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Versions: 00 draft-vasu-ace-core-access-privilege-provisioning

Internet Engineering Task Force                                   Vasu K
INTERNET-DRAFT                                                 Rahul A J
Intended Status: Standard Track                                 Yangneng
Expires: April 19, 2016                                           Huawei
                                                            Oct 19, 2015


             Service Provisioning for Constrained Devices
              draft-vasu-core-ace-service-provisioning-00


Abstract

   As more constrained devices are integrating with current Internet,
   the ubiquitous computing in scenarios like smart home is very
   important. In smart home, the constrained devices (ex. thermostat)
   need to be provisioned in such a way that it can inter-operate with
   any kind of devices like other constrained devices (ex. Air
   conditioner) or client devices (ex. smart phone). This document
   provides a method to support service provisioning based on pre-
   configured admission and resource control policies, where this method
   explains device's service access in two different use cases: first
   provisioning the service when a constrained device accessing the
   service provided by other constrained device, second, accessing the
   service provided by constrained device from the client device (non
   constrained device).

Status of this Memo This Internet-Draft is submitted to IETF in full
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   This Internet-Draft will expire on April 19, 2016.




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Copyright and License 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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   publication of this document. Please review these documents
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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 . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3 Terminology  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4  System Architecture . . . . . . . . . . . . . . . . . . . . . .  6
   5 Network Topology . . . . . . . . . . . . . . . . . . . . . . . .  9
   6 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     6.1 Register Service . . . . . . . . . . . . . . . . . . . . . . 10
       6.3.1 Resource Control . . . . . . . . . . . . . . . . . . . . 14
     6.4 Search for services by device  . . . . . . . . . . . . . . . 18
     6.5 Service request and response . . . . . . . . . . . . . . . . 18
   7  Security Considerations . . . . . . . . . . . . . . . . . . . . 22
   8  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 22
   9  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 23
     9.1  Normative References  . . . . . . . . . . . . . . . . . . . 23
     9.2  Informative References  . . . . . . . . . . . . . . . . . . 23
   10  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24














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1 Introduction

   The work on Constrained Restful Environment (CoRE) aimed to realize
   the restful architecture for constrained devices [RFC7228] in
   constrained networks [RFC4944]. The CORE work group has recently
   standardized constrained application protocol (CoAP) [RFC7252] for
   interacting with constrained resources where general HTTP is not
   memory/energy efficient. The use of web linking for resources
   description and discovery hosted by constrained web servers is
   specified by CORE [RFC6690]. Even though, CoAP allows the direct
   resource access for constrained devices, it is not advisable for
   direct access of resources in networks where multicast procedures are
   infeasible due to heavy network load, and the networks where sleepy
   nodes exist. So, the CoRE working group comes up with a solution
   called resource directory (RD) [draft-ietf-core-resource-directory]
   to host the devices service information, and allow other devices to
   perform lookup procedures through .well-known/core path to resources.

   The services advertised by these constrained devices needs to be
   commissioned and provisioned properly to allow other devices to
   access it. CoRE RD solution is a directory based solution that
   depends on CoAP protocol. CORE RD solution uses
   registration/update/delete/lookup procedures for service
   registration, service update, deleting service, lookup of services
   respectively. Service commissioning is a method which verifies a pre
   registered services with special commissioning tools/agents. These
   tools can be tablets or special embedded devices which initially
   stores the devices identifications in secure manner. Once the
   services are advertised by any device, those services need to be
   verified using commissioner. CORE RD provides a standard procedure to
   interact with commissioner, where commissioner acts like a client
   device to look up and verify the advertised services. Once the
   commissioner verifies the pre-registered services, commissioner can
   put some policy rules on services hosted by devices for resource
   control. These rules defined on (1) how to access the services either
   with other constrained devices or client devices, and (2) on
   operational instructions.

   Architecture is defined to authenticate and authorize client requests
   for a resource on a server using logical entities such as client(C),
   client authorization manager(CAM), server(S), and server
   authorization manager(SAM)[draft-gerdes-ace-actors]. The main goal of
   delegated CoAP authentication and authorization framework (DCAF) is
   the setup of a datagram transport layer security channel between two
   nodes to securely transmit authorization tickets   [draft-gerdes-
   core-dcaf-authorize]. The CAM sends an access request message on
   behalf of client by embedding requested permissions in client
   authorization information (CAI) field of access request message to



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   SAM. A ticket grant message is sent from SAM by embedding the
   permissions given from the server on a specific resource in server
   authorization information (SAI) field of ticket grant message to the
   client. These SAI, CAI use authorization information format (AIF)
   that describes the permissions requested from access request in a
   ticket request, where the underlying access control model will be
   that of an access matrix, which gives a set of permissions for each
   possible combination of a subject and an object [draft-bormann-core-
   ace-aif]. This simple information model also doesn't allow
   conditional access (e.g.,"resource /s/tempC is accessible only if
   client belongs to group1 and does not belong to group2"). Finally,
   the model does not provide any dynamic functions such as enabling
   special access for a set of resources that are specific to a subject.
   But, the services provided by resources in constrained environment,
   need to be authorized and controlled conditionally based on some
   service level agreements or preconfigured policies on resource
   control.

