Home > Articles > Cisco Network Technology > IP Communications/VoIP > IPv6 Internet Security for Your Network

IPv6 Internet Security for Your Network

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Jun 4, 2009.

Chapter Description

This chapter covers how to secure your network when it is connected to the IPv6 Internet.

From the Book

IPv6 Security

IPv6 Security

$51.20 (Save 20%)

Multihoming Issues

IPv6 addresses are allocated by service providers to end-user organizations. IPv6 addresses are intended to be fully hierarchical to help reduce the size of the core Internet routing table. Because IPv6 has the ability to have far more address blocks than IPv4, it would be impossible to have a large number of routes in the Internet backbone routers. With the increasing size of today's IPv4 Internet routing table, many devices struggle to handle the storage and the workload of processing the changes. Both memory and processor capacity are factors in the maximum size of the IP routing table. The size of the Forwarding Information Base (FIB) and the Routing Information Base (RIB) increases with the number of routes. As the FIB gets larger, so does the lookup time, which affects the forwarding rate. As the size of the routing table increases, so does the time of convergence. If Internet routers contain both IPv4 and IPv6, the problem gets worse.

Because IPv6 addresses are fully hierarchical, you probably do not need to use BGP, except in the default-free zone of the Internet backbone. An ISP could simply use a static route to point to the address block that has been allocated to the customer. In turn, the customer could simply use a default route to point toward the ISP for routing traffic to all unknown prefixes. This would simplify device configurations and also reduce the need for BGP, which would reduce the number of protocols the routers needed to run.

Many large organizations that connect to today's IPv4 Internet enjoy the redundancy that comes from connecting to two or more ISPs. This is part of an enterprise organization's disaster recovery and business continuity plan. The organization takes in routes from these providers (full routes, partial routes, or just the default route) and advertises its own address space from its own Autonomous System Number (ASN). Therefore, if one ISP connection were to fail, the BGP routing tables would converge and the customer would maintain its Internet connectivity.

If the rules of IPv6 addressing hierarchy were relaxed, many organizations could advertise their prefixes to the Internet. The address space would become fragmented, and the size of the Internet routing tables would expand out of control. Because of this fear, the addressing hierarchy has been enforced by the IANA, the IETF, the regional registries, and the ISPs. However, various registries (notably ARIN) have started to allow customers to obtain provider independent (PI) address space. This address space is not likely to be routed by service providers, but it does give customers additional addresses should they need them.

Many larger organizations still have a desire to have redundant connections to the Internet. Multinational organizations want to have Internet connections on the different continents they operate, for example. This is a requirement to reduce the latency that would result in back-hauling their Internet traffic to one central Internet attachment point. The redundancy and availability needs of customers must be addressed in some way. Customers must be allowed to be multihomed to the Internet. However, problems arise when sites have multiple address assignments from multiple ISPs. If one ISP link goes down, the other ISP does not readvertise the other ISP's address space. The customer addresses its web servers in one ISP's address space, and if that ISP fails, the web servers cannot be reached through the other ISP link. Therefore, alternatives must exist to allow the redundancy and failover between service providers without violating the address hierarchy rule.

The IETF has performed much work on the subject of multihoming. This early work is documented in RFC 3582, "Goals for IPv6 Site-Multihoming Architectures." Now the Site Multihoming by IPv6 Intermediation working group (shim6) is developing solutions to address sites that are multihomed. The primary solution that exists today is to use a "shim" that can be a new layer between the network layer and the transport layer. Above the shim are stable routable IPv6 addresses that allow applications to work as they have before and do not disrupt DNS information. The addresses above the shim are called Upper Layer IDs (ULID). Below the shim, IPv6 addresses can be used from either assigned blocks to get the packets forwarded to the destination.

Two hosts that want to communicate reliably both need to support the shim layer, and an initial shim protocol exchange needs to take place. During this exchange, both shim hosts share their available addresses with each other. This exchange shares the locator IDs between the two hosts. After this protocol exchange, both hosts are communicating with each other. If one of the address blocks loses connectivity because of an ISP failure, it can simply switch to using the other address space.

Figure 3-6 shows an example of how shim6 might work. Two sites have connections to two ISPs each, and each site has been allocated two /48 prefixes each. The two hosts need to communicate with each other, regardless of which ISP is available. They first communicate over whichever address space is available and then perform their shim protocol exchange. During this exchange, they share with each other their list of locator IDs, which are the address blocks the sites have been assigned by their ISPs. They are then able to communicate by using the shim header that contains the ULIDs. If host 2 loses its ISP2 connection, host 1 can use the locator ID for the remaining available prefix for host 2 that is still operational. Notice that the ULIDs did not change and thus the applications maintained state.

If an attacker could spoof packets with the shim header, several types of vulnerabilities would exist. One possible set of attacks comes from an attacker that is in the middle of the communication between two shim6 hosts. That attacker could perform redirection attacks to try to hijack the session. If the attacker could impersonate the locator IDs and the ULIDs, he could take over the communications. If the attacker could get a host to cache a locator ID, the attacker could redirect traffic to another network for an extended period of time.

Another type of attack would be a flooding attack, where an attacker would use its own locator ID to redirect a large volume of traffic to the victim. However, shim6 hosts perform a reachability probe-and-reply process to determine that the locator ID belongs to the remote host.

One solution to these security issues is for both hosts to use Hash Based Addresses (HBA) to ensure authenticity of the two hosts' locator IDs. These HBAs are a cryptographic one-way hash of the set of prefixes available for communications. This provides hijack protection because the HBAs cannot be tampered with in transit without detection. Performing the hash using nonces also helps prevent against replay attacks. Some form of public-key infrastructure (PKI) mechanism could also be used to secure the exchange between hosts.

There are additional security implications of using a shim between the IPv6 header and the upper-layer headers. Firewalls need to keep track of multiple sets of address space from different providers. This means that the firewall policies will grow, and the complexity of maintaining the rules and the management overhead will also grow. This is because hosts will have multiple addresses that could be used to source packets that can make it difficult to create granular firewall policies. Firewalls need to be shim-aware and parse the packets carefully, and they need to be able to handle sessions that start out without a shim and then transition to using a shim. Packet filters also need to be aware of session state when the ULIDs change within the shim.

Currently discussions are ongoing within the IETF about the use of shim6 and how it impacts other aspects of the IPv6 protocol and the operations of an IPv6 network. There are only a couple of implementations for hosts. There are discussions about integrating this functionality into routers so that they can perform this process on behalf of devices that do not have sufficient resources to create the shim themselves. There is also discussion about how the shim could be used for traffic engineering purposes instead of a simple multihoming solution. For the most updated information on this topic, you can go to the shim6 IETF working group site at http://www.ietf.org/html.charters/shim6-charter.html.

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time.

Overview

Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Cisco Press products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@ciscopress.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security

Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children

This site is not directed to children under the age of 13.

Marketing

Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out

Users can always make an informed choice as to whether they should proceed with certain services offered by Cisco Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.ciscopress.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links

This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020