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Versions: (draft-badra-netconf-rfc5539bis) 00 01 02 03 04 05 06 07 08 09 10 RFC 7589

NETCONF Working Group                                           M. Badra
Internet-Draft                                          Zayed University
Obsoletes: 5539 (if approved)                                  A. Luchuk
Intended status: Standards Track                     SNMP Research, Inc.
Expires: April 3, 2015                                  J. Schoenwaelder
                                                Jacobs University Bremen
                                                      September 30, 2014


     Using the NETCONF Protocol over Transport Layer Security (TLS)
                    draft-ietf-netconf-rfc5539bis-06

Abstract

   The Network Configuration Protocol (NETCONF) provides mechanisms to
   install, manipulate, and delete the configuration of network devices.
   This document describes how to use the Transport Layer Security (TLS)
   protocol to secure the exchange of NETCONF messages.  This revision
   of RFC 5539 documents the new message framing for NETCONF 1.1 and it
   obsoletes RFC 5539.

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 April 3, 2015.

Copyright Notice

   Copyright (c) 2014 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



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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  NETCONF over TLS  . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Connection Initiation . . . . . . . . . . . . . . . . . .   3
     2.2.  Message Framing . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  Connection Closure  . . . . . . . . . . . . . . . . . . .   4
     2.4.  X.509-based Authentication, Identification and
           Authorization . . . . . . . . . . . . . . . . . . . . . .   4
       2.4.1.  Server Identity . . . . . . . . . . . . . . . . . . .   4
       2.4.2.  Client Identity . . . . . . . . . . . . . . . . . . .   4
       2.4.3.  Deriving NETCONF Usernames from X.509 Certificates  .   5
     2.5.  Cipher Suites . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Contributor's Address . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Changes from RFC 5539  . . . . . . . . . . . . . . .   8
   Appendix B.  Change Log (to be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . .   8
     B.1.  draft-ietf-netconf-rfc5539bis-06  . . . . . . . . . . . .   8
     B.2.  draft-ietf-netconf-rfc5539bis-05  . . . . . . . . . . . .   8
     B.3.  draft-ietf-netconf-rfc5539bis-04  . . . . . . . . . . . .   8
     B.4.  draft-ietf-netconf-rfc5539bis-03  . . . . . . . . . . . .   9
     B.5.  draft-ietf-netconf-rfc5539bis-02  . . . . . . . . . . . .   9
     B.6.  draft-ietf-netconf-rfc5539bis-00  . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The NETCONF protocol [RFC6241] defines a mechanism through which a
   network device can be managed.  NETCONF is connection-oriented,
   requiring a persistent connection between peers.  This connection
   must provide integrity, confidentiality, peer authentication, and
   reliable, sequenced data delivery.

   This document defines how NETCONF messages can be exchanged over
   Transport Layer Security (TLS) [RFC5246].  The TLS protocol provides
   support for certificate-based mutual authentication, key derivation,
   protected ciphersuite negotiation, and key management capabilities.



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   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].

2.  NETCONF over TLS

   Since TLS is application-protocol-independent, NETCONF can operate on
   top of the TLS protocol transparently.  This document defines how
   NETCONF can be used within a TLS session.

2.1.  Connection Initiation

   The peer acting as the NETCONF client MUST act as the TLS client.
   The TLS client actively opens the TLS connection and the TLS server
   passively listens for the incoming TLS connection on the TCP port
   6513.  The TLS client MUST therefore send the TLS ClientHello message
   to begin the TLS handshake.  Once the TLS handshake has finished, the
   client and the server MAY begin to exchange NETCONF messages.  Client
   and server identity verification (as described in Section 2.4) is
   done before the <hello> message is sent.  This means that the
   identity verification is completed before the NETCONF session has
   started.

   The well-known port number 6513 is used by NETCONF servers to listen
   for connections established by NETCONF clients.  NETCONF clients
   connect to the server on the server port 6513 in order to send
   NETCONF messages to the NETCONF server.