   Considering an example use case scenario such as thermostat device
   measures the current room temperature, and can service for air
   conditioner device to set automatic temperatures. In a smart home,
   user wants to regulate his room temperature automatically using his
   airconditioner device. Here, this airconditioner device can adjust
   its temperature to either cool the room or heat the room by accessing
   the service provided by the thermostat. Suppose this user leaves the
   home in the morning in hot summer and leaves the office in the
   evening to reach to home. But, before he reaches his room he wants to
   make his room cool enough. So he has to switch on the airconditioner
   from his mobile one hour before he leaves the office. So, before
   adjusting his aircconditioner to make the room cool enough, he might
   have to know the current room temperature. Thus he access the service
   provided by the thermostat to read the room temperature and adjust
   the airconditioner. However, there is a problem here on how to access
   these services which are provided by user's home devices itself, what
   is the authenticity level to access from outside the home, even
   within home what is the access control/resource control of these
   devices because the neighboring device which are not authenticated
   can also access these service if those devices are within the
   constrained network range. Finally it is important to admit access of
   the service by client based on the configuration policies so that the
   devices can be protected from hazardous conditions, and allows only
   pre-agreed operations on devices.

   The service provisioning presented in this document provides a method
   to support admission, and resource control policies using
   commissioning procedure. The method explains the device's service
   access in two different use cases: first provisioning the service
   when a constrained device accessing the service provided by other



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   constrained device, second, accessing the service provided by
   constrained device from the client device. Even though it is out of
   scope of the present document, it also considers a secure way of
   service commissioning as part of security.


2 Motivation

   CORE RD solution provides various automated operations such as
   service registrations, service update, service removal, and service
   lookups initiated by endpoints and clients. However, managing this
   centralized directory server by allowing authorized users to perform
   these tasks, setting some service level agreements on clients to
   access these services, and providing limited or scope oriented
   lookups by other endpoints or clients require efficient service
   provisioning mechanism. The service provisioning method presented in
   this document deals on how a registered service from devices can be
   accessed by various clients or other devices. Moreover, it also
   provides a method for handling this resource/service access control
   mechanism using web service model for efficient service provisioning
   from outside the constrained home environment.

3 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].

      o "CORE", CORE is a Constrained RESTful Environment providing a
      framework for resource-oriented application intended to run on
      constrained networks [RFC7228].

      o "COAP" The Constrained Application Protocol (CoAP) is a
      specialized web transfer protocol for use with constrained nodes
      and networks [RFC7252].

      o "RD" The Resource Directory (RD) is a directory based server to
      host the descriptions of resources and allowing the lookups to be
      performed for those resources by various client devices.

      o "Commissioner" Commissioning agent is tool/device that verifies
      the devices operation, integrity check with the network.

      o "Constrained Device" These are embedded computing devices that
      are expected to be as resource constrained in terms of RAM/ROM
      size, and to be deployed with the constrained environment such as
      6LoWPAN Networks.




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      o "Client" A client device is like resource constrained client
      such as other constrained device (ex. Air conditioner) or rich
      client devices such as Mobile/Laptop/Tablet etc, which access the
      services hosted by constrained devices (ex. thermostat).

      o "Provisioning Server" this server is a process of verifying
      service requester, providing access controls or admission controls
      on resources to be accessed and inter-operating with various
      devices without bothering about kind of network protocols used. It
      also provides web access model outside the constrained
      environment.

      o "Device Profile" A device profile comprises a set of attributes
      that are associated with a particular device. These include
      services, features, names, descriptions etc.


4  System Architecture

      The system architecture is better explained with two different
      scenarios: (1) Constrained device access the service advertised by
      other constrained device is as shown in Fig 1. Here, one
      constrained device such as air-conditioner can access the service
      such as current room temperature advertised by other constrained
      device (ex. thermostat). This advertised service is to be
      commissioned by commissioner, and then it should be set with some
      admission and resource control policies by provisioning server.
      And, finally the service is allowed to advertise its service
      access from other constrained devices. Any device that is
      interested in that advertised service, need to do service lookup
      from RD Server. Once obtaining the path to the advertised service,
      the constrained      client device can request a service to the
      device which hosts the service. Before sending the request, it
      MUST establish a secure channel between these two nodes [draft-
      schmitt-ace-twowayauth-for-iot]. Once the incoming request comes
      from the constrained client device, the device which hosts the
      service MUST authorize and provision for conditional access of its
      service from the provisioning server. The notification regarding
      the registered services to the commissioning agent can be sent
      from the RD server, which can be implementation specific and left
      for the user to choose any standard procedures and is out of scope
      of present document. Detailed operational procedure will be
      explained in the later sections of this document.








