Secure Shell Working Group J. Galbraith Internet-Draft VanDyke Software Expires: September 17, 2003 P. Remaker Cisco Systems, Inc March 19, 2003 Session Channel Break Extension draft-ietf-secsh-break-00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 17, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract The Break Extension provides a way to send a break signal during a SSH terminal session. Galbraith & Remaker Expires September 17, 2003 [Page 1] Internet-Draft Session Channel Break Extension March 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. The Break Request . . . . . . . . . . . . . . . . . . . . . . . 4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . 6 Galbraith & Remaker Expires September 17, 2003 [Page 2] Internet-Draft Session Channel Break Extension March 2003 1. Introduction The SSH session channel provides a mechanism for the client-user to interactively enter commands and receive output from a remote host while taking advantage of the SSH transport's privacy and integrity features. A common application of the telnet protocol is the "Console Server" whereby a telnet NVT can be connected to a physical RS-232/V.24 asynchronous port, allowing the telnet NVT to appear as a locally attached terminal to that port, and allowing that port to appear as a network addressable device. A number of major computer equipment vendors provide high level administrative functions through an asynchronous serial port and generally expect the attached terminal to be capable of send a BREAK signal, which is defined as the TxD signal being held in a SPACE state for a time greater than a whole character time, typically interpreted as 250 to 500 ms. The telnet protocolprovides a means to send a "BREAK" signal, which is defined as a "a signal outside the USASCII set which is currently given local meaning within many systems." [1] Console Server vendors interpret the TELNET break signal as a physical break signal, which can then allow access to the full range of administartive functions available on an asynchronous serial console port. The lack of a similar facility in the SSH session channel has forced users to continue the use of telnet for the "Console Server" function. Galbraith & Remaker Expires September 17, 2003 [Page 3] Internet-Draft Session Channel Break Extension March 2003 2. The Break Request The following following channel specific request can be sent to request that the remote host perform a break operation. byte SSH_MSG_CHANNEL_REQUEST uint32 recipient channel string "break" boolean want_reply uint32 break-length in milliseconds If the break length cannot be controlled by the application receiving this request, the break length parameter SHOULD be ignored and the default break signal length of the chipset or underlying chipset driver SHOULD be sent. If the application can control the break-length, the following suggestions are made reagarding break duration. If a break duration request of greater than 3000ms is received, it SHOULD be processed as a 3000ms break, in order to an unreasonably long break request causing the port to become unavailable for as long as 47 days while executing the break. Applications that require a longer break may choose to ignore this requirement. If break duration request of less than 500ms, is requested a break of 500ms SHOULD be sent since most devices will recognize a break of that length. In the event that an application needs a shorter break, this can be ignored. If the break-length parameter is 0, the break SHOULD be sent as 500ms or the default break signal length of the chipset or underlying chipset driver . If the want_reply boolean is set, the server MUST reply using SSH_MSG_CHANNEL_SUCCESS or SSH_MSG_CHANNEL_FAILURE [4] messages. If a break of any kind was preformed, SSH_MSG_CHANNEL_SUCCESS MUST be sent. If no break was preformed, SSH_MSG_CHANNEL_FAILURE MUST be sent. This operation SHOULD be support by most general purpose SSH clients. Galbraith & Remaker Expires September 17, 2003 [Page 4] Internet-Draft Session Channel Break Extension March 2003 References [1] Postel, J. and J. Reynolds, "Telnet Protocol Specification", STD 8, RFC 854, May 1983. [2] Rinne, T., Ylonen, T., Kivinen, T. and S. Lehtinen, "SSH Protocol Architecture", draft-ietf-secsh-architecture-13 (work in progress), September 2002. [3] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. Lehtinen, "SSH Transport Layer Protocol", draft-ietf-secsh-transport-15 (work in progress), September 2002. [4] Rinne, T., Ylonen, T., Kivinen, T. and S. Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-16 (work in progress), September 2002. Authors' Addresses Joseph Galbraith VanDyke Software 4848 Tramway Ridge Blvd Suite 101 Albuquerque, NM 87111 US Phone: +1 505 332 5700 EMail: galb-list@vandyke.com Phillip Remaker Cisco Systems, Inc 170 West Tasman Drive San Jose, CA 95120 US EMail: remaker@cisco.com Galbraith & Remaker Expires September 17, 2003 [Page 5] Internet-Draft Session Channel Break Extension March 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. 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