2.2.  Message Framing

   All NETCONF messages MUST be sent as TLS "application data".  It is
   possible that multiple NETCONF messages be contained in one TLS
   record, or that a NETCONF message be transferred in multiple TLS
   records.

   The previous version [RFC5539] of this document used the framing
   sequence defined in [RFC4742], under the assumption that it could not
   be found in well-formed XML documents.  However, this assumption is
   not correct [RFC6242].  In order to solve this problem, this document
   adopts the framing protocol defined in [RFC6242] as follows:

   The <hello> message MUST be followed by the character sequence
   ]]>]]>.  Upon reception of the <hello> message, the peers inspect the
   announced capabilities.  If the :base:1.1 capability is advertised by
   both peers, the chunked framing mechanism defined in Section 4.2 of
   [RFC6242] is used for the remainder of the NETCONF session.
   Otherwise, the old end-of-message-based mechanism (see Section 4.3 of
   [RFC6242]) is used.



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2.3.  Connection Closure

   A NETCONF server will process NETCONF messages from the NETCONF
   client in the order in which they are received.  A NETCONF session is
   closed using the <close-session> operation.  When the NETCONF server
   processes a <close-session> operation, the NETCONF server SHALL
   respond and close the TLS session as described in Section 7.2.1 of
   [RFC5246].

2.4.  X.509-based Authentication, Identification and Authorization

   Implementations MAY optionally support TLS certificate-based
   authentication [RFC5246].  If the implementation supports TLS
   certificate-based authentication, then the following sections apply.

2.4.1.  Server Identity

   If the certificate presented by a NETCONF server has passed
   certification path validation [RFC5280] to a configured trust anchor,
   the NETCONF client MUST carefully examine the certificate presented
   by the server to determine if it meets the client's expectations.  If
   the NETCONF client has external information as to the expected
   identity of the NETCONF server, the hostname check MAY be omitted.
   Otherwise, the NETCONF client MUST check its understanding of the
   NETCONF server hostname against the server's identity as presented in
   the server Certificate message, in order to prevent man-in-the-middle
   attacks.

   Matching is performed according to the rules and guidelines defined
   in [RFC6125].  If the match fails, the NETCONF client MUST either ask
   for explicit user confirmation or terminate the connection and
   indicate the NETCONF server's identity is suspect.

   Additionally, NETCONF clients MUST verify the binding between the
   identity of the NETCONF servers to which they connect and the public
   keys presented by those servers.  NETCONF clients SHOULD implement
   the algorithm in Section 6 of [RFC5280] for general certificate
   validation, but MAY supplement that algorithm with other validation
   methods that achieve equivalent levels of verification (such as
   comparing the NETCONF server certificate against a local store of
   already-verified certificates and identity bindings).

2.4.2.  Client Identity

   The NETCONF server MUST verify the identity of the NETCONF client to
   ensure that the incoming request to establish a NETCONF session is
   legitimate before the NETCONF session is started.




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   The NETCONF protocol [RFC6241] requires that the transport protocol's
   authentication process MUST result in an authenticated NETCONF client
   identity whose permissions are known to the server.  The
   authenticated identity of a client is commonly referred to as the
   NETCONF username.

   The username provided by the NETCONF over TLS implementation will be
   made available to the NETCONF message layer as the NETCONF username
   without modification.  If the username does not comply to the NETCONF
   requirements on usernames [RFC6241], i.e., the username is not
   representable in XML, the TLS session MUST be dropped.

2.4.3.  Deriving NETCONF Usernames from X.509 Certificates

   After completing the TLS handshake, the NETCONF server attempts to
   derive a NETCONF username from the X.509 certificate presented by the
   NETCONF client.  If the NETCONF server cannot derive a valid NETCONF
   username from the presented certificate, then the NETCONF server MUST
   close the TLS connection, and MUST NOT accept NETCONF messages over
   it.  The NETCONF server uses the algorithm defined in
   [I-D.ietf-netconf-server-model] to extract a NETCONF username from
   the X.509 certificate presented by the NETCONF client.