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       +------+  +-------+   +-----+   +--------+  +----------+
       |Device1  |Device2|   | RD  |   |Provis  |  |Commision
       |(Air     |(Thermo|   |     |   |ioning  |  |ing       |
       |Condi |  |  stat)|   |Serv     |Sever   |  |Agent     |
       |tioner)  |       |   |er   |   |        |  |          |
       +--|---+  +----|--+   +--|--+   +----|---+  +-----|----+
          |           |         |           |            |
          |           |         |           |            |
          |           |Register |           |            |
          |           ----------//          |            |
          |           | Service/|  Verify Preregistered\ |/
          |           |         ------------------------//
          |           |         |    Service|         // |
          |           |         |           |        /   |
          |           |         |           |            |
          |           |         |           |            |
          |           |         |           |            |
          |           |         |           |//Define    |
          |           |         |          /-------------
          |           |         |         / \ Policies   |
          |Search a Service  \  |           |            |
          ---------------------//           |            |
          |           |       //|           |            |
          |           |      /  |           |            |
          |           |         |           |            |
          |           |         |           |            |
          |Request    |         |           |            |
          -----------/          |           |            |
          |Service   /|         |           |            |
          |         / |         |           |            |
          |           |Check for authorization           |
          |           |admission, Resource  |            |
          |           ---------------------//            |
          |           | Control Policies  //|            |
          |           |         |        /  |            |
          |           |         |           |            |
          |           |         |           |            |
          |           | // Service Grant/Deny            |
          |           /---------------------             |
          |          /|\        |           |            |
          |  /        |         |           |            |
         \//Service  |          |           |            |
          /\----------          |           |            |
          |    Grant/Deny       |           |            |
          |           |         |           |            |

      Fig 1.Constrained device accessing service from constrained device




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       +--------+  +-------+  +-------+  +---------+ +---------+
       |Client  |  |Device2|  |RD     |  |Provision| |Commissi |
       |(Smart  |  |(Thermo|  |Server |  |ing Server |oning    |
       | Phone) |  | stat) |  |       |  |         | |Agent    |
       |        |  |       |  |       |  |         | |         |
       |        |  |       |  |       |  |         | |         |
       +---|----+  +---|---+  +---|---+  +----|----+ +-----|---+
           |           |          |           |            |
           |           |          |           |            |
           |           |Register  |           |            |
           |           -----------/           |            |
           |           |Service   /           |            |
           |           |         /|           |            |
           |           |          |  /        |            |
           |           |          |//Verify Preregistered  |
           |           |          --------------------------
           |           |          |\    Service            |
           |           |          |           |            |
           |           |          |           |            |
           |           |          |           |  /         |
           |           |          |           |//Define    |
           |           |          |           -------------
           |           |          |           |\ Policies  |
           |           |          |           |            |
           | Request for Service  |        \               |
           ----------------------------------//            |
           |           |          |         //|            |
           |           |          |        /  |            |
           |           |          |           |            |
           |           |  /       |           |            |
           |           |// Request| for Service            |
           |           -----------------------             |
           |           |          |           |            |
           |           |          |           |            |
           |           |          |           |            |
           |           | Service Grant/Deny\  |            |
           |           ----------------------/             |
           |           |          |         //|            |
           |           |          |        /  |            |
           |           |          |           |            |
           |           |          |           |            |
           |  //       |          |           |            |
           |//   Service Grant/Deny           |            |
           \----------------------------------            |
           | \         |          |           |            |
           |           |          |           |            |

           Fig 2. Client accessing service from Constrained device



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      2) Client device access the service advertised by constrained
      device is as shown in Fig 2. For example, the client device such
      as smart phone can access the service (ex. room temperature)
      advertised by other constrained device (ex. thermostat). The
      client can access the service within a home environment or outside
      the home environment. So, in this scenario, the provisioning
      server maintains the service as a web service.

      This advertised service is to be commissioned by commissioner,
      then to be set with some admission and resource control policies
      by provisioning server. And, finally the service is allowed to
      advertise its access from the client devices. Any client that
      wishes to access this web service looks for corresponding
      operations provided from the provisioning server.


5 Network Topology

      The constrained devices such as Thermostat, Airconditioner may use
      small memory constrained sensors/actuators for simple services
      such as cooling/heating the room or just to measure the current
      room temperature. These memory constrained embedded devices may
      implement the 6LoWPAN stack such as uIP (provided by Contiki), and
      provide access for communication to other external queries from
      client devices such as smart phone which typically implements rich
      stack TCP/IP. Even though RD server or Provisioning server are
      shown as separate servers in the LAN as given in Fig 3, these can
      be hosted on a single server running two different processes.
      Moreover, the commissioner implements a standard procedure to
      interact with devices as a separate agent process which is out of
      scope of the present document and has been left to user's choice
      while satisfying the mentioned operations in the current draft. On
      the other hand, these specific operations can be implemented
      separately as a third party and to be used at the commissioning
      agent. The lower level communication technology can be implemented
      either through Bluetooth (BT) or near field communication (NFC) to
      verify the devices unique ID (for ex. using MAC). Even though, the
      implementation procedure for commissioner is out of scope for the
      present document, it is shown as sample interaction with RD
      server/provisioning server as part of commissioning procedure in
      subsequent sections. Even though the present document discusses
      about 6LoWPAN based sensor network, it can be easily moved to any
      other technology such as Zigbee/BLE/Wireless HART without any
      changes in the architecture or design, because the present
      document abstracted the communication networks with their edge
      routers. The communication and routing mechanisms or procedure
      between edge router and sensor devices/client devices are out of
      scope of the present document.



