SECURING PASSIVE OPTICAL NETWORK AGAINST SIGNAL INJECTION ATTACK
SALIM MOHAMMED ABDULLAH AL-HINAI
A project report submitted in partial fulfilment of the requirements for the award of the degree of
Master of Engineering (Electronics and Telecommunications)
School of Electrical Engineering Faculty of Engineering Universiti Teknologi Malaysia
iii DEDICATION
This project report is dedicated to my family especially my parents, and wife. It is also dedicated to my supervisor, who guides me to achieve the target.
iv
ACKNOWLEDGEMENT
I wish to express my sincere appreciation to all those who have helped me in various way, to complete this thesis. First and foremost, I thank God almighty who provided me with strength, direction and showered me with blessings throughout. My sincerest gratitude to my supervisor Assoc. Prof. Dr. Nadiatulhuda Zulkifli for her continuous guidance, encouragement and motivation.
I also recognized Universiti Teknologi Malaysia (UTM) for the facilities in the faculty and library which help me a lot in completing my thesis.
My fellow postgraduate class mates should also be recognized for their support. My sincere appreciation also extends to all my colleagues and others who have provided assistance at various occasions. Their views and tips are useful indeed. Unfortunately, it is not possible to list all of them in this limited space. I am grateful to all my family members.
v ABSTRACT
Passive Optical Network (PON) is a promising solution to the last-mile problem in access networks. Security is a very crucial aspect to be considered especially in the current environments that are characterized by much larger data transport capacity. Moreover, securing the physical layer requires urgent attention as it will become more critical in future PON that has much longer distance with the involvement of more users. Thus, it is vulnerable to a variety of attacks, including denial of service (DoS) which jams a network, eavesdropping and masquerade. DoS attack can take place when a continuous upstream signal is transmitted from Optical Network Unit (ONU) to Optical Line Terminal (OLT) with high enough power, causing the OLT to receive the data with high bit error rate. This research proposes a method to secure PON from high power injection attack. The solution is based on the idea of deploying an optical attenuator in the upstream communication towards the splitter to prevent any high signal power injection attack and restrict it up to an acceptable power level. One of the most important benefits of the proposed work is its straightforward implementation in the existing GPON network with minimum cost and effort. The GPON network under studied that focuses on the upstream communication based on standard ITU-T G.984 ( data rate of 1.25 Gbps) examined the effects of varied optical fiber distances and number of ONUs. The performance of the proposed method is evaluated using Optisystem to determine the feasibility of the concept. Findings from the simulation results revealed that the optical attenuator compensated the jamming degradation attack up to eight ONUs and maximum distance of 20 km. The proposed system design also found that the method has limitation to reduce the attack at higher ONU numbers e.g. 16 and 32 due to high insertion loss. The overall performance confirms that this method is useful to protect the GPON system and minimize the high power for low insertion loss power splitter.
vi ABSTRAK
Rangkaian Optik Pasif (PON) merupakan penyelesaian berpotensi kepada masalah batu-terakhir dalam rangkaian akses. Keselamatan adalah aspek yang sangat penting untuk dipertimbangkan terutamanya dalam persekitaran semasa yang dicirikan oleh kapasiti pengangkutan data yang lebih besar. Lebih-lebih lagi, lapisan fizikal yang memerlukan perhatian segera kerana ia akan menjadi lebih kritikal pada PON masa hadapan yang melibatkan jarak lebih jauh dan lebih ramai pengguna. Oleh itu, ia terdedah kepada pelbagai serangan, termasuk penafian perkhidmatan (DoS) yang meresapi rangkaian, pengintipan dan penyamaran. Serangan DoS boleh berlaku apabila isyarat hulu berterusan dihantar dari Unit Rangkaian Optik (ONU) ke Terminal Talian Optik (OLT) dengan kuasa yang cukup tinggi, menyebabkan OLT menerima data dengan kadar ralat bit yang tinggi. Penyelidikan ini mencadangkan kaedah untuk menjamin PON daripada serangan suntikan kuasa tinggi. Penyelesaian ini adalah berdasarkan idea yang menggerakkan pelemah optik dalam komunikasi huluan ke arah pembahagi untuk mengelakkan sebarang serangan suntikan kuasa isyarat tinggi dan menyekatnya ke tahap kuasa yang boleh diterima. Salah satu faedah yang paling penting dalam penyelesaian yang dicadangkan adalah pelaksanaannya yang jelas dalam rangkaian GPON yang sedia ada dengan kos dan usaha yang minimum. Rangkaian GPON yang dipelajari memberi tumpuan kepada komunikasi hulu berdasarkan standard ITU-T G.984 (kadar data 1.25 Gbps) dengan mengambilkira kesan pelbagai jarak gentian optik dan bilangan ONUs. Prestasi kaedah yang dicadangkan dinilai dengan menggunakan Optisystem untuk menguji perlaksanaan konsep tersebut. Penemuan dari keputusan simulasi menunjukkan bahawa penguat optik mampu untuk menghadapi serangan kemerosotan signal kualiti sehingga lapan ONUs dan jarak maksimum 20 km. Reka bentuk sistem yang dicadangkan juga mendapati bahawa kaedah yang dicadangkan mempunyai had untuk mengurangkan serangan bagi nombor ONU yang lebih tinggi, misalnya 16 dan 32 kerana kehilangan kuasa pembahagi kuasa yang tinggi. Prestasi keseluruhan mengesahkan bahawa kaedah ini berguna untuk melindungi sistem GPON dan meminimumkan serangan tinggi kuasa untuk kes kehilangan kuasa pembahagi yang rendah.
