IPv6 Security (Networking Technology Series)

IPv6 Security (Networking Technology Series)

by Scott Hogg, Eric Vyncke


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IPv6 Security

Protection measures for the next Internet Protocol

As the world’s networks migrate to the IPv6 protocol, networking professionals need a clearer understanding of the security risks, threats, and challenges this transition presents. In IPv6 Security, two of the world’s leading Internet security practitioners review each potential security issue introduced by IPv6 networking and present today’s best solutions.

IPv6 Security offers guidance for avoiding security problems prior to widespread IPv6 deployment. The book covers every component of today’s networks, identifying specific security deficiencies that occur within IPv6 environments and demonstrating how to combat them.

The authors describe best practices for identifying and resolving weaknesses as you maintain a dual stack network. Then they describe the security mechanisms you need to implement as you migrate to an IPv6-only network. The authors survey the techniques hackers might use to try to breach your network, such as IPv6 network reconnaissance, address spoofing, traffic interception, denial of service, and tunnel injection.

The authors also turn to Cisco® products and protection mechanisms. You learn how to use Cisco IOS® and ASA firewalls and ACLs to selectively filter IPv6 traffic. You also learn about securing hosts with Cisco Security Agent 6.0 and about securing a network with IOS routers and switches. Multiple examples are explained for Windows, Linux, FreeBSD, and Solaris hosts. The authors offer detailed examples that are consistent with today’s best practices and easy to adapt to virtually any IPv6 environment.

Scott Hogg, CCIE® No. 5133, is Director of Advanced Technology Services at Global Technology Resources, Inc. (GTRI). He is responsible for setting the company’s technical direction and helping it create service offerings for emerging technologies such as IPv6. He is the Chair of the Rocky Mountain IPv6 Task Force.

Eric Vyncke, Cisco Distinguished System Engineer, consults on security issues throughout Europe. He has 20 years’ experience in security and teaches security seminars as a guest professor at universities throughout Belgium. He also participates in the Internet Engineering Task Force (IETF) and has helped several organizations deploy IPv6 securely.

  • Understand why IPv6 is already a latent threat in your IPv4-only network
  • Plan ahead to avoid IPv6 security problems before widespread deployment
  • Identify known areas of weakness in IPv6 security and the current state of attack tools and hacker skills
  • Understand each high-level approach to securing IPv6 and learn when to use each
  • Protect service provider networks, perimeters, LANs, and host/server connections
  • Harden IPv6 network devices against attack
  • Utilize IPsec in IPv6 environments
  • Secure mobile IPv6 networks
  • Secure transition mechanisms in use during the migration from IPv4 to IPv6
  • Monitor IPv6 security
  • Understand the security implications of the IPv6 protocol, including issues related to ICMPv6 and the IPv6 header structure
  • Protect your network against large-scale threats by using perimeter filtering techniques and service provider–focused security practices
  • Understand the vulnerabilities that exist on IPv6 access networks and learn solutions for mitigating each

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.

Category: Networking: Security

Covers: IPv6 Security

Product Details

ISBN-13: 9781587055942
Publisher: Cisco Press
Publication date: 01/05/2009
Series: Networking Technology Series
Pages: 576
Sales rank: 653,497
Product dimensions: 7.30(w) x 9.00(h) x 1.30(d)

About the Author

Scott Hogg, CCIE No. 5133, has been a network computing consultant for more than 17 years. Scott provides network engineering, security consulting, and training services, focusing on creating reliable, high-performance, secure, manageable, and cost-effective network solutions. He has a bachelor’s degree in computer science from Colorado State University and a master’s degree in telecommunications from the University of Colorado. In addition to his CCIE he has his CISSP (No. 4610) and many other vendor and industry certifications. Scott has designed, implemented, and troubleshot networks for many large enterprises, service providers, and government organizations. For the past eight years, Scott has been researching IPv6 technologies. Scott has written several white papers on IPv6 and has given numerous presentations and demonstrations of IPv6 technologies. He is also currently the chair of the Rocky Mountain IPv6 Task Force and the Director of Advanced Technology Services at Global Technology Resources, Inc. (GTRI), a Cisco Gold partner headquartered in Denver, Colorado.

