Router Security Strategies: Securing IP Network Traffic Planes

• Copyright 2008
• Pages: 672
• Edition: 1st

• eBook (Watermarked)
• ISBN-10: 0-13-279836-0
• ISBN-13: 978-0-13-279836-5

Router Security Strategies: Securing IP Network Traffic Planes provides a compre-hensive approach to understand and implement IP traffic plane separation and protection on IP routers. This book details the distinct traffic planes of IP networks and the advanced techniques necessary to operationally secure them. This includes the data, control, management, and services planes that provide the infrastructure for IP networking. 

The first section provides a brief overview of the essential components of the Internet Protocol and IP networking. At the end of this section, you will understand the fundamental principles of defense in depth and breadth security as applied to IP traffic planes. Techniques to secure the IP data plane, IP control plane, IP management plane, and IP services plane are covered in detail in the second section.

The final section provides case studies from both the enterprise network and the service provider network perspectives. In this way, the individual IP traffic plane security techniques reviewed in the second section of the book are brought together to help you create an integrated, comprehensive defense in depth and breadth security architecture.

“Understanding and securing IP traffic planes are critical to the overall security posture of the IP infrastructure.  The techniques detailed in this book provide protection and instrumentation enabling operators to understand and defend against attacks. As the vulnerability economy continues to mature, it is critical for both vendors and network providers to collaboratively deliver these protections to the IP infrastructure.”

–Russell Smoak, Director, Technical Services, Security Intelligence Engineering, Cisco

Gregg Schudel, CCIE® No. 9591, joined Cisco in 2000 as a consulting system engineer supporting the U.S. service provider organization. Gregg focuses on IP core network security architectures and technology for interexchange carriers and web services providers.

David J. Smith, CCIE No. 1986, joined Cisco in 1995 and is a consulting system engineer supporting the service provider organization. David focuses on IP core and edge architectures including IP routing, MPLS technologies, QoS, infrastructure security, and network telemetry.

• Understand the operation of IP networks and routers
• Learn about the many threat models facing IP networks, Layer 2 Ethernet switching environments, and IPsec and MPLS VPN services

• Learn how to segment and protect each IP traffic plane by applying defense in depth and breadth principles

• Use security techniques such as ACLs, rate limiting, IP Options filtering, uRPF, QoS, RTBH, QPPB, and many others to protect the data plane of IP and switched Ethernet networks

• Secure the IP control plane with rACL, CoPP, GTSM, MD5, BGP and ICMP techniques and Layer 2 switched Ethernet-specific techniques
• Protect the IP management plane with password management, SNMP, SSH, NTP, AAA, as well as other VPN management, out-of-band management, and remote access management techniques

• Secure the IP services plane using recoloring, IP fragmentation control, MPLS label control, and other traffic classification and process control techniques

 This security book is part of the Cisco Press® Networking Technology Series. Security titles from Cisco Press help networking professionals secure critical data and resources, prevent and mitigate network attacks, and build end-to-end self-defending networks.

