| Network Working Group | M. Cotton |
| Internet-Draft | L. Vegoda |
| Obsoletes: 5735 (if approved) | ICANN |
| Intended status: Best Current Practice | August 2012 |
| Expires: January 31, 2013 |
Special Use IPv4 Addresses
draft-vegoda-cotton-rfc5735bis-03
This document describes the global and other specialized IPv4 address blocks that have been assigned by the Internet Assigned Numbers Authority (IANA). It does not address IPv4 address space assigned to operators and users through the Regional Internet Registries, nor does it address IPv4 address space assigned directly by IANA prior to the creation of the Regional Internet Registries. It also does not address allocations or assignments of IPv6 addresses or autonomous system numbers. This document obsoletes RFC 5735 and updates RFC 6441.
The substantive change between this document and RFC 5735 is that it includes 100.64.0.0/10, which was assigned in RFC 6598.
This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http:/⁠/⁠datatracker.ietf.org/⁠drafts/⁠current/⁠.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 31, 2013.
Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http:/⁠/⁠trustee.ietf.org/⁠license-⁠info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document.
Throughout its history, the Internet has employed a central Internet Assigned Numbers Authority (IANA) responsible for the allocation and assignment of various identifiers needed for the operation of the Internet [RFC1174]. In the case of the IPv4 address space, the IANA allocates parts of the address space to Regional Internet Registries (RIRs) according to their established needs. These RIRs are responsible for the registration of IPv4 addresses to operators and users of the Internet within their regions.
On an ongoing basis, IANA assignmnets have been made using policies established by the IETF to support the Internet Standards Process described in Section 4 of [RFC2860].
Small portions of the IPv4 address space have been allocated or assigned directly by the IANA for global or other specialized purposes. These allocations and assignments have been documented in a variety of RFCs and other documents. This document is intended to collect these scattered references and provide a current list of special use IPv4 addresses.
This document is a revision of RFC 5735 [RFC5735], which it obsoletes; its primary purpose is to reflect the changes to the list of special IPv4 assignments since the publication of RFC 5735. It is a companion to [RFC5156] which describes special IPv6 addresses.
0.0.0.0/8 - Addresses in this block refer to source hosts on "this" network. Address 0.0.0.0/32 may be used as a source address for this host on this network; other addresses within 0.0.0.0/8 may be used to refer to specified hosts on this network [RFC1122], section 3.2.1.3.
10.0.0.0/8 - This block is set aside for use in private networks. Its intended use is documented in [RFC1918]. As described in that RFC, addresses within this block do not legitimately appear on the public Internet. These addresses can be used without any coordination with IANA or an Internet registry.
127.0.0.0/8 - This block is assigned for use as the Internet host loopback address. A datagram sent by a higher level protocol to an address anywhere within this block loops back inside the host. This is ordinarily implemented using only 127.0.0.1/32 for loopback. As described in [RFC1122], Section 3.2.1.3, addresses within the entire 127.0.0.0/8 block do not legitimately appear on any network anywhere.
100.64.0.0/10 - This block is used as Shared Address Space. [RFC6598] states that Shared Address Space can only be used in Service Provider networks or on routing equipment that is able to do address translation across router interfaces when addresses are identical on two different interfaces.
169.254.0.0/16 - This is the "link local" block. As described in [RFC3927], it is allocated for communication between hosts on a single link. Hosts obtain these addresses by auto-configuration, such as when a DHCP server cannot be found.
172.16.0.0/12 - This block is set aside for use in private networks. Its intended use is documented in [RFC1918]. As described in that RFC, addresses within this block do not legitimately appear the public Internet. These addresses can be used without any coordination with IANA or an Internet registry.
192.0.0.0/24 - This block is reserved for IETF protocol assignments. At the time of writing this document, there are no current assignments. Allocation policy for future assignments is given in [RFC5736].
192.0.2.0/24 - This block is assigned as "TEST-NET-1" for use in documentation and example code. It is often used in conjunction with domain names example.com or example.net in vendor and protocol documentation. As described in [RFC5737], addresses within this block do not legitimately appear on the public Internet and can be used without any coordination with IANA or an Internet registry. See [RFC1166].
