thesis front page -...

28
v ABSTRACT Intrusion Detection Systems (IDS) are developed to be the defense against these security threats. Current signature based IDS like firewalls and anti viruses, which rely on labeled training data, generally can not detect novel attacks. A method that offers a promise to solve this problem is the anomaly based IDS. Literature has shown that direction towards reducing false positive rate and thus enhancing the detection rate and speed have shifted from accurate machine learning classifiers to the adaptive models like bio-inspired models. Consequently, this study has been introduced to enhance the detection rate and speed up the detection process by reducing the network traffic features. Moreover, it aimed to investigate the implementation of the bio-inspired Immune Network approach for clustering different kinds of attacks. This approach aimed at enhancing the detection rate of novel attacks and thus decreasing the high false positive rate in IDS. Rough Set method was applied to reduce the dimension of KDD CUP ’99 dataset which used by this study and select only the features that best represent all kinds of attacks. Immune Network clustering was then applied using aiNet algorithm in order to cluster normal data from attacks in the testing dataset. The results revealed that detection rate and speed were enhanced by using only the most significant features. Furthermore, it was found that Immune Network clustering method is robust in detecting novel attacks in the test dataset. The principal conclusion was that IDS is enhanced by the use of significant network traffic features besides the implementation of the Immune Network clustering to detect novel attacks.

Upload: others

Post on 18-Oct-2019

5 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

v

ABSTRACT

Intrusion Detection Systems (IDS) are developed to be the defense against

these security threats. Current signature based IDS like firewalls and anti viruses,

which rely on labeled training data, generally can not detect novel attacks. A method

that offers a promise to solve this problem is the anomaly based IDS. Literature has

shown that direction towards reducing false positive rate and thus enhancing the

detection rate and speed have shifted from accurate machine learning classifiers to

the adaptive models like bio-inspired models. Consequently, this study has been

introduced to enhance the detection rate and speed up the detection process by

reducing the network traffic features. Moreover, it aimed to investigate the

implementation of the bio-inspired Immune Network approach for clustering

different kinds of attacks. This approach aimed at enhancing the detection rate of

novel attacks and thus decreasing the high false positive rate in IDS. Rough Set

method was applied to reduce the dimension of KDD CUP ’99 dataset which used

by this study and select only the features that best represent all kinds of attacks.

Immune Network clustering was then applied using aiNet algorithm in order to

cluster normal data from attacks in the testing dataset. The results revealed that

detection rate and speed were enhanced by using only the most significant features.

Furthermore, it was found that Immune Network clustering method is robust in

detecting novel attacks in the test dataset. The principal conclusion was that IDS is

enhanced by the use of significant network traffic features besides the

implementation of the Immune Network clustering to detect novel attacks.

Page 2: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

vi

ABSTRAK

Sistem Pengesanan Pencerobohan (IDS) dibangunkan untuk menangani

ancaman keselamatan ini. Sistem pengesanan berteraskan tandatangan seperti

dinding api dan anti-virus kebiasaannya tidak dapat mengecam serangan-serangan

baru manakala sistem pengesanan berbentuk ‘anomaly’ berupaya menyelesaikan

masalah sebegini. Kajian menunjukkan tumpuan telah beralih kepada pengurangan

false alarm serta pembaikan terhadap tahap pengesanan dan kelajuan pengesanan

dengan aplikasi seperti pengesanan berbentuk ‘machine-learning’ kepada kaedah

berdasarkan ‘bio-inspired’. Oleh itu, kajian projek ini dibangunkan untuk

menambahbaik kadar pengesanan serta kelajuan proses pengesanan ini dengan

mengurangkan atribut pada paket rangkaian trafik. Secara spesifiknya, fokus kajian

projek ini tertumpu kepada pengaplikasian pendekatan ‘bio-inspired Immune

Network’ pada sistem pengesanan pencerobohan dengan mengumpukkan (cluster)

kepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar

pengesanan terhadap serangan-serangan baru dan menurunkan kadar ‘false positive’.

Kaedah ‘Rough Set’ digunakan untuk mengurangkan dimensi atribut pada paket-

paket rangkaian set data KDD CUP ’99 serta memilih atribut-atribut yang terbaik

bagi mewakili semua jenis serangan. Algoritma aiNet digunakan bagi mengasingkan

kan data normal dari data serangan pada set data pengujian. Hasil kajian

menunjukkan kadar pengesanan serta kelajuan proses pengesanan boleh dicapai

dengan menggunakan atribut-atribut rangkaian yang penting. Disamping itu, Immune

Network berupaya mengesan jenis-jenis serangan yang baru. Kesimpulannya,

penambahbaikan pada sistem pengesanan pencerobohan ini boleh diperolehi dengan

menggunakan atribut-atribut rangkaian yang penting sahaja mewakili semua jenis

serangan dan Immune Network berupaya mengklusterkan serangan-serangan baru.