Eric Vynckeis a Distinguished System Engineer for Cisco working as a technical consultant for security covering Europe. His main area of expertise for 20 years has been security from Layer 2 to applications. He has helped several organizations deploy IPv6 securely. For the past eight years, Eric has participated in the Internet Engineering Task Force (IETF) (he is the author of RFC 3585). Eric is a frequent speaker at security events (notably Cisco Live [formerly Networkers]) and is also a guest professor at Belgian Universities for security seminars. He has a master’s degree in computer science engineering from the University of Liège in Belgium. He worked as a research assistant in the same university before joining Network Research Belgium, where he was the head of R&D; he then joined Siemens as a project manager for security projects including a proxy firewall. He coauthored the Cisco Press book LAN Switch Security: What Hackers Know About Your Switches. He is CISSP No. 75165.

Table of Contents


Chapter 1 Introduction to IPv6 Security

Reintroduction to IPv6 3

IPv6 Update 6

IPv6 Vulnerabilities 7

Hacker Experience 8

IPv6 Security Mitigation Techniques 9


Recommended Readings and Resources

Chapter 2 IPv6 Protocol Security Vulnerabilities

The IPv6 Protocol Header


ICMPv6 Functions and Message Types

ICMPv6 Attacks and Mitigation Techniques

Multicast Security

Extension Header Threats

Extension Header Overview

Extension Header Vulnerabilities

Hop-by-Hop Options Header and Destination Options Header

IPv6 Extension Header Fuzzing

Router Alert Attack

Routing Headers

RH0 Attack

Preventing RH0 Attacks

Additional Router Header Attack Mitigation Techniques

Fragmentation Header

Overview of Packet Fragmentation Issues

Fragmentation Attacks

Preventing Fragmentation Attacks

Virtual Fragment Reassembly

Unknown Option Headers

Upper-Layer Headers

Reconnaissance on IPv6 Networks

Scanning and Assessing the Target

Registry Checking

Automated Reconnaissance

Speeding Up the Scanning Process

Leveraging Multicast for Reconnaissance

Automated Reconnaissance Tools

Sniffing to Find Nodes

Neighbor Cache

Node Information Queries

Protecting Against Reconnaissance Attacks

Layer 3 and Layer 4 Spoofing



Chapter 3 IPv6 Internet Security

Large-Scale Internet Threats

Packet Flooding

Internet Worms

Worm Propagation

Speeding Worm Propagation in IPv6

Current IPv6 Worms

Preventing IPv6 Worms

Distributed Denial of Service and Botnets

DDoS on IPv6 Networks

Attack Filtering

Attacker Traceback

Black Holes and Dark Nets

Ingress/Egress Filtering

Filtering IPv6 Traffic

Filtering on Allocated Addresses

Bogon Filtering

Bogon Filtering Challenges and Automation

Securing BGP Sessions

Explicitly Configured BGP Peers

Using BGP Session Shared Secrets

Leveraging an IPsec Tunnel

Using Loopback Addresses on BGP Peers

Controlling the Time-to-Live (TTL) on BGP Packets

Filtering on the Peering Interface

Using Link-Local Peering

Link-Local Addresses and the BGP Next-Hop Address

Drawbacks of Using Link-Local Addresses

Preventing Long AS Paths

Limiting the Number of Prefixes Received

Preventing BGP Updates Containing Private AS Numbers

Maximizing BGP Peer Availability

Disabling Route-Flap Dampening

Disabling Fast External Fallover

Enabling Graceful Restart and Route Refresh or Soft Reconfiguration

BGP Connection Resets

Logging BGP Neighbor Activity

Securing IGP

Extreme Measures for Securing Communications Between BGP Peers

IPv6 over MPLS Security

Using Static IPv6 over IPv4 Tunnels Between PE Routers

Using 6PE

Using 6VPE to Create IPv6-Aware VRFs

Customer Premises Equipment

Prefix Delegation Threats



Multihoming Issues



Chapter 4 IPv6 Perimeter Security

IPv6 Firewalls

Filtering IPv6 Unallocated Addresses

Additional Filtering Considerations

Firewalls and IPv6 Headers

Inspecting Tunneled Traffic

