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Versions: 00 01

Network Working Group                                           M. Sethi
Internet-Draft                                                  Ericsson
Intended status: Informational                          October 18, 2018
Expires: April 21, 2019


         Enabling Network Access for IoT devices from the Cloud
                      draft-st-t2trg-nw-access-01

Abstract

   This document describes a method for enabling and configuring network
   access for IoT devices that are first authenticated at a server.
   This server may be run by the manufacturer of the IoT device as an
   online cloud service.  This specification is intended for off-the-
   shelf IoT devices that have just been purchased by the user.  Many of
   these devices have only limited user interfaces that can be used for
   configuring network access credentials.  The device configuration is
   also made more challenging by the fact that these devices may exist
   in large numbers.

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 April 21, 2019.

Copyright Notice

   Copyright (c) 2018 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



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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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Deployment Architecture . . . . . . . . . . . . . . . . . . .   4
   4.  Manufacturer Dependancy and End-of-life . . . . . . . . . . .   7
   5.  Alternative Manufacture Independent Deployment Models . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative references  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative references  . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   There is an increase in the deployment of Internet of Things (IoT)
   appliances such as wireless baby monitors, printers, speakers and
   smart TVs.  To enable rapid adoption while reducing the cost of
   deployment, these appliances typically use the existing Wi-Fi
   infrastructure (Access Point) for Internet connectivity.  However,
   configuring the network-access credentials for these off-the-shelf
   appliances is cumbersome.  Typically this process requires the user
   to pair the appliance with his/her smartphone over bluetooth and then
   configure the Wi-Fi SSID and passphrase.

   This process is not only cumbersome, but requires the appliance to be
   shipped with an additional network interface (only for
   configuration).  It also moves the problem of securely configuring
   the network-access credentials to the problem of secure bluetooth
   pairing.  Besides, relying on a single passphrase for the entire
   network may not be sustainable in the long run.  While changing the
   passphrase to revoke/remove a device from the network is easy today
   when most devices have a keyboard and only a few (2-5) devices are
   connected to the network (Access Point), this would be much harder
   when the devices are many (10-100) and have limited input
   capabilities.

   Once configured and connected to the Internet, the user still has to
   register the IoT device with the manufacturer.  This maybe to receive
   services or software updates.  For example, the user may connect his/
   her Wi-Fi weighing scale to keep track his/her weight online and
   receive software updates for new features.



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   This draft explains an example deployment scenario that relies on
   802.1x [IEEE-802.1X] and EAP [RFC3748] authentication to register the
   device with the manufacturer and enable network access (provision
   WiFi credentials) for the IoT device at the same time.  Using the
   802.1x authentication even in SOHO (small office and home) scenarios
   is a big assumption.  The following arguments may correctly apply
   against such a model:

   o  Most home access points currently do not support 802.1x
      authentication: This is however in most cases only a software
      limitation.  Many existing APs can support 802.1x authentication
      after firmware updates.

   o  Home users do not understand RADIUS [RFC6929] peering and cannot
      configure 802.1x authentication: This is often very true.
      However, there are mechanisms with which the burden on the user
      can be significantly reduced.  We will discuss some possible
      alternatives in the next section.

   o  Most SOHO (Small office and Home) deployments are small and a
      network wide shared secret provides reasonable security: This is
      an incorrect assumption.  While the deployments are small today,
      as more and more physical devices such as barbie dolls [barbie],
      weighing scales [scale], door bells [doorbell], and thermostats
      [nest] are connected to the Internet, using the same secret for
      the entire network is no longer sustainable.  This is necessary to
      prevent attacks where for example, a compromised WiFi weighing
      scale also compromises the NEST thermostat that is using the same
      network secret.

   o  An enterprise simply won't trust an external entity to remotely
      control their network and add new devices: This is true.  However,
      what we are suggesting in this memo is to allow an IoT device
      manufacturer to put a new IoT device into a separate Virtual LAN
      and enable limited Internet connectivity for it.  It is possible
      that certain enterprises may be willing.  However, we accept that
      this may not be the case in all enterprise settings.

   The architecture and solution presented in this draft is a
   generalized version of the original idea presented by Sethi et al.
   [Sethi14].

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].




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3.  Deployment Architecture

   We first look at deployments where the online cloud service is run by
   the manufacturer.  One such deployment architecture is shown in
   Figure 1.  The IoT device is shown on the left.  The device uses EAP
   for network-access authentication.

   The Manufacturer IoT device registration portal is shown on the
   right.  The manufacturer is responsible for running a AAA server that
   authenticates the IoT devices and then informs the users Access Point
   (AP) to enable Internet connectivity for the IoT device.