vii TABLE OF CONTENTS TITLE PAGE DECLARATION ii DEDICATION iii ACKNOWLEDGEMENT iv ABSTRACT v ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF ABBREVIATIONS xiv
LIST OF SYMBOLS xvii
LIST OF APPENDICES xviii
CHAPTER 1 INTRODUCTION 1 1.1 Overview 1 1.2 Problem Statement 3 1.3 Objectives 4 1.4 Scope of Work 4 1.5 Research Methodology 5 1.5.1 Work Schedule 5 1.6 Thesis Outlines 5
CHAPTER 2 LITERATURE REVIEW 7
2.1 Introduction 7
2.2 Evolution of the GPON 8
2.3 Passive Optical Network Architecture 9
2.3.1 Optical Network Terminal 9
2.3.2 Optical Line Terminal 10
viii
2.4 GPON FTTH Access Network Architecture 11
2.4.1 FTTH Core Network 11
2.4.2 Central Office 12
2.4.3 FTTH Feeder Network 12
2.4.4 FTTH Distribution Network 12
2.4.5 User Area 13
2.5 GPON Security Flaws 13
2.6 Related Work to GPON Security Weaknesses 14
2.7 Summary 21
CHAPTER 3 RESEARCH METHODOLOGY 22
3.1 Overview 22
3.2 Research Methodology Flowchart 23
3.3 Operational Methodology Flowchart 24
3.4 Research Design 25
3.5 Problem Formulation 25
3.6 Simulation Tools 25
3.7 GPON System Design over OTDM 25
3.8 System Description 26
3.8.1 Transmitter Design 27
3.8.2 Optical Distribution Network 28
3.8.3 Receiver Design 28
3.9 The Functionality of Optical Attenuator Against
Injection Attack 30
3.10 Fundamental of Optical Attenuator 30
3.11 Types of Fiber Optical Attenuator 31
3.11.1 Fixed Optical Attenuator Model 31 3.11.2 Variable Optical Attenuator Model 31 3.11.3 Loopback Optical Attenuator Model 32 3.12 Operation Theory of Optical Attenuator 32
3.12.1 Gap Loss Operation Theory 33
3.12.2 Absorption Theory 33
ix
3.13 Variable Optical Attenuator Mechanism 34
3.14 High Power Attack Principle 35
3.15 Optical Delay Calculation 37
3.16 Power Budget 38
3.16.1 Power Budget Calculation 39
3.16.2 Power Budget Calculation without Jamming 39 3.16.3 Power Budget Calculation with Jamming 40 3.16.4 Calculation of Optical Attenuator Value 40
3.17 Bit Error Rate and Q-Factor 42
3.18 Summary 43
CHAPTER 4 RESULTS AND DISCUSSION 44
4.1 Overview 44
4.2 Verification of GPON Model Design 44
4.3 GPON Model without Jamming WOJ 45
4.3.1 Performance Analysis of GPON-WoJ 49 4.3.2 Optical Spectrum Analyzer of GPON-WoJ 52
4.4 GPON Model with Jamming WJ 53
4.4.1 Performance Analysis of GPON-WJ 56 4.4.2 Optical Spectrum Analyzer of GPON-WJ 58 4.5 GPON Model with Optical Attenuator WOA 59 4.5.1 Performance Analysis of GPON -WOA 62 4.5.2 Optical Spectrum Analyzer of GPON-WOA 64
4.6 Overall GPON Models Comparison 65
4.6.1 The Performance of Q-Factor with Distance 65 4.6.2 The Performance of BER with Distance 66 4.6.3 The Performance of BER with ONUs 66
4.7 Power Budget Results 67
4.8 Summary 69
CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 70
5.1 Conclusion 70
x
REFERENCES 72
xi
LIST OF TABLES
TABLE NO. TITLE PAGE
Table 1.1 Project Schedule 5
Table 2.1 ITU/IEE PON Standard 9
Table 2.2 Related Work on Security Weaknesses in GPON 18
Table 3.1 Parameter's values for GPON upstream 29
Table 3.2 Time Delay 37
Table 3.3 Power Budget Calculation for 20 km 39
Table 3.4 Eye Diagram Explanation 43
