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Versions: (draft-richardson-6tisch-roll-enrollment-priority) 00

6lo Working Group                                          M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Informational                        September 16, 2019
Expires: March 19, 2020


           Enabling secure network enrollment in RPL networks
                 draft-ietf-roll-enrollment-priority-00

Abstract

   [I-D.6tisch-enrollment-enhanced-beacon] defines a method by which a
   potential [I-D.ietf-6tisch-minimal-security] can announce itself as a
   available for new Pledges to Join a network.  The announcement
   includes a priority for join.  This document provides a mechanism by
   which a RPL DODAG root can disable join announcements, or adjust the
   base priority for join operation.

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 https://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 March 19, 2020.

Copyright Notice

   Copyright (c) 2019 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
   (https://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




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Protocol Definition . . . . . . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Change history . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC7554] describes the use of the time-slotted channel hopping
   (TSCH) mode of [ieee802154].  [I-D.ietf-6tisch-minimal-security] and
   [I-D.ietf-6tisch-dtsecurity-secure-join] describe mechanisms by which
   a new node (the "pledge)" can use a friendly router as a Join Proxy.
   [I-D.6tisch-enrollment-enhanced-beacon] describes an extension to the
   802.15.4 Enhanced Beacon that is used by a Join Proxy to announce its
   existence such that Pledges can find them.

   It has become clear that not every routing member of the mesh ought
   to announce itself as a Join Proxy.  There are a variety of local
   reasons by which a 6LR might not want to provide the Join Proxy
   function.  They include available battery power, already committed
   network bandwidth, and also total available memory available for Join
   proxy neighbor cache slots.

   There are other situations where the operator of the network would
   like to selective enable or disable the join process in a particular
   DODAG.

   As the join process involves permitting unencrypted traffic into the
   best effort part of a (TSCH) network, it would be better to have the
   join process off when no new nodes are expected.

   A network operator might also be able to recognize when certain parts
   of the network are overloaded and can not accomodate additional join
   traffic, and it would like to adjust the join priority among all
   nodes in the subtree of a congested link.




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   This document describes an RPL DIO option that can be used to
   announce a minimum join priority.  Each potential Join Proxy would
   this value as a base on which to add (decreasing likely hood of
   attracting traffic) values relating to local conditions.

   A network operator can set this value to the maximum value allowed,
   effectively disable all new join traffic.

1.1.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
   [RFC2119] and indicate requirement levels for compliant STuPiD
   implementations.

   In addition, the terminology of [I-D.ietf-6tisch-terminology] and
   from [I-D.ietf-anima-voucher] are used.

2.  Protocol Definition

   The following option is defined to transmission in the DIO issued by
   the DODAG root.  It may also be added by a router on part of the sub-
   tree as a result of some (out of scope for this document) management
   function.

   6LRs that see this DIO Option SHOULD increment the minimum priority
   if they observe congestion on the channel used for join traffic.
   (TODO: how much?  Do we need to standardize this?)

   A 6LR which would otherwise be willing to act as a Join Proxy, will
   examine the minimum priority field, and to that number, add any
   additional local consideration (such as upstream congestion).  The
   resulting priority, if less than 0x7f should enable the Join Proxy
   function.

       0                   1                   2
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Type = TBD01|Opt Length = 1|R| min. priority  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   min.priority  a 7 bit field which provides a base value for the
      Enhanced Beacon Join priority.  A value of 0x7f (127) disables the
      Join Proxy function entirely.






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   R  a reserved bit that SHOULD be set to 0 by senders, and MUST be
      ignored by receivers.  The reserved bit SHOULD be copied to
      options created.

3.  Security Considerations

   As per [RFC7416], RPL control frames either run over a secured layer
   2, or use the [RFC6550] Secure DIO methods.  This option can be
   placed into either a "clear" (layer-2 secured) DIO, or a layer-3
   Secure DIO.  As such this option will have both integrity and
   confidentiality mechanisms applied to it.

