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Versions: (draft-winterbottom-geopriv-held-identity-extensions) 00 01 02 03 04 05 06 RFC 6155

Geopriv                                                  J. Winterbottom
Internet-Draft                                                M. Thomson
Intended status: Standards Track                      Andrew Corporation
Expires: March 10, 2010                                    H. Tschofenig
                                                  Nokia Siemens Networks
                                                               R. Barnes
                                                        BBN Technologies
                                                       September 6, 2009


    Use of Device Identity in HTTP-Enabled Location Delivery (HELD)
             draft-ietf-geopriv-held-identity-extensions-00

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   The list of current Internet-Drafts can be accessed at
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   This Internet-Draft will expire on March 10, 2010.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.





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Abstract

   When a Location Information Server receives a request for location
   information (using the locationRequest message), described in the
   base HTTP Enabled Location Delivery (HELD) specification, it uses the
   source IP address of arriving message as a pointer to the location
   determination process.  This is sufficient in environments where the
   location of a Device can be determined based on its IP address.

   Two additional use cases are addresses by this document.  In the
   first, location configuration requires additional or alternative
   identifiers from the source IP address provided in the request.  In
   the second, an entity other than the Device requests the location of
   the Device.

   This document extends the HELD protocol to allow the location request
   message to carry Device identifiers.  Privacy and security
   considerations describe the conditions where requests containing
   identifiers are permitted.
































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Applications . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Device Identity  . . . . . . . . . . . . . . . . . . . . . . .  7
     3.1.  Identifier Suitability . . . . . . . . . . . . . . . . . .  7
       3.1.1.  Subjective Network Views . . . . . . . . . . . . . . .  7
       3.1.2.  Transient Identifiers  . . . . . . . . . . . . . . . .  8
     3.2.  Identifier Format and Protocol Details . . . . . . . . . .  9
     3.3.  Identifiers  . . . . . . . . . . . . . . . . . . . . . . . 10
       3.3.1.  IP Address . . . . . . . . . . . . . . . . . . . . . . 10
       3.3.2.  MAC Address  . . . . . . . . . . . . . . . . . . . . . 10
       3.3.3.  TCP or UDP Port Number . . . . . . . . . . . . . . . . 11
       3.3.4.  Network Access Identifier  . . . . . . . . . . . . . . 11
       3.3.5.  URI  . . . . . . . . . . . . . . . . . . . . . . . . . 12
       3.3.6.  Hostname . . . . . . . . . . . . . . . . . . . . . . . 12
       3.3.7.  Directory Number . . . . . . . . . . . . . . . . . . . 12
       3.3.8.  Cellular Telephony Identifiers . . . . . . . . . . . . 12
       3.3.9.  DHCP Unique Identifier . . . . . . . . . . . . . . . . 13
   4.  XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 14
   5.  Privacy Considerations . . . . . . . . . . . . . . . . . . . . 17
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
     6.1.  Identifier Suitability . . . . . . . . . . . . . . . . . . 19
     6.2.  Location Configuration Protocol Requests . . . . . . . . . 19
     6.3.  Third Party Requests . . . . . . . . . . . . . . . . . . . 20
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 21
     7.1.  URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:held:id . . . . . . . . . . 21
     7.2.  XML Schema Registration  . . . . . . . . . . . . . . . . . 21
     7.3.  Registration of HELD 'badIdentifier' Error Code  . . . . . 22
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
     9.1.  Normative references . . . . . . . . . . . . . . . . . . . 24
     9.2.  Informative references . . . . . . . . . . . . . . . . . . 24
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26















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1.  Introduction

   Protocols for requesting and providing location information require a
   way for the requestor to specify the location that should be
   returned.  In a location configuration protocol (LCP), the location
   being requested is the requestor's location.  This fact can make the
   problem of identifying the Device simpler for LCPs, since IP
   datagrams that carry the request already carry an identifier for the
   Device, namely the source IP address of an incoming request.
   Existing LCPs, such as HELD [I-D.ietf-geopriv-http-location-delivery]
   and DHCP ([RFC3825], [RFC4776]) rely on the source IP address or
   other information present in protocol datagrams to identify a Device.

