File Transfer Protocol HOST Command for Virtual Hosts
RFC 7151
| Document | Type |
RFC - Proposed Standard
(March 2014; No errata)
Updates RFC 959
Was draft-hethmon-mcmurray-ftpext-ftp-hosts (individual in app area)
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-ietf-ftpext2-hosts | ||
| Stream | IETF | ||
| Formats | plain text pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | Tony Hansen | ||
| Shepherd write-up | Show (last changed 2013-10-16) | ||
| IESG | IESG state | RFC 7151 (Proposed Standard) | |
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Barry Leiba | ||
| Send notices to | (None) | ||
| IANA | IANA review state | IANA OK - Actions Needed | |
| IANA action state | RFC-Ed-Ack | ||
Internet Engineering Task Force (IETF) P. Hethmon
Request for Comments: 7151 Hethmon Brothers
Updates: 959 R. McMurray
Category: Standards Track Microsoft Corporation
ISSN: 2070-1721 March 2014
File Transfer Protocol HOST Command for Virtual Hosts
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 is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7151.
Copyright Notice
Copyright (c) 2014 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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Hethmon & McMurray Standards Track [Page 1]
RFC 7151 FTP HOST Command for Virtual Hosts March 2014
Table of Contents
1. Introduction ....................................................2
2. Document Conventions ............................................3
2.1. Basic Tokens ...............................................3
2.2. Server Replies .............................................4
3. The HOST Command ................................................4
3.1. Syntax of the HOST Command .................................5
3.2. HOST Command Semantics .....................................7
3.2.1. REIN Command Semantics ..............................8
3.2.2. User-PI Usage of HOST ...............................9
3.2.3. State Diagrams .....................................11
3.3. HOST Command Errors .......................................16
3.4. FEAT Response for HOST Command ............................17
4. Security Considerations ........................................17
5. IANA Considerations ............................................19
6. References .....................................................19
6.1. Normative References ......................................19
6.2. Informative References ....................................20
Appendix A. Unworkable Alternatives ...............................21
A.1. Overloading the CWD Command ................................21
A.2. Overloading the ACCT Command ...............................21
A.3. Overloading the USER Command ...............................22
A.4. Conclusion .................................................23
Appendix B. Acknowledgements ......................................23
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, because
an FTP server distinguishes incoming FTP connections by IP addresses
rather than DNS names. Therefore, all DNS names that share a common
IP address are handled by the same FTP server and share the same
Network Virtual File System (NVFS).
This means that different virtual hosts cannot offer different
virtual file systems to clients, nor can they offer different
authentication systems. Any scheme to overcome this issue needs to
indicate not only the destination IP address but also the virtual
hostname that is associated with the desired virtual FTP server.
Typical user-FTP processes currently use hostnames to perform
hostname-to-IP-address resolution and then ignore hostnames for the
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