Extension Negotiation in Secure Shell (SSH)
draft-ietf-curdle-ssh-ext-info-13
| The information below is for an old version of the document | |||
|---|---|---|---|
| Document | Type | Active Internet-Draft (curdle WG) | |
| Last updated | 2017-09-14 | ||
| Replaces | draft-ssh-ext-info | ||
| Stream | IETF | ||
| Intended RFC status | Proposed Standard | ||
| Formats | pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Daniel Migault | ||
| Shepherd write-up | Show (last changed 2017-06-01) | ||
| IESG | IESG state | IESG Evaluation | |
| Consensus Boilerplate | Yes | ||
| Telechat date |
Needs 3 more YES or NO OBJECTION positions to pass. |
||
| Responsible AD | Eric Rescorla | ||
| Send notices to | Daniel Migault <daniel.migault@ericsson.com> | ||
| IANA | IANA review state | IANA OK - Actions Needed | |
Internet-Draft D. Bider
Updates: 4252, 4253, 4254 (if approved) Bitvise Limited
Intended status: Standards Track September 14, 2017
Expires: March 14, 2018
Extension Negotiation in Secure Shell (SSH)
draft-ietf-curdle-ssh-ext-info-13.txt
Abstract
This memo updates RFC 4252, RFC 4253, and RFC 4254 to define a
mechanism for SSH clients and servers to exchange information about
supported protocol extensions confidentially after SSH key exchange.
Status
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Copyright
Copyright (c) 2017 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.
Bider [Page 1]
Internet-Draft Extension Negotiation in SSH September 2017
Table of Contents
1. Overview and Rationale ...........................................3
1.1. Requirements Terminology ...................................3
1.2. Wire Encoding Terminology ..................................3
2. Extension Negotiation Mechanism ..................................3
2.1. Signaling of Extension Negotiation in SSH_MSG_KEXINIT .......3
2.2. Enabling Criteria ...........................................4
2.3. SSH_MSG_EXT_INFO Message ....................................4
2.4. Message Order ...............................................4
2.5. Interpretation of Extension Names and Values ................5
3. Initially Defined Extensions .....................................6
3.1. "server-sig-algs" ...........................................6
3.2. "delay-compression" .........................................7
3.2.1. Awkwardly Timed Key Re-Exchange ......................8
3.2.2. Subsequent Re-Exchange ...............................8
3.2.3. Compatibility Note: OpenSSH up to 7.5 ................8
3.3. "no-flow-control" ...........................................9
3.3.1. Prior "No Flow Control" Practice .....................9
3.4. "elevation" ................................................10
4. IANA Considerations .............................................11
4.1. Additions to existing tables ...............................11
4.2. New table: Extension Names .................................11
4.2.1. Future Assignments to Extension Names ...............11
5. Security Considerations .........................................11
6. References ......................................................12
6.1. Normative References .......................................12
6.2. Informative References .....................................12
Author's Address ...................................................13
Acknowledgments ....................................................13
Bider [Page 2]
Internet-Draft Extension Negotiation in SSH September 2017
1. Overview and Rationale
Secure Shell (SSH) is a common protocol for secure communication on
the Internet. The original design of the SSH transport layer [RFC4253]
lacks proper extension negotiation. Meanwhile, diverse implementations
take steps to ensure that known message types contain no unrecognized
information. This makes it difficult for implementations to signal
capabilities and negotiate extensions without risking disconnection.
Show full document text