RFC 5156

Special-Use IPv6 Addresses

📅 published April 2008, from ietf

RFC 5156: Special-Use IPv6 Addresses 🎀

RFC number and title: RFC 5156, Special-Use IPv6 Addresses
Author: Marc Blanchet, Viagenie
Category: Informational
Date: April 2008

Status of This Memo ✨

Okay so this memo just gives info to the Internet community 💅 It does not specify an Internet standard of any kind, and distribution of it is unlimited 🌈

Abstract 🦋

This doc is a roundup of special IPv6 addresses that other RFCs already defined 📚 You can use it as a checklist of invalid routing prefixes when you're building filtering policies for routes and IP packets 🫶 It does not cover addresses that get handed out to operators and users through the Regional Internet Registries.

Table of Contents 🍓

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.  Address Blocks  . . . . . . . . . . . . . . . . . . . . . . . . 2
  2.1.  Node-Scoped Unicast . . . . . . . . . . . . . . . . . . . . 2
  2.2.  IPv4-Mapped Addresses . . . . . . . . . . . . . . . . . . . 2
  2.3.  IPv4-Compatible Addresses . . . . . . . . . . . . . . . . . 2
  2.4.  Link-Scoped Unicast . . . . . . . . . . . . . . . . . . . . 2
  2.5.  Unique-Local  . . . . . . . . . . . . . . . . . . . . . . . 3
  2.6.  Documentation Prefix  . . . . . . . . . . . . . . . . . . . 3
  2.7.  6to4  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
  2.8.  Teredo  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
  2.9.  6bone . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
  2.10. ORCHID  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
  2.11. Default Route . . . . . . . . . . . . . . . . . . . . . . . 4
  2.12. IANA Special-Purpose IPv6 Address Registry  . . . . . . . . 4
  2.13. Multicast . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
  6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
  6.2.  Informative References  . . . . . . . . . . . . . . . . . . 5

1. Introduction 💖

Same deal as the abstract: this is a compilation of special IPv6 addresses from other RFCs, and it's a checklist of invalid routing prefixes for filtering routes and IP packets 🧚 It doesn't talk about addresses that operators and users get from the Regional Internet Registries.

The doc is organized by address type, and the format is similar to [RFC3330] 🌸

Some filtering tips are included, but you're not required to implement them 🫶

The addresses listed in this document must not be hard-coded into implementations. Don't do it, bestie 🙈

2. Address Blocks 👑

2.1. Node-Scoped Unicast 🎀

::1/128 is the loopback address [RFC4291].

::/128 is the unspecified address [RFC4291].

These two addresses should not appear on the public Internet 💅

2.2. IPv4-Mapped Addresses ✨

::FFFF:0:0/96 are the IPv4-mapped addresses [RFC4291]. Addresses within this block should not appear on the public Internet 🦋

2.3. IPv4-Compatible Addresses 🍓

::<ipv4-address>/96 are the IPv4-compatible addresses [RFC4291]. These addresses are deprecated, and they should not appear on the public Internet 💀

2.4. Link-Scoped Unicast 🌈

fe80::/10 are the link-local unicast [RFC4291] addresses. Addresses within this block should not appear on the public Internet 🫶

2.5. Unique-Local 🧚

fc00::/7 are the unique-local addresses [RFC4193]. Addresses within this block should not appear by default on the public Internet. How to advertise these addresses is described further in [RFC4193] 💜

2.6. Documentation Prefix 📚

2001:db8::/32 are the documentation addresses [RFC3849]. They're used for documentation purposes such as user manuals, RFCs, and so on. Addresses within this block should not appear on the public Internet 🙈

2.7. 6to4 🌸

2002::/16 are the 6to4 addresses [RFC3056]. The 6to4 addresses may be advertised when the site is running a 6to4 relay or offering a 6to4 transit service. Running such a service [RFC3964] comes with filtering rules that are specific to 6to4 [RFC3964]. The IPv4 addresses disallowed in 6to4 prefixes are listed in section 5.3.1 of [RFC3964] 🔥

2.8. Teredo 🦋

2001::/32 are the Teredo addresses [RFC4380]. The Teredo addresses may be advertised when the site is running a Teredo relay or offering a Teredo transit service ✨

