Reasons to Move the Network Address Translator - Protocol Translator (NAT-PT) to Historic Status
RFC 4966
| Document | Type |
RFC - Informational
(July 2007; Errata)
Obsoletes RFC 2766
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-ietf-v6ops-natpt-to-exprmntl | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | WG Document | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 4966 (Informational) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | David Kessens | ||
| Send notices to | (None) | ||
Network Working Group C. Aoun
Request for Comments: 4966 Energize Urnet
Obsoletes: 2766 E. Davies
Category: Informational Folly Consulting
July 2007
Reasons to Move the Network Address Translator - Protocol Translator
(NAT-PT) to Historic Status
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document discusses issues with the specific form of IPv6-IPv4
protocol translation mechanism implemented by the Network Address
Translator - Protocol Translator (NAT-PT) defined in RFC 2766. These
issues are sufficiently serious that recommending RFC 2766 as a
general purpose transition mechanism is no longer desirable, and this
document recommends that the IETF should reclassify RFC 2766 from
Proposed Standard to Historic status.
Aoun & Davies Informational [Page 1]
RFC 4966 NAT-PT Issues Analysis July 2007
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Issues Unrelated to an DNS-ALG . . . . . . . . . . . . . . . . 7
2.1. Issues with Protocols Embedding IP Addresses . . . . . . . 7
2.2. NAPT-PT Redirection Issues . . . . . . . . . . . . . . . . 8
2.3. NAT-PT Binding State Decay . . . . . . . . . . . . . . . . 8
2.4. Loss of Information through Incompatible Semantics . . . . 9
2.5. NAT-PT and Fragmentation . . . . . . . . . . . . . . . . . 10
2.6. NAT-PT Interaction with SCTP and Multihoming . . . . . . . 11
2.7. NAT-PT as a Proxy Correspondent Node for MIPv6 . . . . . . 12
2.8. NAT-PT and Multicast . . . . . . . . . . . . . . . . . . . 12
3. Issues Exacerbated by the Use of DNS-ALG . . . . . . . . . . . 13
3.1. Network Topology Constraints Implied by NAT-PT . . . . . . 13
3.2. Scalability and Single Point of Failure Concerns . . . . . 14
3.3. Issues with Lack of Address Persistence . . . . . . . . . 15
3.4. DoS Attacks on Memory and Address/Port Pools . . . . . . . 16
4. Issues Directly Related to Use of DNS-ALG . . . . . . . . . . 16
4.1. Address Selection Issues when Communicating with
Dual-Stack End-Hosts . . . . . . . . . . . . . . . . . . . 16
4.2. Non-Global Validity of Translated RR Records . . . . . . . 18
4.3. Inappropriate Translation of Responses to A Queries . . . 19
4.4. DNS-ALG and Multi-Addressed Nodes . . . . . . . . . . . . 19
4.5. Limitations on Deployment of DNS Security Capabilities . . 19
5. Impact on IPv6 Application Development . . . . . . . . . . . . 20
6. Security Considerations . . . . . . . . . . . . . . . . . . . 20
7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.1. Normative References . . . . . . . . . . . . . . . . . . . 22
9.2. Informative References . . . . . . . . . . . . . . . . . . 23
Aoun & Davies Informational [Page 2]
RFC 4966 NAT-PT Issues Analysis July 2007
1. Introduction
The Network Address Translator - Protocol Translator (NAT-PT)
document [RFC2766] defines a set of network-layer translation
mechanisms designed to allow nodes that only support IPv4 to
communicate with nodes that only support IPv6, during the transition
to the use of IPv6 in the Internet.
[RFC2766] specifies the basic NAT-PT, in which only addresses are
translated, and the Network Address Port Translator - Protocol
Translator (NAPT-PT), which also translates transport identifiers,
allowing for greater economy of scarce IPv4 addresses. Protocol
translation is performed using the Stateless IP/ICMP Translation
Algorithm (SIIT) defined in [RFC2765]. In the following discussion,
where the term "NAT-PT" is used unqualified, the discussion applies
to both basic NAT-PT and NAPT-PT. "Basic NAT-PT" will be used if
points apply to the basic address-only translator.
A number of previous documents have raised issues with NAT-PT. This
document will summarize these issues, note several other issues
carried over from traditional IPv4 NATs, and identify some additional
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