   The Access Point (AP) at the user premises is shown in the middle.
   The AP provides Internet connectivity to the user devices.  The AP
   must support 802.1x authentication and it uses RADIUS [RFC6929] or
   DIAMETER [RFC6733] to communicate with the Manufacturer IoT device
   registration portal.  For simplicity, the rest of this memo uses
   RADIUS as the example protocol.  However, it should be noted that the
   same objectives can be achieved with DIAMETER.

   As shown in Figure 1 the AP may optionally have a local RADIUS server
   (which maybe the case in small office environments).  In another
   deployment scenario shown in Figure 2, it is possible that the AP
   only has a local RADIUS client and routes all the EAP authentication
   messages to a single online RADIUS server (which maybe the case in
   home environments).  In this case (Figure 2), the online RADIUS
   server may be run by the AP manufacturer for example.  This would
   unburden the user from the task of maintaining a secure RADIUS server
   and setting up the necessary RADIUS peerings for IoT devices from
   different manufacturers.

   For routing the EAP messages between the IoT device and the
   manufacturer portal, a RADIUS peering is needed between the AP
   (authenticator) and the AAA server that is run by the manufacturer.
   This peering may be secured with a shared secret or certificate-based
   TLS.

   For correct routing of EAP messages from an IoT device to the device
   portal of the manufacturer, the realm part of the Network Access
   Identifier (NAI) [RFC7542] is used by the local RADIUS server in the
   AP (Figure 1) or the online RADIUS server (Figure 2).  For example,
   the RADIUS server in either case could see that the NAI is of the
   form "device@examplevendor.com" and proxy the authentication request
   to the online service run by the Example Vendor at
   aaa.examplevendor.com on port 1812.  As stated, the vendor service
   would only allow authentication request from trusted RADIUS servers
   that have peering relationship.  The vendor service will then run
   several rounds of EAP message exchanges to authenticate the device.



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   On successful authentication, the vendor service informs the RADIUS
   server to enable network access for the device by sending a RADIUS
   Access-Accept message.


                                              +------------------+
                                              |Manufacturer IoT  |
                      +------------+          |  device portal   |
                      |Access Point|          | +----------+     |
   +-----------+      | +--------+ | RADIUS   | |  RADIUS  |     |
   |           |      | | RADIUS +--------------+  Server  |     |
   |   IoT     | EAP  | | Server | |DIAMETER  | +-----+----+     |
   |  Device   +------+ +--------+ |          |       |          |
   |           |      |            |          | +-----+----+     |
   +-----------+      |            |          | |    AAA   |     |
                      +------------+          | |   Server |     |
                                              | +----------+     |
                                              +------------------+



             Figure 1: Deployment Architecture (Small Office)


                                               +------------------+
                                               |Manufacturer IoT  |
                +------------+  +-----------+  |device portal     |
                |Access Point|  |AP Manf.   |  | +----------+     |
   +-------+    | +--------+ |  |Service    |  | |RADIUS    |     |
   |  IoT  |    | | RADIUS | |  | +-------+------+Server    |     |
   | Device| EAP| | Client +------+RADIUS | |  | +-----+----+     |
   |       +----+ +--------+ |  | |Server | |  |       |          |
   +-------+    |            |  | +-------+ |  | +-----+----+     |
                |            |  |           |  | |    AAA   |     |
                +------------+  +-----------+  | |   Server |     |
                                               | +----------+     |
                                               +------------------+



                 Figure 2: Deployment Architecture (Home)

   The exact EAP method used for authentication can be decided by the
   IoT device manufacturer.  For example, the manufacturer may provision
   certificates on the device which are then used for EAP-TLS [RFC5216]
   authentication.  After successful authentication, the AAA server
   sends a RADIUS Access-Accept message enabling Internet connectivity
   for the IoT device.  An example message flow in shown in Figure 3.



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           IoT device             AP                 Manufacturer IoT
                                                      device portal
      -------------------     -------------         --------------------
                              <- EAP-Request/
                              Identity
      EAP-Response/
      Identity (MyID) ->

                              Forward auth messages
                              to IoT device portal
                              by looking at realm
                              in MyID

                                                       <- EAP-Request/
                                                      EAP-Type=EAP-TLS
                                                        (TLS Start)
      EAP-Response/
      EAP-Type=EAP-TLS
      (TLS client_hello)->
                                                    <- EAP-Request/
                                                    EAP-Type=EAP-TLS
                                                    (TLS server_hello,
                                                      TLS certificate,
                                             [TLS server_key_exchange,]
                                              TLS certificate_request,
                                                 TLS server_hello_done)
      EAP-Response/
      EAP-Type=EAP-TLS
      (TLS certificate,
       TLS client_key_exchange,
       TLS certificate_verify,
       TLS change_cipher_spec,
       TLS finished) ->
                                                  <- EAP-Request/
                                                  EAP-Type=EAP-TLS
                                              (TLS change_cipher_spec,
                                                   TLS finished)
      EAP-Response/
      EAP-Type=EAP-TLS ->
                              <- EAP-Success    <-Radius Access-Accept