   Aside from the datagrams that form a request, a location information
   server (LIS) does not necessarily have access to information that
   could further identify the Device.  In some circumstances, as shown
   in [I-D.ietf-geopriv-l7-lcp-ps], additional identification
   information can be included in a request to identify a Device.

   This document extends the HELD protocol to support the inclusion of
   additional identifiers for the Device in HELD location requests.  An
   XML schema is defined that provides a structure for including these
   identifiers in HELD requests.

   An important characteristic of this addition to the HELD protocol is
   that it also expands the potential scope of HELD beyond that of an
   LCP.  The scope of an LCP is limited to the interaction between a
   Device and a LIS.  That is, an LCP is limited to the Device
   retrieving information about their own location.  With this addition,
   authorized third party location recipients (LRs) are able to make
   requests that include identifiers to retrieve location information
   about a particular Device.

   The usage of HELD for purposes beyond the Device-LIS interaction
   obviously introduces a new set of privacy concerns.  In an LCP, the
   requester is implicitly authorized to access the requested location
   information, because it is their own location.  In contrast, a third
   party LR must be explicitly authorized when requesting the location
   of a Device.  Establishing appropriate authorization and other
   related privacy concerns are discussed in Section 5.

1.1.  Applications

   The use of additional identifiers in HELD falls into two categories.
   A Device can use these parameters to provide additional
   identification information to a LIS.  Identification information,
   such as the MAC address of the interface card of a Target, can be
   used to reduce the time required to determine the location by a LIS.



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   In other cases, a LIS might require Device identification before any
   location information can be generated.

   A third party LR can be granted authorization to make requests for a
   given Device.  In particular, network services can be permitted to
   retrieve location for a Device that is unable to acquire location
   information for itself (see Section 6.3 of
   [I-D.ietf-ecrit-phonebcp]).  This allows use of location-dependent
   applications - particularly essential services like emergency calling
   - where Devices do not support a location configuration protocol
   (LCP) or they are unable to successfully retrieve location
   information.







































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2.  Terminology

   This document uses the term Location Information Server (LIS) and
   location configuration protocol (LCP) as described in
   [I-D.ietf-geopriv-l7-lcp-ps].

   The term Device is used specifically as the subject of an LCP,
   consistent with [I-D.ietf-geopriv-http-location-delivery].  This
   document also uses the term Target to refer to any entity that might
   be a subject of the same location information.  Target is used in a
   more general sense, including the Device, but also any nearby entity,
   such as the user of a Device.  A Target has a stake in setting
   authorization policy on the use of location information.  Both Device
   and Target are defined in [RFC3693].

   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.  Device Identity

   Identifiers are used as the starting point in location determination.
   They should not be confused with measurement information
   ([I-D.thomson-geopriv-held-measurements]).  Measurement information
   is information about a Device and the time varying details of its
   network attachment.  Identifiers might be associated with a different
   Device over time, but the their purpose is to identify the Device,
   not to describe its environment or network attachment.

3.1.  Identifier Suitability

   Use of any identifier MUST only be allowed if it identifies a single
   Device at a particular time.  In some circumstances, certain of these
   identifiers are either temporary or could potentially identify
   multiple devices.  Identifiers that are transient or ambiguous could
   be exploited by an attacker to either gain information about another
   device or to coerce the LIS into producing misleading information.

   The identifiers described in this section MUST only be used where
   that identifier is used as the basis for location determination.
   Considerations relating to the use of identifiers for a Device
   requesting its own location are discussed in Section 5 of
   [I-D.ietf-geopriv-l7-lcp-ps]; this section discusses use of
   identifiers for authorized third party requests.

      It is tempting for a LIS implementation to allow alternative
      identifiers for convenience or some other perceived benefit.
      However, care needs to be taken to ensure that the binding between
      the indicated identifier and the identifier that is used for
      location determination is unique and not subject to attacks.

   Identifiers can have a different meaning to different entities on a
   network.  An identifier in one network context might have a
   completely different meaning in a different context.  Errors in
   perspective arise in both topology (all network entities have a
   subjective view of the network) and time (the network changes over
   time).

3.1.1.  Subjective Network Views

   Subjective views of the network mean that the identifier a requests
   uses to refer to one physical entity could actually apply to a
   different physical entity when used in a different network context.
   Unless an authorized third party requester and LIS operate in the
   same network context, each could have a different subjective view of
   the meaning of the identifier.




