6lo Working Group M. Richardson
Internet-Draft Sandelman Software Works
Intended status: Informational February 02, 2018
Expires: August 6, 2018
Enabling secure network enrollment in RPL networks
draft-richardson-6tisch-roll-enrollment-priority-00
Abstract
[I-D.richardson-6tisch-join-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
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 6, 2018.
Copyright Notice
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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.richardson-6tisch-join-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.
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.
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.
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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
none so far.
7. References
7.1. Normative References
[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-04 (work in progress), October
2017.
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[I-D.richardson-6tisch-join-enhanced-beacon]
Dujovne, D. and M. Richardson, "IEEE802.15.4 Informational
Element encapsulation of 6tisch Join Information", draft-
richardson-6tisch-join-enhanced-beacon-03 (work in
progress), January 2018.
[ieee802154]
IEEE Standard, ., "802.15.4-2015 - IEEE Standard for Low-
Rate Wireless Personal Area Networks (WPANs)", 2015,
<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
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-13 (work
in progress), November 2017.
[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.
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[I-D.ietf-6tisch-terminology]
Palattella, M., Thubert, P., Watteyne, T., and Q. Wang,
"Terminology in IPv6 over the TSCH mode of IEEE
802.15.4e", draft-ietf-6tisch-terminology-09 (work in
progress), June 2017.
[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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