192.88.99.0/24 - This block is allocated for use as 6to4 relay anycast addresses, in to [RFC3068]. In contrast with previously described blocks, packets destined to addresses from this block do appear in the public Internet. [RFC3068], Section 7 describes operational practices to prevent the malicious use of this block in routing protocols.
192.168.0.0/16 - This block is set aside for use in private networks. Its intended use is documented in [RFC1918]. As described in that RFC, addresses within this block do not legitimately appear the public Internet. These addresses can be used without any coordination with IANA or an Internet registry.
198.18.0.0/15 - This block has been allocated for use in benchmark tests of network interconnect devices. [RFC2544] explains that this range was assigned to minimize the chance of conflict in case a testing device were to be accidentally connected to part of the Internet. Packets with source addresses from this range are not meant to be forwarded across the Internet.
198.51.100.0/24 - This block is assigned as "TEST-NET-2" for use in documentation and example code. It is often used in conjunction with domain names example.com or example.net in vendor and protocol documentation. As described in [RFC5737], addresses within this block do not legitimately appear on the public Internet and can be used without any coordination with IANA or an Internet registry.
203.0.113.0/24 - This block is assigned as "TEST-NET-3" for use in documentation and example code. It is often used in conjunction with domain names example.com or example.net in vendor and protocol documentation. As described in [RFC5737], addresses within this block do not legitimately appear on the public Internet and can be used without any coordination with IANA or an Internet registry.
224.0.0.0/4 - This block, formerly known as the Class D address space, is allocated for use in IPv4 multicast address assignments. The IANA guidelines for assignments from this space are described in [RFC5771].
240.0.0.0/4 - This block, formerly known as the Class E address space, is reserved for future use, see [RFC1112], section 4.
The one exception to this is the "limited broadcast" destination address 255.255.255.255. As described in [RFC0919] and [RFC0922], packets with this destination address are not forwarded at IP layer.
Address Block Present Use Reference
------------------------------------------------------------------
0.0.0.0/8 "This" Network RFC 1122, sect 3.2.1.3
10.0.0.0/8 Private-Use Networks RFC 1918
100.64.0.0/10 Shared Address Space RFC 6598
127.0.0.0/8 Loopback RFC 1122, sect 3.2.1.3
169.254.0.0/16 Link Local RFC 3927
172.16.0.0/12 Private-Use Networks RFC 1918
192.0.0.0/24 IETF Protocol Assignments RFC 5736
192.0.2.0/24 TEST-NET-1 RFC 5737
192.88.99.0/24 6to4 Relay Anycast RFC 3068
192.168.0.0/16 Private-Use Networks RFC 1918
198.18.0.0/15 Network Interconnect
Device Benchmark Testing RFC 2544
198.51.100.0/24 TEST-NET-2 RFC 5737
203.0.113.0/24 TEST-NET-3 RFC 5737
224.0.0.0/4 Multicast RFC 5771
240.0.0.0/4 Reserved for Future Use RFC 1112, sect 4
255.255.255.255/32 Limited Broadcast RFC 919, sect 7
This document describes the past and current practices, but does not create any new requirements for assignments or allocations by the IANA.
The particular assigned values of special use IPv4 addresses cataloged in this document do not directly raise security issues. However, the Internet does not inherently protect against abuse of these addresses; if you expect (for instance) that all packets from a private address space such as the 10.0.0.0/8 block or the link local block 169.254.0.0/16 originate within your subnet, all routers at the border of your network should filter such packets that originate from outside your network. Attacks have been mounted that depend on the unexpected use of some of these addresses.
It should also be noted that some of these address blocks may be used legitimately outside of a single administrative domain, and may appear on the global Internet. Security policy should not blindly filter all of these address spaces without due consideration, and network operators are encouraged to review this document, and references contained therein, and determine what security policies should be associated with each of these address blocks within their specific operating environments.
Many people have made comments on draft versions of this document. The authors would especially like to thank Scott Bradner, Randy Bush, Harald Alvestrand, Peter Koch, Alfred Hoenes, and Jari Arkko for their constructive feedback and comments. They would also like to offer a special note of thanks to APNIC, which nominated 198.51.100.0/24 and 203.0.113.0/24.