Layer 2 Firewalls

Firewalls Generate ICMP Unreachables

Logging and Performance

Firewalls and NAT

Cisco IOS Router ACLs

Implicit IPv6 ACL Rules

Internet ACL Example

IPv6 Reflexive ACLs

Cisco IOS Firewall

Configuring IOS Firewall

IOS Firewall Example

IOS Firewall Port-to-Application Mapping for IPv6

Cisco PIX/ASA/FWSM Firewalls

Configuring Firewall Interfaces

Management Access

Configuring Routes

Security Policy Configuration

Object Group Policy Configuration

Fragmentation Protection

Checking Traffic Statistics

Neighbor Discovery Protocol Protections



Chapter 5 Local Network Security

Why Layer 2 Is Important

ICMPv6 Layer 2 Vulnerabilities for IPv6

Stateless Address Autoconfiguration Issues

Neighbor Discovery Issues

Duplicate Address Detection Issues

Redirect Issues

ICMPv6 Protocol Protection

Secure Neighbor Discovery

Implementing CGA Addresses in Cisco IOS

Understanding the Challenges with SEND

Network Detection of ICMPv6 Attacks

Detecting Rogue RA Messages

Detecting NDP Attacks

Network Mitigation Against ICMPv6 Attacks


Reducing the Target Scope


Extending IPv4 Switch Security to IPv6

Privacy Extension Addresses for the Better and the Worse

DHCPv6 Threats and Mitigation

Threats Against DHCPv6

Mitigating DHCPv6 Attacks

Mitigating the Starvation Attack

Mitigating the DoS Attack

Mitigating the Scanning

Mitigating the Rogue DHCPv6 Server

Point-to-Point Link

Endpoint Security



Chapter 6 Hardening IPv6 Network Devices

Threats Against Network Devices

Cisco IOS Versions

Disabling Unnecessary Network Services

Interface Hardening

Limiting Router Access

Physical Access Security

Securing Console Access

Securing Passwords

VTY Port Access Controls

AAA for Routers

HTTP Access

IPv6 Device Management

Loopback and Null Interfaces

Management Interfaces

Securing SNMP Communications

Threats Against Interior Routing Protocol

RIPng Security

EIGRPv6 Security

IS-IS Security

OSPF Version 3 Security

First-Hop Redundancy Protocol Security

Neighbor Unreachability Detection



Controlling Resources

Infrastructure ACLs

Receive ACLs

Control Plane Policing

QoS Threats



Chapter 7 Server and Host Security

IPv6 Host Security

Host Processing of ICMPv6

Services Listening on Ports

Microsoft Windows



Sun Solaris

Checking the Neighbor Cache

Microsoft Windows



Sun Solaris

Detecting Unwanted Tunnels

Microsoft Windows



Sun Solaris

IPv6 Forwarding

Microsoft Windows



Sun Solaris

Address Selection Issues

Microsoft Windows



Sun Solaris

Host Firewalls

Microsoft Windows Firewall

Linux Firewalls

BSD Firewalls

OpenBSD Packet Filter



Sun Solaris

Securing Hosts with Cisco Security Agent 6.0



Chapter 8 IPsec and SSL Virtual Private Networks

IP Security with IPv6

IPsec Extension Headers

IPsec Modes of Operation

Internet Key Exchange (IKE)

IKE Version 2

IPsec with Network Address Translation

IPv6 and IPsec

Host-to-Host IPsec

Site-to-Site IPsec Configuration

IPv6 IPsec over IPv4 Example

Configuring IPv6 IPsec over IPv4

Verifying the IPsec State

Adding Some Extra Security

Dynamic Crypto Maps for Multiple Sites

IPv6 IPsec Example

Configuring IPsec over IPv6

Checking the IPsec Status

Dynamic Multipoint VPN

Configuring DMVPN for IPv6

Verifying the DMVPN at the Hub

Verifying the DMVPN at the Spoke

Remote Access with IPsec




Chapter 9 Security for IPv6 Mobility

Mobile IPv6 Operation

MIPv6 Messages

Indirect Mode

Home Agent Address Determination

Direct Mode

Threats Linked to MIPv6

Protecting the Mobile Device Software

Rogue Home Agent

Mobile Media Security

Man-in-the-Middle Threats

Connection Interception

Spoofing MN-to-CN Bindings

DoS Attacks

Using IPsec with MIPv6

Filtering for MIPv6

Filters at the CN

Filters at the MN/Foreign Link

Filters at the HA

Other IPv6 Mobility Protocols

Additional IETF Mobile IPv6 Protocols

Network Mobility (NEMO)

