Mobile Adhoc Networks Manet the essay

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Much work remains to enable a seamless

Integration, for example that can extend IP to support mobile network devices. (Chlamtac, Conti, and Liu, 2003)

4G is stated to begin with the assumption "that future networks will be entirely packet-switched, using protocols evolved from those in use in today's Internet." (Chlamtac, Conti, and Liu, 2003) It is reported that a 4G wireless network that is all IP-based "has intrinsic advantages over its predecessors." (Chlamtac, Conti, and Liu, 2003)

IP is stated to be both compatible with and independent of "the actual radio access technology" meaning that 'the core 4G network can be designed and evolves independently from access networks. Using IP-based core network also means the immediate tapping of the rich protocol suites and services already available, for example, voice and data convergence, can be supported by using readily available VoIP set of protocols such as MEGACOP, MGCP, SIP, H.323, SCTP. Finally the converged all-IP wireless core networks will be packet based and support packetized voice and multimedia on top of data. This evolution is expected to greatly simplify the network and to reduce costs for maintaining separate networks, for different traffic types." (Chlamtac, Conti, and Liu, 2003)

It is reported that 4G IP-based systems will be cheaper and more efficient than 3G. The basis for this is first that equipment costs are forecasted to be "four to ten times lower than equivalent circuit-switched equipment for 2G and 3G wireless infrastructures." (Chlamtac, Conti, and Liu, 2003) In addition, an open converged IP wireless environment brings about a reduction in costs for network build-out and maintenance and that will not be a requirement for purchasing extra spectrum since 2G/3G spectrum can be reused in 4G and the majority of the spectrum required by WLAN and WPAN is public and therefore does not make a requirement of a license.

It is reported that MANETS have been used mainly for "tactical network related applications to improve battlefield communications survivability" as the dynamic nature of military operations means that military cannot rely on access to fixed pre-placed communication infrastructure in battlefield." (Chlamtac, Conti, and Liu, 2003)

Mobile ad hoc networks are stated to create a "suitable framework to address the issues in radio signal limitations and specifically interference through provision of a multi-hop wireless network without pre-placed infrastructure and connectivity beyond LOS." (Chlamtac, Conti, and Liu, 2003)

Ad hoc wireless networks are stated to inherit the traditional problems of wireless communications and wireless networking:

(1) The wireless medium has neither absolute nor readily observable boundaries outside of which stations are known to be unable to receive network frames;

(2) The channel is unprotected from outside signals;

(3) The wireless medium is significantly less reliable than wired media;

(4) The channel has time-varying and asymmetric propagation properties; and (5) hidden-terminal and exposed-terminal phenomena may occur. (Chlamtac, Conti, and Liu, 2003)

C. MANET Applications

Chlamtac, Conti and Liu (2003) report the MANET applications listed in Figure 2.

Figure 2

MANET Applications

Source: Chlamtac, Conti, and Liu (2003)

D. MANET Security Issues

It is reported that an issue that presents great challenges is securing the wireless ad hoc networks and that toward this end understanding the possible types of attacks that may occur is the first step towards development of good solutions for security. Ad hoc networks are stated to "have to cope with the same kinds of vulnerabilities as their wired counterparts as well as with new vulnerabilities specific to the ad hoc context." (Chlamtac, Conti, and Liu, 2003)

Traditional vulnerabilities are further emphasized in the ad hoc environment. It is reported that passive attack involves the attacker listening to the network rather than sending information and this type of passive attack does not actually interrupt the operation of a protocol but instead attempts to mine information that would be valuable. However, the active attack is different in that information is inserted into the network.

