AD HOC NETWORK

SEMINAR REPORT
ON

AD HOC NETWORK


BY

RUPESH S. CHORDIYA
T.E. Information Tech.

Roll No.-312

Academic Year
(2006-2007)

GUIDE
Prof. N.P.Pathak
Head,
Dept. of Information Tech.
VIIT, Pune.



CERTIFICATE


This is to certify that Mr. Rupesh S. Chordiya successfully
Completed his Seminar on Ad-Hoc Network .
In partial fulfillment of Third year of degree course in Information
Technology in the academic year 2006-2007

Date: / / 2007






Prof. N.P.Pathak. Prof. N.P.Pathak.
Head Seminar Guide
Dept. of Information Tech. Dept. of Info. Tech.
VIIT, Pune. VIIT, Pune.






Prof. Dr. A.S.Tavildar
Principal
VIIT,Pune.







BRACT’s
Vishwkarma Institute of Information Technology, Pune – 48
Department of Information Technology
Survey No. 2/3/4, Kondhwa (Bk.), Pune – 411048.




ACKNOWLEDGEMENT

It gives me immense pleasure to present my seminar on” Ad-Hoc Network ” .The able guidance of all teaching staff of department made this study possible .They have been a constant source of encouragement throughout the completion of this seminar.
I would like to express my grateful thanks to Prof. N.P.Pathak who has motivated me and guided properly for this seminar report .I would also like to express my sincere thanks to Info Dept. giving me opportunity to explore the subject by conducting this seminar.




Rupesh S. Chordiya
T.E.(Information Tech.)
VIIT, Pune










BRACT’s
Vishwkarma Institute of Information Technology, Pune – 48
Department of Computer Engineering & Information Technology
Survey No. 2/3/4, Kondhwa (Bk), Pune – 411048.
INDEX
List of Figures
Fig 5.1 Wireless Network Interface Card.
2. Fig 6.2 Setting SSID.
Fig 6.2 Setting Properites.
Fig 6.3 Setting IP Address.
List of Chapters

1) Introduction 1

2) Characteristics of Ad Hoc 2

3) Types of wireless network 3

4) Working of Ad Hoc network 4

5)Network interface card 8

6)Set up and installation procedure of NIC 9

7) Network of wireless sensors 13

8) Layers in Ad Hoc network 15

9) Ad-Hoc Network Communication 18

10)Protocols required for Ad Hoc Network 19

11) Applications of Ad Hoc 22

12) Security in Ad Hoc network 23

13) Bibliography 29


Chapter 1
Introduction
Ad hoc networks are key factor in the evolution of wireless communication. Self-organizing Ad hoc networks of PDAs (Personal Digital Assistants) or laptops are in disaster relief, conference, and battlefield environments.
An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any centralized administration or standard support services. In such an environments, it may be necessary for one mobile host to enlist the aid of other in forwarding a packet to its destinations, due to limited propagation range of each mobile host’s wireless transmission routing protocols for routing in ad hoc networks, treating each mobile as a router.

Difference between wired and wireless network:
An access point is a network that ties network services together. The most basic of wired access points is hub. Hubs connect network services computers, printers and devices together. Hub provides a common point of connection for these various devices to communicate.
Their pitfall is that each device must wait its turn to communicate. Otherwise there collision. This reduces throughput. Switches have largely replaced hubs. Both hubs and switches are based on the IEEE 802.11b protocol. This provides a maximum theoretical throughput of 11 mbps. However because of overhead, interference and encryption is usually far less. Speed of 6 to 8 Mbps is considered excellent.
The primary advantage of wired networks are that of speed and security. Wireless networks are considered less secure. As you data is being blasted onto airways, but wireless networks are easier to setup.


Chapter 2
Characteristics of Ad hoc
Ad hoc have several salient characteristics:
1) Dynamic topologies: Nodes are free to move arbitrary, thus the network topology which is typically multihop may change randomly and rapidly at unpredictable times, and may consist of both bi-directional and unidirectional links.

2) Bandwidth-constrained, variable capacity links: Wireless links will continue to have significantly lower capacity than their hardwired counterparts. In addition, the realized throughput of wireless communication after accounting for the effects of multiple access, fading, noise and interference condition, etc. is often less than a radio’s maximum transmission rate.One effect of the relatively low moderate link capacities is that congestion is typically the norm rather than the exception i.e. often much less than a radio’s maximum transmission rate.