IEEE .16e

Mobile Ad-hoc Networks



Chapter 10 Securing the Transition Mechanisms

Understanding IPv4-to-IPv6 Transition Techniques



Configured Tunnels

6to4 Tunnels

ISATAP Tunnels

Teredo Tunnels


Protocol Translation

Implementing Dual-Stack Security

Exploiting Dual-Stack Environment

Protecting Dual-Stack Hosts

Hacking the Tunnels

Securing Static Tunnels

Securing Dynamic Tunnels




Securing 6VPE

Attacking NAT-PT

IPv6 Latent Threats Against IPv4 Networks



Chapter 11 Security Monitoring

Managing and Monitoring IPv6 Networks

Router Interface Performance

Device Performance Monitoring

SNMP MIBs for Managing IPv6 Networks

IPv6-Capable SNMP Management Tools

NetFlow Analysis

Router Syslog Messages

Benefits of Accurate Time

Managing IPv6 Tunnels

Using Forensics

Using Intrusion Detection and Prevention Systems

Cisco IPS Version 6.1

Testing the IPS Signatures

Managing Security Information with CS-MARS

Managing the Security Configuration



Chapter 12 IPv6 Security Conclusions

Comparing IPv4 and IPv6 Security

Similarities Between IPv4 and IPv6

Differences Between IPv4 and IPv6

Changing Security Perimeter

Creating an IPv6 Security Policy

Network Perimeter

Extension Headers

LAN Threats

Host and Device Hardening

Transition Mechanisms


Security Management

On the Horizon

Consolidated List of Recommendations



1587055945 TOC 11/25/2008



Internet Protocol version 6 (IPv6) is the next version of the protocol that is used for communications on the Internet. IPv6 is a protocol that has been in existence for many years, but it has not yet replaced IPv4. IPv4 has some limitations that were not anticipated when it was first created. Because IPv6 overcomes many of these limitations, it is the only viable long-term replacement for IPv4.

While the migration to IPv6 has started, it is still in its early stages. Many international organizations already have IPv6 networks, the U.S. federal organizations are working on their transitions to IPv6, and others are contemplating what IPv6 means to them. However, many organizations already have IPv6 running on their networks and they do not even realize it. Many computer operating systems now default to running both IPv4 and IPv6, which could cause security vulnerabilities if one is less secure than the other. IPv6 security vulnerabilities currently exist, and as the popularity of the IPv6 protocol increases, so do the number of threats.

When a security officer wants to secure an organization, he must be aware of all potential threats, even if this threat is a ten-year-old protocol that represents less than 1 percent of the overall Internet traffic in 2008. Don’t be blinded by this 1 percent: This figure is doomed to increase in the coming years, and chances are good that your network is already exposed to some IPv6 threats. It’s better to be safe than sorry.

Just like the early deployment of many technologies, security is often left to the final stages of implementation. Our intent in writing this book is to improve the security ofearly IPv6 deployments from day one. Any organization considering or already in the midst of transitioning to IPv6 does not want to deploy a new technology that cannot be secured right from the outset. The transition to IPv6 is inevitable, and therefore this book can help you understand the threats that exist in IPv6 networks and give you ways to protect against them. Therefore, this book gives guidance on how to improve the security of IPv6 networks.

Goals and Methods

Currently, many organizations have slowed their migration to IPv6 because they realize that the security products for IPv6 might be insufficient, despite the fact that the network infrastructure is ready to support IPv6 transport. They realize that they cannot deploy IPv6 without first considering the security of this new protocol. This book intends to survey the threats against IPv6 networks and provide solutions to mitigate those threats. It covers the issues and the best current practices.

This book is arranged so that it covers the threats first and then describes ways to combat these threats. By outlining all the risks and showing that a solution exists for each threat, you can feel more comfortable with continuing the transition to IPv6. You learn about techniques attackers might use to breach your networks and what Cisco products to use to protect the networks.

However, showing attacks without solutions is socially irresponsible, so the focus is on the current techniques that are available to make the IPv6 network more secure and on the best current practices.

By reading this book, you can gain an understanding of the full range of IPv6 security topics.

