Issues with Private IP Addressing in the Internet
RFC 6752
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RFC - Informational
(September 2012; No errata)
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Last updated |
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2015-10-14
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IETF
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plain text
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RFC 6752 (Informational)
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Consensus Boilerplate |
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Unknown
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Responsible AD |
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Ron Bonica
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The document shepherd is Chris Morrow (christopher.morrow@gmail.com).
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Internet Engineering Task Force (IETF) A. Kirkham
Request for Comments: 6752 Palo Alto Networks
Category: Informational September 2012
ISSN: 2070-1721
Issues with Private IP Addressing in the Internet
Abstract
The purpose of this document is to provide a discussion of the
potential problems of using private, RFC 1918, or non-globally
routable addressing within the core of a Service Provider (SP)
network. The discussion focuses on link addresses and, to a small
extent, loopback addresses. While many of the issues are well
recognised within the ISP community, there appears to be no document
that collectively describes the issues.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6752.
Copyright Notice
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. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Kirkham Informational [Page 1]
RFC 6752 Private IP Addressing in the Internet September 2012
Table of Contents
1. Introduction ....................................................2
2. Conservation of Address Space ...................................3
3. Effects on Traceroute ...........................................3
4. Effects on Path MTU Discovery ...................................6
5. Unexpected Interactions with Some NAT Implementations ...........7
6. Interactions with Edge Anti-Spoofing Techniques .................9
7. Peering Using Loopbacks .........................................9
8. DNS Interaction .................................................9
9. Operational and Troubleshooting Issues .........................10
10. Security Considerations .......................................10
11. Alternate Approaches to Core Network Security .................12
12. References ....................................................13
12.1. Normative References .....................................13
12.2. Informative References ...................................13
Appendix A. Acknowledgments ......................................14
1. Introduction
In the mid to late 1990s, some Internet Service Providers (ISPs)
adopted the practice of utilising private (or non-globally unique)
[RFC1918] IP addresses for the infrastructure links and in some cases
the loopback interfaces within their networks. The reasons for this
approach centered on conservation of address space (i.e., scarcity of
public IPv4 address space) and security of the core network (also
known as core hiding).
However, a number of technical and operational issues occurred as a
result of using private (or non-globally unique) IP addresses, and
virtually all these ISPs moved away from the practice. Tier 1 ISPs
are considered the benchmark of the industry and as of the time of
writing, there is no known tier 1 ISP that utilises the practice of
private addressing within their core network.
The following sections will discuss the various issues associated
with deploying private [RFC1918] IP addresses within ISP core
networks.
The intent of this document is not to suggest that private IP
addresses can not be used with the core of an SP network, as some
providers use this practice and operate successfully. The intent is
to outline the potential issues or effects of such a practice.
Note: The practice of ISPs using "squat" address space (also known
as "stolen" space) has many of the same, plus some additional, issues
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