Page 3: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

vii

TABLE OF CONTENTS

CHAPTER

TITLE

PAGE

DECLARATION ii DEDICATION iii AKNOWLEDGEMENTS iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES xi LIST OF FIGURES xiii

1 INTRODUCTION

1

1.1 Introduction 1 1.2 Problem Background 4 1.3 Problem Statement 7 1.4 Research Question 7 1.5 Project Hypothesis 8 1.6 Project Aim 8 1.7 Objectives 8 1.8 Project Scope 9 1.9 Significance of the Project 9

1.10 Organization of Report 10

Page 4: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

viii

2 LITERATURE REVIEW

11

2.1 Introduction 11

2.2 Intrusion Detection System 12

2.2.1 Host-based Intrusion Detection System 13

2.2.2 Network-based Intrusion Detection System 14

2.2.3 Misuse Intrusion Detection System 15

2.2.3.1 Snort 16

2.2.4 Anomaly Intrusion Detection 17 2.2.4.1 Architecture of Network-based Anomaly Detection

18

2.2.4.2 Components of Anomaly Detection 19

2.2.4.3 Techniques used to develop Anomaly

Detection

21

2.2.4.4 Rough Set Theory Preliminaries 25 2.2.4.5 Feature Reduction in Intrusion Detection 27

2.2.4.6 KDD CUP ’99 Dataset 28

2.2.4.7 Receiver Operating Characteristics (ROC) 31

2.3 K-Means clustering 32

2.3.1 K-Means Definition 33

2.3.2 K-Means Algorithm 33

2.3.3 K-Means clustering in intrusion detection 34

2.4 Fundamentals of Human Immune System 35

2.5 Artificial Immune System 38 2.5.1 Clonal Selection 39 2.5.2 Negative Selection 40

2.5.3 Immune Network Theory 42 2.6 Related work 49 2.7 Summary

53

Page 5: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

ix

3

RESEARCH METHODOLOGY 54

3.1 Introduction 54

3.2 Problem Visualization 55

3.3 Solution Concept 56

3.4 Overview of Research Framework 57

3.5 Research Design 59

3.5.1 Phase 1: Feature Reduction 59

3.5.1.1 Experimental Setup 60

3.5.1.2 Experimental Results 60

3.5.1.3 Result Analysis 60

3.5.2 Phase 2: Immune Network Clustering 61

3.5.2.1 Dataset Preparation 61

3.5.2.2 Normalization 62

3.5.2.3 Parameters Settings of aiNet 62

3.5.2.4 Experimental Results and Analysis 62 3.5.3 Phase 3: Evaluation of the Immune Network

Clustering method

63

3.6 Summary

65

4 FEATURE REDUCTION USING ROUGH SET 66

4.1 Introduction 66

4.2 Experiments 67

4.2.1 Data 67

4.2.2 Experimental Procedure 71

4.3 Experimental Results 76

4.4 Result Analysis 81

4.4.1 Data Reduction Rate 81

4.4.2 Comparison with other Studies 82

4.4.3 Receiver Operating Characteristics (ROC) 83

Page 6: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

x

5 ARTIFICIAL IMMUNE NETWORK FOR

CLUSTERING ATTACKS IN IDS

87

5.1 Introduction 87

5.2 Experimental Setup 88

5.2.1 Data Samples Preparation 88

5.2.2 Normalization 90

5.2.3 aiNet 90

5.3 Experimental Results 92

5.4 Comparison with K-Means Clustering method 97

5.5 Result Analysis and Discussion 100 5.6 Summary

102

6 CONCLUSION AND FUTURE WORK 103

6.1 Introduction 103

6.2 Project Achievements and Challenges 104

6.3 Future Work 105 6.4 Summary

106

REFERENCES 107

Page 7: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Features of Intrusion Detection Dataset

30

2.2 Related studies

50

3.1 Summary of problem and solution concept

57

3.2 The overall research plan

64

4.1 Distribution of classes in the KDD ’99 Dataset

67

4.2 Distribution of different attacks in the Probe class

68

4.3 Distribution of different attacks in the DoS class

69

4.4 Distribution of different attacks in the U2R class

70

4.5 Distribution of different attacks in the R2L class

70

4.6 The distribution of data for each class in the data samples

71

4.7 Distribution of different attacks in the Probe class in data Samples

72

4.8 Distribution of different attacks in the DoS class in data samples

72

4.9 Distribution of different attacks in the U2R class in data samples

72

4.10 Distribution of different attacks in the R2L class in data samples

73

Page 8: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

xii

4.11 The most 8 significant features obtained by Rough Set in three different samples of data.

76

4.12 The most 8 significant features obtained by Rough Set

76

4.13 The 8 significant features description

77

4.14 The classification accuracy obtained by Rough Set on three different samples using the 41 features.

78

4.15 The classification accuracy obtained by Rough Set on three different samples using the 8 features.

79

4.16 The performance obtained by Rough Set on three data samples before and after Feature Reduction.

80

4.17 Classification accuracy with BN approach in (Chebrolu, S. et al., 2004)

82

4.18 Detection Rate and False Positive Rate for RS classifier

84

5.1 The distribution of the normal and attacks in the data samples of group1.

88

5.2 The distribution of the normal and attacks in data samples of group 2

89

5.3 clustering results obtained by aiNet clustering technique on the data samples of group 1

92

5.4 The result of clustering data samples in two categories (normal and anomalies)

93

5.5 Detection Rate and False Positive Rate for the clustering done by aiNet algorithm using data samples of group 1

94

5.6 Detection Rate and False Positive Rate for the clustering done by aiNet algorithm using data samples of group 2.

96

5.7 Detection Rate and False Positive Rate for the clustering done by k-means algorithm using the data samples of group 1.