Table of Contents

Foreword xix

Introduction xx

Part I

IP Network and Traffic Plane Security Fundamentals 3

Chapter 1

Internet Protocol Operations Fundamentals 5

IP Network Concepts 5

Enterprise Networks 7

Service Provider Networks 9

IP Protocol Operations 11

IP Traffic Concepts 19

Transit IP Packets 20

Receive-Adjacency IP Packets 21

Exception IP and Non-IP Packets 22

Exception IP Packets 22

Non-IP Packets 23

IP Traffic Planes 24

Data Plane 25

Control Plane 27

Management Plane 29

Services Plane 30

IP Router Packet Processing Concepts 32

Process Switching 36

Fast Switching 39

Cisco Express Forwarding 44

Forwarding Information Base 44

Adjacency Table 45

CEF Operation 46

General IP Router Architecture Types 50

Centralized CPU-Based Architectures 50

Centralized ASIC-Based Architectures 52

Distributed CPU-Based Architectures 54

Distributed ASIC-Based Architectures 56

Summary 62

Review Questions 62

Further Reading 63

Chapter 2

Threat Models for IP Networks 65

Threats Against IP Network Infrastructures 65

Resource Exhaustion Attacks 66

Direct Attacks 67

Transit Attacks 70

Reflection Attacks 74

Spoofing Attacks 75

Transport Protocol Attacks 76

UDP Protocol Attacks 78

TCP Protocol Attacks 78

Routing Protocol Threats 81

Other IP Control Plane Threats 83

Unauthorized Access Attacks 85

Software Vulnerabilities 87

Malicious Network Reconnaissance 88

Threats Against Layer 2 Network Infrastructures 89

CAM Table Overflow Attacks 89

MAC Spoofing Attacks 90

VLAN Hopping Attacks 92

Private VLAN Attacks 93

STP Attacks 94

VTP Attacks 95

Threats Against IP VPN Network Infrastructures 96

MPLS VPN Threat Models 96

Threats Against the Customer Edge 98

Threats Against the Provider Edge 99

Threats Against the Provider Core 101

Threats Against the Inter-Provider Edge 103

Carrier Supporting Carrier Threats 103

Inter-AS VPN Threats 105

IPsec VPN Threat Models 108

Summary 111

Review Questions 112

Further Reading 113

Chapter 3

IP Network Traffic Plane Security Concepts 117

Principles of Defense in Depth and Breadth 117

Understanding Defense in Depth and Breadth Concepts 118

What Needs to Be Protected? 119

What Are Defensive Layers? 119

What Is the Operational Envelope of the Network? 122

What Is Your Organization’s Operational Model? 123

IP Network Traffic Planes: Defense in Depth and Breadth 123

Data Plane 124

Control Plane 124

Management Plane 125

Services Plane 126

Network Interface Types 127

Physical Interfaces 128

Logical Interfaces 131

Network Edge Security Concepts 133

Internet Edge 133

MPLS VPN Edge 136

Network Core Security Concepts 138

IP Core 139

MPLS VPN Core 140

Summary 141

Review Questions 141

Further Reading 142

Part II

Security Techniques for Protecting IP Traffic Planes 145

Chapter 4

IP Data Plane Security 147

Interface ACL Techniques 147

Unicast RPF Techniques 156

Strict uRPF 157

Loose uRPF 161

VRF Mode uRPF 163

Feasible uRPF 167

Flexible Packet Matching 168

QoS Techniques 170

Queuing 170

IP QoS Packet Coloring (Marking) 171

Rate Limiting 173

IP Options Techniques 174

Disable IP Source Routing 175

IP Options Selective Drop 175

ACL Support for Filtering IP Options 177

Control Plane Policing 178

ICMP Data Plane Mitigation Techniques 178

Disabling IP Directed Broadcasts 181

IP Sanity Checks 182

BGP Policy Enforcement Using QPPB 183

IP Routing Techniques 187

IP Network Core Infrastructure Hiding 187

IS-IS Advertise-Passive-Only 187

IP Network Edge External Link Protection 189

Protection Using More Specific IP Prefixes 190

Protection Using BGP Communities 191

Protection Using ACLs with Discontiguous Network Masks 192

Remotely Triggered Black Hole Filtering 193

IP Transport and Application Layer Techniques 200

TCP Intercept 200

Network Address Translation 201

IOS Firewall 203

IOS Intrusion Prevention System 205

Traffic Scrubbing 206

Deep Packet Inspection 207

Layer 2 Ethernet Security Techniques 208

Port Security 208

MAC Address—Based Traffic Blocking 209

Disable Auto Trunking 210

VLAN ACLs 211

IP Source Guard 212

Private VLANs 212

Traffic Storm Control 213

Unknown Unicast Flood Blocking 214

Summary 214

Review Questions 214

Further Reading 215

Chapter 5

IP Control Plane Security 219

Disabling Unused Control Plane Services 220

ICMP Techniques 220

Selective Packet Discard 222

SPD State Check 223

SPD Input Queue Check 226

SPD Monitoring and Tuning 226

IP Receive ACLs 230

IP Receive ACL Deployment Techniques 232

Activating an IP Receive ACL 233

IP Receive ACL Configuration Guidelines 234

IP Receive ACL Feature Support 241

Control Plane Policing 241

CoPP Configuration Guidelines 243

Defining CoPP Policies 243

Tuning CoPP Policies 252

Platform-Specific CoPP Implementation Details 260