3) Energy constrained operation: Some or all of the nodes in a MANET is a may rely on batteries or other exhaustible means for their enery. For these nodes, the most important system design criteria for optimizing may be energy conservation.

1) Limited physical security: Mobile wireless networks are generally more prone to physical security threads than are fixed cable nets. The increased possibility of eavesdropping, spoofing, and denial of service attacks should be carefully considered. Existing link security technique is applied within wireless networks to reduce security threads. As a benefit, the decentralized nature of network control in MANET’s provide additional robustness against the single point of failure of more centralized approaches.






Chapter 3
Types of wireless network:

1) Infrastructure network
2) Ad hoc network

Infrastructure network:

To connect one or more wireless PC’s to an existing network, a wireless access point is needed. Sometimes these devices combine a router and an SDSL modem, making them ideal for Internet connection sharing. Simply plug the access point into Ethernet hub and configure it with utility supplied by the vendor. Assign a wireless workgroup name (SSID) and this name when configuring wireless PC’s to run in infrastructure mode.

Ad hoc network:
Two or more PC’s with wireless network cards can be configured to form what is referred as Ad hoc wireless network. Simply set all the network card to connect to the same wireless workgroup name (SSID) and to use Ad hoc mode. In Windows XP this done using the properties for the wireless network card. Other operating system will require configuration utility that came with the card.












Chapter 4
Working of Ad hoc
Using a wireless network, stations within the network can communicate with other without physical wire between them. A station in the wireless network is also called a node and more than two nodes form a network. A particular type of wireless network that does not have a fixed infrastructure is called an Ad hoc network. If nodes in the wireless Ad hoc network are mobile then the network is called a mobile Ad hoc Networks (MANET). In MANET, a node can be a host or a router. When a node is acting as a router, directs information to other nodes. Routing males the nodes interact in arbitrary manner build dynamic topology free networks.

A natural method for trying to provide routing in ad hoc networks is to simply treat each mobile host as router and to run a conventional routing protocol between them.
In effect mobile host B in above fig acts as router between the “network” directly reachable by A and the “network” directly reachable by C.Hosts A transmits its packet for C to be witch then forwards them to C.Conventional routing are based on either

1)Distance vector or
2)Link state algorithm

1)Distance vector :
In distance vector routing, each route maintained a table giving the distance from itself to all possible destinations. Each router periodically this information to each of its neighbor routers and uses values received from its neighbors to compute updated values for its won table. By comparing the distance received for its neighbors, a router can determine which of its neighbor is the correct “next hop” on the shortest path toward each destination. When presented a packet for forwarding to some destination. When presented a packet for forwarding to some destination, each router simply forwards the packet to the correct next hop router. By transmitting routing table updates more frequently such as when information in the table changes, the algorithm converges more quickly to correct path(for example, when a link comes up or goes down),but the overhead in the CPU time and network bandwidth for transmitting routing updates increases. Example of distances vector routing protocols for the ARPANET,RIP(used in parts of the Internet, in Novell’s IPX, and in Xerox’s XNS) RTMP(used in Apple Talk).

2)Link state algorithm:
In link state routing, each router maintains a complete picture of the topology of the entire network. Each router monitors the cost of the link to each of its neighbor, and periodically broadcasts an update of this information to all other routers in the network. Given this information of the cost of each link in the network, each router computes the shortest path to possible destination.
When presented a packet for forwarding to some destination, each router forwards the packet to the next hop route based on its current best path to that destination. Link state routing protocols converge much more quickly as conditions in the network change, but generally require more CPU time (to compute the complete the shortest path to each possible destination) and more network bandwidth (to broadcast the routing update from router to all other routers in the entire network) than distance vector algorithms. Example of link state routing protocols includes the “new” routing that replaced the original protocol for then ARPANET, IS-IS (adopted by ISO as a standard routing protocol).
The problem of routing is divided into the two areas of route discovery and route maintainance. In order for one host to communicate with another, it must initially discover a suitable route to use in sending packet to that destination. As long as conditions remain unchanged, this route should then continue to work for as long it is needed. However as the status of different links or used in this route, change, changes in the route may be necessary or a new route may need to be discover.

