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Versions: 00 01 02 03 04 05 06 07 08 09 10 RFC 4744

Network Working Group                                            E. Lear
Internet-Draft                                                K. Crozier
Expires: May 16, 2005                                      Cisco Systems
                                                       November 15, 2004


  Using the NETCONF Protocol over Blocks Extensible Exchange Protocol
                                 (BEEP)
                       draft-ietf-netconf-beep-03

Status of this Memo

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   patent or other IPR claims of which I am aware have been disclosed,
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   This Internet-Draft will expire on May 16, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   This document specifies an application protocol mapping for the
   NETCONF protocol over the Blocks Extensible Exchange Protocol (BEEP).









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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1   Why BEEP?  . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  BEEP Transport Mapping . . . . . . . . . . . . . . . . . . . .  4
     2.1   NETCONF Session Establishment  . . . . . . . . . . . . . .  4
     2.2   Capabilities Exchange  . . . . . . . . . . . . . . . . . .  4
     2.3   NETCONF Session Usage  . . . . . . . . . . . . . . . . . .  4
     2.4   NETCONF Session Teardown . . . . . . . . . . . . . . . . .  5
     2.5   BEEP Profile for NETCONF . . . . . . . . . . . . . . . . .  5
       2.5.1   BEEP  Profile  . . . . . . . . . . . . . . . . . . . .  5
   3.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   5.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 10
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   6.1   Normative References . . . . . . . . . . . . . . . . . . . . 11
   6.2   Informative References . . . . . . . . . . . . . . . . . . . 11
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
   A.  Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 13
       Intellectual Property and Copyright Statements . . . . . . . . 14































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1.  Introduction

   The NETCONF protocol [1] defines a simple mechanism through which a
   network device can be managed.  NETCONF is designed to be usable over
   a variety of application protocols.  This document specifies an
   application protocol mapping for NETCONF over the Blocks Extensible
   Exchange Protocol (BEEP) [2] .

   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 RFC 2119 [4].

1.1  Why BEEP?

   Use of BEEP is natural as an application protocol for transport of
   XML.  As a peer to peer protocol, BEEP provides an easy way to
   implement NETCONF, no matter which side of the connection was the
   initiator.  This "bidirectionality" allows for either side to play
   the role of the manager with no protocol changes.  Either side can
   open a channel.  Either side could initiate an RPC.  This is
   particularly important to support operational models that involve
   small devices connecting to a manager, and those devices that must
   reverse the management connection in the face of firewalls and NATs.

   The SASL profile used by BEEP allows for a simple and direct mapping
   to the existing security model for CLI, while TLS provides a strong
   well tested encryption mechanism with either server or server and
   client-side authentication.























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2.  BEEP Transport Mapping

   All NETCONF over BEEP implementations MUST implement the profile and
   functional mapping between NETCONF and BEEP as described below.

2.1  NETCONF Session Establishment

   Managers may be either BEEP listeners or initiators.  Similarly,
   agents may be either listeners or initiators.  Thus the initial
   exchange takes place without regard to whether a manager or the agent
   is the initiator.  After the transport connection is established, as
   greetings are exchanged, they should each announce their support for
   TLS [6] and optionally SASL [5] (see below), as well as for the
   SYSLOG profile [7].  Once greetings are exchanged, if TLS is to be
   used and available by both parties, the listener STARTs a channel
   with the TLS profile.

   Once TLS has been started, a new greeting is sent by both initiator
   and listener, as required by the BEEP RFC.

   At this point, if SASL is desired, the initiator starts BEEP channel
   1 to perform a SASL exchange to authenticate itself.  When SASL is
   completed, the channel MUST be closed.

   Once authentication has occurred, there is no need to distinguish
   between initiator and listener.  We now distinguish between manager
   and agent.

2.2  Capabilities Exchange

   The manager now establishes an NETCONF a new channel.  As initiators
   assign odd channels and listeners assign even channels, this next
   channel is BEEP channel 1 or 2, depending on whether the manager is
   the initiator or the listener.

   Certain NETCONF capabilities may require additional BEEP channels.
   When such capabilities are defined, a BEEP mapping must be defined as
   well.

   At this point, the NETCONF session is established, and capabilities
   have been exchanged.

2.3  NETCONF Session Usage

   Nearly all NETCONF operations are executed through the <RPC> tag.  To
   issue an RPC, the manager transmits on the operational channel a BEEP
   MSG containing the RPC and its arguments.  In accordance with the
   BEEP standard, RPC requests may be split across multiple BEEP frames.



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   Once received and processed, the agent responds with BEEP RPYs on the
   same channel with the response to the RPC.  In accordance with the
   BEEP standard, responses may be
split across multiple BEEP frames.

2.4  NETCONF Session Teardown

   Upon receipt of <close-session> from the manager, once the agent has
   completed all RPCs, it will close BEEP channel 0.  When an agent
   needs to initiate a close it will do so by closing BEEP channel 0.
   Although not required to do so, the agent should allow for a
   reasonable period for a manager to release an existing lock prior to
   initiating a close.  Once the agent has closed channel 0, all locks
   are released, and each side follows tear down procedures as specified
   in [3].  Having received a BEEP close or having sent <close-session>,
   a manager MUST NOT send further requests.  If there are additional
   activities due to expanded capabilities, these MUST cease in an
   orderly manner, and should be properly described in the capability
   mapping.

