2 3 1371395239 3. Impact of Wormhole Full

International Journal of Computer Networking,

Wireless and Mobile Communications (IJCNWMC)

ISSN 2250-1568

Vol. 3, Issue 3, Aug 2013, 21-32

© TJPRC Pvt. Ltd.

IMPACT OF WORMHOLE ATTACK ON PERFORMANCE OF LEACH IN WIRELESS

SENSOR NETWORKS

PRIYA MAIDAMWAR & NEKITA CHAVHAN

Wireless Communication and Computing, Department of Computer Science & Engineering G H. Raisoni College of

Engineering, Nagpur, India

ABSTRACT

Routing is a major issue in development of Wireless sensor network. Due to resource constrained nature of WSN,

it becomes a research hotspot to design reasonable routing protocol to extend life of sensor nodes. A typical hierarchical

routing protocol LEACH uses self organizing and dynamic cluster formation which makes it attractive to various routing

attacks, such as denial of service, black hole, wormhole and Sybil attacks. Wormhole attack is a denial of service attack

launched by malicious nodes by creating a tunnel through which the packets are replayed to malicious nodes disrupting the

communication channel and corrupting the network routing. Dynamic nature of WSN results in very high or low number of

cluster heads which degrades performance of network. This paper describes simulation of LEACH protocol and thus

optimization of network through controlling number of CHs that minimizes energy dissipation & extend lifetime of

network. Also in order to check the reliable operation of LEACH, we implement wormhole attack and evaluated the impact

on LEACH protocol in terms of metrics like throughput, average end-to-end delay, packet delivery ratio and packet drop

ratio. The evaluation of LEACH with wormhole attack has been done with the help of NS2 simulator.

KEYWORDS: Cluster Head, LEACH Protocol, NS2, Wireless Sensor Network, Wormhole Attack

INTRODUCTION

Sensor networks refers to a heterogeneous system consisting of multiple detection stations called sensor nodes

with a communications infrastructure intended to monitor and record conditions at diverse locations. Also sensor networks

are responsible for sensing and transmission of data. Since large amount of data is to be processed with limited number of

sensor nodes, data transmission is critical and challenging task. Hence routing protocols for such kind of networks should

be designed by considering these limitations in mind. In the conventional wireless networks, the node energy is finite and

cannot be charged, hence ability to use energy effectively is a major factor to be considered while designing routing

protocol.

Due to large quantity of sensor nodes, recharging the batteries in WSNs is infeasible task. Hence, network lifetime

is a primary concern in sensor network design. In order to prolong the network lifetime, several routing protocols exists.

These routing protocols are classified into two types depending on network topology: Flat routing protocols and

Hierarchical routing protocols. Since flat routing protocols require maintaining routing table data and cannot aggregate the

information, they are not applicable for large scale sensor networks. Hierarchical routing protocol can solve this issue to

some extent.

Low-energy adaptive clustering hierarchy (LEACH) is one of the routing protocols in WSN. In LEACH topology

is organized into clusters. Few nodes are selected as cluster heads (CHs) and other nodes use these CHs as routers to the

base station (BS). CH performs all the data processing such as data fusion and aggregation. CHs are elected dynamically in

22 Priya Maidamwar & Nekita Chavhan

order to balance the energy dissipation of nodes. LEACH-C assumes centralized CH election, where each sensor node

sends information about its location to the BS at the beginning of each round, to decide which nodes are to become CHs.

The CHs are chosen based on their locations and their remaining energy such that clusters with more energy are elected as

CHs [1].

Wormhole tunnel is created by any two malicious nodes (generally at distant location) which collude together to

create an illusion that they are just one hop away and thereby routing the packets to them as neighbor nodes. As soon as

wormhole entities create the tunnel successfully, they can drop the packets, replay, tampers the packets or selectively

forward them. In our study, we analyze performance of LEACH (Low Energy Adaptive Clustering Hierarchy) protocol.

Also paper aims at studying the wormhole attack behavior and its performance impact on LEACH routing protocol using

NS2 Network simulator. The organization of paper is as follows: Section 2 introduces the LEACH routing protocol,

Section 3 describes how wormhole attack is launched in LEACH routing protocol, Section 4 deals with simulation of

wormhole attack in LEACH, its result analysis and section 5 explains the conclusion.

