Special Use IPv4 Addresses
Internet Corporation for Assigned Names and Numbers
4676 Admiralty Way, Suite 33090292Marina del ReyUnited States+310-823-9358michelle.cotton@icann.org
http://www.iana.org/
Internet Corporation for Assigned Names and Numbers
4676 Admiralty Way, Suite 33090292Marina del ReyUnited States+310-823-9358leo.vegoda@icann.org
http://www.iana.org/
specialaddressesipv4
This document obsoletes RFC 3330. It 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. It also does not address allocations
or assignments of IPv6 addresses or autonomous system numbers.
Special IPv6 addresses are described in RFC 5156.
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 . 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, the IANA has been designated by the IETF
to make assignments in support of the Internet Standards
Process . Section 5 of this document describes that
assignment process.
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 3330 , which it
obsoletes; its primary purpose is to re-publish the technical
content of RFC 3330 mostly unchanged as an Informational RFC.
The terms "Specification Required", "Expert Review", "IESG Approval",
"IETF Review", and "Standards Action", are used in this memo to
refer to the processes described in .
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in BCP 14, .
Address blocks that were reserved for a special purpose in RFC 3330 but are no
longer reserved for any special purpose and are available for allocation are no
longer listed in Sections 4 or 5. The following blocks have become available:
- 14.0.0.0/8 is no longer set aside for assignments to the international system
of Public Data Networks , page 181. It is now available
for allocation to RIRs in the normal way;
- 24.0.0.0/8 is no longer listed as the addresses in that block have been managed
by the American Registry for Internet Numbers (ARIN) in the normal way since 2001;
- 39.0.0.0/8 is no longer listed as it has been subject to allocation to an RIR
for assignment in the normal manner since 2001;
- 128.0.0.0/16 is not reserved and is subject to future allocation by a Regional
Internet Registry for assignment in the normal manner;
- 191.255.0.0/16 is not reserved and is subject to future allocation by a RIR for
assignment in the normal manner; and
- 223.255.255.0/24 is not reserved and is subject to future allocation by an RIR for
assignment in the normal manner.
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 , page 30.
10.0.0.0/8 - This block is set aside for use in private networks.
Its intended use is documented in . Addresses within this
block SHOULD NOT appear on the public Internet and 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 should loop back inside the host.
This is ordinarily implemented using only 127.0.0.1/32 for loopback,
and addresses within this block SHOULD NOT appear on any network
anywhere , page 31.
169.254.0.0/16 - This is the "link local" block. As described in
, 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 . Addresses within
this block SHOULD NOT appear on the public Internet and 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.
192.0.2.0/24 - This block is assigned as "TEST-NET" 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. Addresses within this block SHOULD NOT appear on the
public Internet and can be used without any coordination with IANA or
an Internet registry.
192.88.99.0/24 - This block is allocated for use as 6to4 relay
anycast addresses, according to .
192.168.0.0/16 - This block is set aside for use in private
networks. Its intended use is documented in . Addresses
within this block SHOULD NOT appear on the public Internet and 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. 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.
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
.
240.0.0.0/4 - This block, formerly known as the Class E address
space, is reserved. The "limited broadcast" destination address
255.255.255.255 SHOULD NOT be forwarded outside the local network of
the source. The remainder of this space is reserved for future use.
See , page 2.
The IANA has responsibility for making assignments of protocol
parameters used in the Internet according to the requirements of the
"Memorandum of Understanding Concerning the Technical Work of the
Internet Assigned Numbers Authority" . Among other things,
requires that protocol parameters be assigned according to
the criteria and procedures specified in RFCs, including Proposed,
Draft, and full Internet Standards and Best Current Practice
documents, and any other RFC that calls for IANA assignment.
The domain name and IP address spaces involve policy issues (in
addition to technical issues) so that the requirements of
do not apply generally to those spaces. Nonetheless, the IANA is
responsible for ensuring assignments of IPv4 addresses as needed in
support of the Internet Standards Process. When a portion of the
IPv4 address space is specifically required by an RFC, the technical
requirements (e.g., size, prefix length) for the portion should be
described . Immediately before the RFC is published, the
IANA will, in consultation with the Regional Internet Registries,
make the necessary assignment and notify the RFC Editor of the
particulars for inclusion in the RFC as published.
As required by , the IANA will also make necessary
experimental assignments of IPv4 addresses, also in consultation
with the Regional Internet Registries.
This document describes the IANA's past and current practices and
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
the 10.0.0.0/8 block originate within your subnet, all border
routers should filter such packets that originate from elsewhere.
Attacks have been mounted that depend on the unexpected use of some
of these addresses.
Many people have made comments on draft versions of this document.
The IANA would especially like to thank Scott Bradner, Randy Bush,
Harald Alvestrand and Alfred Hoenes for their constructive feedback
and comments.