Wireless mobile ad hoc networking in its very nature results in new security challenges in the design of MANET networks. These types of networks are reported to be "generally more vulnerable to information and physical security threats." (Chlamtac, Conti, and Liu, 2003) Vulnerability includes those to:

(1) Channels and modes; and (2) Absence of infrastructure and dynamically changing topology, all serve to make the network security of the MANET one that is difficult in nature. (Chlamtac, Conti, and Liu, 2003)

Factors affecting the security of MANETS include:

(1) Broadcast wireless channels allow message eavesdropping and injection;

(2) Nodes do not reside in physically protected places and easily fall under the attackers' control;

(3) The absence of infrastructure makes the classical security solutions based on certification authorities and online servers inapplicable and (4) The security of routing protocols in the MANET dynamic environment is an additional challenge. (Chlamtac, Conti, and Liu, 2003)

Active attacks are categorized as follows:

(1) IMPERSONATION. In this type of attack, nodes may be able to join the network undetectably, or send false routing information, masquerading as some other trusted node. The Black Hole attack falls in this category: here a malicious node uses the routing protocol to advertise itself as having the shortest path to the node whose packets it wants to intercept. A more subtle type of routing disruption is the creation of a tunnel (or Wormhole) in the network between two colluding malicious nodes;

(2) DENIAL OF SERVICE. The Routing Table Overflow and the Sleep Depravation attacks fall in this category. In the former, the attacker attempts to create routes to non-existent nodes to overwhelm the routing-protocol implementations. In the latter, the attacker attempts to consume batteries of other nodes by requesting routes, or by forwarding unnecessary packets; and (3) DISCLOSURE ATTACK. A location disclosure attack can reveal something about the physical location of nodes or the structure of the network. Two types of security mechanisms can generally be applied: preventive and detective. Preventive mechanisms are typically based on key-based cryptography. Keys distribution is therefore at the center of these mechanisms. Secret keys are distributed through a pre-established secure channel, and this makes symmetric cryptography generally difficult to apply in ad hoc networks. Public keys are distributed through certificates that bind a public key to a device. In the centralized approach, certificates are provided, stored, and distributed by the Certificate Authority. Since no central authority, no centralized trusted third party, and no central server are possible in MANET, the key management function needs to be distributed over nodes. (Chlamtac, Conti, and Liu, 2003)

It is stated that Bluetooth and 802.11 "...implement mechanisms based on cryptography to prevent unauthorized accesses, and to enhance the privacy on radio." Chlamtac, Conti, and Liu, 2003) Wired Equivalent Privacy (WEP) provides security in the IEEE 802.11 standard. WEP is stated to support "...both data encryption and integrity. The security is based on a 40-bit secret key. The secret key can either be a default key shared by all the devices of a WLAN, or a pairwise secret key shared only by two communicating devices. " (Chlamtac, Conti, and Liu, 2003)

WEP does not provide support for the exchange of pair-wise secret keys as it must be manually installed on each of the devices. Furthermore, WEP is stated to suffer "from design flaws and weaknesses, to correct the WEP problems a task group part of the IEEE 802.11i standardization is designing the new 802.11 security architecture." (Chlamtac, Conti, and Liu, 2003)

Cryptographic security mechanisms are used by Bluetooth which are reported to be implemented in the data layer link and it is stated that "a key management service provides each device with asset of symmetric cryptographic keys required for the initialization of a secret channel with another device, the execution of an authentication protocol, and the exchange of encrypted data on the secret channel." (Chlamtac, Conti, and Liu, 2003)

Security routing protocols are reported to be that which copes with "malicious nodes that can disrupt the correct functioning of a routing protocol by modifying routing information, by fabricating false routing information and by impersonating other nodes." (Chlamtac, Conti, and Liu, 2003)

It is reported that the 'Secure Routing Protocol' " conceived as an extension that can be applied to several existing reactive routing protocols. SRP is based on the assumption of the existence of a security association between the sender and the receiver based on a shared secret key negotiated at the connection setup. SRP combats attacks that disrupt the route discovery process. A node initiating route discovery is able to identify and discard false routing information. Similarly to SRP, Ariadne assumes that each pair of communicating nodes has two secret keys (one for each direction of the communication). Ariadne is a secure ad hoc routing protocol based on DSR and the TESLA authentication protocol." (Chlamtac, Conti, and Liu, 2003)

It is additionally reported…[continue]

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