Network Working Group S. Tatham Internet-Draft PuTTY Updates: 4254 (if approved) D. Tucker Intended status: Standards Track OpenSSH Expires: June 11, 2017 December 8, 2016 IUTF8 Terminal Mode in Secure Shell (SSH) draft-sgtatham-secsh-iutf8-04 Abstract This document updates RFC 4254 by specifying a new opcode in the Secure Shell terminal modes encoding. The new opcode describes the widely used IUTF8 terminal mode bit, which indicates that terminal I/ O uses the UTF-8 character encoding. Status of This Memo 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). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on June 11, 2017. Copyright Notice Copyright (c) 2016 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. Tatham & Tucker Expires June 11, 2017 [Page 1]
Internet-Draft IUTF8 Terminal Mode in SSH December 2016 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 2 3. New IUTF8 opcode for terminal mode encoding . . . . . . . . . 2 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 3 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 7.1. Normative References . . . . . . . . . . . . . . . . . . 3 7.2. Informative References . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction The Secure Shell (SSH) connection protocol [RFC4254] provides an encoding for terminal modes, used in the "pty-req" channel request type. A commonly used terminal mode is IUTF8, which indicates that the terminal driver should assume that terminal I/O uses the UTF-8 character encoding [RFC3629]. This is typically used by the kernel's terminal driver on the server to decide how many bytes of input to treat as a single logical character during line editing. SSH currently does not provide an encoding for IUTF8. This document specifies one. 2. Conventions Used in This Document 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 [RFC2119]. 3. New IUTF8 opcode for terminal mode encoding The opcode value 42 is defined for the IUTF8 terminal mode. As [RFC4254] section 8 specifies for all opcodes in the range 1 to 159, it is therefore followed by a single uint32 argument. The value 0 indicates that the IUTF8 mode is disabled, and the value 1 indicates that it is enabled. As with all other encoded terminal modes, the client SHOULD transmit a value for this mode if it knows about one, and the server MAY ignore it. Tatham & Tucker Expires June 11, 2017 [Page 2]
Internet-Draft IUTF8 Terminal Mode in SSH December 2016 4. IANA Considerations This document augments the "Encoding of Terminal Modes" list in section 8 of [RFC4254]. IANA is requested to update the SSH encoded terminal modes registry with the following additional entry: opcode mnemonic description ------ -------- ----------- 42 IUTF8 Terminal input and output is assumed to be encoded in UTF-8. Figure 1 5. Security Considerations The security considerations of [RFC4254] apply. This additional terminal mode encoding is believed to have no security implications differing from the existing set of encoded terminal modes. 6. Acknowledgements The authors are indebted to Colin Watson for originally suggesting this terminal mode in 2006, and David Madore and Jakub Jelen for prior implementation efforts. This document was written using the xml2rfc tool described in [RFC7749]. 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 2003, <http://www.rfc-editor.org/info/rfc3629>. [RFC4254] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Connection Protocol", RFC 4254, DOI 10.17487/RFC4254, January 2006, <http://www.rfc-editor.org/info/rfc4254>. Tatham & Tucker Expires June 11, 2017 [Page 3]
Internet-Draft IUTF8 Terminal Mode in SSH December 2016 7.2. Informative References [RFC7749] Reschke, J., "The "xml2rfc" Version 2 Vocabulary", RFC 7749, DOI 10.17487/RFC7749, February 2016, <http://www.rfc-editor.org/info/rfc7749>. Authors' Addresses Simon Tatham PuTTY Email: anakin@pobox.com Darren Tucker OpenSSH Email: dtucker@openssh.com Tatham & Tucker Expires June 11, 2017 [Page 4]