2.5  BEEP Profile for NETCONF

   There are two commands in the BEEP profile.  <rpc> and <rpc-reply>.

2.5.1  BEEP  Profile

      <!-- DTD for netconf operations over BEEP

        Refer to this DTD as:

          <!ENTITY % NETCONF PUBLIC "netconf/Operation/1.0" "">
          %NETCONF;
        -->

      <!--   Contents

          Overview

          Includes
          Profile Summaries
          Entity Definitions

          Operations
           rpc
           rpc-reply
        -->

      <!--  Overview   NETCONF operation channel  -->




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      <!-- Includes -->

             <!ENTITY % BEEP PUBLIC "-//Blocks//DTD BEEP//EN"
                        "">
             %BEEP;

      <!--  Profile summaries


          BEEP profile NETCONF

          role        MSG                       RPY        ERR
          ====        ===                       ===        ===
          I or L      rpc                               ok         error
          I or L      rpc-reply                 ok         error

      -->

      <!--
        Entity Definitions

              entity        syntax/reference     example
              ======        ================     =======

        a RPC
           RPC-DATA       Alpha
        a RPC reply number
              RPC-REPLY      1*3DIGIT
      -->

      <!ENTITY % RPC-REPLY    "CDATA">
      <!ENTITY % RPC-DATA     "CDATA">

       -->

      <!--
        RPC command
        -->

      <!ELEMENT RPC        (#PCDATA)>
      <!ATTLIST RPC
                RPC-DATA        %RPC_DATA;                 #REQUIRED>

   <!--
        Result of RPC.
        -->

      <!ELEMENT RPC-REPLY    (#PCDATA)>



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      <!ATTLIST RPC-REPLY
                RPC-REPLY       %RPC-REPLY;                #REQUIRED
                RPC-DATA    %RPC-DATA              #REQUIRED>


      <!-- End of DTD -->













































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3.  Security Considerations

   Configuration information is by its very nature sensitive.  Its
   transmission in the clear and without integrity checking leaves
   devices open to classic so-called "person in the middle" attacks.
   Configuration information often times contains passwords, user names,
   service descriptions, and topological information, all of which are
   sensitive.  A NETCONF application protocol, therefore, must minimally
   support options for both confidentiality and authentication.

   BEEP makes use of both transport layer security and SASL.  We require
   that TLS be used in BEEP as described by the BEEP standard.
   Client-side certificates are strongly desirable, but an SASL
   authentication is the bare minimum.  SASL allows for the use of
   protocols such as RADIUS [10], so that authentication can occur off
   the box.

   SASL authentication will occur on the first channel creation, and
   prior to issuance of any protocol operations.  No further
   authentication may occur during the same session.  This avoids a
   situation where rights are different between different channels.  If
   an implementation wishes to support multiple accesses by different
   individuals with different rights, then multiple sessions are
   required.

   Different environments may well allow different rights prior to and
   then after authentication.  An authorization model is not specified
   in this document.  When an operation is not properly authorized then
   a simple "permission denied" is sufficient.  Note that authorization
   information may be exchanged in the form of configuration
   information, which is all the more reason to ensure the security of
   the connection.



















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4.  IANA Considerations

   The IANA will assign a TCP port for NETCONF.
















































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5.  Acknowledgments

   This work is the product of the NETCONF IETF working group, and many
   people have contributed to the NETCONF discussion.  Most notably, Rob
   Ens, Phil Schafer, Andy Bierman, Wes Hardiger, Ted Goddard, and
   Margaret Wasserman all contributed in some fashion to this work,
   which was originally to be found in the NETCONF base protocol
   specification.  Thanks also to Weijing Chen, Keith Allen, Juergen
   Schoenwaelder, and Eamon O'Tuathail for their very constructive
   participation.









































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6.  References

6.1  Normative References

   [1]  Enns, R., "NETCONF Configuration Protocol",
        draft-ietf-netconf-prot-03 (work in progress), June 2004.

   [2]  Rose, M., "The Blocks Extensible Exchange Protocol Core", RFC
        3080, March 2001.

   [3]  Rose, M., "Mapping the BEEP Core onto TCP", RFC 3081, March
        2001.

   [4]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [5]  Myers, J., "Simple Authentication and Security Layer (SASL)",
        RFC 2222, October 1997.

   [6]  Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and
        P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January
        1999.

   [7]  New, D. and M. Rose, "Reliable Delivery for syslog", RFC 3195,
        November 2001.

6.2  Informative References

   [8]   Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
         "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
         REC REC-xml-20001006, October 2000.

   [9]   Hollenbeck, S., Rose, M. and L. Masinter, "Guidelines for the
         Use of Extensible Markup Language (XML) within IETF Protocols",
         BCP 70, RFC 3470, January 2003.

   [10]  Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
         Authentication Dial In User Service (RADIUS)", RFC 2865, June
         2000.












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Authors' Addresses

   Eliot Lear
   Cisco Systems
   Glatt-com
   Glattzentr
um, Zurich  8301
   CH

   EMail: lear@cisco.com


   Ken Crozier
   Cisco Systems
   170 W. Tasman Dr.
   San Jose, CA  95134-1706
   US

   EMail: kcrozier@cisco.com

































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Appendix A.  Change Log

   03, 04: minor gnits relating to <close-session>

   02: added comments about locking

   01: Removed management channel, rpc-status, rpc-abort, and associated
   profile changes.











































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