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)
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Authors | Paul Hethmon , Robert McMurray | ||
Last updated | 2015-10-14 | ||
Replaces | draft-ietf-ftpext2-hosts | ||
Stream | IETF | ||
Formats | plain text html 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 theShow full document text