98

Page 9: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

xiii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 A basic IDS taxonomy

13

2.2 Generic ANIDS functional architecture

19

2.3 A basic ROC graph showing five discrete classifiers (Tom Fawcett, 2006).

32

2.4 The structure of immune system (de Castro and Zuben, 1999)

36

2.5 B-cell and t-cell receptor for pattern recognition (de Castro and Timmis,2003)

37

2.6 Clonal Selection process

39

2.7 Immune network theory

42

2.8 View on idiotypic immune network

44

2.9 Dataset with three clusters

45

2.10 Corresponding network structure

46

3.1 Research problem visualization

55

3.2 Overview of the overall research plan for development the proposed model

58

4.1 KDD CUP ’99 Dataset Distribution

68

4.2 Distribution of attacks in Probe Class

69

Page 10: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

xiv

4.3 Distribution of attacks in DoS Class

69

4.4 Distribution of attacks in U2R Class

70

4.5 Distribution of attacks in R2L Class

71

4.6 Some of reducts produced by Rough Set for sample 1.

74

4.7 Some of rules produced by ROSETTA for data sample 1.

75

4.8 A comparison between the classification accuracy of the three samples using 41 features.

78

4.9 A comparison between the classification accuracy of the three samples using 8 features.

80

4.10 A comparison in classification time spent by a classifier on the three data samples before and after Feature Reduction

81

4.11 A comparison with BN approach in (Chebrolu S. et al., 2004).

82

4.12 ROC Curve for the RS classifier.

85

5.1 Trade-off between the final number of output cells(N) and the suppression threshold Sσ .

91

5.2 ROC curve for sample 1

94

5.3 ROC curve for sample 2

95

5.4 ROC curve for sample 3

95

5.5 ROC curve for sample1 of group 2 using aiNet

97

5.6 ROC curve for sample1 of group 2 using K-Means

99

5.7 The comparison between the ROC curves of both aiNet and K-Means methods for the same data sample.

100

Page 11: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

1

CHAPTER 1

INTRODUCTION

1.1 Introduction

Due to the increase use of computer networks in many aspects of life, the

number of vulnerabilities also is increasing causing the network resources

unavailable and violates the system confidentiality, integrity and availability.

Intrusions pose a serious security threat for the stability and the security of

information in the network environment. A network intrusion attack encompasses a

wide range of activities. It includes attempting to destabilize the network, gaining

unauthorized access to files with privileges, or mishandling and misusing of software

(Jiang et al., 2006).

Intrusion Detection Systems (IDS’s) are security tools that, like other

measures such as antivirus software, firewalls, and access control schemes, are

intended to strengthen the security of information and communication systems

(Teodoro, 2009). An Intrusion Detection System is an important component of the

computer and information security framework. Its main goal is to differentiate

Page 12: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

2

between normal activities of the system and behaviors that can be classified as

intrusive.

The purpose of IDS is to detect unauthorized use or access to the computer

system or network from the outside environment by those who do not have the

authority or access rights to such systems. The main goal of intrusion detection is to

build a system that could automatically scan the network activity and detect such

intrusion attacks. An IDS is used to detect several types of malicious behaviors that

can compromise the security and trust of a computer system or network. This

includes network attacks against vulnerable services, data driven attacks on

applications, host based attacks such as privilege escalation, unauthorized logins and

access to sensitive files, and malware (viruses, Trojan horses, and worms).

There are two main intrusion detection approaches: anomaly intrusion

detection system and misuse intrusion detection system .The anomaly detection

focuses on the unusal activities of patterns and uses the normal behavior patterns to

identify an intrusion. The misuse detection recognizes known attack patterns and

uses well-defined patterns of the attack. On the other hand, IDS’s may be categorized

according to the host system into two types:

i. Host-based IDS (HIDS)

ii. Network-based IDS(NIDS)

The first operates at the host level and monitors a single host machine using the audit

trails of the host operating system, whereas the other operates at the network level

and monitors any number of hosts on the network.

According to Zainal et al., (2006), IDS can be treated as pattern recognition

problem or rather classified as learning system. They stated that, an appropriate

representation space for learning by selecting relevant attributes to the problem

Page 13: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

3

domain is an important issue for learning systems. Bello et al., (2005) suggested

that feature reduction is necessary to reduce the dimensionality of training dataset.

They claimed that feature reduction also enhances the speed of data manipulation

and improves the classification rate by reducing the influence of noise.

Furthermore, Kim et al., (2005) stated that the goal of feature reduction is to

find a feature subset in order to maximize some performance criterion, such as

classification accuracy. They claimed that selecting important features is an

important issue in intrusion detection.

In literature, numbers of anomaly detection systems were developed based

on many different machine learning techniques. For example, some studies apply

single learning techniques, such as neural networks, genetic algorithms, support

vector machines, bio-inspired algorithms , etc. On the other hand, some systems are

based on combining different learning techniques, such as hybrid or ensemble

techniques. In particular, these techniques were developed as classifiers, which were

used to classify or recognize whether the incoming network access is normal access

or an attack.

Computing models inspired by biology are a way to make use of concepts,

principles and mechanisms underlying biological systems. This type of computing

includes among others, fields as evolutionary algorithms, neural networks, molecular

computing quantum computing and immunological computation. The trend now is

going towards the bio-inspired systems because of the ability of those systems to

adapt naturally with the environment in which they applied. The human immune

system provides inspiration for solving a wide range of innovative problems.

The Immune Network theory as originally proposed by Jerne, (1974a)

hypothesized a novel viewpoint of lymphocyte activities, natural antibody

Page 14: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

4

production, pre-immune repertoire selection, tolerance and self/non-self

discrimination, memory and the evolution of the immune system. It was suggested

that the immune system is composed of a regulated network of cells and molecules

that recognize one another even in the absence of antigens. The immune system was

formally defined as an enormous and complex network of paratopes that recognize

sets of idiotopes, and of idiotopes that are recognized by sets of paratopes, thus it

could recognize as well as be recognized (de Castro et al., 2001).