DESCRIPTION OF LEACH PROTOCOL

Heinzelman introduced a hierarchical clustering algorithm for sensor networks, called Low Energy Adaptive

Clustering Hierarchy (LEACH). LEACH arranges the nodes in the network into small clusters and chooses one of them as

the cluster-head. Remaining nodes are cluster members of this protocol.

The Network Model of Leach

The network model that LEACH protocol uses is described as follows:

All the nodes in the network have the same initial energy and have ability to communicate with the base station.

The position of the base station is far away from the wireless sensor network area.

The nodes within the network are changing their position and hence movable.

All sensor nodes are able to control their transmit power to change the communication range [2].

The network topology of LEACH protocol is shown in Figure1.

Figure 1: The Network Model [3]

Description of Leach Algorithm

LEACH protocol presents a dynamic CHs selection in recursive manner. This process distributes equal amount of

energy to each sensor node, so as to achieve the balance in energy consumption and extend the network lifetime. The

operation of LEACH is divided into rounds; each round consists of two phases: the set-up phase and the steady state

phase.

Impact of Wormhole Attack on Performance of Leach in Wireless Sensor Networks 23

In the set-up phase, the clusters are organized and cluster-heads are elected. In the steady state phase, the

transmission and reception of data to the BS takes place in reality. The length of time taken by steady state phase is longer

than the time taken by the set-up phase in order to reduce overhead. During the set-up phase, a fraction of predetermined

nodes, p elects themselves as cluster-heads as described follows. A sensor node selects a random number r, between 0 and

1. According to this, if random number is less than a threshold value T(n) the node becomes a cluster-head for the current

round. The threshold value is measured based on an equation that incorporates the desired percentage to become a cluster-

head denoted as p, the current round denoted as r, and the set of nodes denoted as G that have not been selected as a

cluster-head in the last (1/p) rounds. It is calculated as follows:

T (n) = if n € G

All elected cluster-heads broadcast an advertisement message to the rest of the nodes in the network that they are

the new cluster-heads. Other non-cluster-head nodes, upon receiving this advertisement, decide on the cluster to which they

want to join depending on the signal strength of the advertisement. The non-cluster-head nodes inform the appropriate

cluster-heads that they will be a member of the cluster. After receiving the messages from the nodes, those are desired to

join the particular cluster, the cluster-head creates a TDMA schedule based on the number of nodes in the cluster and

assigns each node a time slot when it can transmit [5].

This schedule is broadcast to all the nodes in the cluster. During the steady-state phase, cluster-head, upon

receiving entire data, aggregates it and sends it to the base station. Therefore actual data transmission begins in this phase.

After an interval of time, the network goes back into the set-up phase again and enters another round of selecting new

cluster-heads. In order to reduce interference from nodes each cluster-head communicates using different CDMA codes

with the cluster-heads belonging to other clusters [3].

Work Process of Leach

The following figure elaborates the functioning of LEACH protocol. The functioning of LEACH protocol begins

with collection of network parameters (routing protocol, number of packets, packet size, link layer type, MAC type, queue

length, packet type) as an input.

Figure 2: Work Flow


WORMHOLE ATTACK IN LEACH ROUTING PROTOCOL

Wormhole attack is a network layer attack launched by malicious nodes by creating a high speed tunnel through

which packets are replayed to malicious nodes disrupting the communication channel and corrupting the routing process.

Wormhole attack is launched in LEACH routing protocol. The malicious nodes create a high speed tunnel,

thereby causing RREQ to reach the destination at a faster rate compared to usual path. According to LEACH protocol,

destination discards all the later RREP packets received, even though they are from authenticated node. The destination

then chooses the false wormhole tunnel infected path to send the RREP causing the inclusion of wormhole tunnel in the

data flow route [4].

The tunnel can be created in one of the four ways: packet encapsulation, creation of out of band link using

specialized hardware channel, packet relay approach and usage of high power transmission.

SIMULATION STUDY

The latest version 2.34 of NS-2 has been used for the simulation of the developed system. NS-2 is a discrete event

simulator targeted at networking research.

Here, wormhole attack is simulated in NS2 by using encapsulation of packet approach in LEACH routing

protocol. At one end of the wormhole tunnel, the packets are encapsulated and at the other ending end of tunnel, packets

are decapsulated. Here, wormhole peers are far apart but this tunnel creates an illusion that wormhole peers are one hop

count apart as shown in figure 1. The latency of the wormhole tunnel is very high. Once wormhole tunnel is created,

wormhole peer nodes would drop the packets.

