RFC 9099 / Intro & Overview

Recently RFC 9099 Operational Security Considerations for IPv6 Networks was published. It was authored by Éric VynckeKiran Kumar ‘KK’ Chittimaneni, Merike Kaeo und myself, and we plan to write a little series on its objectives & main recommendations on the APNIC Blog. To prepare for that let me provide a short overview of it in this post.

RFC 9099 was a long time in the making (nearly nine years! between the first Internet-Draft in the OPSEC working group and the final publication). As you’ll see in a second it covers many IPv6 areas which by themselves are in the centre of nearly religious debates (like filtering of extension headers, or ULAs + other addressing topics). Hence quite a bit lengthy e-mail threads on the WG’s mailing list were created, which made reaching consensus not necessarily easier. Also at some point IETF procedures – this sounds better than ‘politics’, doesn’t it? 😉 – kicked in which led to additional delays (for those interested in this dimension of work within the IETF see Geoff Huston’s lucid Opinion: The making of an RFC in today’s IETF).

The document is focused on what we call ‘managed environments’ like service provider/operator networks or enterprise environments, and it is organized in several sections:

  • Addressing: evidently the addressing architecture chosen for a specific IPv6 deployment can have significant impact on a network’s security posture (when it comes to routing, traffic filtering or logging), so the various types of IPv6 addresses and their security implications are presented in detail in this section.
  • Extension headers: as those constitute one of the main technical differences between IPv4 and IPv6, and at the same time they have interesting (one could even write: ‘challenging’) security properties, they’re discussed in a dedicated section.
  • Link-layer security: examining the local communication mechanisms of IPv6 both from an offensive and from a defense point of view makes the main content of this section. Here all the stuff like NDP attacks, rogue router advertisements, and their related protection mechanisms are described. Again, this is an area where major differences between IPv4 and IPv6 exist.
  • Control plane security: very important topic from an infrastructure security perspective which is why it has an own section.
  • Routing security: same as for the previous section – overall very similar security best practices as in IPv4 networks have to be applied for IPv6 in this space as well, e.g. the excellent guidance provided in RFC 7454 BGP Operations and Security.
  • Logging/monitoring: some elements of the overall IPv6 architecture (like the ephemeral nature of IPv6 addresses, the fact that usually several of them co-exist on a given interface, or their general format) have significant impact on the way how logging and security monitoring are done in many organizations. These are looked at in detail in this segment.
  • Transition/Coexistence Technologies: from my experience various organizations underestimate the efforts for properly security dual-stack deployments (which btw is another argument for going v6-only where you can). Furthermore the use of tunnel technologies traditionally creates headaches for security practitioners, so they merit respective considerations (at least we thought so. This section was heavily contested during the development of the RFC as people thought that the related security challenges do not stem from IPv6 itself but mostly from operational deficiencies in IPv4 networks, namely those not aware of the concurrent presence of IPv6 in their world).
  • General device hardening: a security guidance document wouldn’t be complete without this, right? 😉
  • Enterprise-specific security considerations: deploying IPv6 in enterprise environments needs some additional reflections (see also RFC 7381 Enterprise IPv6 Deployment Guidelines) which is why we cover the security side of things in a dedicated chapter, which in turn is split into two subsections on external and on internal security.
  • Service provider security considerations: obviously operator networks need proper IPv6 security. While many of the needed security controls are already covered in earlier parts of the RFC some operator-specific aspects like lawful intercept are discussed here.

This post was meant to make you aware of RFC 9099 in case you didn’t know it before, and to provide a quick overview of its content. Additional posts with technical details on its individual areas will be published on the APNIC blog.

Additional references

Published by Enno

Old-school networking guy with a certain focus on network security. This blog is a private blog and it contains private musings, even though I have a day job around the Internet Protocol. I leave it to the valued reader to guess which version of it ;-). Some tweets on related topics at https://twitter.com/enno_insinuator.

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