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             -------                      --------
           //       \                  //        \
          /                          //            \
         /                          /
        /                          /
        | +--------+    |           |        +--------+|
       |  |RD Server---| |         | +-----+ |Thermostat|
       |  +--------+   | | LAN     | |Edge | +--------+ |
       |               |------|-------     |            |
       |  +----------+ | |    |    | |Router 6LoWPAN    |
        | |Provision --||     |     |+-----+           |
         |Server    |  /     |          +--------+   /
         +----------+ /      |          |Aircondioner
                     /       |       \  +--------+//
           \       //        |         \        //
             -------          |           --------
                              |
                              |
                              |
                              |
                              |
                             -|-----
                          //- |     -\
                        //  +-|----+   \
                       /    |Edge  |
                      /     |Router|
                      |     +------+      |
                     |                     |
                     |    WiFi             |
                     |   +-------+ +-----+ |
                     |   |Smart  | |Commisioning
                      |  |Phone  | | Agent|
                        +-------+ +-----+/
                                        /
                        \             //
                          \-       -//
                             -------

                    Fig 3. Network Topology

6 Operations

6.1 Register Service

      The constrained device which hosts the service MUST register its
      service with the RD server using its unique identifier (for ex.
      MAC id, UDDI registry etc.) and IP address as shown in Fig 4. The
      device MUST send a POST request for registering its service.



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      Before sending a request, it MUST establish a secure channel
      between these two nodes [draft-schmitt-ace-twowayauth-for-iot].
      Once the service has been registered with the RD server, the RD
      server may notify the registered information of a device (for
      ex.its unique identifier and device name) to a commissioning
      agent.

         +---------+                                         +---------+
         |         |                                         |         |
         | Device  |                                         |RD Server|
         |         |                                         |         |
         +----+----+                                         +-----+---+
              |                                                    |
              |                                                    |
              |                                               `.   |
              | POST /rd?ep=node1&d=example.com&et=temperature-no`.|
              +--------------------------------------------------,'.
              | gp=thermostat&con=DeviceID(100)                ,'  |
              |                                              ,'    |
              |   ,'                                               |
              | ,'  2.01 Created Location: /rd/7521                |
              `.----------------------------------------------------
              | `-.                                                |
              |    `.                                              |
              |                                                    |

                   Fig. 4 Registering a Service


      6.2 Verify pre-registered service

      The commissioning agent MUST verify any pre registered service
      with the RD server as shown in Fig 5. The commissioning agent
      sends a GET request for domain lookup. Before sending the request,
      it MUST establish a secure channel between these two nodes
      [DTLS][TLS]. Once obtaining the specific domain, it MUST look for
      the group to which the service belongs. Once obtaining the
      specific domain and group, it MUST send a service look up with the
      RD server for the registered service. Once obtaining the service
      information about a specific device, the commissioning agent MUST
      verify the registered service. This service information is later
      used to create service registry in the provisioning server as
      explained in the following section. The example service
      information (denoted as SRV) looks like as shown in Fig 6.







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       +---------------+                                  +----------+
       |Commissioning  |                                  | RD Server|
       |Agent          |                                  |          |
       +------+--------+                                  +--------+-+
              |                                                    |
              |                                                    |
              |     GET /rd-lookup/d                           `.  |
              +--------------------------------------------------:'.
              |                                                .'  |
              |                                                    |
              | .'2.05 Content </rd>;d=example.com,</rd>;d=example.com
              ::---------------------------------------------------+
              | `-.                                                |
              |   GET /rd-lookup/gp?ep=node1&d=example.com      `. |
              +---------------------------------------------------/.
              |                                                 .' |
              |                                                    |
              | .'2.05 Content <coap://ip:port>;gp=thermostat;ep=node1
              ::---------------------------------------------------+
              | `-.                                                |
              |                                               `.   |
              | GET /rd-lookup/res?rt=temp&gp=thermostat&d=example.com
              +--------------------------------------------------:'.
              |                                                .'  |
              |                                                    |
              | .'2.05 Content <coap://host:port>;rt=temp;gp=thermostat
              ::---------------------------------------------------+
              | `-.                              d=example.com     |
      +---------------------------+                                |
      |Authentication of Service  |                                |
      |Info and DeviceID          |                                |
      +---------------------------+ POST Verified User; DeviceID`. |
              +---------------------------------------------------::
              | .'                                             .-' |
              .`.__________________________________________________|
              |  `.    2.00 OK                                     |

            Fig. 5 Verify pre registered service

               SRV {
                     Name: Node1
                     Group: Thermostat
                     Domain: myhome.com
                     Type: Temperature node
                     Device ID: 1001
                     Device IP: <host:port>
                   }
                     Fig 6. Example Service Informaion



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      6.3 Define policies on resource control

