Address Protected Neighbor Discovery for Low-power and Lossy Networks
draft-sarikaya-6lo-ap-nd-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Behcet Sarikaya , Frank Xia , Pascal Thubert | ||
| Last updated | 2015-07-06 | ||
| Replaced by | draft-ietf-6lo-ap-nd, RFC 8928 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
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| Send notices to | (None) |
draft-sarikaya-6lo-ap-nd-00
6lo B. Sarikaya, Ed.
Internet-Draft Huawei USA
Intended status: Standards Track F. Xia
Expires: January 7, 2016 Huawei Technologies Co., Ltd.
P. Thubert, Ed.
Cisco
July 6, 2015
Address Protected Neighbor Discovery for Low-power and Lossy Networks
draft-sarikaya-6lo-ap-nd-00
Abstract
This document defines an extension of 6LoWPAN Neighbor Discovery for
application in low-power and lossy networks. The protocol is
specified to be protected and to support multi-hop operation. A node
computes its Cryptographic, Unique Interface ID, and associates one
or more of its Registered Addresses with that Cryptographic ID in
place of the EUI-64 that is used in RFC 6775 to uniquely identify the
interface of the Registered Address. Once an address is registered
with a Cryptographic ID, only the owner of that ID can modify the
state in the 6LR and 6LBR regarding the Registered Address.
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
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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 January 7, 2016.
Copyright Notice
Copyright (c) 2015 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
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(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
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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Interactions . . . . . . . . . . . . . . . . . . . . 4
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Protocol Operations . . . . . . . . . . . . . . . . . . . 7
4.3. Multihop Operation . . . . . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative references . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
Neighbor discovery for IPv6 [RFC4861] and stateless address
autoconfiguration [RFC4862], together referred to as neighbor
discovery protocols (NDP), are defined for regular hosts operating
with wired/wireless links. These protocols are not suitable and
require optimizations for resource constrained, low power hosts
operating with LLN for low-power and lossy networks. Neighbor
Discovery optimizations for 6LoWPAN networks include simple
optimizations such as a host address registration feature using the
address registration option (ARO) which is sent in unicast Neighbor
Solicitation (NS) and Neighbor Advertisement (NA) messages [RFC6775].
With 6LoWPAN ND [RFC6775], the ARO option includes a EUI-64 address
to uniquely identify the interface of the Registered Address on the
registering device, so as to correlate further registrations for the
same address and avoid address duplication. The EUI-64 address is
not secured and its ownership cannot be verified. It results that
any device claiming the same EUI-64 address may take over a
registration and attract the traffic for that address.
In this document, we extend 6LoWPAN ND to protect the address
ownership with cryptographic material, but as opposed to Secure
Neighbor Discovery (SEND) [RFC3971], [RFC3972], the cryptographic
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material is not embedded in the Interface ID (IID) in an IPv6 address
but used as a correlator associated to the registration of the IPv6
address. This approach is made possible with 6LoWPAN ND [RFC6775],
where the 6LR and the 6LBR maintain a state for each Registered
Address. If a cryptographic ID is associated with an original
6LoWPAN ND registration and stored in the registration state, then it
can be used to validate that any update to the registration state is
made by the owner of that ID.
To achieve this, this specification replaces the EUI-64 address, that
is used in 6LoWPAN ND to avoid address duplication, with
cryptographic material whose ownership can be verified; it also
provides new means for the 6LR to validate ownership of the
registration thus that of the registered address by the registering
device. The resulting protocol is called Protected address
autoconfiguration and registration protocol (ND-PAAR).
A node generates one 64-bit cryptographic ID and uses it as Unique
Interface ID in the registration of (one or more of) its addresses
with the 6LR, which it attaches to and uses as default router. The
6LR validates ownership of the cryptographic ID typically upon
creation or update of a registration state, for instance following an
apparent movement from a point of attachment to another. The ARO
option is modified to carry the Unique Interface ID, and through the
DAR/DAC exchange, the 6LBR is kept aware that this is the case, i.e.
unique and whether the 6LR has verified the claim.
2. Terminology
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].