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   In this case, the third party receives information that is correct
   only within the network context of the LIS.  The location information
   provided by the LIS is probably misleading: the requester believes
   that the information relates to a different entity than it was
   generated for.

      In IP networks, network address translation (NAT) and other forms
      of address modification create network contexts.  Entities on
      either side of the point where modification occurs have a
      different view of the network.  Private use addresses [RFC1918]
      are the most easily recognizable identifiers that have limited
      scope.

   A LIS can be configured to recognize scenarios where the subjective
   view of a requester might not coincide with the view of the LIS.  The
   LIS can either provide location information that takes the view of
   the requester into account, or it can reject the request.

      For instance, a LIS might operate within a network that uses a
      private address space, with NAT between that network and other
      networks.  A third party request that originates in an external
      network with an IP address from the private address space might
      not be valid - it could be identifying an entity within another
      address space.  The LIS can be configured to reject such requests,
      unless it knows by other means that the request is valid.

      In the same example, the requester might include an address from
      the external space in an attempt to identify a host within the
      network.  The LIS could use knowledge about how the external
      address is mapped to a private address, if that mapping is fixed,
      to determine an appropriate response.

   The residential gateway scenario in Section 3.1 of
   [I-D.ietf-geopriv-l7-lcp-ps] is a particular example of where a
   subjective view is permitted.  The LIS knowingly provides Devices on
   the remote side of the residential gateway with location information,
   in spite of the ambiguity.  The LIS provides location information
   with appropriate uncertainty to allow for the fact that the
   residential gateway serves a small geographical area.

3.1.2.  Transient Identifiers

   Some identifiers are temporary and can, over the course of time, be
   assigned to different physical entities.  An identifier that is
   reassigned between the time that a request is formulated by a
   requester and when the request is received by the LIS causes the LIS
   to locate a different entity than the requester intended.  The
   response from the LIS might be accurate, but the request incorrectly



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   associates this information with the wrong subject.

   A LIS should be configured with information about any potentially
   temporary identifiers.  It can use this information to identify when
   changes have occurred.  A LIS must not provide location information
   if the identifier it uses might refer to a different Device.  If an
   identifier might have been reassigned recently, or it is likely to be
   reassigned, it is not suitable as an identifier.

   It's possible that some degree of uncertainty could persist where
   identifiers are reassigned frequently; the extent to which errors
   arising from using transient identifiers are tolerated is a matter
   for local policy.

3.2.  Identifier Format and Protocol Details

   XML elements are used to express the Device identity.  The "target"
   element is used as a general container for identity information.
   This document defines a basic set of identifiers.  An example HELD
   request, shown in Figure 1, includes an IP version 4 address.

     <locationRequest xmlns="urn:ietf:params:xml:ns:geopriv:held"
                      responseTime="8">
       <locationType exact="true">geodetic</locationType>
       <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
         <ip v="4">192.0.2.5</ip>
       </device>
     </locationRequest>

                                 Figure 1

   A LIS that supports this specification echoes the "target" element in
   a successful HELD response, including the identifiers that were used
   as the basis for location determination.  Absence of this indication
   means that the location information was generated using the source IP
   address in the request.

   If an identifier is invalid, not supported by the LIS, or the
   requester is not authorized to use that identifier, a HELD error
   response of "badIdentifier".  This code is registered in Section 7.3.

   If the LIS requires an identifier that is not provided in the
   request, the desired identifiers MAY be identified in the HELD error
   response, using the "requiredIdentifiers" element.  This element
   contains a list of XML qualified names [W3C.REC-xml-names11-20060816]
   that identify the identifier elements required by the LIS.  Namespace
   prefix bindings for the qualified names are taken from document
   context.  Figure 2 shows an example error indicating that the



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   requester needs to include a MAC address (Section 3.3.2) if the
   request is to succeed.

     <error xmlns="urn:ietf:params:xml:ns:geopriv:held"
            code="badIdentifier">
       <message xml:lang="en">MAC address required</message>
       <requiredIdentifiers
           xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
         mac
       </requiredIdentifiers>
     </error>

                                 Figure 2

3.3.  Identifiers

   A limited selection of identifiers are included in this document.
   The basic Device identity schema allows for the inclusion of elements
   from any namespace, therefore additional elements can be defined
   using different XML namespaces.