       +----------------+                        +---------------+
       |Commissioning   |                        |Provisioning   |
       | Agent          |                        | Server        |
       +------+---------+                        +--------+------+
              |  POST /thermostat /HTTP/1.1            `. |
              +------------------------------------------/.
              |  HOST thermostat.ps.example.com        .' |
              |  Content-Type: application/text           |
              |  SRV { Name: Node1                        |
              |        Group: Thermostat                  |
              |        Domain: myhome.com                 |
              |        Type: Temperature-node             |
              |        DeviceID: 1001                     |
              |        DeviceIP: <host:port> }            |
              |                                           |
              | .'     HTTP/1.1 200 OK                    |
              ::------------------------------------------'
              | `.     Content-Type: application/text     |
              |        { sID (service ID) }               |
              |                                           |
              |  POST /thermostat /HTTP/1.1            `. |
              +------------------------------------------::
              |  HOST thermostat.ps.example.com        .' |
              |  Content-Type: application/text           |
              |  AC { ServiceID: 1234                     |
              |       Auth: Basic Auth Support            |
              |       Count: 10                           |
              |       Admission Control: R,W,R/W,D }      |
              |                                           |
              | .'    HTTP/1.1 200 OK                     |
              ::------------------------------------------+
              | `.    Content-Type: application/text      |
              |                                           |
              |  POST /thermostat /HTTP/1.1            `. |
              +------------------------------------------::
              |  HOST thermostat.ps.example.com        .' |
              |  Content-Type: application/text           |
              |  RC { If C is from G1 allow {R,W};        |
              |       If C is from G2&!G3 allow {R};      |
              |       If C is from d1&g1 allow {R,W,D};   |
              |        : }                                |
              | .'    HTTP/1.1 200 OK                     |
              ::------------------------------------------+
              | `.    Content-Type: application/text      |
              |                                           |
            Fig. 7 Defining Policies on Resource and Access Control



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      Once the hosted service has been verified by commissioning agent
      (CA), the CA MUST create a service registry with the provisioning
      server as explained in Fig 7. The provisioning server SHOULD send
      a service ID as a response back to the commissioning agent after
      creating the service entry.

      This service ID can be later used by the commissioning agent to
      permanently DELETE the service entry ( if required). The
      commissioning agent MUST create some admission control policies
      such as read (R), write (W), read/write (R/W), delete (D), number
      of simultaneous connection on resource etc.  on the registered
      service. Once the admission control policies has been set on a
      specific device, the resource control policies such as conditional
      access of a service, quality of service agreements (based on the
      priority levels set for clients) can be set on that registered
      service. These conditional access on service can be implemented
      with simple conditional statements as explained in section 6.3.1
      (for ex. "client (c) can access service with only read (R), write
      (W) permissions if it only belongs to group (g)"). The
      implementation or information format details of these conditional
      statements is out of scope of the present document (TBD). The
      example admission control and resource control policies are as
      shown in Fig 8, and Fig 9 respectively.

               AC {
                     Service ID: 12345
                     Auth: Basic Auth Support
                     Count: 10
                     Admission Control: R, W, R/W, D
                       :
                       :
                  }

                     Fig 8. Example Admission Control Policies

               RC {
                     If c is from g1 allow {R,W}
                     If C is from g2 & !g3 {R}
                     If C is from d1 & g1 allow {R, W, D}
                       :
                       :
                  }

                     Fig 9. Example Resource Control Policies

6.3.1 Resource Control

      Resource control policies for constrained devices are expressed in



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      terms of conditional expressions as explained in Fig. 9. Consider
      a scenario where we define the client (C) (who accesses the
      resource) in terms of groups/levels. For example in a typical home
      building, we assign each floor as a group. Suppose for a three
      floor building, the clients such as mobile phone/air conditioner
      can belong to any of the floor within a building. And we allow
      various permissions for the clients according to the group it
      belongs to, as specified in Fig 10.

                            ---------------------------
                            |       |     |   |   |   |
                            |Client |  R  | W | U | D |
                            |-------------|---|---|---|
                            |G1     |  *  | - | * | - |
                            |       |     |   |   |   |
                            |G2     |  *  | * | - | - |
                            |       |     |   |   |   |
                            |G3     |  -  | - | - | * |
                            |--------------------------
                           Fig 10. Example Permissions on Methods

      Supposed we assigned the priorities for different groups as C
      belongs to {G1, G2, G3} => {P1, P3, P2}. Moreover, if we would
      like to assign different QoS classes for clients, depending on the
      applications they use then it is required to control QoS policies
      in resource control. QoS is defined in terms of various parameters
      such as {availability, reliability, serviceability, data accuracy,
      aggregation delay, coverage, fault tolerance, network lifetime} in
      wireless sensor networks. It is assumed that based on these
      parameters, QoS is defined in terms of various classes such as
      {Q1, Q2, Q3}, then it is required that some of the clients can
      make some pre-level agreements on QoS requirement for their
      applications either based on the groups it belongs to or based on
      the priority of the clients request (Suppose, C belongs to {Q1,
      Q2, Q3}). Method for defining QoS classes is out of scope of the
      present document. Once defining the groups, its priorities, QoS
      classes, and permissions, then the conditional statements which
      define the resource control policies can be defined as follows:

      ST1: If the client belongs to G1 then it is allowed with
      permissions {R, R/W, U}, priority {P1}, QoS {Q1}, and operations
      {turn it up, read}; else if the client belongs to G2 then it is
      allowed with permissions {R, W, R/W}, priority {P3}, QoS {Q2}, and
      operations {turn it up, read}; else if the client belongs to G3
      then it is allowed with permissions {D}, priority {P2}, QoS {Q3},
      and operations {turn it down}.