By dealing with very large number of data over networks, it is very difficult

to classify them manually to detect possible intrusions. Labeled data can be obtained

by simulating intrusions, but this is limited to the set of known attacks and will fail to

address the new types of attacks that may occur in the future. As a result of that

limited ability in detecting unknown attacks, the detection system will not be able to

play its role in securing the network data. So a technique for detecting intrusions

when the data is unlabeled is needed, as well as detecting new and unknown types of

attacks .

1.2 Problem Background

Kim and Park, (2003) proposed a network-based Support Vector Machine

SVM IDS, and demonstrated it through results of 3 kinds of experiments. They have

shown that SVM IDS can be an effective choice of implementing IDS. They

discovered that there are some miss-classified input vectors and those degrade the

performance of SVM IDS. They claimed that the performance of SVM IDS can be

improved by applying Genetic Algorithm (GA) based feature extraction. They

further suggested that Decision Tree (DT) method can also be used to extract features

instead of GA.

Page 15: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

5

Shon et al., (2005) employed a GA for selecting proper TCP/IP packet fields

to be applied to support vector learning in order to distinguish anomaly attacks from

normal packets. Their results showed that their proposed GA and the time delay

preprocessing were reasonable for feature reduction. Moreover, they claimed that the

two approaches using supervised and unsupervised SVM provide a high correction

rate, but high false positive alarms.

A multi-level hybrid classification model combining DT and Bayesian

Network (BN) clustering has been proposed by Xiang, (2008). Their results on KDD

CUP’99 dataset, a benchmark dataset used to evaluate IDS, were compared with

other popular approaches such as multi-level tree classifier and winners of KDD

CUP’99. It was shown that this new approach is very efficient in detecting intrusions

with an extremely low false-negative rate of 3.23%, while keeping an accepTable

level of false-positive rate of 3.2%. Although the false positive rate was reported to

be as low as 0.5% for the KDDCUP’99 winner (Pfahringer, 2000), the corresponding

false negative rate was merely 9.1%, which is much higher than their result (3.23%).

Zanero and Savaresi, (2004) stated that the problem of IDS does not lie only

in the sheer number of vulnerabilities that are discovered every day. They claimed

that there are also an unknown number of unexposed vulnerabilities that may not be

immediately available to the experts for analysis and inclusion in the knowledge

base. In order to overcome this problem, they introduced an unsupervised anomaly

detection based on clustering. They satated that their approach increase the detection

rate of different kinds of unknown attacks

In most circumstances, labeled data or purely normal data is not readily

available since it is time consuming and expensive to manually classify it. Purely

normal data is also very hard to obtain in practice, since it is very hard to guarantee

that there are non intrusions when they were collecting network traffic (Leung and

Page 16: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

6

Leckie, 2005). They stated that to address these problems, they used a new type of

intrusion detection algorithm called unsupervised anomaly detection.

Data reduction can be achieved by filtering, data clustering and feature

selection (Chebrolu et al., 2004). Generally, the capability of anomaly intrusion

detection is often hindered by the inability to accurately classify a variation of

normal behavior as an intrusion. Additionally, network traffic data is huge, and it

causes a prohibitively high overhead and often becomes a major problem in IDS

(Sung and Mukkamala, 2004).

According to Chakraborty, (2005), the existence of these irrelevant and

redundant features generally affects the performance of machine learning or pattern

classification algorithms. Hassan, et al., (2003) proved that proper selection of

feature set has resulted in better classification performance. (Sung and Mukkamala,

2004) have demonstrated that the elimination of these unimportant and irrelevant

features did not significantly lowering the performance of IDS.

Chebrolu et al., (2004) tackled the issue of effectiveness of an IDS in terms

of real-time and detection accuracy from the feature reduction perspective. In their

work, features were reduced using two techniques, Bayesian Network (BN) and

Classification and Regression Trees (CART). They have experimented using four

sets of feature subset which are 12, 17, 19 and all the variables (41) from one

network connection. Dataset used was KDD CUP 99. They suggested that using the

full 41 features do drop the detection rate of the IDS.

Page 17: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

7

1.3 Problem Statement

In most circumstances, labeled data is not available since it is time consuming

and very expensive to classify it manually. Meanwhile there is always a dynamic

change in traffic patterns as well as an emerging of novel attacks. All these problems

make the supervised approach unpractical solution for IDS. To solve these problems,

researchers move to work on unsupervised approach, namely clustering as this

unsupervised approach does not depend on the labeled data. Various unsupervised

methods have been proposed but the detection rate of IDS is rather inadequate in

comparison to supervised approaches.

1.4 Research Question

To cater the problems stated in secion 1.3 this study was carried out to answer the

following questions:

1. How to reduce the dimension of input data or how to choose the features that

best represent all types of attacks?

2. How Immune Network clustering method perform in detecting new attack

types?

3. How to evaluate the performance of the Immune Network method for

clustering?

Page 18: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

8

1.5 Project Hypothesis

The Feature Reduction using Rough Set method and the Immune Network

clustering for network-based IDS would yield a good performance in terms of

detection accuracy, speed and identifying new attack types.

1.6 Project Aim

The aim of this project was to reduce the data features and classify /cluster

the data such that it gives a lower false positive rate, improves accuracy, speed, and

improves the ability of classifying new attack types of unknown dataset.

1.7 Objectives

To accomplish the aim of this project, a few objectives have been identified:

1. To improve the accuracy and speed of detecting attacks by selecting

significant data features that best represent all attack types.

2. To investigate the ability of Immune Network method for clustering

normal traffic from attacks thus detection rate for unknown attacks can be

further improved.

3. To compare the performance of the Immune Network clustering with

a traditional clustering method, namely K-Means on the test data.