Route Discovery:
At instant of time, an Ad hoc network can be described by a graph of the nodes (router +hosts). Two nodes are connecting (i. E. have arc between them two may a more powerful transmitter than the other, it is possible that A is connected to B but B is not connected to A. However for simplicity we will assume all connection is symmetric. It should also be noted that the more fact that two nodes are within radio range of each other does mean that they are connected. They may be buildings, hills, and other obstacles that block their communication.
To describe the algorithm, consider the Ad hoc network, in which a process at node A wants to send a packet to node I. The AODV algorithm maintains a table at each node, keyed by destination, giving information about that destination, including which neighbor to send packets to in order to reach the destination. Suppose that A looks in its table and does not find for I. It now has to discover a route I. This property f discovering routes only when they are needed to what makes this algorithm “on demand”.

To locate I, A constructs a special ROUTE REQUEST packet and broadcasts it. The packet reaches B and D. In fact, the reason B and D are connected to A in the graph is that they can receive communicate from A.F for example is not shown with an arc to A because it cannot receive A’s radio signal. Thus F is not connected to A.
The format of the ROUTE REQUEST packet shown. It contains the source and destination address, typically their IP address which identify who is looking whom. It also contains a Request ID, which is local counter maintained separately by each node
And incremented each time a ROUTE REQUEST is broadcast. Together the Source and Request Id fields uniquely identify the ROUTE REQUEST packet to allow nodes to discard any duplicate they may receive.

Source
Request
Destination
Source
Dest
Hop
Address
ID
Address
Sequence#
Sequence#
Count


Format of ROUTE REQUEST packet


In addition to the request ID counter, each node also maintains a second sequence counter incremented whenever a ROUTE REQUEST is sent (or reply to someone else ROUTE REQUEST). It function a little bit like a clock and is used to tell new route from old route. The further field of A’s sequence counter the fifth field is the most recent value odd. It’s sequence number that A has seen (0 of it has never seen it). The use if this field will become clear shortly. The final field hop count keeps track of how many hopes the packet has made. It is initialized to 0.
When a ROUTE REQUEST packet arrive at a node (B and D in this case),it is processing in the following steps.
1. The (Source address, Request ID) pair is looked up in a local history table to see if this request has already been seen and processed. If it is duplicate, It is discarded and processing stops. If it is not a duplicate, the pair is entered into the history table so future duplicates can be rejected and processed continues.
2. The receiver looks up the destination in its route table. If a fresh route to the destination is known, a ROUTE REQUEST packet is sent back to the source telling it how to get the destination (basically: Use me).Fresh mean that the destination sequence number stored in the routing table is greater than or the destination sequence number in the ROUTE REQUEST packet. If it is less, the stored route is older than previous route the source had for the destination, so step3,is executed.
3. Since the receiver does not know a fresh route to the destination, it increments the hop count field and rebroadcast the route packet. It also extracts the data from the packet and stores it a new entry in its reverse route so that the reply can get back to the source later. The fig used for building the reverse route. A timer also started for the newly made reverse route entry. If it expires the entry is deleted.








Chapter 5
Wireless Network Interface Card

Using a wireless network,station within the network can communicate with each other without a physical wire between them.A network interface card is used to connect a computer to an Ethernet network.The card provides an interface to the media. This may be either using an external Transceiver card PCb.The card usually also contains the protocol Contrail(MAC) data link protocol used by Ethernet.
Fig 5.1 Wireless Network Interface Card
Each network interface card is assigned an Ethernet source address by manufacturer of the network interface card(this is normally stored in a prom on the network interface card).The addresses are globally unique,and are assigned in block of 16(or 8)million to the two Ehternet network interface will ever have the same.









Chapter 6
Setup and installation procedure
Introduction:
Ad hoc is a wireless network consists of number of station without access points.Without using an access point or any connection to a network.A client unit in Ad hoc operation mode can communicat directly to other units just as using a cross over Ethernet cable connecting two hosts together via a NIC card for direct connection when configured an Ad hoc mode without an access point being present.Ad hoc operation is ideal for small networks of no more 2-4 computers.Larger networks would require the use or perhaps several access points.

Configuration for Wireless Station A
To configure Ad hoc mode on your wireless NIC card please follow the following step.
1) Double click on the utility icon in your window task bar the utility will pop up on your window screen
2) Select configuration tab.

















Fig 6.1 Setting SSID
3) Select Ad hoc from the operation mode pull down menu,fill you an SSID and select a channel you want to use than press OK to apply.

4) Since there is no DHCP server to give the host IP you must designate a static IP for your station.From Window start select Control Panel>Network connection>Wireless Network Connection.
5) From general tab select TCP/IP and click property.