2.9. 6bone 🍓

5f00::/8 were the addresses of the first instance of the 6bone experimental network [RFC1897] 🧃

3ffe::/16 were the addresses of the second instance of the 6bone experimental network [RFC2471] 🧃

Both 5f00::/8 and 3ffe::/16 were returned to IANA [RFC3701]. These addresses are subject to future allocation, similar to current unallocated address space. Addresses within these blocks should not appear on the public Internet until they're reallocated 🌈

2.10. ORCHID 💜

2001:10::/28 are Overlay Routable Cryptographic Hash IDentifiers (ORCHID) addresses [RFC4843]. These addresses are used as identifiers and are not routable at the IP layer. Addresses within this block should not appear on the public Internet 🫶

2.11. Default Route ⭐

::/0 is the default unicast route address 🛣️

2.12. IANA Special-Purpose IPv6 Address Registry 👑

There's an IANA registry (iana-ipv6-special-registry) [RFC4773] for Special-Purpose IPv6 address block assignments, made for experiments and other purposes. Addresses within this registry should be reviewed for Internet routing considerations 🎀

2.13. Multicast 💅

ff00::/8 are multicast addresses [RFC4291]. They contain a 4-bit scope in the address field, and only some values are of global scope [RFC4291]. Only addresses with global scope in this block may appear on the public Internet 🌸

Multicast routes must not appear in unicast routing tables. Keep those separate, periodt 💖

3. Security Considerations 🔐

This is a big one, so listen up 👀 Filtering the invalid routing prefixes listed in this document should improve the security of networks 🔥

4. IANA Considerations 🧚

To keep things consistent and to provide cross-referencing for the community, IANA put the following paragraph in the header of the iana-ipv6-special-registry:

"Other special IPv6 addresses requiring specific considerations for global routing are listed in RFC 5156."

5. Acknowledgements 🫶

Florent Parent, Pekka Savola, Tim Chown, Alain Baudot, Stig Venaas, Vincent Jardin, Olaf Bonness, David Green, Gunter Van de Velde, Michael Barnes, Fred Baker, Edward Lewis, Marla Azinger, Brian Carpenter, Mark Smith, Kevin Loch, Alain Durand, Jim Bound, Peter Sherbin, Bob Hinden, Gert Doering, Niall O'Reilly, Mark Townsley, Jari Arkko, and Iain Calder all gave input and suggestions to this document. Thank you, legends 💖

6. References 📚

6.1. Normative References 💜

[RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
           Architecture", RFC 4291, February 2006.

6.2. Informative References 🌈

[RFC1897]  Hinden, R. and J. Postel, "IPv6 Testing Address
           Allocation", RFC 1897, January 1996.

[RFC2471]  Hinden, R., Fink, R., and J. Postel, "IPv6 Testing Address
           Allocation", RFC 2471, December 1998.

[RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
           via IPv4 Clouds", RFC 3056, February 2001.

[RFC3330]  IANA, "Special-Use IPv4 Addresses", RFC 3330,
           September 2002.

[RFC3701]  Fink, R. and R. Hinden, "6bone (IPv6 Testing Address
           Allocation) Phaseout", RFC 3701, March 2004.

[RFC3849]  Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
           Reserved for Documentation", RFC 3849, July 2004.

[RFC3964]  Savola, P. and C. Patel, "Security Considerations for
           6to4", RFC 3964, December 2004.

[RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
           Addresses", RFC 4193, October 2005.

[RFC4380]  Huitema, C., "Teredo: Tunneling IPv6 over UDP through
           Network Address Translations (NATs)", RFC 4380,
           February 2006.

[RFC4773]  Huston, G., "Administration of the IANA Special Purpose
           IPv6 Address Block", RFC 4773, December 2006.

[RFC4843]  Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix
           for Overlay Routable Cryptographic Hash Identifiers
           (ORCHID)", RFC 4843, April 2007.

Author's Address 🖋️

Marc Blanchet Viagenie 2600 boul. Laurier, suite 625 Quebec, QC G1V 4W1 Canada

EMail: Marc.Blanchet@viagenie.ca URI: http://www.viagenie.ca

Full Copyright Statement ⚖️

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