Readers are expected to be familiar with all the terms and concepts
that are discussed in [RFC3971], [RFC3972], "neighbor Discovery for
IP version 6" [RFC4861], "IPv6 over Low-Power Wireless Personal Area
Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and
Goals" [RFC4919], neighbor Discovery Optimization for Low-power and
Lossy Networks [RFC6775] where the 6LoWPAN Router (6LR) and the
6LoWPAN Border Router (6LBR) are introduced, and
[I-D.chakrabarti-nordmark-6man-efficient-nd], which proposes an
evolution of [RFC6775] for a larger applicability.
The document also conforms to the terms and models described in
[RFC5889] and uses the vocabulary and the concepts defined in
[RFC4291] for the IPv6 Architecture.
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This document uses [RFC7102] for Terminology in Low power And Lossy
Networks.
3. Requirements
In this section we state requirements of a secure neighbor discovery
protocol for low-power and lossy networks.
The protocol MUST be based on the Neighbor Discovery Optimization for
Low-power and Lossy Networks protocol defined in [RFC6775] due to the
host-initiated interactions to allow for sleeping hosts, elimination
of multicast-based address resolution for hosts, etc.
New options to be added to Neighbor Solicitation messages MUST lead
to small packet sizes. Smaller packet sizes facilitate low-power
transmission by resource constrained nodes on lossy links.
The support of the registration mechanism SHOULD be extended to more
LLN links than IEEE 802.15.4, matching at least the LLN links for
which a 6lo "IPv6 over foo" specification exists, as well as Low-
Power Wi-Fi.
As part of this extension, a mechanism to compute a unique Identifier
should be provided, with the capability to form a Link Local Address
that SHOULD be unique at least within the LLN connected to a 6LBR
discovered by ND in each node within the LLN.
The Address Registration Option used in the ND registration SHOULD be
extended to carry the relevant forms of Unique Interface IDentifier.
The Neighbour Discovery should specify the formation of a site-local
address that follows the security recommendations from [RFC7217].
4. Protocol Interactions
Protected address autoconfiguration and registration neighbor
discovery protocol (ND-PAAR) modifies Neighbor Discovery Optimization
for Low-power and Lossy Networks [RFC6775] as explained in this
section.
4.1. Overview
The scope of the present work is a 6LoWPAN Low Power Lossy Network
(LLN), typically a stub network connected to a larger IP network via
a Border Router called a 6LBR per [RFC6775].
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---+-------- ............ ------------
| External Network |
|
+-----+
| | LLN Border
| | router
+-----+
o o o
o o o o
o o LLN o o o
o o o o
o
Figure 1: Basic Configuration
The 6LBR maintains a registration state for all devices in the
attached LLN, and, in conjunction with the first-hop router (the
6LR), is in position to validate uniqueness and grant ownership of an
IPv6 address before it can be used in the LLN. This is a fundamental
difference with a classical network that relies on IPv6 address auto-
configuration [RFC4862], where there is no guarantee of ownership
from the network, and any IPv6 Neighbor Discovery packet must be
individually secured [RFC3971].
In a route-over mesh network, the 6LR is directly connected to the
host device; this specification expects that peer-wise Layer-2
security is deployed so that all the packets from a particular host
are identified as such by the 6LR. The 6LR may be multiple hops away
from the 6LBR. Packets are routed between the 6LR and the 6LBR via
other 6LRs; this specification expects that a chain of trust is
established so that a packet that was validated by the first 6LR can
be safely routed by the next 6LRs and 6LBR.
