A new Request for Comments is now available in online RFC libraries.


        RFC 3424

        Title:      IAB Considerations for UNilateral Self-Address
                    Fixing (UNSAF) Across Network Address Translation
        Author(s):  L. Daigle, Ed., IAB
        Status:     Informational
        Date:       November 2002
        Mailbox:    iab@iab.org
        Pages:      9
        Characters: 18165
        Updates/Obsoletes/SeeAlso:   None

        I-D Tag:    draft-iab-unsaf-considerations-02.txt

        URL:        ftp://ftp.rfc-editor.org/in-notes/rfc3424.txt


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.

This document is a product of the Internet Architecture Board.

This memo provides information for the Internet community.  It does
not specify an Internet standard of any kind.  Distribution of this
memo is unlimited.

This announcement is sent to the IETF list and the RFC-DIST list.
Requests to be added to or deleted from the IETF distribution list
should be sent to IETF-REQUEST@IETF.ORG.  Requests to be
added to or deleted from the RFC-DIST distribution list should
be sent to RFC-DIST-REQUEST@RFC-EDITOR.ORG.

Details on obtaining RFCs via FTP or EMAIL may be obtained by sending
an EMAIL message to rfc-info@RFC-EDITOR.ORG with the message body
help: ways_to_get_rfcs.  For example:

        To: rfc-info@RFC-EDITOR.ORG
        Subject: getting rfcs

        help: ways_to_get_rfcs

Requests for special distribution should be addressed to either the
author of the RFC in question, or to RFC-Manager@RFC-EDITOR.ORG.  Unless
specifically noted otherwise on the RFC itself, all RFCs are for
unlimited distribution.echo
Submissions for Requests for Comments should be sent to
RFC-EDITOR@RFC-EDITOR.ORG.  Please consult RFC 2223, Instructions to RFC
Authors, for further information.