Fig 6.2 Setting Properites
6) Fill your network IP address and subnet mask and click OK to finish.
Fig 6.3 Setting IP Address

Configuation for Wireless Station B

To configure Ad hoc mode on your wireless NIC card please follow the following step.

1) Double click on the utility icon in your Windows task bar the utility will pop up your windows screen.
2) Select configure tab.
3) Select Ad hoc from the operation mode pull down menu.fill you an SSID and select a channel you want to use than press OK to apply.
4) Since there is no DHCP server to give IP you must first design a static IP for your station.From Windows start select Control Panel>Network Connection>Wireless Network connection.
5) From general tab select TCP/IP and click property.
6) Fill your network IP address and subnet mask and click OK to finish.
7) Station A now is able to connect to station B.














Chapter 7
Network of Wireless Sensors:

The two main goals of a wireless sensor network are detect events of interest and estimate parameters that characterize these events. The resulting information needs to be transmitted to one or more locations outside the network. The movement of data through the different protocol layers in a cluster based wireless sensor network of sensors is relatively short. During the process of distribution detection/estimation and data fusion the radio transmission are among nodes within a cluster, under the control of a cluster are identical, it may be more desirable longer range radio are useful additions.

The processing occurring at different at different layers in the protocol stack for such a cluster –cluster system’s short range radio (“radio 1”)is used to communicate among the sensors in a cluster. The sensor layer is responsible for the collaboration signal processing, this processing can include beam forming as well as the distributed detection/estimation and data fusion. Let us now consider how the system operates. An emitter generates observation at one or more sensors. In the fig only node A receive a particular observation. The sensor layer process the observation and makes a tentative decision, thereby doing data reduction down to a few bits. This information is placed in a very short data packet is to sent to all other nodes in the cluster (Nodes B and Nodes c).

Assumed to be within one hop. Therefore, the packet can bypass the transport and network layers and go directly to the MAC layer for transmission at appropriate time. Upon reception of the packet, the other node updates their tentative decision. These decisions may then be rebroadcast to all nodes in the cluster. The number of parameters, such as decision and a confidence measure, now need to be transmitted from the cluster to a remote location using the larger mobile ad hoc network. So a summary packet is generated and sent down to the network layer as shown by the solid lines in the right side of nodeC. The network layer uses its routing protocol to select the nest hop in the MANET.The network packet is encapsulated by the MAC and transmitted. The actual transmission may use the same radio system as was used for the cluster based processing [1],albeit with increased uses different channel for the intracluster and intercluster communication. However it is also possible to use a completely different radio.


























Chapter 8
Layers in Ad hoc Networks:

Physical layer:
The physical layer may need to adapt to rapid SNR changes in wireless and mobility. Technique include
Power control
Multi-user detection
Direction antenna

Data Link layer:
A CSMA/CA (Carrier Sense Multiple Access Avoidance) protocol has been implemented. The basic idea behind this is, that using several different types of control packages, it is possible to detect and avoid collision of data package transfer. This technique works decentralized, which is great for ad hoc networking environments.

Network layer:
The function of the network layer is to
1) Provide (IP) address to end hosts and
2) Set up routes between source and destination proactively(routes discovery to make routes ready to use we need route maintenance.

Objectives of the network layer:
· Efficient (minimizing signaling overhead in route discovery and route maintenance)
· Stability (in computing routes, the routes eventually converge)
· Fast convergence rate
· Quos (find routes that support requested quos)
· Stability (whether the network is able to provide an acceptable level of service to packets even the presence of a large number of nodes in the network)
· Energy efficiency


TCP will probably be the first transport protocol that is used in ad hoc networks.
The following two cases need different approaches:
TCP over wired/wireless network with one wireless link on the path 802.11 WLAN and Personal Communication Services (PCS) cellular network.
TCP over ad hoc networks, where the entire link on the path are wireless.

TCP combines error control (ARQ) flow control (not over the received buffer)and congestion control(not clogging the network not overloading the capacity in the routers).TCP enjoys simplicity of control and gains widest acceptance. However this simplicity as control is at the cost efficiency loss. TCP is not able to distinguish the presence of quality of wireless links. Single bit error could trigger congestion control mode(TCP getting packet/bit errors.TCP needs to handle delay (RTT) and packet loss that very different from those wired networks.