Who Should Read This Book

This book is intended to be read by people in the IT industry who are responsible for securing computer networks. You should already know the basics of the IPv6 protocol and networking technology. This book is not an introduction to IPv6. There are many good books and online resources that can teach you about IPv6, and there are many great books on computer network security.

The intent of this book is to dive deeper into the protocol and discuss the protocol details from a security practitioner’s perspective. It is a book for experts by experts. It covers the theory but at the same time gives practical examples that can be implemented.

How This Book Is Organized

This book starts with a foundation of the security aspects of the IPv6 protocol. The early topics of this book are arranged from the outward perimeter of an organization’s network inward to the LAN and server farms. The later chapters of the book cover advanced topics. This book can be read completely from start to finish; however, if you want to “skip around,” that is fine. You should eventually read every chapter to gain a comprehensive knowledge of the subject matter.

Some of the information (such as tables and commands) in this book is for reference. You should refer back to this book when it comes time to implement. This gives you cookie-cutter examples to follow that should be in line with the best current practices for securing IPv6. However, do not just go through this book and implement every command listed. Perform some of your own basic research on these commands to make sure that they perform exactly what you intend your network to do.

IPv6 security is an incredibly active research area, and new protocols and new products will continually be developed after this book is written. It is our goal that the “shelf life” of this book is many years because the concepts will still be valid even as Cisco security products continue to evolve with the threat landscape. Every effort was made to make this book as current as possible at the time it was published, but you are advised to check whether new methods are available at the time of reading. The IPv6 security field is quickly evolving as IPv6 gets more widely deployed.

Chapters 1 through 12 cover the following topics:

•Chapter 1, “Introduction to IPv6 Security”: This short chapter reintroduces IPv6, describes how widely it is deployed, discusses its vulnerabilities, and identifies what hackers already know about IPv6. Some initial mitigation techniques are presented.
•Chapter 2, “IPv6 Protocol Security Vulnerabilities”: This chapter discusses the aspects of the IPv6 protocol itself that have security implications. Security issues related to ICMPv6 and the IPv6 header structure are covered. Demonstrations are conducted that show the protocol vulnerabilities, and solutions are given to mitigate those risks. This chapter also covers security issues of IPv6 network reconnaissance and address spoofing.
•Chapter 3, “IPv6 Internet Security”: This chapter covers the large-scale threats against the IPv6 Internet and describes perimeter-filtering techniques that can help protect against those threats. Security for BGP peering is detailed in addition to other service provider–focused security practices. IPv6 MPLS security, security of customer equipment, IPv6 prefix delegation, and multihoming are reviewed.
•Chapter 4, “IPv6 Perimeter Security”: This chapter covers the security threats that exist for perimeter networks that utilize IPv6. The chapter covers common filtering techniques that are deployed at the perimeter of the network. This chapter also covers IPv6 access lists, the IOS Firewall feature set, and the PIX/ASA/FWSM firewalls.
•Chapter 5, “Local Network Security”: This chapter examines the threats against LANs. Many vulnerabilities exist on IPv6 access networks, and these vulnerabilities are covered along with many solutions for mitigating them. The chapter covers issues related to Neighbor Discovery Protocol, autoconfiguration addressing, and DHCPv6 communications on a LAN. This chapter also reviews SEND and describes how it can be implemented.
•Chapter 6, “Hardening IPv6 Network Devices”: This chapter covers the security improvements that can be made to a network device running IPv6. Techniques for securing the management of network devices are reviewed. This chapter reviews ways to secure routing protocols and covers first-hop router redundancy protocols. Techniques for controlling the device’s resources are detailed in addition to ways to control network traffic.
•Chapter 7, “Server and Host Security”: This chapter covers the ways to secure a computer running IPv6. It is important to harden IPv6 nodes from the threats that exist. Microsoft, Linux, BSD, and Solaris operating system IPv6 security techniques are detailed. This chapter covers how host-based firewalls and Cisco Security Agent (CSA) can be used to protect IPv6 hosts.
•Chapter 8, “IPsec and SSL Virtual Private Networks”: This chapter covers the basics of IPsec. The chapter reviews techniques for setting up site-to-site VPN links using IPv6, dynamic multipoint VPNs, as well as remote-access VPNs. The use of ISATAP over an IPsec client connection and the use of SSL VPNs with AnyConnect client are covered.
•Chapter 9, “Security for IPv6 Mobility”: This chapter covers Mobile IPv6 and describes how securing this protocol can be challenging. Mobile IPv6 is reviewed, and the security implications are discussed. This chapter gives recommendations on how Mobile IPv6 can be used responsibly and safely. Additional IPv6-capable mobility solutions are covered along with their security implications.
•Chapter 10, “Securing the Transition Mechanisms”: This chapter discusses the various techniques that are used to help organizations migrate from IPv4 to IPv6. Dual-stack, tunnel, and NAT migration techniques are covered along with their security issues. Each of these techniques has its own security implications and solutions for securing the traffic. This chapter covers the threats by showing examples of how an attacker might try to infiltrate a network. The security protections that can be used to keep the network safe during migration are also covered.
•Chapter 11, “Security Monitoring”: This chapter covers the various systems that are currently available to monitor the security of IPv6 networks. Monitoring a network and the computers on the network is a critical aspect of any security practice. IPv6 networks are the same in this regard and must be managed appropriately. The topics of forensics, intrusion detection and prevention, security information management, and configuration management are covered.
•Chapter 12, “IPv6 Security Conclusions”: This chapter summarizes the common themes discussed throughout the book. Commonalities between IPv4 security and IPv6 security are discussed. This chapter contains discussions about creating IPv6-specific security policies. This chapter also reviews what the future holds for IPv6 security. A consolidated list of IPv6 security recommendations is provided.