      ST2: Allow the client with priority {P1}, QoS {Q1}, operations



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      {turn it up, turn it down, read}, and allow only with permissions
      {R} in G1; permissions {R, R/W, D} in G2; and permissions {D} in
      G3.

      ST3: Allow the client with priority {P1}, QoS {Q1}, and allow with
      permissions {R}, operations {read} in G1; allow with permissions
      {R, R/W, D}, operations {turn it up, turn it down, read} in G2;
      and allow with permissions {D}, operations {turn it down} in G3.

      Above conditional statements are few examples on how to define the
      conditional statements, the statements can be defined on any
      manner based on the resource control policies we would like to
      achieve. The above statements can be better explained in plain
      semantic notation as shown in Fig 11(a)-13(a), and the
      corresponding JSON representations for message exchange is
      explained in Fig 11(b)-13(b). These statements can be even
      implemented using data modeling language such as YANG or ASN 1.1
      which is out of scope of the present document.

       C
       {
          G1                               |"[
          {                                |"C":{"G1":{"Allow":"R,U",
              Allow {R,U}                  |"Priority":"P1","QoS":"Q1",
              Priority {P1}                |"Operations":"turnup,read"},
              QoS {Q1}                     |"G2":{"Allow":"R,W",
              Operations {tunr it up, read}|"Priority":"P3","QoS":"Q2",
          }                                |"Operations":"turn it
          G2                               |up,read"},"G3":{"Allow":"D",
          {                                |"Priority":"P2","QoS":"Q3",
              Allow {R,W}                  |"Operations":"turn it down"
              Priority {P3}                |}}]"
              QoS {Q2}                     |
              Operations {turn it up, read}|
          }                                |
          G3                               |
          {                                |
              Allow {D}                    |
              Priority {P2}                |
              QoS {Q2}                     |
              Operations {turn it down}    |
          }                                |
       }                                   |

                      (a)                                 (b)

             Fig 11. ST1: (a) Semantic Notation  (b) JSON Representation




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       C                                 | "[
       {                                 | "Priority":"P1","QoS":"Q1",
          Priority {P1}                  | "Operations":"turn it up,
          QoS {Q1}                       | turn it down, read",
          Operations {turn it up,turn it | "C":{"G1":{"Allow":"R"},
                      down, read}        |      "G2":{"Allow":"R,W,D"},
          G1                             |      "G3":{"Allow":"D"}}
          {                              | ]"
              Allow {R}                  |
          };                             |
          G2                             |
          {                              |
              Allow {R,W,D}              |
          };                             |
          G3                             |
          {                              |
              Allow {D}                  |
          };                             |
       }                                 |

                    (a)                                  (b)
             Fig 12. ST2: (a) Semantic Notation  (b) JSON Representation

       C                                    | "[
       {                                    | "Priority":"P1","QoS":
           Priority {P1}                    | "Q1","C":{"G1": {"Allow":
           QoS {Q1}                         | "R","Operations":"read"},
           G1                               | "G2":{"Allow":"R,W,D",
           {                                | "Operations":"turn it up,
               Allow {R}                    | turn it down, read"},
               Operations {read}            | "G3":{"Allow":"D",
           };                               | "Operations":"turn it
           G2                               | down"}}]"
           {                                |
               Allow {R,W,D}                |
               Operations {turn it up, turn |
                           down, read}      |
           };                               |
           G3                               |
           {                                |
               Allow {D}                    |
               Operations {turn it down}    |
           };                               |
       }                                    |

                    (a)                                   (b)
             Fig 13. ST3: (a) Semantic Notation (b) JSON Representation




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6.4 Search for services by device

      Any client device (as explained for scenario 2) MUST interacts
      with the provisioning server and looks for deployed services by
      devices. Moreover, the provisioning server can verify the complete
      authorization, admission, and resource control of any device's
      services. Whereas, if any other constrained devices (ex. air
      conditioner) searches for services hosted by other constrained
      device (as explained for scenario 1) MUST interact with the RD
      server as shown in Fig 10. Here, initially the device queries for
      all services that are hosted by other devices, then it searches
      within the domain for specific service, its SRV info, and path to
      the hosted service. Before sending a request, it MUST establish a
      secure channel between these two nodes [draft-schmitt-ace-
      twowayauth-for-iot].