                    Figure 3: Example message sequence







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4.  Manufacturer Dependancy and End-of-life

   There is a valid concern about the over-reliance on the IoT device
   manufacturer for the initial network bootstrapping.  After all, not
   all device manufacturers maybe willing or capable to run such an
   online service throughout the lifetime of the IoT device.

   For example, the Revolv smart home hub lost all manufacturer support
   after the it was acquired [revolv].  As noted by
   [I-D.irtf-t2trg-iot-seccons], such end-of-life of devices may be
   planned or unplanned (for example when the manufacturer goes bankrupt
   or when the vendor just decides to abandon a product).  A user should
   still be able to use/bootstrap/re-bootstrap this device.  This can
   require some form of authorization handover.

   Another question is whether there would be someone willing to
   continue offering an online AAA service for devices which are no
   longer supported by the original manufacturer.  Whether this can be
   mandated by regulation or by having sufficient business incentives
   cannot be addressed in this draft.  However, we would note that there
   are examples of open-source communities supporting existing devices
   irrespective of any manufacturer support.  OpenWrt for home routers
   and Cyanogenmod (continued as Lineage OS) for smartphones are two
   such popular examples.

   With some support from the IoT device manufacturer, the deployment
   models described thus far in this document are thankfully flexible
   enough to allow the user to choose an online AAA server different
   from the original device manufacturer.  The RADIUS peering can simply
   be updated to reflect this change.  For example, once the credentials
   for all the devices at aaa.examplevendor.com have been transferred to
   a new AAA server run by an open source community at
   aaa.openvendor.com, the RADIUS peering in can simply be updated to
   forward EAP requests from devices with NAI realm as examplevendor.com
   to aaa.openvendor.com at port 1812.

5.  Alternative Manufacture Independent Deployment Models

   In this section we look at some alternative deployment modes which
   don't rely on any pre-provisioned credentials of any sort on the IoT
   device.  Consider the deployment architecture shown in Figure 4.
   While it looks similar to the figures above, the key difference is
   that the IoT device portal can now be any third-party online service
   rather than relying on manufacturer.  As above, the AP is expected to
   forward all EAP authentication requests from IoT devices to a single
   online RADIUS server by setting up the necessary peering.





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   The user can now pre-register the credentials for new devices that
   will join the WiFi network.  For example, the user can specify a
   secret that will be used by the device for joining the network.  The
   device can then run EAP-PSK [RFC4764] with the online RADIUS server
   for securely joining the network.  The online RADIUS server can
   prevent the user from registering the same (or similar) secrets for
   the different devices in the network.  This would ensure that devices
   in network do not share the same secret.


                                              +------------------+
                                              |       IoT        |
                      +------------+          |  device portal   |
                      |Access Point|          | +----------+     |
   +-----------+      | +--------+ | RADIUS   | |  RADIUS  |     |
   |           |      | | RADIUS +--------------+  Server  |     |
   |   IoT     | EAP  | | Client | |          | +-----+----+     |
   |  Device   +------+ +--------+ |          |       |          |
   |           |      |            |          | +-----+----+     |
   +-----------+      |            |          | |    AAA   |     |
                      +------------+          | |   Server |     |
                                              | +----------+     |
                                              +------------------+


                 Figure 4: Deployment Architecture (Home)

   Other EAP methods, such as EAP-NOOB [I-D.aura-eap-noob] can also be
   deployed with the architecture shown above.  EAP-NOOB does not
   require any pre-provisioned credentials on the IoT device.  Instead
   of requiring the user to input the same PSK on the two ends, the user
   simply transfers an out-of-band (OOB) message between the device and
   the server.  This can be especially useful for IoT devices which lack
   the necessary user interface for entering PSKs.

6.  Security Considerations

   Fake device: It may seem that any device can simply join the users
   network because the attacker can always setup a fake registration
   portal and pretend to successfully authenticate every device.
   However, this is not really the case.  Any device can be connected to
   the user's access point only if there is radius peering to the
   attackers registration portal.

   There still remains the question of how does the device know which AP
   to try and connect to.  To aid this discovery, it is necessary that
   IoT devices only use EAP methods that provide mutual authentication
   (such as EAP-TLS, EAP-PSK and EAP-NOOB).