Page 19: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

9

1.8 Project Scope

The scope of this project is defined as follows:

1. The dataset that was used in this study is the KDD Cup 1999, a common

benchmark for evaluation of intrusion detection techniques.

2. The feature reduction model was developed using Rough Set Theory to get

the most significant features that best represent all attack types.

3. The Immune Network model was adopted using the original Immune

Network algorithm (aiNet).

4. Evaluation / Comparison was done with a traditional clustering method,

namely K-Means.

1.9 Significance of the Project

This study evaluates the performance of feature reduction and Immune

Network clustering for the network-based IDS in terms of accuracy, speed of

detection and the ability to classify new attack types in the test dataset. The results

were compared with K-Means clustering method to see whether this approach can

give better performance. The result of the study was contributed to the identification

of an improved approach for IDS. This new approach could be used to develop a

methodology that will be valuable in future studies of anomaly based IDS

improvements.

Page 20: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

107

REFERENCES

Allen, J., Christie, A., Fithen, W., McHugh, J., Pickel, J., and Stoner, E. (2000). State

of the Practice of Intrusion Detection Technologies. Tech. rep., Carnegie

Mellon University January.

Ayara, M., Timmis, J., de Lemos, R., de Castro, L.N., Duncan, R. (2003).Negative

Selection: How to Generate Detectors. Technical Report, Computing

Laboratory.University of Kent at Canterury. U.K.

Bivens, A., Palagiri, C ., Smith, R., Szymanski, B ., and Embrechts, M. (2002).

Network-Based Intrusion Detection using Neural Networks. Rensselaer

Polytechnic Institute Troy, New York 12180-3590.

Burbeck, K. and Nadjm-Tehrani,S. (2005). ADWICE – Anomaly Detection with

Real-Time Incremental Clustering. LNCS 3506, pp. 407–424, Springer. In

proceedings of the 7th International Conference on Information Security and

Cryptology, Seoul, Korea.

Bello, R. , Nowe, Y. Caballero, Y. Gomex, and P. Vrancx (2005), A Model

Based on Ant Colony System and Rough Set Theory to Feature Selection.

GECCO’05, June 25-29, Washington DC, United States. Pp. 275-276.

Chandola,V., Banerjee, A., and Kumar V. (2007). Anomaly Detection: A Survey.

Technical Report, TR 07-017.

Chandola,V., Banerjee, A., and Kumar V. (2009). Anomaly Detection: A Survey.

ACM Computing Surveys, Vol. 41(3).

Chakraborty, B. (2005). Feature Subset Selection by Neuro-rough Hybridization.

LNCS, Springer Hiedelberg, pp. 519-526.

Page 21: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

108

Chebrolu, S ., Abraham, A. and Thomas, J.P. (2004). Feature Deduction and

Ensemble Design of Intrusion Detection Systems. International Journal of

Computers and Security .Vol 24, Issue pp. 295-307.

Chimphlee, W., Abdul Hanan Abdullah, Mohd Noor Md Sap and Chimphlee, S

(2005). Unsupervised Anomaly Detection with Unlabeled Data using

Clustering, Proc. Int. Conf. on ICT- Mercu Buana ICT2005. pp. 42-49.

Dasgupta, D., Ji, Z., and González , F. (2003). Artificial Artificial Immune System

(AIS) Research in the Last Five Years. Proceedings of The 2003 Congress on

Evolutionary Computing.

De Castro, L.N., Zuben ,F. (1999). Artificial Immune System: part I -Basic theort

and aoolications. Technical Report TR – DCA 01/99.

De Castro, L.N and Zuben, F.J. (2000). The Clonal Selection Algorithm with

Engineering Applications. In Workshop Proceedings of GECCO, pp. 36-37,

Workshop on Artificial Immune Systems and Their Applications, Las Vegas

, USA.

De Castro, L.N., and Zuben, F., (2001). aiNet: An Artificial Immune Network for

Data Analysis . Idea Group Publishing, USA.

De Castro, L.N. and Timmis, J. (2002). An Artificial Immune Network for

Multimodal Function. Proceedings of the 2002 Congress on, Vol.1, pp. 699-

704.

De Castro,L.N., and Timmis, J. (2002). Artificial Immune Systems: A Novel

Paradigm to Pattern Recognition. In Artificial Neural Networks in Pattern

Recognition,University of Paisley, UK, pp. 67-84.

De Castro L.N., Timmis, J. (2003). Artificial immune systems as a novel soft

computing paradigm. Soft Computing 7 526–544 Springer-Verlag.

Denning, DE. (1987). An intrusion-detection model. IEEE Transactions on software

engineering.

Depren, O., Topallar, M., Anarim, E. and Ciliz, M.K. An intelligent intrusion

detection system (IDS) for anomaly and misuse detection in computer

networks, Expert Systems with Applications, Volume 29, Issue 4 , pp. 713-

722, 2005.

Duda, R., Hart, E. ,.Tork, D.G. (2001): Pattern classification. (2nd Edition)

(9780471056690): Richard O. Duda, Peter E. Hart, David G. Stork: Books.

Page 22: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

109

Eick,C., and Zeidat N., (2005). Using Supervised Clustering to Enhance

ClassifierS. The15th International Symposium on Methodologies, Springer.

Eskin, E., W. N. Grundy, and Y. Singer (2000). Protein family classification using

sparse Markov transducers. In Proc. of the Eighth Intl. Conf. on Intelligent

Systems for Molecular Biology, Menlo Park, CA, pp. 134–145. AAAI Press.

Eskin, E., Arnold, A., Prerau, M., Portnoy, L., and Stolfo, S.(2002). A geometric

framework for unsupervised anomaly detection: detecting intrusions in

unlabeled data. In Applications of Data Mining in Computer Security.