3.3.1.  IP Address

   The "ip" element can express a Device identity as an IP address.  An
   optional "v" attribute identifies the IP version.  The element uses
   the textual format specific to the indicated IP version.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <ip v="6">2001:DB8::1:ea7:fee1:d1e</ip>
     </device>

   In situations where location configuration does not require
   additional identifiers, using IP address as an identifier enables
   authorized third party requests.

3.3.2.  MAC Address

   The media access control (MAC) address used by the IEEE 802 family of
   access technologies is an identifier that is assigned to a particular
   network device.  A MAC address is a unique sequence that is either
   assigned at the time of manufacture of a device, or assigned by a
   local administrator.  A MAC address rarely changes; therefore, a MAC
   address is an appropriate identifier for a Device.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <mac>A0-12-34-56-78-90</mac>
     </device>




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   A LIS that operates on the same layer 2 segment as a Device sees the
   MAC address of the Device and can authenticate the device in that
   fashion.  If a router is interposed between LIS and Device, other
   means of authentication are required.

3.3.3.  TCP or UDP Port Number

   On its own, a TCP or UDP port number is insufficient to uniquely
   identify a single host, but in combination with an IP address, it can
   be used in some environments to uniquely identify a Device.

   Use of a particular port number can be transient; often significantly
   more than use of any given IP address.  However, widespread use of
   network address translation (NAT) means that some Devices cannot be
   uniquely identified by IP address alone.  An individual Device might
   be identified by a flow of packets that it generates.  Providing that
   a LIS has sufficient knowledge of the mappings used by the NAT, an
   individual target on the remote side of the NAT might be able to be
   identified uniquely.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <ip v="6">2001:DB8::1:ea7:fee1:d1e</ip>
       <udpport>51393</udpport>
     </device>

   Use of port numbers is especially reliant on the value remaining
   consistent over time.

3.3.4.  Network Access Identifier

   A Network Access Identifier (NAI) [RFC4282] is an identifier used in
   network authentication in a range of networks.  The identifier
   establishes a user identity within a particular domain.  Often,
   network services use an NAI in relation to location records, tying
   network access to user authentication and authorization.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <nai>user@example.net</nai>
     </device>

   The formal grammar for NAI [RFC4282] permits invalid Unicode, which
   cannot be expressed using XML.  Therefore, this expression of NAI
   permits escaping.  Non-unicode characters (and any other character)
   are expressed using a backslash ('\') followed by two hexadecimal
   digits representing the value of a single octet.

   The canonical representation of an NAI is the sequence of octets that
   is produced from the concatenation of UTF-8 encoded sequences of



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   unescaped characters and octets derived from escaped components.
   This sequence MUST conform to the constraints in [RFC4282].

3.3.5.  URI

   A Device can be identified by a URI.  Any URI can be used providing
   that the requester and LIS have a common understanding of the
   semantics implied by use of the URI.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <uri>sip:user@example.net;gr=kjh29x97us97d</uri>
     </device>

3.3.6.  Hostname

   A domain name can be used as the basis for identification using the
   "hostname" element.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <hostname>host.example.net</hostname>
     </device>

3.3.7.  Directory Number

   Telephony devices are typically identified by the number that is used
   to reach them.  Within enterprises, where globally accessible
   telephone numbers might not be used, a directory number is the usual
   form of identification.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <dn>7515</dn>
     </device>

3.3.8.  Cellular Telephony Identifiers

   A range of different forms of mobile station identifiers are used for
   different cellular telephony systems.  Elements are defined for these
   identifiers.  The following identifiers are defined:

   msisdn:  The Mobile Subscriber Integrated Services Digital Network
      Number (MSISDN) is an E.164 number between 6 and 15 digits long.

   imsi:  The International Mobile Subscriber Identity (IMSI) an
      identifier associated with all GSM and UMTS mobile subscribers.







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   imei:  The International Mobile Equipment Identifier (IMEI) is a
      unique device serial number up to 15 digits long.

   min:  The Mobile Identification Number (MIN) is a unique number
      assigned to CDMA handsets.

   mdn:  The Mobile Directory Number (MDN) is an E.164 number, with
      usage similar to MSISDN.