Table 4.1 GPON Q-Factor & BER Performance of 1 km WOJ 47 Table 4.2 GPON Q-Factor & BER Performance of 10 km WOJ 48 Table 4.3 GPON Q-Factor & BER Performance of 20 km WOJ 48 Table 4.4 GPON Q-Factor & BER Performance of 30 km WOJ 48 Table 4.5 GPON Q-Factor & BER Performance of 1 km WJ 54 Table 4.6 GPON Q-Factor & BER Performance of 10 km WJ 55 Table 4.7 GPON Q-Factor & BER Performance of 20 km WJ 55 Table 4.8 GPON Q-Factor & BER Performance of 30 km WJ 55 Table 4.9 GPON Q-Factor & BER Performance of 1 km WOA 61 Table 4.10 GPON Q-Factor & BER Performance of 10 km WOA 61 Table 4.11 GPON Q-Factor & BER Performance of 20 km WOA 61 Table 4.12 GPON Q-Factor & BER Performance of 30 km WOA 62
xii
LIST OF FIGURES
FIGURE NO. TITLE PAGE
Figure 1.1 Scenarios of XG-PON1 with GPON 1
Figure 1.2 Broadcasting mechanisms in TDM-GPON 2
Figure 1.3 Scenario denial of service attack 3
Figure 2.1 Time division multiplexing 8
Figure 2.2 GPON FTTH access network architecture 11
Figure 2.3 Technologies for the optical switch 15
Figure 2.4 Diagram of optical steganography technique 17
Figure 2.5 Approach of reflected signal setup 18
Figure 3.1 Research methodology flowchart 23
Figure 3.2 Operational methodology flowchart 24
Figure 3.3 GPON model over OTDM 26
Figure 3.4 ONU transmitter design 27
Figure 3.5 ODN design 28
Figure 3.6 OLT receiver design 29
Figure 3.7 Proposed design 30
Figure 3.8 Fixed optical attenuator 31
Figure 3.9 Variable optical attenuator 32
Figure 3.10 Gap-loss attenuator layout 33
Figure 3.11 Light absorption attenuator layout 34
Figure 3.12 Light reflection attenuator layout 34
Figure 3.13 Variable optical attenuator layout 35
Figure 3.14 In-band and out-band jamming attack 36
Figure 3.15 High power attack princple 37
Figure 3.16 Eye diagram 42
xiii
Figure 4.2 GPON model without jamming (TX) 46
Figure 4.3 GPON model without jamming (RX) 46
Figure 4.4 Eye diagram of GPON model without jamming 47
Figure 4.5 Q-Factor vs ONUs WOJ chart 49
Figure 4.6 Q-Factor vs distance WOJ chart 50
Figure 4.7 BER vs ONUs WOJ chart 50
Figure 4.8 BER vs distance WOJ Chart 51
Figure 4.9 BER vs ONUs WOJ chart 20 km 51
Figure 4.10 Spectrum plot of received signal 20 km WOJ 52
Figure 4.11 GPON model with jamming signal 53
Figure 4.12 Eye diagram of GPON model with jamming signal 54
Figure 4.13 Q-Factor vs ONUs WJ chart 56
Figure 4.14 Q-Factor vs distance WJ chart 57
Figure 4.15 BER vs ONUs WJ chart 57
Figure 4.16 BER vs distance WJ chart 58
Figure 4.17 Spectrum plot of received signal 20 km WJ 59 Figure 4.18 GPON model with optical attenuator WOA 60
Figure 4.19 Eye diagram of GPON model WOA 60
Figure 4.20 Q-Factor vs ONUs WOA chart 62
Figure 4.21 Q-Factor vs distance WOA chart 63
Figure 4.22 BER vs ONUs WOA chart 63
Figure 4.23 BER vs ONUs WOA chart 20 km 64
Figure 4.24 Spectrum plot of received signal 20 km WOA 65 Figure 4.25 GPON models Q-Factor vs distance chart 65
Figure 4.26 GPON models BER vs distance chart 66
xiv
LIST OF ABBREVIATIONS
AAA - Authentication Authorization Accounting AES - Advanced Encryption Standard
APD - Avalanched Photo Detector APON - ATM Passive Optical Network ATB - Access Terminal Box
APD BER BPON BRAS - - - -
Avalanched Photo Detector Bit Error Rate
Broadband Passive Optical Network Broadband Remote Access Server CATV CO - - Cable TV Central office CW dB - - Continuous Wave Decibel CATV DoS - -
Community Access Television Denial of Service DS EDFA EPON - - - Downstream
Erbium Doped Fiber Amplifier Ethernet Passive Optical Network FAT
FDT
- -
Fiber Access Terminal Feeder Disruption Terminal FSAN FTTB FTTdp FTTH FTTM FTTO - - - - - -