Application Layer:

Application needs to be designed to handle
1) Frequently disconnection and with peer application
2) Time varying delay and packet loss statistics.

Factors that can change the topology of Ad hoc network:
· Mobility
· Change of power (also note that different criterion of error reception results in different topology)
· MAC layer (different scheduler for the contending nodes result in different topology)
· Mode of nodes (sleeping/active mode if a node goes to a sleeping mode its links Are gone from the topology)
























Chapter 9
Ad hoc network communication:
Communication between two hosts in the ad hoc networks is not always direct it can proceed in a multihop fashion so that every hosts is also a router. Ad hoc network hosts can use protocols such as the IEEE 802.11 media access control standard to communicate via the same frequency or they can directly proportional to the distance between hosts, direct single hop transmission to communicate via other hosts in the network.

An Ad hoc is a peer to peer network that allows direct communication between any two nodes, when adequate radio propagation conditions exists between these two nodes and subject to transmission power limitations of the nodes. If there is no direct link between the source and the destination nodes, multi hop routing is used. In multi hop routing, a packet is forwarded from one node to another, until it reaches the destination. Of course, appropriate routing protocols are necessary to discover routes between the source and the destination, or even to determine the presence or absence of a path to the destination node. Because of the lack of central elements, distributed protocols have to be used.

Active routing in Ad hoc
Ad hoc networks are wireless multihop network whose highly volatile topology makes the design and operation of a standard routing protocol hard.With an active networking approach one can define and deploy routing logic at runtime in order to adapt to special circumstances and requirements. Several active Ad hoc routing protocols then configure the forwarding behavior of mobile nodes, allowing data packets to be efficiently routed between any two nodes of both implemented. Isolated a simple forwarding layer in terms of both implementations and performance enables to stream delay sensitive audio data over the Ad hoc network. In the control plane, active packets permanently monitor the connectivity and setup and modify the routing state.


Chapter 10
Ad hoc routing protocols:

Ad hoc routing protocol can be divided into two main categories:
1) Table-Driven Routing:
In Table Driven routing each host attempts to maintain consistent and up-to-date routing information to every host in the network. This is same in principle as the routing protocols used in the wired networks except some modification have been made especially for Ad hoc networks.

Each algorithm is unique in how they maintain the routing tables and in how they propagate the routing information.

Destination-Sequenced Distance Vector Routing (DSDV):
It eliminates route looping, increases convergence speed and reduces control message overhead. In DSDV, each node maintains a nest-hop table, which it exchanges with its neighbors. There are two types of next hop table exchanges: periodic full-table broadcasts and the incremental updating. The relative frequency of the full table broadcast and the incremental updating is determined by the node mobility. In each data packet sent during a nest hop table broadcast or incremental updating,te source appends a sequence number. This sequence number is propagated by all nodes receiving the corresponding distance vector updates, and is stored in the next hop table entry of these nodes. A node after receiving number is larger than the recorded one or if the new sequence number is the same as the recorded one but the new route is shorter. In order to further reduce the control message overhead, a settling time is estimated for each route, A node updates to its neighbors with a new route only if the settling time is estimated for each route has expired and the route remains optimal.

Wireless Routing Protocol (WRP):
It reduces the amount of route looping and has mechanism to ensure the reliable exchange of update message. In WRP, each node maintains a distance-table matrix, which contains all destinations nodes and for each destination node all neighbors through which the destination node can be reached. For each neighbor destination pair if a route exists the route length is recorded. Also recorded is the predecessor the last node along a route before the destination node. Each node neighbor broadcasts acknowledgement is expected from all neighbor nodes. If some acknowledgement are expected from all neighbor nodes. If some acknowledgement are missing the broadcast will be repeated with a message retransmission list specifying the subnet of neighbours, update its own routing table only if the consistency of the new information is checked against the predecessor information from all its neighbors.


2) Source-Initiated On Demand Routing:
In Source-Initiated On-Demand Routing, routes are created only when necessary (when a source node wants to send packets to a destination node it does not know the route to).This process is call route discovery. Nodes that are not in the active paths neither forwards packets nor maintain any routing information, hence saving memory/power consumption.
Each algorithm is unique in how they perform route discovery, route maintenance and route deletion.

