An FTP Application Layer Gateway (ALG) for IPv4-to-IPv6 Translation
draft-tsou-behave-ftp46-00

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Internet Engineering Task Force                             T. Tsou, Ed.
Internet-Draft                                 Huawei Technologies (USA)
Updates: 6384 (if approved)                                 S. Perreault
Intended status: Informational                                  Viagenie
Expires: December 17, 2012                                      J. Huang
                                                     Huawei Technologies
                                                           June 15, 2012

  An FTP Application Layer Gateway (ALG) for IPv4-to-IPv6 Translation
                       draft-tsou-behave-ftp46-00

Abstract

   An FTP ALG for NAT64 was defined in RFC 6384.  Its scope was limited
   to an IPv6 client connecting to an IPv4 server.  This memo updates
   RFC 6384 with the case of an IPv4 client connecting to an IPv6
   server.

Status of this Memo

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   This Internet-Draft will expire on December 17, 2012.

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   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  PASV to EPSV  . . . . . . . . . . . . . . . . . . . . . . . . . 4
   5.  EPSV (IPv4) to EPSV (IPv6)  . . . . . . . . . . . . . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   9.  Normative References  . . . . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6

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1.  Overview

   During the transition from IPv4 to IPv6, some operators need to
   deploy NAT in their network.  Some subscribers have the need to run
   IPv4 based FTP servers at home, and some of the FTP [RFC0959] control
   messages carry IP address and port number in the payload, which will
   cause a NAT traversal problem.

   [RFC6384] defines FTP ALG for NAT64, but only for the case where the
   FTP client is on the inside of the NAT64.  The case where an FTP
   server is on the inside of the NAT64 is not covered.

   When the FTP server is behind NAT, it can publish its service address
   via a redirect server located in the internet, or via modified DDNS
   system, or other possible methods.  It is out of the scope of this
   memo.

1.1.  Requirements Language

   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 RFC 2119 [RFC2119].

2.  Terminology

3.  Scenarios

   There can be several scenarios if NAT is involved.

   In this scenario, the FTP client is behind NAT, FTP ALG need to
   handle the EPRT / PORT command in FTP active mode, translate the IP
   address and port.  This scenario has been covered by [RFC6384], but
   only for NAT64.  This scenario for other kinds of NAT has not been
   covered.

           +--------+    +-------+     +----------+    +--------+
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