2.5.  Cipher Suites

   Implementations of the protocol specified in this document MAY
   implement any TLS cipher suite that provides mutual authentication
   [RFC5246].  However, implementations MUST support TLS 1.2 [RFC5246]
   and are REQUIRED to support the mandatory-to-implement cipher suite.

3.  Security Considerations

   NETCONF is used to access configuration and state information and to
   modify configuration information, so the ability to access this
   protocol should be limited to users and systems that are authorized
   to view the NETCONF server's configuration and state or to modify the
   NETCONF server's configuration.

   Configuration or state data may include sensitive information, such
   as usernames or security keys.  So, NETCONF requires communications
   channels that provide strong encryption for data privacy.  This
   document defines a NETCONF over TLS mapping that provides for support
   of strong encryption and authentication.  The security considerations
   for TLS [RFC5246] and NETCONF [RFC6241] apply here as well.

   NETCONF over TLS requires mutual authentication.  Neither side should
   establish a NETCONF over SSH connection with an unknown, unexpected,
   or incorrect identity on the opposite side.  This document does not



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   support third-party authentication (e.g., backend Authentication,
   Authorization, and Accounting (AAA) servers) due to the fact that TLS
   does not specify this way of authentication and that NETCONF depends
   on the transport protocol for the authentication service.  If third-
   party authentication is needed, the SSH transport can be used.

   RFC 5539 assumes that the end-of-message (EOM) sequence, ]]>]]>,
   cannot appear in any well-formed XML document, which turned out to be
   mistaken.  The EOM sequence can cause operational problems and open
   space for attacks if sent deliberately in NETCONF messages.  It is
   however believed that the associated threat is not very high.  This
   document still uses the EOM sequence for the initial <hello> message
   to avoid incompatibility with existing implementations.  When both
   peers implement base:1.1 capability, a proper framing protocol
   (chunked framing mechanism; see Section 2.2) is used for the rest of
   the NETCONF session, to avoid injection attacks.

4.  IANA Considerations

   Based on the previous version of this document, RFC 5539, IANA has
   assigned a TCP port number (6513) in the "Registered Port Numbers"
   range with the service name "netconf-tls".  This port will be the
   default port for NETCONF over TLS, as defined in Section 2.1.  Below
   is the registration template following the rules in [RFC6335].


      Service Name:           netconf-tls
      Transport Protocol(s):  TCP
      Assignee:               IESG <iesg@ietf.org>
      Contact:                IETF Chair <chair@ietf.org>
      Description:            NETCONF over TLS
      Reference:              RFC XXXX
      Port Number:            6513


5.  Acknowledgements

   The authors like to acknowledge Martin Bjorklund, Olivier Coupelon,
   Mehmet Ersue, Miao Fuyou, David Harrington, Alfred Hoenes, Simon
   Josefsson, Eric Rescorla, Dan Romascanu, Kent Watsen, Bert Wijnen and
   the NETCONF mailing list members for their comments on this document.
   Charlie Kaufman, Pasi Eronen, and Tim Polk provided a thorough review
   of previous versions of this document.

   Juergen Schoenwaelder was partly funded by Flamingo, a Network of
   Excellence project (ICT-318488) supported by the European Commission
   under its Seventh Framework Programme.




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6.  Contributor's Address

   Ibrahim Hajjeh
   Ineovation
   France

   EMail: ibrahim.hajjeh@ineovation.fr

7.  References

7.1.  Normative References

   [I-D.ietf-netconf-server-model]
              Watsen, K. and J. Schoenwaelder, "NETCONF Server
              Configuration Model", draft-ietf-netconf-server-model-03
              (work in progress), September 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, March 2011.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.

   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
              Cheshire, "Internet Assigned Numbers Authority (IANA)
              Procedures for the Management of the Service Name and
              Transport Protocol Port Number Registry", BCP 165, RFC
              6335, August 2011.