Full Service Access Network Fiber to the Building
Fiber to the Distribution Point Fiber to the Home
Fiber to the Mobile Fiber to the Office Gbps
GPON
- -
Gigabits per Second
Gigabits Passive Optical Network GUI
HFC
- -
Graphical User Interface Hybrid Fiber Coaxial
xv IEEE
ISP
- -
Institute of Electrical and Electronics Engineers Internet Service Provider
ITU KM
- -
International Telecommunication Union Kilometer
MAC - Media Access Controller MZM - Mach-Zehnder Modulator
Nm - Nano meter
NG-PON - Next Generation Passive Optical Network NRZ - Non Return to Zero
OCDMA - Optical Code Division Multiple Access ODF ODN OFDM OLT ONU ONT - - - - - -
Optical Distribution Frame Optical Distribution Network
Orthogonal Frequency Division Multiplexing Optical Line Terminal
Optical Network Unit Optical Network Terminal OOK OTDM OTDR - - - On – off keying
Optical Time Division Multiplexing Optical Time Domain Reflectometer PLOAM
PD
- -
Physical Layer Operation, Administration and Maintenance Photodiode
PON PRBS
- -
Passive Optical Network Pseudo-Random bit sequence PSTN QoS RTT SMF SFP - - - - -
Public Switch Telephone Network Quality of Service
Round Trip Time Single Mode Fiber
Small Form-Factor Pluggable TB T-CONT - - Terminal Box Transmission Container TCP TDM - -
Transmission Control Protocol Time Division Multiplexing TDMA - Time Division Multiple Access
xvi US VDC - - Upstream
Voltage Direct Current VOA OTDM WJ - - -
Variable Optical Attenuator Wavelength Division Multiplexer With Jamming
WOA WOJ
- -
With Optical Attenuator Without Jamming
xvii
LIST OF SYMBOLS
B - Bit Data Rate
I - Sequence of Channel
N - Total Number of Channel
𝑃𝑏 - Power Budget
𝑃𝑇𝑖𝑛 - Transmitted Power
𝑃𝑅𝑚𝑖𝑛 - Minimum Receiver Sensitivity
𝑃𝑜 - Received Optical Power
𝑃𝑀 - Power Margin
𝐶𝑙 - Channel Losses
𝐽𝑃𝑇𝑖𝑛 - Jamming Power
xviii
LIST OF APPENDICES
APPENDIX TITLE PAGE
Appendix A GPON OLT SFP Specification 76
Appendix B Fiber Optical Splitter Ratio 78
1 CHAPTER 1
INTRODUCTION
1.1 Overview
Nowadays, most high-speed optical access network operate base on in Passive Optical Network (PON) technology which is a promising solution to the last-mile problem in the access networks as shown below in Figure 1.1. The optical fiber network offers a higher capacity to the subscribers compared to other access technologies such as coaxial, copper or hybrid fiber-coaxial (HFC). PONs are widely implemented due to the absence of the active devices in Optical Distribution Network (ODN). The subscribers use device called Optical Network Units (ONUs). Meanwhile, another device called Optical Line Termination (OLT) is located in the central office and is operated by service provider.
Figure 1.1 Scenarios of XG-PON1 with GPON [1]
2
Similar to other access network technologies, security is a very crucial aspect to be considered especially in the modern communication networks that are distinguished by large amount of data and high speeds. Moreover, securing the physical layer issues need urgent attention as it will become more critical in future PON that has much longer distance with the involvement of more users. One of the critical issues is the ONU users can intercept the data that sent to other ONUs due to the broadcasting mechanism in Time Division Multiplexing – Gigabit Passive Optical Network (TDM-GPON) as shown in Figure 1.2.