   A malicious node (that was part of the RPL control plane) could see
   these options and could, based upon the observed minimal join
   priority signal a confederate that it was a good time to send
   malicious join traffic.

   A malicious node (that was part of the RPL control plane) could also
   send DIOs with a different minimal join priority which would cause
   downstream mesh routers to change their Join Proxy behaviour.  Lower
   minimal priorities would cause downstream nodes to accept more
   pledges than the network was expecting, and higher minimal priorities
   cause the join process to stall.

   The use of layer-2 or layer-3 security for RPL control messages
   prevents the above two attacks.

4.  Privacy Considerations

   There are no new privacy issues caused by this extension.

5.  IANA Considerations

   Allocate a new number TBD01 from Registry RPL Control Message
   Options.  This entry should be called Minimum Join Priority.

6.  Acknowledgements

   This has been reviewed by Pascal Thubert and Thomas Wattenye.

7.  References

7.1.  Normative References








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   [I-D.6tisch-enrollment-enhanced-beacon]
              Dujovne, D. and M. Richardson, "IEEE802.15.4 Informational
              Element encapsulation of 6tisch Join and Enrollment
              Information", draft-6tisch-enrollment-enhanced-beacon-00
              (work in progress), July 2018.

   [I-D.ietf-6tisch-minimal-security]
              Vucinic, M., Simon, J., Pister, K., and M. Richardson,
              "Minimal Security Framework for 6TiSCH", draft-ietf-
              6tisch-minimal-security-12 (work in progress), July 2019.

   [ieee802154]
              IEEE standard for Information Technology, ., "IEEE Std.
              802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
              and Physical Layer (PHY) Specifications for Low-Rate
              Wireless Personal Area Networks", n.d.,
              <http://standards.ieee.org/findstds/
              standard/802.15.4-2015.html>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC6550]  Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
              Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
              JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
              Low-Power and Lossy Networks", RFC 6550,
              DOI 10.17487/RFC6550, March 2012,
              <https://www.rfc-editor.org/info/rfc6550>.

   [RFC7416]  Tsao, T., Alexander, R., Dohler, M., Daza, V., Lozano, A.,
              and M. Richardson, Ed., "A Security Threat Analysis for
              the Routing Protocol for Low-Power and Lossy Networks
              (RPLs)", RFC 7416, DOI 10.17487/RFC7416, January 2015,
              <https://www.rfc-editor.org/info/rfc7416>.

   [RFC7554]  Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
              IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
              Internet of Things (IoT): Problem Statement", RFC 7554,
              DOI 10.17487/RFC7554, May 2015,
              <https://www.rfc-editor.org/info/rfc7554>.

7.2.  Informative References







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   [I-D.ietf-6tisch-architecture]
              Thubert, P., "An Architecture for IPv6 over the TSCH mode
              of IEEE 802.15.4", draft-ietf-6tisch-architecture-26 (work
              in progress), August 2019.

   [I-D.ietf-6tisch-dtsecurity-secure-join]
              Richardson, M., "6tisch Secure Join protocol", draft-ietf-
              6tisch-dtsecurity-secure-join-01 (work in progress),
              February 2017.

   [I-D.ietf-6tisch-terminology]
              Palattella, M., Thubert, P., Watteyne, T., and Q. Wang,
              "Terms Used in IPv6 over the TSCH mode of IEEE 802.15.4e",
              draft-ietf-6tisch-terminology-10 (work in progress), March
              2018.

   [I-D.ietf-anima-voucher]
              Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
              "Voucher Profile for Bootstrapping Protocols", draft-ietf-
              anima-voucher-07 (work in progress), January 2018.

   [RFC8137]  Kivinen, T. and P. Kinney, "IEEE 802.15.4 Information
              Element for the IETF", RFC 8137, DOI 10.17487/RFC8137, May
              2017, <https://www.rfc-editor.org/info/rfc8137>.

Appendix A.  Change history

   version 00.

Author's Address

   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca
















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