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Network Working Group                                          D. Moffat
Internet-Draft                                          Sun Microsystems
Expires: June 10, 2002                                 December 10, 2001


                          SSH Agent Forwarding
                     draft-ietf-secsh-agent-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 June 10, 2002.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   SSH is a protocol for secure remote login and other secure network
   services over an insecure network.  One of the common authentication
   mechanisms used with SSH is public key.  This document describes the
   authentication agent forwarding protocol, which runs as a channel
   over [SSH-TRANS] it is designed to ensure that the sensitive private
   keys never leave the users control even when using SSH to login over
   multiple hops.








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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1 Agent Operations . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Security Considerations  . . . . . . . . . . . . . . . . . . .  3
   3.  Additional Information . . . . . . . . . . . . . . . . . . . .  4
       References . . . . . . . . . . . . . . . . . . . . . . . . . .  4
       Author's Address . . . . . . . . . . . . . . . . . . . . . . .  4
       Full Copyright Statement . . . . . . . . . . . . . . . . . . .  5










































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1. Introduction

   This protocol is designed to facilitate an ad hoc secure single sign
   on mechanism using the SSH protocol.  A typical scenario is that a
   user has their private keys stored on their laptop (host A) and uses
   the SSH protocol to remotely connect to their corporate VPN (host B)
   access point.  Then uses further SSH connections to reach a specific
   host (host C) within the enterprise network.

   Without agent forwarding the user is required to have a copy of their
   private key on host A and host B so that the connection to host C can
   be made using public key authentication.  The key pairs used for the
   host A to B and the host B to C connection maybe the same but this is
   not always the case.

   This presents a security risk since the users private key(s) must be
   stored on host B which is likely to be a host the end user is not in
   control of even though they do trust it.  It is likely that the
   private keys on host A and host B are stored in an encrypted format,
   this means the user has at least two passwords to enter to make the
   connection from A to C.

   Ideally the private keys should remain on a device in the direct
   control of the end user (host A in this example) and all encryption
   and signing operations involving the private key should be performed
   on this device, regardless of the location of the entity requesting
   the operation.

1.1 Agent Operations

   The following interactions with the agent are requried: ADD, DELETE,
   LIST, SIGN.

   An agent implementation MUST support requests to forward operations
   using all public key types, defined in [SSH-USERAUTH] even those that
   the implementation doesn't support natively.

2. Security Considerations

   This protocol is designed only to run as a channel of the SSH
   protocol.

   The goal of this extension is to ensure that the users private keys
   never leave the machine they are physically at.  Ideally the private
   keys should be stored on a password protected removable media such as
   a smartcard.





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3. Additional Information

   The current document editor is: Darren.Moffat@Sun.COM.  Comments on
   this internet draft should be sent to the IETF SECSH working group,
   details at: http://ietf.org/html.charters/secsh-charter.html

References

   [FIPS-186]      Federal Information Processing Standards Publication,
                   ., "FIPS PUB 186, Digital Signature Standard", May
                   1994.

   [SSH-ARCH]      Ylonen, T., "SSH Protocol Architecture", I-D draft-
                   ietf-architecture-11.txt, July 2001.

   [SSH-TRANS]     Ylonen, T., "SSH Transport Layer Protocol", I-D
                   draft-ietf-transport-11.txt, July 2001.

   [SSH-USERAUTH]  Ylonen, T., "SSH Authentication Protocol", I-D draft-
                   ietf-userauth-13.txt, July 2001.

   [SSH-CONNECT]   Ylonen, T., "SSH Connection Protocol", I-D draft-
                   ietf-connect-14.txt, July 2001.


Author's Address

   Darren J Moffat
   Sun Microsystems
   901 San Antonio Road
   Palo Alto  94303
   USA

   EMail: Darren.Moffat@Sun.COM

















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Full Copyright Statement

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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