Chapter 1: Introduction to IPv6

Cisco Press

This chapter covers the following subjects:

  • Reintroduction to IPv6: Brief overview of IPv6

  • IPv6 Update: Describes the current state of IPv6 adoption

  • IPv6 Vulnerabilities: Describes the weaknesses in IPv6 that are key areas of focus

  • Hacker Experience: Covers the current state of attack tools and skills

  • IPv6 Security Mitigation Techniques: Introduces the high-level methods of securing IPv6

The Internet Protocol (IP) is the most widely used communications protocol. Because it is the most pervasive communication technology, it is the focus of hundreds of thousands of IT professionals like you. Because so many people rely on the protocol, the safety of communications is top of mind. The security research that is performed on IP is conducted by both benevolent and malevolent people. All the security research has caused many patches and adjustments to IP, as it has been deployed internationally. In hindsight, it would have been better if deeper consideration were given to the security of the protocol before it was extensively deployed.

This book provides you with insight into the security ramifications of a new version of IP and provides guidance to avoid issues prior to deployment. This chapter provides a brief background on this next version of IP, IPv6. You learn why it is important to consider the security for IPv6 before its wide-scale deployment. A review of the current risks and industry knowledge of the vulnerabilities is provided, as well as the common ways that IPv6 can be secured.

Reintroduction to IPv6

The Internet Engineering Task Force (IETF) is the organization that is responsible for defining the Internet Protocol standards. When the IETF developed IPv4, the global expansion of the Internet and the current Internet security issues were not anticipated. In IPv4's original design, network security was only given minor consideration. In the 1980s, when IPv4 was developing, the "Internet" was constructed by a set of cooperative organizations. As IPv4 was developed and the Internet explosion took place in the 1990s, Internet threats became prolific. If the current environment of Internet threats could have been predicted when IPv4 was being developed, the protocol would have had more security measures incorporated into its design.

In the early 1990s, the IETF realized that a new version of IP would be needed, and the Task Force started by drafting the new protocol's requirements. IP Next Generation (IPng) was created, which then became IPv6 (RFC 1883). IPv6 is the second network layer standard protocol that follows IPv4 for computer communications across the Internet and other computer networks. IPv6 offers several compelling functions and is really the next step in the evolution of the Internet Protocol. These improvements came in the form of increased address size, a streamlined header format, extensible headers, and the ability to preserve the confidentiality and integrity of communications. The IPv6 protocol was then fully standardized at the end of 1998 in RFC 2460, which defines the header structure. IPv6 is now ready to overcome many of the deficiencies in the current IPv4 protocol and to create new ways of communicating that IPv4 cannot support.

IPv6 provides several improvements over its predecessor. The advantages of IPv6 are detailed in many other books on IPv6. However, the following list summarizes the characteristics of IPv6 and the improvements it can deliver:

  • Larger address space: Increased address size from 32 bits to 128 bits

  • Streamlined protocol header: Improves packet-forwarding efficiency

  • Stateless autoconfiguration: The ability for nodes to determine their own address

  • Multicast: Increased use of efficient one-to-many communications

  • Jumbograms: The ability to have very large packet payloads for greater efficiency

  • Network layer security: Encryption and authentication of communications

  • Quality of service (QoS) capabilities: QoS markings of packets and flow labels that help identify priority traffic

  • Anycast: Redundant services using nonunique addresses

  • Mobility: Simpler handling of mobile or roaming nodes


NOTE - Remember the following IPv6 terminology:

  • A node is any system (computer, router, and so on) that communicates IPv6.

  • A router is any Layer 3 device capable of routing and forwarding IPv6 packets.

  • A host is a node that is a computer or any other access device that is not a router.

  • A packet is the Layer 3 message sourced from an IPv6 node destined for an IPv6 address.


During the development of IPv6, one of the requirements was that this new protocol must have flexible transition mechanisms. It should be easy to transition to this new protocol gradually, over many years. Because it was evident that IPv6 would become very popular, the transition would need to be slow and methodical.

Running both IPv4 and IPv6 at the same time, called dual stack, is one of the primary transition strategies. This concept describes the scenario in which a router supports two or more different routed protocols and forwards each type of traffic, independent of the behavior of the other routed protocol. Seasoned network engineers will recall the concept of "ships-in-the-night routing." This term refers to the fact that packets from either protocol can pass by each other without affecting each other or having anything to do with each other. Because "dual stacking" can be a dominant migration strategy, running a network with both protocols can open that network to attacks on both protocols. Attacks can also evolve that leverage a combination of vulnerabilities in IPv4 and IPv6.

In addition to dual stack, the transition to IPv6 involves various types of tunneling approaches where IPv6 is carried over IPv4 networks that have yet to migrate to IPv6. There will likely be attacks on the transition mechanisms themselves to gain access to either the IPv4 or IPv6 portions of a network. The security of IPv6 systems must be assessed before IPv6 is permitted to be enabled on current and future networks and systems.

Because IPv6 and IPv4 are both network layer protocols, many of the network layer vulnerabilities are therefore similar. However, because the protocol layers above and below the IP layer remain the same for either IP version, many of those attacks will not change. Because the two protocols are related, the similarities between the protocols can create similar attack patterns. IPv6 could improve security in some areas, but in other areas, it could also open new threats. Chapter 2, "IPv6 Protocol Vulnerabilities," focuses on the attacks against the IPv6 protocol itself and describes ways to protect against them.