© Copyright Pearson Education. All rights reserved.

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IPv6 Security 5 out of 5 based on 0 ratings. 2 reviews.
DMolfetas More than 1 year ago
This reference explains how to secure an IPV6 network across the major boundaries and potential targets for breaches: LAN, WAN, firewall-perimeter, VPN, and locking down the router. Many of these guidelines are also relevant to an IPV4 infrastructure and this book is a resource for both network and information security specialists who construct and maintain production environments. IPV6 Security encompasses two sets of concepts: the Self Defending Network's Collaboration, Integration, and Adaptability and InfoSec's Confidentiality, Integrity and Availability. Some noteworthy citations for ensuring security include configuring a WAN BGP session with a Message Digest 5 (MD5) algorithm password and using Secure Neighbor Discovery (SEND) for safeguarding IPV6 layer two addresses. As IPV6 uses named access control lists instead of numbered ACLs, the book explores both access control entries (ACE) and the IPV6 IOS commands in detail. Security is also examined for the IPV6 routing protocols, which include EIGRPv6, RIPng, and OSPFv3. Endpoint and server safeguards are also discussed since BSD, Vista and Server 2008 have IPV6 support incorporated in the operating systems. Since adopting a protection policy is one segment of a secure network, utilities such as Multi-Router Traffic Grapher (MRTG) and CiscoWorks LAN Management Solution are examined for capturing data traffic statistics. Setting a baseline and measuring performance are necessary steps for detecting when a security violation has occurred. IPV6 Security is a must-read resource for those actively engaged in both IPV6 and security implementation. As IPV6 is in its beginning stages and is incorporated into dual-stack architectures with IPV4, there is much to learn. Since information security should always be a consideration, this book offers many examples to consider for protecting the integrity of both the network and data. From a scale of 1-5, this book receives a 5 ranking and I look forward to reading the next book from the authors.
network_guy More than 1 year ago
In my quest to learn and transition to IPv6 from IPv4, I learned that you have to have a stable background in learning new materials. IPv6 has been around awhile but now just getting a little more used from many companies and myself. Along with the transition comes concerns with security as IPv4 didn't have much security. With this book [IPv6 Security] the authors took the technology and really explained some very detail and practical aspects of IPv6 with security enhancements. I realyy enjoyed reading this book. The authors did a good job in bringing the IPv6 protocol to the forefront by explaning different parts of the security features like mobile security, running dual stack protocols, IPv6 deployment solutions, address spoofing, and many other network problems. The authors used Cisco products to explain the security mechanisms. they also teach you how to use Cisco IOS® and ASA firewalls and ACLs to filter out IPv6 traffic. This book is one for the ages in describing, explaining, and implementing security in an IPv6 netowrk. Overall the book is great. I gave it a 5 start because of the deep explaining of the IPv6 protocol and security.