       +---------------+                                   +----------+
       | Device        |                                   | RD Server|
       | (aircondit    |                                   |          |
       |   ioner)      |                                   |          |
       +-----+---------+                                   +-------+--+
             |                                                     |
             |  GET /rd-lookup/gp?d=example.com                `.  |
             +---------------------------------------------------`.:
             |                                                 .-' |
             | .'2.05 Content <gp="thermostat">                    |
             ::----------------------------------------------------+
             | `-.                                                 |
             |   GET /rd-lookup/ep?gp=thermostat                `. |
             +----------------------------------------------------::
             |                                                  .' |
             | .'2.05 Content <Node1> <Node2>                      |
             ::----------------------------------------------------+
             | `.                                                  |
             |                                                     |
             | GET /rd-lookup/ep?et=temperature&gp=thermostat   `. |
             +----------------------------------------------------`.
             |                                                  .' |
             |                                                     |
             | .'2.05 Content <coap://ip:port>;ep="Node1"          |
             ::----------------------------------------------------+
             | `-.                                                 |
             |                                                     |
            Fig. 10 Search for services by device



6.5 Service request and response



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      In scenario 1 (as shown in Fig 1), service request and response
      MUST use coap based communication to access the service as shown
      in Fig 11. Before sending a request, it MUST establish a secure
      channel between these two nodes [draft-schmitt-ace-twowayauth-for-
      iot]. Suppose, the constrained client device (for ex.
      airconditioner) want to access the service hosted by another
      constrained device (for ex. thermostat), then the client device
      MUST send a coap based GET request to thermostat. Then, this
      device (thermostat) SHOULD send a POST request to provision this
      service request with the provisioning server by sending clients
      <IP:port>. Based on the clients <IP:port>, the provisioning server
      MUST find the client (ex. airconditioner) details such as service
      information, group, domain, and type details.

      +------------+              +-------------+          +-----------+
      |Airconditi  |              |Thermostat   |          |Provision  |
      |oner        |              | (IP1)       |          |ining Server
      | (IP2)      |              |             |          | (IP3)     |
      +-----+------+              +------+------+          +--------+--+
            |                            |                          |
            |coap://thermostat.        `.|                          |
            +----------------------------::                         |
            |    example.com/temp     .' |POST /thermostat       `. |
            |                            +-------------------------::
            |                            |HOST thermostat.ps.    .' |
            |                            |             example.com  |
            |                            |Content-Type: application/txt
            |                            |{ SRC: <IP1,port>         |
            |                            |  DST: <IP3,port>         |
            |                            |  Client: <IP2,port> }    |
            |                            |                          |
            |                            |  +--------------------------+
            |                            |  |Check for Admission,      |
            |                            |  |ResourceControl of thermost
            |                            |  |for airconditioner        |
            |                            |  +--------------------------+
            |                            |                          |
            |                            | .'2.00 OK { Permit/Deny }|
            | .'URI-Path: temp CON 200    ::------------------------+
            ::---------------------------+ `-.                      |
            | `.("thermostat","aaaa::212.|                          |
            |  7402.2.202","temp",27)    |                          |
            |                            |                          |
         Fig. 11 Request/Response within Constrained Environment


      Once the client is identified, the provisioning server MUST check
      for authorization, admission and resource control policies of



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      hosted service (ex. thermostat). Once the service request is
      authorized to access then the URI-Path for hosted service along
      with the value is sent as a coap response to client device (air
      conditioner). Here, the request is conditional i.e. based on the
      resource control policies of a resource (such as thermostat) for a
      client (airconditioner), the permissions are given to access the
      resource.


      +-------------+               +------------+           +---------+
      |             |               |Provision   |           |         |
      | Client      |               |ining Server|           |Thermostat
      |             |               |            |           |         |
      +-----+-------+               +-----+------+           +------+--+
            |                             |                         |
            |http://thermostat.        `. |                         |
            +----------------------------::                         |
            |  example.com/temp        .' |                         |
            |            +-----------------------------+            |
            |            |Check for Admission,         |            |
            |            |Resource Control of thermostat            |
            |            |for airconditioner           |            |
            |            +-----------------------------+            |
            |                             |                         |
            |                             | coap://thermostat.   `. |
            |                             +------------------------::
            |                             |example.com/temp      .' |
            |                             |                         |
            |                             |                         |
            |                             | .'URI-Path: temp CON 200|
            |                             ::------------------------+
            |                             | `.                      |
            | .' HTTP/1.1 200 OK          |                         |
            ::----------------------------+                         |
            | `. Temperature: 27          |                         |
            |                             |                         |
          Fig. 12 Request/Response from outside Constrained Environment


      Service request and response in scenario 2 (as shown in Fig 2),
      uses simple http based communication to access the service from
      the PS. Provisioning Server then sends a coap based GET request to
      the ultimate device that hosts service. Before sending this
      request to the actual device for service, PS authorizes the
      service request. Once, the service request is authorized to
      access, then the URI-path for hosted service along with the value
      is sent as HTTP response to client device. PS can implement a
      reverse proxy case for HTTP-CoAP protocol translation defined in



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      [draft-ietf-core-http-mapping].