     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <msisdn>11235550123</msisdn>
     </device>

3.3.9.  DHCP Unique Identifier

   The Dynamic Host Configuration Protocol (DHCP) uses a binary
   identifier for its clients.  The DHCP Unique Identifier (DUID) is
   expressed in Option 61 of DHCPv4 (see [RFC4361]) or Option 1 of
   DHCPv6 and follows the format defined in Section 9 of [RFC3315].  The
   "duid" element includes the binary value of the DUID expressed in
   hexadecimal.

     <device xmlns="urn:ietf:params:xml:ns:geopriv:held:id">
       <duid>1234567890AaBbCcDdEeFf</duid>
     </device>

























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4.  XML Schema

  <?xml version="1.0"?>
  <xs:schema
      targetNamespace="urn:ietf:params:xml:ns:geopriv:held:id"
      xmlns:xs="http://www.w3.org/2001/XMLSchema"
      xmlns:id="urn:ietf:params:xml:ns:geopriv:held:id"
      elementFormDefault="qualified" attributeFormDefault="unqualified">

    <!-- Device Identity -->
    <xs:element name="device" type="id:deviceIdentity"/>
    <xs:complexType name="deviceIdentity">
      <xs:sequence>
        <xs:any namespace="##any" processContents="lax"
                minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>

    <xs:element name="requiredIdentifiers" type="id:qnameList"/>
    <xs:simpleType name="qnameList">
      <xs:list itemType="xs:QName"/>
    </xs:simpleType>

    <xs:element name="ip" type="id:ipAddress"/>
    <xs:complexType name="ipAddress">
      <xs:simpleContent>
        <xs:extension base="xs:token">
          <xs:attribute name="v" use="optional">
            <xs:simpleType>
              <xs:restriction base="xs:token">
                <xs:pattern value="[\da-fA-F]"/>
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>

    <xs:element name="mac" type="id:macAddress"/>
    <xs:simpleType name="macAddress">
      <xs:restriction base="xs:token">
        <xs:pattern value="[\da-fA-F]{2}(-[\da-fA-F]{2}){5}"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:element name="udpport" type="id:portNumber"/>
    <xs:element name="tcpport" type="id:portNumber"/>
    <xs:simpleType name="portNumber">



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      <xs:restriction base="xs:nonNegativeInteger">
        <xs:maxInclusive value="65535"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:element name="nai" type="xs:token"/>

    <xs:element name="uri" type="xs:anyURI"/>

    <xs:element name="dn" type="id:digits"/>
    <xs:simpleType name="digits">
      <xs:restriction base="xs:token">
        <xs:pattern value="[\d]+"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:element name="hostname" type="id:domainName"/>
    <xs:simpleType name="domainName">
      <xs:restriction base="xs:token">
        <!-- the following pattern does not include whitespace;
             whitespace is added only to conform to document
             formatting restrictions -->
        <xs:pattern value="([A-Za-z\d]([A-Za-z\d-]*[A-Za-z\d])*\.)*
                           [A-Za-z\d]([A-Za-z\d-]*[A-Za-z\d])*"/>
      </xs:restriction>
    </xs:simpleType>

    <xs:element name="duid" type="xs:hexBinary"/>

    <xs:element name="msisdn" type="id:e164"/>
    <xs:element name="imsi" type="id:e164"/>
    <xs:element name="imei" type="id:digit15"/>
    <xs:element name="min" type="id:digit10"/>
    <xs:element name="mdn" type="id:e164"/>
    <xs:simpleType name="e164">
      <xs:restriction base="id:digit15">
        <xs:minLength value="6"/>
      </xs:restriction>
    </xs:simpleType>
    <xs:simpleType name="digit15">
      <xs:restriction base="id:digits">
        <xs:maxLength value="15"/>
      </xs:restriction>
    </xs:simpleType>
    <xs:simpleType name="digit10">
      <xs:restriction base="id:digits">
        <xs:length value="10"/>
      </xs:restriction>



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    </xs:simpleType>

  </xs:schema>
















































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5.  Privacy Considerations

   The authorization model for a location configuration protocol assumes
   that the LR is also the Target, and that providing that LR with
   information about its own location is allowed.  We call this property
   "LCP policy".  In effect, an LCP server (that is, the LIS) follows a
   single rule policy that states that the Target is the only authorized
   Location Recipient.