Cisco 12000 CoPP Implementation 260

Cisco Catalyst 6500/Cisco 7600 CoPP Implementation 264

Neighbor Authentication 269

MD5 Authentication 270

Generalized TTL Security Mechanism 273

Protocol-Specific ACL Filters 277

BGP Security Techniques 279

BGP Prefix Filters 280

IP Prefix Limits 282

AS Path Limits 283

BGP Graceful Restart 283

Layer 2 Ethernet Control Plane Security 285

VTP Authentication 285

DHCP Snooping 286

Dynamic ARP Inspection 289

Sticky ARP 291

Spanning Tree Protocol 292

Summary 294

Review Questions 294

Further Reading 295

Chapter 6

IP Management Plane Security 299

Management Interfaces 300

Password Security 303

SNMP Security 306

Remote Terminal Access Security 309

Disabling Unused Management Plane Services 311

Disabling Idle User Sessions 315

System Banners 316

Secure IOS File Systems 319

Role-Based CLI Access 320

Management Plane Protection 324

Authentication, Authorization, and Accounting 326

AutoSecure 329

Network Telemetry and Security 330

Management VPN for MPLS VPNs 335

Summary 341

Review Questions 342

Further Reading 343

Chapter 7

IP Services Plane Security 347

Services Plane Overview 347

Quality of Service 350

QoS Mechanisms 351

Classification 353

Marking 353

Policing 354

Queuing 354

MQC 355

Packet Recoloring Example 356

Traffic Management Example 358

Securing QoS Services 361

MPLS VPN Services 362

MPLS VPN Overview 363

Customer Edge Security 364

Provider Edge Security 365

Infrastructure ACL 366

IP Receive ACL 366

Control Plane Policing 367

VRF Prefix Limits 367

IP Fragmentation and Reassembly 368

Provider Core Security 370

Disable IP TTL to MPLS TTL Propagation at the Network Edge 370

IP Fragmentation 371

Router Alert Label 371

Network SLAs 372

Inter-Provider Edge Security 372

Carrier Supporting Carrier Security 373

Inter-AS VPN Security 374

IPsec VPN Services 376

IPsec VPN Overview 376

IKE 377

IPsec 378

Securing IPsec VPN Services 386

IKE Security 386

Fragmentation 387

IPsec VPN Access Control 391

QoS 393

Other IPsec Security-Related Features 394

Other Services 394

SSL VPN Services 395

VoIP Services 396

Video Services 397

Summary 399

Review Questions 399

Further Reading 400

Part III

Case Studies 403

Chapter 8

Enterprise Network Case Studies 405

Case Study 1: IPsec VPN and Internet Access 406

Network Topology and Requirements 407

Router Configuration 409

Data Plane 418

Control Plane 420

Management Plane 422

Services Plane 424

Case Study 2: MPLS VPN 426

Network Topology and Requirements 426

Router Configuration 428

Data Plane 435

Control Plane 437

Management Plane 438

Services Plane 440

Summary 441

Further Reading 441

Chapter 9

Service Provider Network Case Studies 443

Case Study 1: IPsec VPN and Internet Access 444

Network Topology and Requirements 445

Router Configuration 448

Data Plane 455

Control Plane 458

Management Plane 460

Services Plane 463

Case Study 2: MPLS VPN 463

Network Topology and Requirements 464

Router Configuration 467

Data Plane 474

Control Plane 474

Management Plane 477

Services Plane 481

Summary 483

Further Reading 483

Part IV

Appendixes 485

Appendix A

Answers to Chapter Review Questions 487

Appendix B

IP Protocol Headers 497

IP Version 4 Header 499

TCP Header 510

UDP Header 518

ICMP Header 521

ICMP Echo Request/Echo Reply Query Message Headers 525

ICMP Time to Live Exceeded in Transit Error Message Header 529

ICMP Destination Unreachable, Fragmentation Needed and Don’t Fragment was

Set Error Message Header 533

Other ICMP Destination Unreachable Error Message Headers 539

Ethernet/802.1Q Header 543

IEEE 802.3 Ethernet Frame Header Format 543

IEEE 802.1Q VLAN Header Format 547

MPLS Protocol Header 551

Further Reading 554

Appendix C

Cisco IOS to IOS XR Security Transition 557

Data Plane Security Commands 558

Control Plane Security Commands 562

Management Plane Security Commands 578

Services Plane Security Commands 592

Further Reading 595

Appendix D

Security Incident Handling 597

Six Phases of Incident Response 597

Preparation 598

Understand the Threats 598

Deploy Defense in Depth and Breadth Security Strategies 598

Establish Well-Defined Incident Response Procedures 599

Establish an Incident Response Team 600

Identification 600

Classification 600

Traceback 601

Reaction 601

Post-Mortem Analysis 602

Cisco Product Security 602

Cisco Security Vulnerability Policy 603

Cisco Computer and Network Security 603

Cisco Safety and Security 603

Cisco IPS Signature Pack Updates and Archives 603

Cisco Security Center 603

Cisco IntelliShield Alert Manager Service 603

Cisco Software Center 604

Industry Security Organizations 604

Regional Network Operators Groups 605

Further Reading 606

Index

608

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