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   The devices can then opportunistically try to connect with APs that
   are withing range (ignoring all open APs and APs that use WPA2-PSK).
   The devices would successfully connect to an AP, if it can forward
   the EAP messages to the right RADIUS server in the device portal.
   However, there may be scenarios where many APs setup peering with a
   few popular online IoT device portals.  The devices in this case
   would connect to an unintended AP.  While encryption of higher layer
   traffic is expected, this would still have negative consequences as
   IoT devices may inadvertently connect to and consume bandwidth from
   the wrong AP.

   To prevent such inadvertent scenarios, additional information about
   the AP must be provided to the IoT device portal when the RADIUS
   peering is setup.  The IoT device portal can then ask the user
   whether he/she wants to allow a new IoT device that is attempting to
   connect through his AP.  Fortunately, such AP information can easily
   be communicated over RADIUS using, for example, the NAS-Identifier
   attribute.

7.  IANA Considerations

   There are no IANA impacts in this memo.

8.  References

8.1.  Normative references

   [I-D.aura-eap-noob]
              Aura, T. and M. Sethi, "Nimble out-of-band authentication
              for EAP (EAP-NOOB)", draft-aura-eap-noob-03 (work in
              progress), July 2018.

   [I-D.irtf-t2trg-iot-seccons]
              Garcia-Morchon, O., Kumar, S., and M. Sethi, "State-of-
              the-Art and Challenges for the Internet of Things
              Security", draft-irtf-t2trg-iot-seccons-15 (work in
              progress), May 2018.

   [IEEE-802.1X]
              Institute of Electrical and Electronics Engineers, "Local
              and Metropolitan Area Networks: Port-Based Network Access
              Control", IEEE Standard 802.1X-2004. , December 2004.

   [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>.




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   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, Ed., "Extensible Authentication Protocol
              (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
              <https://www.rfc-editor.org/info/rfc3748>.

   [RFC4764]  Bersani, F. and H. Tschofenig, "The EAP-PSK Protocol: A
              Pre-Shared Key Extensible Authentication Protocol (EAP)
              Method", RFC 4764, DOI 10.17487/RFC4764, January 2007,
              <https://www.rfc-editor.org/info/rfc4764>.

   [RFC5216]  Simon, D., Aboba, B., and R. Hurst, "The EAP-TLS
              Authentication Protocol", RFC 5216, DOI 10.17487/RFC5216,
              March 2008, <https://www.rfc-editor.org/info/rfc5216>.

   [RFC6733]  Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
              Ed., "Diameter Base Protocol", RFC 6733,
              DOI 10.17487/RFC6733, October 2012,
              <https://www.rfc-editor.org/info/rfc6733>.

   [RFC6929]  DeKok, A. and A. Lior, "Remote Authentication Dial In User
              Service (RADIUS) Protocol Extensions", RFC 6929,
              DOI 10.17487/RFC6929, April 2013,
              <https://www.rfc-editor.org/info/rfc6929>.

   [RFC7542]  DeKok, A., "The Network Access Identifier", RFC 7542,
              DOI 10.17487/RFC7542, May 2015,
              <https://www.rfc-editor.org/info/rfc7542>.

8.2.  Informative references

   [barbie]   Gibbs, Samuel., "Hackers can hijack Wi-Fi Hello Barbie to
              spy on your children", November 2015,
              <https://www.theguardian.com/technology/2015/nov/26/
              hackers-can-hijack-wi-fi-hello-barbie-to-spy-on-your-
              children>.

   [doorbell]
              Kumar, M., "How to Hack WiFi Password from Smart
              Doorbells", January 2016, <thehackernews.com/2016/01/
              doorbell-hacking-wifi-pasword.html>.

   [nest]     Nest, "Nest Learning Thermostat", January 2016,
              <https://nest.com/thermostat/meet-nest-thermostat/>.

   [revolv]   "Nest is permanently disabling the Revolv smart home hub",
              The Verge , April 2016,
              <https://www.theverge.com/2016/4/4/11362928/
              google-nest-revolv-shutdown-smart-home-products>.



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   [scale]    Withings, "Body", January 2016,
              <https://www.withings.com/eu/en/products/body>.

   [Sethi14]  Sethi, M., Oat, E., Di Francesco, M., and T. Aura, "Secure
              Bootstrapping of Cloud-Managed Ubiquitous Displays",
              Proceedings of ACM International Joint Conference on
              Pervasive and Ubiquitous Computing (UbiComp 2014), pp.
              739-750, Seattle, USA , September 2014,
              <http://dx.doi.org/10.1145/2632048.2632049>.

Author's Address

   Mohit Sethi
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland

   EMail: mohit@piuha.net
































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