disrupting and forwarding of data packets. The transport layer protocols provide end-to-end connection, reliable packet delivery, ?ow control and congestion control. Like TCP (transmission control protocol) in the Internet model nodes in a MANET are also vulnerable to the SYN ?ooding and session hijacking attacks.The chances of getting attacks in the MANET’s will be increased due to lack of infrastructure and wireless medium in the networks which are established in ad-hoc basis. This chapter will discuss some popular attacks frequently encountered. Attacks in MANETs can be classi?ed on the basis of their effects on the network, behavior of attacking node, the origin or, the method of performing attack using vulnerabilities and exposures in the network. On the basis of effect on the network, attacks can be classi?ed as active or passive. The passive attacker will get the information to be exchange between two parties without modifying it. This leads to attack on the con?dentiality of the data. Detection of passive attacks is dif?cult as it does not tamper with the normal functions of the network. In active attacks the attacker is more active to disturb the general functionality of the network. An attacker may jam the network completely or partially by making some part or some subnetwork unreachable from the other network. It may modify, spoof or replay packets. An attacker may be classi?ed as internal or external depending upon whether the attacker is a compromised node within the network or outside of the network. Internal attacks are dif?cult to detect as the compromised nodes are the authorized nodes of the network and hence possess the secret keys required to authenticate the messages. On the other side, internal attacks are dif?cult to launch. As external attacks are easier to launch they occur more frequently and hence they need attention.

Attacks can be classi?ed in various ways on the basis of methods used by an attacker to perform the attack. Modi?cation is a method in which an unauthorized party tampers an asset. For example a node which was attacked can redirect the network traf?c and conduct denial-of-service (DoS) attack by modifying message ?elds or by forwarding routing message with false values. Spoo?ng or masquerading as some good node is another weapon used by malicious nodes to launch different types of attacks. In MANETs, the attacks will be launched by producing false routing messages.

An attack in a network may be at application layer, medium access layer (MAC), transport layer, network layer or physical layer. The well-known physical layer attacks in MANETs are eavesdropping, interference and jamming. The wireless radio signal can be interrupted in many ways. More over an attacker will connect to the wireless medium and over hear the transmission. MAC misbehaving is one of the common attacks at the MAC layer. In this attack, an attacked node does not consider the rules and procedure specified by the MAC protocol. The MAC layer in ad-hoc networks is typically based on CSMA/CA (carrier sense multiple access / collision avoidance) protocol. In this protocol a node senses the channel, waits for some time using back off exponential algorithm if the channel is busy and transmits only if the communication channel is free. A affected node may start transmitting without waiting causing other nodes to continually back-off. In MANETs, the individual node can act as a router to establish and maintain the routes to other nodes with in the network. Establishing an optimal and ef?cient route between the communicating parties is the primary concern of routing protocols in MANETs. An attack on routing may decrease the overall performance of the network and hence paralyze the entire network. Network layer vulnerabilities fall into two categories: routing attacks and packet forwarding attacks. The family of routing attacks refers to any action of advertising routing updates that do not follow the speci?cations of the routing protocols. The speci?c attack behaviors are related to the routing protocol used by the MANET. These attacks are discussed in detail in future sections. Packet forwarding attack is related to disrupting and forwarding of data packets. The transport layer protocols provide end-to-end connection, reliable packet delivery, ?ow control and congestion control. Like TCP (transmission control protocol) in the Internet model nodes in a MANET are also vulnerable to the SYN ?ooding and session hijacking attacks.