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IAB Considerations for UNilateral Self-Address Fixing (UNSAF) Across Network Address Translation (RFC3424)

IP.com Disclosure Number: IPCOM000010298D
Original Publication Date: 2002-Nov-01
Included in the Prior Art Database: 2002-Nov-19
Document File: 10 page(s) / 18K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

L. Daigle: AUTHOR [+3]

Abstract

As a result of the nature of Network Address Translation (NAT) Middleboxes, communicating endpoints that are separated by one or more NATs do not know how to refer to themselves using addresses that are valid in the addressing realms of their (current and future) peers. Various proposals have been made for "UNilateral Self-Address Fixing (UNSAF)" processes. These are processes whereby some originating endpoint attempts to determine or fix the address (and port) by which it is known to another endpoint - e.g. to be able to use address data in the protocol exchange, or to advertise a public address from which it will receive connections.

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Network Working Group� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � L. Daigle, Ed.

Request for Comments: 3424� � � � � � � � � � � � � � � � � � Internet Architecture Board

Category: Informational� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � IAB

� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � November 2002

� � � � IAB Considerations for UNilateral Self-Address Fixing (UNSAF)

� � � � � � � � � � � � � � � � � � Across Network Address Translation

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 Internet Society (2002).� All Rights Reserved.

Abstract

� � As a result of the nature of Network Address Translation (NAT)

� � Middleboxes, communicating endpoints that are separated by one or

� � more NATs do not know how to refer to themselves using addresses that

� � are valid in the addressing realms of their (current and future)

� � peers.� Various proposals have been made for "UNilateral Self-Address

� � Fixing (UNSAF)" processes.� These are processes whereby some

� � originating endpoint attempts to determine or fix the address (and

� � port) by which it is known to another endpoint - e.g. to be able to

� � use address data in the protocol exchange, or to advertise a public

� � address from which it will receive connections.

� � This document outlines the reasons for which these proposals can be

� � considered at best as short term fixes to specific problems and the

� � specific issues to be carefully evaluated before creating an UNSAF

� � proposal.

1. Introduction

� � As a result of the nature of Network Address (and port) Translation

� � (NAT) Middleboxes, communicating endpoints that are separated by one

� � or more NATs do not know how to refer to themselves using addresses

� � that are valid in the addressing realms of their (current and future)

� � peers - the address translation is locked within the NAT box.� For

� � some purposes, endpoints need to know the addresses (and/or ports) by

� � which they are known to their peers.� There are two cases: 1) when

� � the client initiates communication, starting the communication has

� � the side effect of creating an address binding in the NAT device and

Daigle & IAB� � � � � � � � � � � � � � � � Informational� � � � � � � � � � � � � � � � � � � � � [Page 1]

RFC 3424� � � � � � � IAB Considerations for UNSAP Across NAT� � � November 2002

� � allocating an address in the realm that is external to the NAT box;

� � and 2) a server will be accepting connections from outside, but

� � because it does not initiate communication, no NAT binding is

� � created.� In such cases, a mechanism is needed to fix such a binding

� � before communication can take place.

� � "UNilateral Self-Address Fixing (...