The [I-D.ietf-6tisch-architecture] suggests to use RPL [RFC6550] as
the routing protocol between the 6LRs and the 6LBR, and to leverage
[I-D.chakrabarti-nordmark-6man-efficient-nd] to extend the LLN in a
larger multilink subnet [RFC4903]. In that model, a registration
flow happens as shown in Figure 2:
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6LoWPAN Node 6LR 6LBR 6BBR
(RPL leaf) (router) (root)
| | | |
| 6LoWPAN ND |6LoWPAN ND+RPL | Efficient ND | IPv6 ND
| LLN link |Route-Over mesh| IPv6 link | Backbone
| | | |
| NS(ARO) | | |
|-------------->| | |
| 6LoWPAN ND | DAR (then DAO)| |
| |-------------->| |
| | | NS(ARO) |
| | |-------------->|
| | | | DAD
| | | |------>
| | | |
| | | NA(ARO) |
| | |<--------------|
| | DAC | |
| |<--------------| |
| NA(ARO) | | |
|<--------------| | |
Figure 2: (Re-)Registration Flow over Multi-Link Subnet
A new device that joins the network auto-configures an address and
performs an initial registration to an on-link 6LR with an NS message
that carries a new Address Registration Option (ARO) [RFC6775]. The
6LR validates with address with the central 6LBR using a DAR/DAC
exchange, and the 6LR confirms (or infirms) the address ownership
with an NA message that also carries an Address Registration Option.
The registration mechanism in [RFC6775] was created for the original
purpose of Duplicate Address Detection (DAD), whereby use of an
address would be granted as long as the address is not already
present in the subnet. But [RFC6775] does not require that the 6LR
use the registration for source address validation (SAVI).
In order to validate address ownership, that mechanism enables the
6LBR to correlate further claims for a registered address with the
device to which it is granted, based on a Unique Interface IDentifier
(UID) that is derived from the MAC address of the device (EUI-64).
The limitation of the mechanism in [RFC6775] is that it does not
enable to prove the UID itself, so any node connected to the subnet
and aware of the address/UID mapping may effectively fake the same
UID and steal an address.
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This draft uses a randomly generated value as an alternate UID for
the registration. Proof of ownership of the UID is passed with the
first registration to a given 6LR, and enforced at the 6LR, which
validates the proof. With this new operation, the 6LR allows only
packets from a connected host if the connected host owns the
registration of the source address of the packet.
If a chain of trust is present between the 6LR and the 6LBR, then
there is no need to propagate the proof of ownership to the 6LBR.
All the 6LBR need to know is that this particular UID is randomly
generated, so as to enforce that any update via a different 6LR is
also random.
4.2. Protocol Operations
Crypto ID is calculated over EUI-64 or interface id of the node. The
calculation is only done initially at once and not repeated with
every message the node sends. The calculation does not change even
if the node has a new address since crypto ID does not change. This
means that this value which is highly probably unique in the network
can be used to claim multiple targets.
Protocol interactions are as defined in Section 4. The node MUST
send the cyrpto ID in the ARO field.
The Target Address field in NS message is set to the prefix
concatenated with the node's address. This address does not need
duplicate address detection as crypto ID is globally unique. So a
host cannot steal an address that is already registered unless it has
the key for the crypto ID. The same crypto ID can thus be used to
protect multiple addresses e.g. when the node receives a different
prefix.
Local or on-link protocol interactions are given in Figure 3. Crypto
ID and ARO are passed to and stored by the 6LR/6LBR on the first NS
and not sent again the in the next NS.
The 6LR/6LBR ensures first-come/first-serve by storing the ARO and
the crypto ID correlated to the target being registered. Then, if
the node is the first to claim any address it likes, then it becomes
owner of that address and the address is bound to the crypto ID in
the 6LR/6LBR registry. This procedure avoids the constrained device
to compute multiple keys for multiple addresses. The registration
process allows the node to tie all the addresses to the same crypto
ID and have the 6LR/6LBR enforce first come first serve after that.
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6LN 6LR
| |
|<-----------------------RA-------------------------------|
| |
|---------------NS with ARO and Random UID --------------->|
| |
|<-----------------------NA with ARO (status=req-proof) --|
| |
|---------------NS with ARO and Random UID->|
| |
|<-----------------------NA with ARO----------------------|
| |
...
| |
|---------------NS with ARO and Random UID --------------->|
| | |
|<-----------------------NA with ARO----------------------|
...
| |
|---------------NS with ARO and Random UID --------------->|
| | |
|<-----------------------NA with ARO----------------------|
Figure 3: On-link Protocol Operation
4.3. Multihop Operation
In multihop 6LoWPAN, 6LBR sends RAs with prefixes downstream and it
is the 6LR that receives and relays them to the nodes. 6LR and 6LBR
communicate with the ICMPv6 Duplicate Address Request (DAR) and the
Duplicate Address Confirmation (DAC) messages. The DAR and DAC use
the same message format as NS and NA with different ICMPv6 type
values.