      ------------------HTTP begin -------------------------------------
      HTTP POST
      Request:
      POST /thermostat   /HTTP/1.1
      HOST thermostat.example.com
      Content-Type:  application/x-www-form-urlencoded
      Content-Length:  length
      licenseID=string & content=string & paramsXML=string

      Response:
      HTTP/1.1   200 OK
      Content-Type:  text/xml; charset=utf-8
      Content-Length:  length
      <?xml version="1.0" encoding="utf-8"?>
      <string xmlns="http://xyz.com/">
      string
      </string>

      ------------------HTTP end  -------------------------------------

      ------------------ REST via HTTP begin --------------------------
      REST via HTTP POST
      Request:
      POST /thermostat   /HTTP/1.1
      HOST thermostat.example.com
      Content-Type:  application/x-www-form-urlencoded
      Content-Length:  length

      licenseID=string & content=string & paramsXML=string

      Response:
      HTTP/1.1   200 OK
      Content-Type:  text/xml; charset=utf-8
      Content-Length:  length

      string

      ------------------REST via HTTP end -----------------------------

      ------------------SOAP begin ------------------------------------

      SOAP 1.2
      Request:
      POST /Thermostat   /HTTP/1.1
      HOST: www.example.org



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      Content-Type:  application/soap+xml; charset=utf-8
      Content-Length:  length

      <?xml version="1.0"?>
      <soap:envelop>
      Xmlns:soap=http://www.w3.org/2001/12/soap-envelop
      Soap:encodingStyle=http://www.w3.org/2001/12/soapencoding>
      <soap:body xmlns: m="http://www.myhome.org/thermostat">
      <m:GetTemperature>
      <m:thermostat>1</m:thermostat>
      </m:GetTemperature>
      </soap:body>
      </soap:envelop>

      Response:
      HTTP/1.1 200 OK
      Content-Type:  application/soap+xml; charset=utf-8
      Content-Length:  length

      <?xml version="1.0"?>
      <soap:envelop>
      Xmlns:soap=http://www.w3.org/2001/12/soap-envelop
      Soap:encodingStyle=http://www.w3.org/2001/12/soapencoding>
      <soap:body xmlns: m="http://www.example.org/thermostat">
      <m:GetTemperatureResponse>
      <m:temperature>27.8</m:temperature>
      </m:GetTemperatureResponse>
      </soap:body>
      </soap:envelop>

      ------------------SOAP end ----------------------------------


7  Security Considerations

      Security level for message authentication is out of scope of the
      present document. However, the following security consideration
      needs to be considered for the present proposed method. Services
      that run over UDP are unprotected and vulnerable to unknowingly
      become part of a DDoS attack as UDP does not require return
      routability check. Therefore, an attacker can easily spoof the
      source IP of the target entity and send requests to such a service
      which would then respond to the target entity. The TLS/DTLS based
      security solution can be considered for secure message
      communication.


8  IANA Considerations



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      TBD

9  References

9.1  Normative References


9.2  Informative References

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

   [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
      Constrained-Node Networks", RFC 7228, May 2014.

   [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
      "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", RFC
      4944, September 2007.

   [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
      Application Protocol (CoAP)", RFC 7252, June 2014.

   [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
      Format", RFC 6690, August 2012.

   [draft-ietf-core-resource-directory] Shelby, Z., and Bormann, C.,
      "CoRE Resource Directory", draft-ietf-core-resource-directory-02
      (work in progress), November 2014.

   [draft-gerdes-ace-actors] Gerdes, S., "Actors in the ACE
      Architecture", draft-gerdes-ace-actors-03 (work in progress),
      March 2015.

   [draft-gerdes-ace-dcaf-authorize] Gerdes, S., Bergmann, O., Bormann,
      C., "Delegated CoAP Authentication and Authorization Framework
      (DCAF)", draft-gerdes-ace-dcaf-authorize-02, March 2015.

   [draft-bormann-core-ace-aif] Bormann, C., "An Authorization
      Information Format (AIF) for ACE", draft-bormann-core-ace-aif-oo,
      January 2014.

   [draft-schmitt-ace-twowayauth-for-iot] Schmitt, C., Stiller, B.,
      "Two-way Authentication for IoT", draft-schmitt-ace- twowayauth-
      for-iot-01, December 2014.

   [DTLS] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
      Security", RFC 6347, January 2012.




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   [TLS] Dierks, T. and C. Allen, "The TLS Protocol Version 1.2", RFC
      5246, August 2008.

   [draft-ietf-core-http-mapping] Castellani, A., Loreto, S., Rahman,
      A., Fossati, T., and Dijk, E., "Guidelines for HTTP-CoAP Mapping
      Implementations", draft-ietf-core-http-mapping-05, (work in
      progress), Oct 2015.




10  Acknowledgements

   Special thanks to Amit Kumar S,Zhengfei, Fubaicheng,
   Yangjun,Vijayachandran Mariappan, Shashidhar C Shekar,
   Jayaraghavendran K, Ajay Sankar, Puneet Balmukund Sharma, and Rabi
   Narayan Sahoo for extensive comments and contributions that improved
   the text.

   Thanks to Hedanping (Ana), Behcet Sarikaya, and Carsten Bormann for
   helpful comments and discussions that have shaped the document.

Authors' Addresses


   Vasu K
   Huawei Technologies
   Bangalore
   India

   EMail: vasu.kantubukta@huawei.com



   Rahul A Jadhav
   Huawei Technologies
   Bangalore
   India

   EMail: rahul.jadhav@huawei.com


   yangneng
   Huawei Technologies
   Shenzhen
   China

   EMail: yangneng@huawei.com



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