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7.2.  Informative References

   [RFC4742]  Wasserman, M. and T. Goddard, "Using the NETCONF
              Configuration Protocol over Secure SHell (SSH)", RFC 4742,
              December 2006.

   [RFC5539]  Badra, M., "NETCONF over Transport Layer Security (TLS)",
              RFC 5539, May 2009.

Appendix A.  Changes from RFC 5539

   This section lists major changes between this document and RFC 5539.

   o  Documented that NETCONF uses the new message framing if both peers
      support the base:1.1 capability.

   o  Removed redundant text that can be found in the TLS and NETCONF
      specifications.

   o  Merged sections 2 and 3 into a new section 2 and restructured the
      text.

   o  Removed the reference to BEEP.

Appendix B.  Change Log (to be removed by RFC Editor before publication)

B.1.  draft-ietf-netconf-rfc5539bis-06

   o  Removed all call-home related text.

   o  Removed redundant text as discussed at the Toronto IETF meeting.

B.2.  draft-ietf-netconf-rfc5539bis-05

   o  Removed the YANG configuration data model since it became a
      separate document.

   o  Added reference to RFC 3234 plus editorial updates.

B.3.  draft-ietf-netconf-rfc5539bis-04

   o  Added the applicability statement proposed by Stephen Hanna.

   o  Added call-home configuration objects and a tls-call-home feature.

   o  Rewrote the text such that the role swap happens right after the
      TCP connection has been established.




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B.4.  draft-ietf-netconf-rfc5539bis-03

   o  Added support for call home (allocation of a new port number,
      rewrote text to allow a NETCONF client to be a TLS server and a
      NETCONF server to be a TLS client).

   o  Merged sections 2 and 3 into a new section 2 and restructured the
      text.

   o  Extended the IANA considerations section.

   o  Using the cert-to-name mapping grouping from the SNMP
      configuration data model and updated the examples.

   o  Creating an extensible set of YANG (sub)modules for NETCONF
      following the (sub)module structure of the SNMP configuration
      model.

B.5.  draft-ietf-netconf-rfc5539bis-02

   o  Addressed remaining issues identified at IETF 85

      *  Harmonized the cert-maps container of the YANG module in this
         draft with the tlstm container in the ietf-snmp-tls sub-module
         specified in draft-ietf-netmod-snmp-cfg.  Replaced the children
         of the cert-maps container with the children copied from the
         tlstm container of the ietf-snmp-tls sub-module.

      *  Added an overview of data model in the ietf-netconf-tls YANG
         module.

      *  Added example configurations.

   o  Addessed issues posted on NETCONF WG E-mail list.

   o  Deleted the superfluous tls container that was directly below the
      netconf-config container.

   o  Added a statement to the text indicating that support for mapping
      X.509 certificates to NETCONF usernames is optional.  This is
      analogous to existing text indicating that support for mapping
      pre-shared keys to NETCONF usernames is optional.  Resource-
      constrained systems now can omit support for mapping X.509
      certificates to NETCONF usernames and still comply with this
      specification.

   o  Clarified the document structure by promoting the sections of the
      document related to the data model.



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   o  Updated author's addresses.

B.6.  draft-ietf-netconf-rfc5539bis-00

   o  Remove the reference to BEEP.

   o  Rename host-part to domain-part in the description of RFC822.

Authors' Addresses

   Mohamad Badra
   Zayed University

   Email: mbadra@gmail.com


   Alan Luchuk
   SNMP Research, Inc.
   3001 Kimberlin Heights Road
   Knoxville, TN  37920
   USA

   Phone: +1 865 573 1434
   Email: luchuk@snmp.com
   URI:   http://www.snmp.com/


   Juergen Schoenwaelder
   Jacobs University Bremen
   Campus Ring 1
   28759 Bremen
   Germany

   Phone: +49 421 200 3587
   Email: j.schoenwaelder@jacobs-university.de
   URI:   http://www.jacobs-university.de/















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