In ND-PAAR we extend DAR/DAC messages to carry cryptographically
generated UID.
In a multihop 6LoWPAN, the node exchanges the messages shown in
Figure 2. The 6LBR must be aware of who owns an address (EUI-64) to
defend the first user if there is an attacker on another 6LR.
Because of this the content that the source signs and the signature
needs to be propagated to the 6LBR in DAR message. For this purpose
we need the DAR message sent by 6LR to 6LBR MUST contain CGA
Parameters and Digital Signature Option carrying the CGA that the
node calculates and its public key. DAR message also contains ARO.
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It is possible that occasionally, 6LR may miss the node's UID (that
it received in ARO). 6LR should be able to ask for it again. This is
done by restarting the exchanges shown in Figure 3. The result
enables 6LR to refresh the information that was lost. 6LR MUST send
DAR message with ARO to 6LBR. 6LBR as a reply forms a DAC message
with the information copied from the DAR and the Status field is set
to zero. With this exchange, the 6LBR can (re)validate and store the
information to make sure that the 6LR is not a fake.
5. Security Considerations
The same considerations regarding the threats to the Local Link Not
Covered (as in [RFC3971]) apply.
The threats discussed in Section 9.2 of [RFC3971] are countered by
the protocol described in this document as well.
As to the attacks to the protocol itself, denial of service attacks
that involve producing a very high number of packets are deemed
unlikely because of the assumptions on the node capabilities in low-
power and lossy networks.
A collision of ID in ND-PAAR is a really rare event that does not
prevent the protocol operation though it opens a window for a node to
hijack an address from another. The nodes would normally not be
aware that they are in this situation, and the only thing they could
do if they knew would be to steal addresses from one another, so the
damage is limited to these 2 nodes.
6. IANA considerations
TBD.
7. Acknowledgements
TBD.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor
Discovery (ND) Trust Models and Threats", RFC 3756, May
2004.
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[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, June
2007.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals", RFC
4919, August 2007.
[RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
"Elliptic Curve Cryptography Subject Public Key
Information", RFC 5480, March 2009.
[RFC5889] Baccelli, E. and M. Townsley, "IP Addressing Model in Ad
Hoc Networks", RFC 5889, September 2010.
[RFC6550] Winter, T., Thubert, P., 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, March 2012.
[RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,
"Neighbor Discovery Optimization for IPv6 over Low-Power
Wireless Personal Area Networks (6LoWPANs)", RFC 6775,
November 2012.
[RFC7102] Vasseur, JP., "Terms Used in Routing for Low-Power and
Lossy Networks", RFC 7102, January 2014.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217, April 2014.
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[Guide] "Guidelines for 64-bit global Identifier (EUI-64TM)",
November 2012,
<http://standards.ieee.org/develop/regauth/tut/eui64.pdf>.
8.2. Informative references
[I-D.rafiee-6man-ssas]
Rafiee, H. and C. Meinel, "A Simple Secure Addressing
Scheme for IPv6 AutoConfiguration (SSAS)", draft-rafiee-
6man-ssas-11 (work in progress), September 2014.
[I-D.chakrabarti-nordmark-6man-efficient-nd]
Chakrabarti, S., Nordmark, E., Thubert, P., and M.
Wasserman, "IPv6 Neighbor Discovery Optimizations for
Wired and Wireless Networks", draft-chakrabarti-nordmark-
6man-efficient-nd-07 (work in progress), February 2015.
[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-08 (work
in progress), May 2015.
Authors' Addresses
Behcet Sarikaya (editor)
Huawei USA
5340 Legacy Dr. Building 3
Plano, TX 75024
Email: sarikaya@ieee.org
Frank Xia
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012, China
Phone: ++86-25-56625443
Email: xiayangsong@huawei.com
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Pascal Thubert (editor)
Cisco Systems, Inc
Building D
45 Allee des Ormes - BP1200
MOUGINS - Sophia Antipolis 06254
FRANCE
Phone: +33 497 23 26 34
Email: pthubert@cisco.com
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