Kluwer.

Fearon, D. T. and Locksley, R. M. (1996). The Instructive Role of Innate Immunity

in the Acquired Immune Response, Science 272: 50-53.

Finley,T , Joachims, T. (2005). Supervised Clustering with Support Vector

Machines. Proceedings of the 22 nd International Conference on Machine

Learning, Bonn, Germany.

Forrest, S., Perelson, A.S., Allen, L. and Cherukuri, R. (1994) Self-nonself

discriminatioin a computer. Proceedings of IEEE Symposium on Research in

Security and Privacy. 16(18):202-212

Forest. S., Hofmeyr. S. A., Somayaji. A. (1997). Computer Immunology.

Fred, A.L.N., and Jain, A.K. (2005): Combining multiple clusterings using evidence

accumulation. IEEE Transactions on Pattern Analysis and Machine

Intelligence 27(6).

Fawcett, Tom (2006). An introduction to ROC analysis. Pattern Recognition

Letters 27, 861–874. Elseiver.

Gao, J., Chengy, H., Tan, P.N. (2006). A Novel Framework for Incorporating

Labeled Examples into Anomaly Detection. In Proc of SDM'06: SIAM Int'l

Conf. on Data Mining, Bethesda, MD, Apr 20-22.

Gerhard Münz, Sa Li and Georg Carle. (2007) Traffic Anomaly Detection Using

k-means Clustering. In GI/ITG Workshop MMBnet.

Estevez-Tapiador, J. M. , Teodoro,GP.,and Diaz-Verdejo J.E (2004). Anomaly

detection methods in wired networks: a survey and taxonomy, Computer

Communications vol. 27, pp. 1569-1584, 15 October 2004.

Ghali, N. (2009). Feature Selection for Effective Anomaly-Based Intrusion

Detection. IJCSNS International Journal of Computer Science and Network

Security, VOL.9 No.3.

Page 23: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

110

Goldberg, D.E., 1989. Genetic Algorithms in Search, Optimization, and Machine

Learning. Addison-Wesley, Reading, M.A.

González ,F.A., and Dasgupta,D. (2003). Anomaly detection using real-valued

negative selection. Genetic Programming and Evolvable Machines, Vol. 4 ,

No. 4, pp. 383-403.

Grira, N., Crucianu, M., Boujemaa, N. (2005). Unsupervised and Semi-supervised

Clustering: a Brief Survey. in A Review of Machine Learning Techniques for

Processing Multimedia Content, Report of the MUSCLE European Network

of Excellence (6th Framework Programme).

Hassan, A., Nabi Baksh, M.S. Shaharoun, A.M. and Jamaluddin, H.

(2003).Improved SPC Chart Pattern Recognition Using Statistical Feature.

International Journal of Production Research 41(7), , pp. 1587-1603.

Huang,W. and Jiao ,L. (2008). Artificial immune kernel clustering network for

unsupervised image segmentation. Elseiver Progress in Natural Science 18

455–461

Hunt, J.E and Cooke, D.E.. (1995). Recognizing promoter sequences using an

Artificial Immune System. In Proceedings of Intelligent Systems in Macular

Biology, IEEE Press. 81-86.

Ingham K. (2003). Protecting network servers.Technical Report, Department of

Computer Science, University of New Mexico.

Janeway, A. (1993). How the Immune System Recognizes Invaders. Scientific

American. 41-47.

Jerne, N. K. 1974. Network theory of the immune system. 1974. Ann. Immunol.

(Paris). 125c: 373..

Jiang, S., Song, X. , Wang, H. , Han, J. And Li , Q. (2006). A clustering-based

method for unsupervised intrusion detections. Elseiver Pattern Recognition

Letters 27 802–810.

Kabiri, P. , and Ghorbani, A. A (2005). Research on intrusion detection and

response: A survey. In International Journal of Network Security, volume 1.

Kate,R.J., and Mooney, R.J. (2007). Semi-Supervised Learning for Semantic

Parsing using Support Vector Machines. In Human Language Technologies

2007: The Conference of the North American Chapter of the Association for

Computational Linguistics; Companion Volume, Short Papers. Rochester,

New York, pp. 81-84. Association for Computational Linguistics.

Page 24: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

111

Kim, B. J. and Kim, I. K. ,(2005). Machine Learning Approach to Realtime

Intrusion Detection System. In Proceedings of 18 th .Australian Join

Conference on Artificial Intelligence, Sydney, Australia. Vol. 3809. Pp. 153-

163.

Kim ,J. and Bentley,P. (1999). An Evaluation of Negative Selection in an Artificial

Immune System for Network Intrusion Detection. Proceedings of the Genetic

and Evolutionary Computation Conference (GECCO).

Kim, DS., Nguyen, HN., Park, JS. (2005). Genetic algorithm to improve SVM based

network intrusion detection .Information Networking and Applications, 2005.

Kim ,JW. (2002). Integrating Artificial Immune Algorithms for Intrusion Detection.

PhD thesis, University College London.

Kim, D. and Park ,J. (2003). Network-Based Intrusion Detection with Support

Vector Machines. Lecture notes in computer science, 747-756, Springer.

Kim, J. and Bentley, P. (2002). Towards an artificial immune system for network

intrusion detection: an investigation of dynamic clonal selection. In:

Proceeding of the Congress on Evolutionary Computation (CEC-2002),

Honolulu, Hawaii.

Kim, J. and Bentley, P. (2004). Immune memory and gene library evolution in the

dynamical clonal selection algorithm. Journal of Genetic Programming and

Evolvable Machines 5(4): 361–391.