Ad Hoc Demand Distance Vector Routing (AODV):
AODV incorporates the destination sequence number technique of Destination Sequenced-Vector Routing into an On Demand protocol. Each node keeps a nest hop routing table containing the destination to which it currently hesa route. A route expires if it is not used or reactive for a threshold amount of time. If a source has no route to a destination, it broadcasts a route request (RREQ) packet using an expanding ring search procedure, starting from a small Time –To- Live value (maximum hop count) for RREQ, and increasing it if the destination is found. The RREQ contains the last seen sequence number of the destination as well as the source node’s current sequence number. Any node that receives the RREQ updates its next hop table entries with respect to node. A node that has a route to the destination with a higher sequence number than one specified in the RREQ unicasts a route reply ((RREP) packet back to source. Upon receiving the RREP packet, each intermediate node along the RREP routes updates its nest hop table entries with respect to the destination node dropping the redundant RREP packet up stream towards all nodes that have an active route using the broken link. The affected source can then reinitiate route discovery if the route is still needed.


























Chapter 11
Applications of Ad hoc Networks

Akin to packet radio networks, ad-hoc wireless networks have an important role to play in military applications. Soldiers equipped with multi-mode mobile communicators can now communicate in an ad-hoc manner, without the need for fixed wireless base stations. In addition, small vehicular devices equipped with audio sensors and cameras can be deployed at targeted regions to collect important location and environmental information which will be communicated back to a processing node via ad-hoc mobile communications. Ship-to-ship ad-hoc mobile communication is also desirable since it provides alternate communication paths without reliance on ground- or space-based communication infrastructures.

Commercial scenarios for ad-hoc wireless networks include:
§ Conferences/meetings/lectures,
§ Emergency services and
§ Law enforcement.

People today attend meetings and conferences with their laptops, palmtops and notebooks. It is therefore attractive to have instant network formation, in addition to file and information sharing without the presence of fixed base stations and systems administrators. A presenter can multicast slides and audio to intended recipients. Attendees can ask questions and interact on a commonly shared white board. Ad-hoc mobile communication is particularly useful in relaying information (status, situation awareness, etc.) via data, video and/or voice from one rescue team member to another over a small handheld or wearable wireless device. Again, this applies to law enforcement personnel as well.




Chapter 12
Security for Ad Hoc Network
The build up of ad hoc network can be envisaged where support of wireless access or wired backbone is not feasible. Ad hoc wireless network does not have any predefined infrastructure and all network services are configured and created on the fly. Thus it is obvious that with lack of infrastructural support and susceptible wireless link attacks, security in ad hoc network becomes inherent weakness. Achieving security within ad hoc networking is challenging due to following reasons
Dynamic Topologies and Membership
A network topology of ad hoc network is very dynamic as mobility of nodes or membership of nodes is very random and rapid. This emphasizes the need for secure solutions to be dynamic
Vulnerable wireless link
Passive/Active link attacks like eavesdropping, spoofing, denial of service, masquerading,
impersonation are possible
Roaming in dangerous environment Any malicious node or misbehaving node can create hostile attack or deprive all other nodes from providing any service

Nodes within traveling environment with access to common radio link can easily participate to set up ad hoc infrastructure. But the secure communication among nodes requires the secure communication link to communicate. Before establishing secure communication link the node should be capable enough to identify another node.
Every node wants to be sure that delivered identity and credentials to recipient nodes are not compromised. Therefore it is essential to provide security architecture to secure ad hoc networking.


Physical Security

Physical security of the network elements forms the basis for the security architecture in networking. Moreover, the principles of the networking approach highly affect the importance and implications of the physical security. For instance, in web-based intranets of today the firewalls, proxies and any other centralized elements between the secure and non-secure domains are single points of failure, thus the physical security of such elements must be ensured.

KEY ISSUES AND CHALLENGES

1 Link Level Security
In wireless environment the links are susceptible to attacks where eavesdropper can easily spoof the on going communication. As there is no protection like firewalls or access control in ad hoc network any node can become vulnerable to attacks coming from any direction or from any node. The results of such attacks include spoofing of the node’s identity, tampering with node’s credentials, leaking of confidential information or impersonating node. These types of attacks can easily compromise the basic security aspects like confidentiality, integrity, and availability and privacy of the node.

2 Secure Routing
The supported routing protocols within ad hoc network are more vulnerable to attacks as each device acts as a relay
[1] Any tampering with routing information can compromise whole network. An attacker can insert rogue information within routing information or introduce denial of service type attack by replaying old logged or stored information. Also compromised node can route malicious information to other nodes, which can cause serious damage. However proposed routing solutions are capable to operate with dynamic topology but in terms of security measure they provide partial or no solution
[2].Thus implementation of secure routing protocol is one of the challenges within ad hoc network.

