File Transfer Protocol HOST Command for Virtual Hosts
draft-hethmon-mcmurray-ftpext-ftp-hosts-02

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Document Type Active Internet-Draft (individual in app area)
Last updated 2013-07-08 (latest revision 2013-05-16)
Replaces draft-ietf-ftpext2-hosts
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Document shepherd Tony Hansen
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Responsible AD Barry Leiba
Send notices to phethmon@hethmon.com, robmcm@microsoft.com, draft-hethmon-mcmurray-ftpext-ftp-hosts@tools.ietf.org, tony@att.com
Network Working Group                                         P. Hethmon
Internet-Draft                                          Hethmon Brothers
Updates: 959 (if approved)                                   R. McMurray
Intended status: Standards Track                   Microsoft Corporation
Expires: November 15, 2013                                  May 14, 2013

         File Transfer Protocol HOST Command for Virtual Hosts
               draft-hethmon-mcmurray-ftpext-ftp-hosts-02

Abstract

   The File Transfer Protocol, as defined in RFC 959, does not provide a
   way for FTP clients and servers to differentiate between multiple DNS
   names that are registered for a single IP address.  This document
   defines a new FTP command that provides a mechanism for FTP clients
   and servers to identify individual virtual hosts on an FTP server.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 15, 2013.

Copyright Notice

   Copyright (c) 2013 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Document Conventions . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Basic Tokens . . . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Server Replies . . . . . . . . . . . . . . . . . . . . . .  4
   3.  The HOST command . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Syntax of the HOST command . . . . . . . . . . . . . . . .  5
     3.2.  HOST command semantics . . . . . . . . . . . . . . . . . .  8
       3.2.1.  REIN command semantics . . . . . . . . . . . . . . . .  9
       3.2.2.  User-PI usage of HOST  . . . . . . . . . . . . . . . .  9
       3.2.3.  State Diagrams . . . . . . . . . . . . . . . . . . . . 11
     3.3.  HOST command errors  . . . . . . . . . . . . . . . . . . . 17
     3.4.  FEAT response for HOST command . . . . . . . . . . . . . . 18
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 20
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 20
   Appendix A.  Unworkable Alternatives . . . . . . . . . . . . . . . 21
     A.1.  Overloading the CWD command  . . . . . . . . . . . . . . . 21
     A.2.  Overloading the ACCT command . . . . . . . . . . . . . . . 22
     A.3.  Overloading the USER command . . . . . . . . . . . . . . . 22
     A.4.  Conclusion . . . . . . . . . . . . . . . . . . . . . . . . 23
   Appendix B.  Acknowledgements  . . . . . . . . . . . . . . . . . . 23
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24

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1.  Introduction

   It is common on the Internet for many DNS names to resolve to a
   single IP address.  This practice has introduced the concept of a
   "virtual host", where a host appears to exist as an independent
   entity, but in reality shares its physical resources with one or more
   similar hosts.

   Such an arrangement presents some problems for FTP servers, as an FTP
   server distinguishes incoming FTP connections by their IP addresses
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