Knidel ,H., de Castro, L.N., and Zuben, F.J. (2005): a realvalued antibody network

for data clustering. In: GECCO’05, Washington, DC, USA, p. 371–2.

Laskov, P., SchÄafer, C., and Kotenko, I.(2004). Intrusion detection in unlabeled

data with quarter-sphere support vector machines. In: Proc. DIMVA. 71{82}.

Laskov, P., SchÄafer, C., Kotenko, I., and MÄuller, K.R.(2004). Intrusion detection

in unlabeled data with quarter-sphere support vector machines (extended

version).

Laskov,P., Däussel, P., SchÄafer, C. and Rieck, K. (2005). Learnin intrusion

detection:supervised or unsupervised?. Lecture Notes in Computer Science,

2005 – Springer.

Lazarevic, A. (2005). Data Mining for Intrusion Detection. Encyclopedia of Data

Warehousing and Mining, Idea Group.

Leung, K. and Leckie, C. (2005). Unsupervised Anomaly Detection in Network

Page 25: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

112

Intrusion Detection Using Clusters. Appeared at the 28th Australasian

Computer Science Conference, The University of Newcastle, Australia.

Lichodzijewski P. (2002). Network based anomaly detection using self organizing

maps, Technical Report, Nova Scotia: Dalhousie University Halifax.

Li, Z. and H.-Z. Tan (2006), A Combinational Clustering Method Based on Artificial

Immune System and Support Vector Machine, In KES 2006, Part I, LNAI

4251, Gabrys, B., Howlett, R.J. and L.C. Jain (Eds.), Springer-Verlag Berlin

Heidelberg, 153-162.

Li Ming(2004). An approach for reliably identifying signs of DDoS flood attacks

based on LRD traffic pattern recognition. Computers Security;23(7):549e58.

Lu, W. and Traore,I. (2005). A New Unsupervised Anomaly Detection Framework

for Detecting Network Attacks in Real-Time. The 4th international

conference of Cryptography and Information Security(CANS 2005).

Mandala, S., Asri Ngadi, Md., Hanan Abdullah, A.,(2008). A Survey on MANET

Intrusion Detection. International Journal of Computer Science and Security,

Volume (2), Issue (1).

Mosqueira, E. , Alonso-Betanzos, A., del R´ıo, B. , and Lago Pi˜neiro,J. (2007).

A Misuse Detection Agent for Intrusion Detection in a Multi-agent

Architecture. Lecture Notes in Computer Science, Springer.

Ohrn, A., and Komorowski, J. (1997). A Rough Set Toolkit for Analysis of Data, In

Proceedings of the third Joint conference on Information Sciences, Vol(3),

pp.403- 407, USA.

Panda, M., and Patra, M. (2005).SOME Clustering Agorithm to enhance the

performance of network intrusion detection system. Journal of Theoretical

and Applied Information Technology.

Pawlak, Z. (1991). Rough Sets: Theoretical Aspects of Reasoning about Data,

Kluwer Academic Publishers.

Pfahringer Bernhard (2000). Winning the KDD99 classification cup:bagged

boosting. ACM SIGKDD Explorations Newsletter. Volume 1 , Issue 2

(January 2000).

Portnoy, L., Eskin, E., and Stolfo, S.(2001). Intrusion detection with unlabeled data

using clustering. In: Proc. ACM CSS Workshop on Data Mining Applied to

Security.

Page 26: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

113

Powers,S., and He , J. (2008). A hybrid artificial immune system and Self Organising

Map for Network Intrusion Detection. Information Sciences. Elseiver. 178

3024–3042.

Quinlan, J.(1992). C4.5: Programs for Machine Learning. Morgan Kaufmann.

Ramos,V. , and Abraham, A. (2006). ANTIDS: Self-Organized ANT-Based

Clustering model for Intrusion Detevtion System. Arxiv preprint cs/0412068,

arxiv.org.

Rojas, R.(1996). Neural Networks: A Systematic Approach. Springer-Verlag,

Berlin, Deutschland.

Shin, M., Mi, E., Seon,K. , and Park, H. (2003). Automatically Finding Good

Clusters with Seed k-Means. Bioinformatics Research Team, Electronics and

Telecommunications Research Insti- tute, 161 Gajeong-dong, Yuseong-gu,

Daejeon, 305-350, Korea.

Shon,T., Kim, Y., Lee, C., Moon, J. (2005). Machine learning framework for

network anomaly detection using svm. Information Assurance Workshop,

IAW'05

SNORT. URL: http://www.snort.org. Last accessed 07/05/2006. 2006

Soleymani Baghshah, M. and Bagheri Shouraki, S. (2008). A Novel Semi-supervised

Clustering Algorithm for Finding Clusters of Arbitrary Shapes. 13th

International CSI Computer Conference, CSICC 2008 Kish Island, Iran.

Soleymani Baghshah, M., and Bagheri Shouraki, S, (2008).:A fuzzy clustering

algorithm for finding arbitrary shaped clusters. In: Soleymani Baghshah, M.,

Bagheri Shouraki, S..(eds.) 6th ACS/IEEE International Conference on

Computer Systems and Applications.

Spafford, E. H. and Zamboni, D.(2000). Intrusion detection using autonomous

agents. Computer Networks,34(4):547–570.

Srinoy, S., Kurutach, W., Chimphlee, W., and Chimphilee, S. (2005). Network

Anomaly Detection Using Soft Computing, Proceedings of World Academy

of Science, Engineering and Technology, vol. 9, pp.140-144,.