3 Key Management
In general, security goals in ad hoc networks are achieved through cryptographic mechanisms such as public key encryption or digital signature. These mechanisms are supported through centralized key management where trusted Certificate Authority (CA) provides public key certificate to mobile nodes so nodes can develop mutual trust between one another. Any tampering with CA can easily compromise the security of the entire network. The proposed mechanisms used for identification such as shared secret, public key cryptography, third party authentication provide partial solution, as they are vulnerable or unable to scale. All proposed solutions require that the mobile users make proper usage of cryptographic keys. However goal of proper management and safekeeping of small number of cryptographic keys is difficult to achieve in ad hoc network due to random mobility of nodes where continuous connectivity is not maintained

4 Privacy
Spoofing of identity or any confidential information leads to privacy threats and later on that can be engineered to create DoS attacks. Thus privacy is one of the key


















Security in Ad Hoc Networking Proposals
1 DDM
Dynamic Destination Multicast protocol (DDM) is a multicast protocol that is relatively different from many other multicast-based ad hoc protocols. In DDM the group membership is not restricted in a distributed manner, as only the sender of the data is given the authority to control to which the information is really delivered. In this way the DDM nodes are aware of the membership of groups of nodes by inspecting the protocol headers. The DDM approach also prevents outsider nodes from joining the groups arbitrarily. This is not supported in many other protocols directly; if the group membership and the distribution of source data have to be restricted, external means such as the distribution of keys
have to be applied. DDM has two modes of operation: the stateless mode and he soft-state mode. In the stateless mode the maintenance of multicast associations and restriction of group membership are handled totally by encoding the forwarding information in a special header of the data packets; the nodes do not have to store state information. This kind of reactive approach thus guarantees that there are no vainless exchange of control data during idle periods. Thus in small ad hoc networks that need not scale up substantially, this kind of ultra-reactive approach can be extremely useful. The soft-state mode, on the other hand, requires that the nodes remember the next hops of every destination and thus need not fill up the protocol headers with every destination. In both modes the nodes must always be able to keep track of the membership of the groups. According to the authors, DDM is best suited for dynamic networks having small multicast groups. Currently the DDM draft does not, however, propose any solutions for securing the DDM networks as such. Moreover, it does not provide any suggestions for a concrete protocol that handles the necessary access control needed in the restriction of group membership.



2 OLSR
Optimized Link State Routing protocol (OLSR), as defined in is a proactive and tabledriven protocol that applies a multi-tiered approach with multi-point relays (MPR). MPRs allow the network to apply scoped flooding, instead of full node-to-node flooding, with which the amount of exchanged control data can substantially be minimized. This is achieved by propagating the link state information about only the chosen MPR nodes. Since the MPR approach is most suitable for large and dense ad hoc networks, in which the traffic is random and sporadic, also the OLSR protocol as such works best in these kind of environments. The MPRs are chosen so that only nodes with one-hop symmetric
(bi-directional) link to another node can provide the services. Thus in very dynamic networks where there exists constantly a substantial amount of uni-directional links this approach may not work properly. OLSR works in a totally distributed manner, e.g. the MPR approach does not require the use of centralized resources. The OLSR protocol specification does not include any actual suggestions for the preferred security architecture to be applied with the protocol. The protocol is, however, adaptable to protocols such as the Internet MANET Encapsulation Protocol (IMEP), as it has been designed to work
totally independently of other protocols.
3 ODMRP
On-Demand Multicast Routing Protocol (ODMRP) is a mesh-based multicast routing protocol for ad hoc networks, specified in [10]. It applies the scoped flooding approach, in which a subset of nodes - a forwarding group - may forward packets. The membership in the forwarding groups are built and maintained dynamically on-demand. The protocol does not apply source routing. ODMRP is best suited for MANETs where the topology of the network changes rapidly and resources are constrained. ODMRP assumes bi-directional links, which somewhat restricts the potential area of application for this proposal; ODMRP may not be suitable for use in dynamic networks in which nodes may move rapidly and unpredictably and have varying radio transmission power. Currently ODMRP does not define or apply any security means as such, "the work is in progress". The forwarding group membership is controlled with the protocol itself, though.




























Chapter 13

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