Figure 3: Wormhole Tunnel Creation by Packet Encapsulation [4]

A new wormhole LEACH agent is created and attached to the wormhole peer nodes via the front end Otcl of the

NS2. The actual tunneling (encapsulation and decapsulation) of the packet is done in the LEACH protocol implementation

(Leach.tcl). The encap_packet() and the decap_packet() methods of Encapsulator.h are overridden in worm.h & worm.cc.

They are invoked in recvPacket(), NrecvRequest(), recvReply() methods of leach_worm.tcl for creation of wormhole

tunnel [5].

Simulation Environment of Leach Protocol

The parameters shown in Table 1 are configured in NS2. The monitoring area of 100 * 100 rectangular area is set

for simulation, The total number of nodes is 100, The first node's position is at the origin of coordinate (0, 0), whose two

edges are the two coordinate axes. The monitoring area is located in the first quadrant, and base station is outside of the

area for (50,175) .The simulation parameters are shown in Table 1.


Table 1: Simulation Parameters

Parameters Values

Distribution area of nodes 100 * 100

Network monitor area 1000m×1000m

Number of Sensor Nodes ( Including Base Station Nodes) 101

Optimal Number of Cluster Heads 5

Iteration number of the simulated annealing algorithm 1000

Initial Energy of Node 100 J

Wireless communication line bandwidth 1 Mbps

Time of each round 20s

Number of wormhole tunnels 1/2/3/4/5 (upto 10 wormhole peers maximum)

Size of packet header 25 Bytes

Data size of packet 500 Bytes

Simulation time 900s

Eelec 50 nJ/bit

εfriss_amp 10 pJ/bit/m2

εtwo_ray_amp 0.0013 pJ/bit/m4

Efusion 5 nJ/bit

distance threshold d0 70 m

SIMULATION RESULTS

Figure shows dynamic clustering process in which a) represent schematic diagram of nodes distribution and

cluster formation; b) and c) represents schematic diagram of energy consumption after 1st

and 2nd

round

Figure 3 (a): Distribution of Nodes and Cluster Formation

Figure 3 (b): Energy Consumption after First Round


Figure 3 (c): Energy Consumption after Second Round

The results of the simulation are shown in Table 2, which shows Network lifetime, Throughput and Energy

Consumption of the different no. of clusters or cluster heads in the sensor network. Here with 5% of cluster heads higher

throughput is obtained as compared to others. Figure 4, 5 and 6 shows the simulation graphs for percentage of cluster heads

verses energy dissipation, lifetime and throughput of the network respectively. Our goals in conducting the simulation are

as follows: Compare the performance of the clusters Vs lifetime, No. of clusters Vs Energy dissipation, No. of clusters Vs

Throughput.

Table 2: LEACH Simulation Results

No. of Clusters /

% Cluster Head

Lifetime

(s)

Throughput

(kbps)

Energy Consumption

(Joules)

2 360 30065 415.2

3 295.6 32012 412.36

4 512.20 40510 325.30

5 562.40 48228 280.23

6 500.20 36710 356

7 440.21 35020 364

8 265.40 42015 525.23

Figure 4: No. of Clusters Vs Energy Dissipation of the Network


Figure 5: No. of Clusters Vs Lifetime of the Network

Figure 6: No. of Clusters Vs Throughput of the Network

Initially the simulation was done without wormhole attack. Later two nodes were made compromised. In our

scenario, nodes named 5 and 6 were made to behave as wormhole attack malicious nodes. The compromised nodes take

part in the communication at the initial stage, after some time it starts to drop packets.

Figure 7. Shows the nodes are communicating among themselves. In Figure 8. As the energy level of node

decreases, the green nodes turn yellow. Finally after complete energy dissipation nodes turn red.

Figure 7: Scenario of 100 Sensor Nodes


Figure 8: Packet Flow between Sensor Nodes

Network Throughput

Network throughput is measured as the total number of packets received at the destination over a period of time

and is expressed in kbps [6]. Scenario of 100 node is considered with a wormhole link (two wormhole peers) simulated and

number of network connections is increased from 0 to 5.