IPv6 has continued to evolve since December 1998, when the IETF published RFC 2460. As the number of available IPv4 public addresses has reduced, IPv6 has become more attractive. In fact, IPv6 is the only viable solution to this IP address depletion problem. Many of the problems in current IPv4 networks relate to address conservation. For example, perpetuating the use of Network Address Translation (NAT) and double-NAT is not a realistic long-term strategy for Internet expansion.

Today, the identity of users on the Internet is often unknown, and this has created an environment where attackers can easily operate. The use of anonymizer tools such as Tor and open proxies and the use of NAT allow users to hide their source IP addresses and allow hackers to operate without their targets knowing much about the source of the messages. NAT is often misunderstood as a security protection measure because it hides the internal addresses and thus obfuscates the internal network topology. Many network administrators feel a false sense of security and put too much faith in NAT. NAT breaks the use of the full end-to-end communication model that IP Security (IPsec) needs to be fully effective. The firewalls that perform the NAT function have difficulty maintaining the NAT state during failover. Troubleshooting application traffic that flows through a NAT is often difficult. When using IPv6, the use of NAT is not necessary because of the large amount of addresses available. Each node has its own unique address, and it can use that address for internal and external communications.

After the core, distribution, and access layers are dual-stack enabled, the computer systems themselves can be IPv6 enabled. After this takes place, the system administrators can start to enable IPsec tunnels between IPv6-enabled nodes to provide confidentiality and the integrity of the communications between systems. This provides a greater level of security over current unencrypted IPv4 implementations. IPsec deployments utilizing both authentication and encryption are rarely used today for computer-to-computer communication. Today the common method of using IPsec only encrypts the payload in tunnel mode because the NATs that are in place prevent authenticating the header. However, communications between critical systems can optionally be secured with IPv6 IPsec, using both authentication and encryption. Chapter 8, "IPv6 Security (IPsec)," provides further details on how to secure IPv6 communications. IPv6 can uniquely provide this clear end-to-end secure communication because NAT is not needed when IPv6 can provide every node with a globally unique IP address.

IPv6 Update

IPv6 is becoming a reality. The many years of early protocol research have paid dividends with products that easily interoperate. Several early IPv6 research groups have disbanded because the protocol is starting to move into the transition phase. The 6BONE (phased out with RFC 3701) and the KAME (http://www.kame.net) IPv6 research and development projects have wound down and given way to more IPv6 products from a wide variety of vendors. Deployment of IPv6 is not a question of if but when. IPv6 is an eventuality.

The transition to IPv6 continues to take place around the world. The protocol is gaining popularity and is being integrated into more products. There are many IPv6-capable operating systems on the market today. Linux, BSD, Solaris, Microsoft Vista, and Microsoft Server 2008 operating systems all have their IPv6 stacks enabled by default, and IPv6 operates as the preferred protocol stack. Of course, Cisco equipment fully supports dual-stack configuration, and the number of IPv6 features within IOS devices continues to grow. However, the production use of IPv6 is still in the domain of the early adopters.

The rate of IPv6 adoption is growing but is also unpredictable. The timeline for the deployment of IPv6 is long and difficult to measure. Generally speaking, the transition to IPv6 has thus far been based on geography and politics. The Asian and European regions that did not have as many allocated IPv4 addresses have felt the pressure to transition to IPv6. While organizations in North America have more IPv4 addresses, the address-depletion effects are making the migration to IPv6 more urgent. The market segments that are focused on IPv6 are few and far between. There are few IPv6-specific applications that appeal to enterprises, service providers, and consumers that make them want to transition sooner. Some vertical markets such as government and defense, public sector, education, video distribution, and high tech are starting to see the benefits of IPv6 and are working on their transition plans.

There are still many areas of IPv6 where issues remain to be resolved. One of the remaining challenges for IPv6 is that few IPv6 service providers exist. Currently, Internet IPv6 traffic is still light compared to IPv4, but it continues to grow. This can be attributed to the lack of last-mile IPv6 access and customer premises equipment (CPE) that does not support IPv6. Multihoming, which is the concept of connecting to multiple service providers for redundancy, is an issue that will take some time to resolve, but it is doubtful that it is significantly holding back organizations from deploying IPv6. Hardware acceleration for IPv6 is not universal, and many applications lack IPv6 support. Just like the deployment of other networking technologies, network management and security are left to the end. The goal of this book is to raise awareness of the security issues related to IPv6 and to provide methods to secure the protocol before deployment.

IPv6 Vulnerabilities

IPv6 will eventually be just as popular as IPv4, if not more so. Over the next decade as IPv6 is deployed, the number of systems it is deployed on will surpass those on IPv4. While early adopters can help flesh out the bugs, there are still many issues to resolve. IPv6 implementations are relatively new to the market, and the software that has created these systems has not been field tested as thoroughly as their IPv4 counterparts. There is likely to be a period of time where defects will be found, and vendors will need to respond quickly to patching their bugs. Many groups are performing extensive testing of IPv6, so they hopefully can find many of the issues before it is time to deploy IPv6. However, all the major vendors of IT equipment and software have published vulnerabilities in their IPv6 implementations. Microsoft, Juniper, Linux, Sun, BSD, and even Cisco all have published vulnerabilities in their software. As IPv6 has been noticed, it is evident that these major vendors have drawn the attention of the hackers.

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