Figure 1.2 Broadcasting mechanisms in TDM-GPON [2]
Furthermore, in the current PON implementation, security requirements such as authentication and encryption are optional and, in the downstream communication from OLT to ONU, the secret encryption key is sent as sent as plain texts according to the ITU-T G.984 standard [3]. Meanwhile, the upstream communication link from ONU to OLT is not encrypted, and it is vulnerable to a variety of attacks, including denial of service (DoS) which jams a network, eavesdropping and masquerade that is also known as reply attack. Moreover, DoS attack can take place when a continuously transmitting upstream signal with high enough power at an Optical Network Unit (ONU) is injected to block all other ONUs from getting their data as illustrated in Figure 1.3 [4]. Furthermore, the attacker can exploit any reflection signal from the ODN splitter to eavesdrop the data of victim ONU [5]. Therefore, malicious in the upstream channel is difficult to identify due to passive nature elements in the optical network.
3
Figure 1.3 Scenario denial of service attack [4]
Based on the fact, this research aims to investigate the security issues and weaknesses in PON and to enhance the network security by deploying a passive device called optical attenuator in the upstream directions towards the splitter that thwart high power signal attack. By using a passive optical attenuator, the injection of higher power signal can be restricted up to an acceptable power level without any denial of service (DoS). The vest of this chapter describes the overview of the problem statements, objectives, the scope of work, work schedule and thesis outline.
1.2 Problem Statement
Passive optical networks come up with the standard security for data encryption, authentication, and key establishment. In the physical layer of the GPON, the upstream transitions from ONU to OLT are vulnerable to several attacks, including denial of service (DoS) which jams a network and prevent communication in a specific link. Therefore, Dos happens when an attacker injects a continuously signal with high power at a particular wavelength into the fiber to prevent other ONUs from getting their data and degrading the service. It is more serious for in-band jamming attack which occurs when the jamming wavelength is similar to the legitimate frequency. However, an out-of-band jamming attack can also degrade the quality or even denial the service of legitimate signal due to injection of high power
4
wavelength that had a different frequency from the legitimate signal and cause the denial of service due to the inter crosstalk and adjacent channels. Therefore, both attacks can jam the network and degrade the performance of the signal.
1.3 Objectives
The objectives of this research are:
1- To investigate the security issues and weaknesses in the physical layer of the GPON.
2- To simulate the deployment of a passive optical attenuator in the GPON in an upstream direction towards the splitter to prevent any high power signal injection attack.
3- To evaluate the feasibility and transmission performance of the proposed design.
1.4 Scope of Work
The scope of this research concentrates on three parts: 1. Simulation:
- The design and simulation of the GPON system based on TDM.
- The simulation tool that used to achieve the objectives is optisystem software.
2. System Parameters:
- ONU transmitted power range 0-5 dBm.
- Upstream wavelength 1310nm with the data rate 1.25 Gbps. - Continuous wave attacker signal.
- Distance: 1 km, 10 km, 20 km, and 30 km. - Receiver sensitivity -28 dBm.
5 3. Result Analysis:
- Evaluate correctness of GPON operation and evaluate the feasibility of an optical attenuator.
- Assess signal quality through BER and Q-factor.
1.5 Research Methodology
1.5.1 Work Schedule
- Research planning and schedule (Gantt chart)
Table 1.1 Project Schedule
1.6 Thesis Outlines
The project report comprises five chapters which describe the overall project progress and implementation. Each section discusses the different topics related to this project.
Chapter 1 briefly introduces an overview of this project, problem statement, objectives, the scope of work, research methodology and report outlines.
Chapter 2 discusses the literature review on the study of this project. It will include the GPON architecture. Besides that, it introduces the various types of attack, threats, and weakness in GPON. Lastly, review of the previous work which relates to this project is provided.
6
Chapter 3 focuses on the methodology used throughout this project and presents the design and simulation based on OTDM- GPON architecture for different models. The simulation tool that will be used to achieve the objectives is Optisystem software.
Chapter 4 discusses the evaluation and the results of the proposed system’s security and transmission performances parameters for other models. The performance parameter involves Eye diagram, Q factor, and BER and power budget.
Chapter 5 focuses on the conclusion of the whole project and recommendations for future development are given to enhance the security in PON.
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