Stibor, T., and Timmis , J.(2007). An Investigation on the Compression Quality of

aiNet .In: Fogel D (ed) Proc of foundations of computational intelligence.

Sung, A.H. and Mukkamala, S. (2003). Identifying Important Features for Intrusion

Page 27: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

114

Detection Using Support Vector Machines and Neural Networks. In

Proceedings of the Symposium on Applications and Internet (SAINT’03), pp.

209-216.

Sung, A.H. and Mukkamala, S. (2004). The Feature Selection and Intrusion

Detection Problems. ASIAN 2004. LNCS, vol. 3321, Springer Hieldelberg,

pp. 468-482.

Tan, L. and Sherwood, T.,(2005) A High Throughput String Matching Architecture

for Intrusion Detection and Prevention, ISCA 2005.

Tang,W. , Xiong, H., Zhong,S. ,and Wu ,J. (2007). Enhancing Semi-Supervised

Clustering: A Feature Projection Perspective. International Conference on

Knowledge Discovery and Data Mining. Proceedings of the 13th ACM

SIGKDD international conference on Knowledge discovery and data mining

San Jose, California, USA.

Taylor, D. W., Corne, D. W. (2003). An investigation of the Negative Selection

Algorithm for Fault detection in Refrigeration System. ICARIS 2003.

Springer-Verlag Berlin Heidelberg. LNCS 2787: 34-45

Teng, H., S., Chen, K. and Lu, S., C. Security Audit Trail Analysis Using Inductively

Generated Predictive Rules. In Proceedings of the 11th National Conference

on Artificial Intelligence Applications, pages 24-29, IEEE, IEEE Service

Center, Piscataway, NJ, March 1990.

Teodoro,G, Verdejo, Dı´az. , J., Macia´-Ferna´ndez, G., and Va´zquez, E. ,(2009).

Anomaly-based network intrusion detection: Techniques, systems and

challenges. 0167-4048 Elsevier Ltd.

Timmis, J., Neal, M., and Hunt, J. (2000). An Artificial Immune System for Data

Analysis. Journal of the BioSystem. 55: 143-150.

Timmis, J. I. (2001). Artificial Immune System A Novel Data Analysis Technique

Inspired by the Immune Network theory. PHD Thesis. University of Wales.

Aberystwyth, .

Timmis, J., Neal, M. (2001). A Resource Limited Artificial Immune System for Data

Analysis. Journal of Knowledge Based System. 14 (3-4): 121-130.

Wang , L. ,Wang ,L. and Nie,Y., (2006). A Novel Artificial Immune Network Model

and Analysis on Its Dynamic Behavior and Stabilities. ICNC 2006, Part II,

LNCS 4222, pp. 83 – 9. Springer-Verlag Berlin Heidelberg..

Wroblewski, J., 1995. Finding Minimal Reducts Using Genetic Algorithms.

Page 28: THESIS FRONT PAGE - eprints.utm.myeprints.utm.my/id/eprint/11367/6/MuradAbdoRassamMFSKSM2010.pdfkepada kelas-kelas serangan. Tujuannya adalah untuk menambahbaik kadar pengesanan terhadap

115

Proc. of the second Annual Join Conference on Information Sciences.

Wrightsvillle Beachm, NC, p.186-189.

Xiang Cheng, Yonga Png Chin and Swee Menga Lim (2008). Design of multiple-

level hybrid classifier for intrusion detection system using Bayesian

clustering and decision trees . Elsevie Pattern Recognition LettersVolume 29,

Issue 7, 1 May 2008, Pages 918-924

Xiao, R. B., Wang, L., Liu, Y. (2002). A Framework on AIS Based Pattern

Classification and Matching for Engineering Creative Design. IEE

Proceedings of the First International Conference on Machine Learning and

Cybernatics. 4-5 September:1554-1558

Ye, N. and Li, X. , (2001). A Scalable Clustering Technique for Intrusion Signature

Recognition. Proceedings of the 2001 IEEE Workshop on Information

Assurance and Security United States Military Academy, West Point, NY.

Yasami, Y., Khorsandi,S., Mozaffari,SP., and Jalalian ,A., (2008).An unsupervised

network anomaly detection approach by k-Means - IEEE Symposium on

Computers .

Zainal, A., Maarof, M.A. and Shamduddin, S.,(2006). “Feature selection using

rough set in intrusion detection”, in Proc. IEEE TENCON, p.4.

Zainal,A., Maarof ,M.A. and Shamsuddin,S. ,(2006). Research Issues in Adaptive

intrusion detection. PARS06 FSKSM,UTM, Skudai.

Zainal, A., Maarof M.A., Shamsuddin S.,(2007), Feature Selection using Rough-

DPSO in Anomaly Intrusion Detection, ICCSA 2007, LNCS 4705.

Zanero, S. and Savaresi ,S, (2004). Unsupervised learning techniques for an

intrusion detection system .In proceedings of the 2004 ACM symposium on

Applied computing, Nicosia, Cyprus.

Zanero, S.,(2005). Improving Self Organizing Map Performance for Network

Intrusion Detection. In: SDM 2005 Workshop on "Clustering High

Dimensional Data and its Applications”.

Zhang, L., Zhang, G. , Yu , L., Zhang , J., and Bai,Y ., (2004). Intrusion Detection

Using Rough Set Classification. Journal of Zheijiang University Science. pp.

1076-1086.

Zhao, Z., Guo,S., Xu,Q., and Ban,T., (2009).G-Means: A Clustering Algorithm for

Intrusion Detection. M. Köppen et al. (Eds.): ICONIP Part I, LNCS 5506, pp.

563–570. Springer-Verlag Berlin Heidelberg.