The throughput comparison for this scenario is depicted in figure 2. The LEACH throughput decreases when the

wormhole link is present compared to normal LEACH throughput.

Figure 9: LEACH Throughput with and without Wormhole

Average End-to-End Delay

It is the total time taken for the packet to reach from source to destination and measured in seconds [7]. In Fig.,

the time taken for packets to reach destination is high when a wormhole link is present as the link latency is more for

wormhole link. Maximum delay difference observed between normal LEACH and wormhole infected LEACH is around

4.296 secs.


Figure 10: LEACH Delay with and without Wormhole

Packet Delivery Ratio

PDR is the ratio of number of packets received at destination node to that of number of packets sent by source

node. Here it is expressed in percentage [9].

In Fig, it is observed that the PDR has maximum reduction by 32% when a wormhole link is present compared to

normal LEACH’s PDR value. This behavior is due to the reduction in number of packets reaching destination because of

dropping of packets by wormhole peers.

Figure 11: Leach Packet Delivery Ratio with and Without Wormhole

Packet Drop Ratio

Drop rate is the ratio of number of packets dropped during transmission to that of number of packets sent by the

source node. Here it is expressed in percentage. Number of packets dropped is the difference between number of packets

send by source node and number of packets received at destination node [8]. In figure, the drop rate is higher for wormhole

infected LEACH. Packet drop ratio increases by 40%.


Figure 12: LEACH Packet Drop Ratio with and without Wormhole

CONCLUSIONS

This paper focuses primarily on routing protocol in present research of WSN. It summarizes the behavior of

LEACH protocol for wireless sensor network. Because WSNs are useful in real time applications, research in routing

protocol is quite difficult. Simulation Analysis on dynamic clustering process of LEACH protocol is done using NS2

Network Simulator. From the above results we concluded that if the clusters in the network are below or above 5-8% of

the total no of nodes the performance of the network is degraded in terms of energy, throughput and lifetime so when the

no. of cluster heads are 5% of the sensor nodes then the performance is good. In future, study of factors affecting cluster

formation, communication and data-aggregation of cluster-heads will be one of the research topics. Also in this paper, the

study of wormhole attack launched in LEACH routing protocol in WSN is conducted and the simulation study depicts the

performance degradation in terms of parameters like network throughput, average end to end delay, packet delivery ratio,

drop rate.

ACKNOWLEDGEMENTS

My sincere thanks to my honorable guide Prof. Nekita A. Chavhan and others who have contributed towards the

preparation of the paper.

REFERENCES

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2. Lu Jianyin, “Simulation of Improved Routing Protocols LEACH of Wireless Sensor Network”, IEEE 7th

International Conference on Computer Science & Education (ICCSE), pp 662-666, July 14-17, 2012.

3. Wang Yao, Liu Quanli, Gao Guangen, Wang Wei, “An Improved LEACH Protocol with Determined Number

and Fair Distribution of Cluster Heads”, International Conference on System Science and Engineering , pp

568-572 , June 30-July 2, 2012.

4. Dr. A. Francis Saviour Devaraj, Vandana C.P, “Evaluation of Impact of Wormhole Attack on AODV”,

International Journal of Advanced Networking and Applications, Volume: 04 Issue: 04 pp: 1652-1656, 2013.


5. A.Pravin Renold, R.Poongothai, R.Parthasarthy, “Performance Analysis of LEACH with Gray Hole Attack in

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8. Junguo ZHANG, Wenbin LI, Dongxu CUI, Xueliang ZHAO, Zhongxing YIN, “The NS2-based Simulation and

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International Journal of Scientific & Engineering Research, Volume 3, Issue 1, January-2012.

AUTHOR’S DETAILS

Priya Maidamwar received the B.E. degree from K.D.K College of Engineering, Nagpur, and State-

Maharashtra, India. She is pursuing Master of Engineering (M.E.) in Wireless Communication and Computing from G. H.

Raisoni College of Engineering, Nagpur. Maharashtra, India. Her research area includes Wireless network security,

Wireless sensor network.

Nekita Chavhan received the Master of Engineering (M.E.) in Wireless Communication and Computing from

G. H. Raisoni College of Engineering, Nagpur, and State Maharashtra, India. She is working as Assistant Professor in G.

H. Raisoni College of Engineering, Nagpur. Her research area includes Ad-hoc Wireless networks, Wireless sensor

networks and Mobile Technology.

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