   Note:  HELD explicitly takes the position that the Target is a Device
      and not a person.  When discussing privacy, Targets other than a
      Device have a stake in protecting privacy.  Therefore, the more
      general term of Target - any potential subject of location
      information - is used in place of Device.

   When Device identity is used, the "LCP policy" is only applicable if
   the LR and Target are the same entity.  If they are the same, the
   security and privacy considerations of the base HELD protocol
   [I-D.ietf-geopriv-http-location-delivery] MAY be applied by a LIS.
   The usage of the additional identifiers defined in this document by
   the LR MAY cause the LIS to perform additional security verifications
   to take place.

   LR and Target MUST be verified by the LIS to be the same identity,
   assuming that related identities are the same is not sufficient.

      For example, it is not appropriate to apply LCP policy where a
      requester is authenticated by NAI and the supplied Device identity
      is a MAC address, even if that MAC address is currently registered
      with the network under the given NAI.  In this case, the requester
      might be requesting from a different MAC address registered under
      the same NAI.  The correct way of gaining authorization is to
      establish a policy that permits this particular request as a third
      party request.

   The LCP policy does not allow requests made by third parties.  If a
   LIS permits requests from third parties using Device identity, it
   assumes the rule of a Location Server (LS).  As a Location Server,
   the LIS MUST explicitly authorize requests according to the policies
   that are provided by Rule Makers, including the Target.  This
   includes authentication of requesters where required by the
   authorization policies.

   An organization that provides a LIS that allows third party requests
   must provide a means for a Rule Maker to specify authorization
   policies as part of the LIS implementation (e.g, in the form of
   access control lists).  Authorization must be established before
   allowing third party requests for the location of any Target.  Until



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   an authorization policy is established, the LIS MUST reject requests
   by third parties (that is, the default policy is "deny all").

   When the LIS is operated by an access network, the relationship
   between the Target and the LIS can be transient.  However, the
   process of establishing network access usually results in a form of
   agreement between the Target and the network provider.  This process
   offers a natural vehicle for establishing location privacy policies.
   Establishing authorization policy might be a manual process, an
   explicit part of the terms of service for the network, or an
   automated system that accepts formal authorization policies (see
   [RFC4745], [RFC4825]).  This document does not mandate any particular
   mechanism for establishing an authorization policy.






































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6.  Security Considerations

   The security considerations in
   [I-D.ietf-geopriv-http-location-delivery] describe the use of TLS for
   server authentication, confidentiality and protection from
   modification.  These protections apply to both LCP requests and the
   requests made by third parties.

   All HELD requests containing identity MUST be authenticated by the
   LIS.  How authentication is accomplished and what assurances are
   desired is a matter for policy.  The base HELD protocol uses return
   reachability of an IP address implied by the requester being able to
   successfully complete a TCP handshake.  It is RECOMMENDED that any
   means of authentication provide at least this degree of assurance.
   For requests that include Device identity, the LIS MUST support
   authentication of TLS clients.

6.1.  Identifier Suitability

   Transient and ambiguous identifiers can be exploited by malicious
   requests and are not suitable as a basis for identifying a Device.
   Section 3.1 provides further discussion on this subject.

   Identifier transience of can lead to incorrect location information
   being provided.  An attacker could exploit the use of transient
   identifiers.  In this attack, the attacker either knows of a re-
   allocation of that identifier or is able to force the identifier to
   be re-allocated during the processing of the request.

   An attacker could use this to acquire location information for
   another Device or to coerce the LIS to lie on its behalf if this re-
   allocation occurs between the time where authorization is granted and
   location information is granted.

   Ambiguous identifiers present a similar problem.  An attacker could
   legitimately gain authorization to use a particular identifier.
   Since an ambiguous identifier potentially refers to multiple Devices,
   if authorization is granted for one of those Devices, an attacker
   potentially gains access to location information for all of those
   Devices.

6.2.  Location Configuration Protocol Requests

   Requests made by a Device in the context of a location configuration
   protocol are covered by the same set of protections offered by HELD.
   LCP requests are authorized under an "LCP policy" that permits a
   Target access to location information about itself.




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   Identity information provided by the Device is private data that
   might be sensitive.  The Device provides this information in the
   expectation that it assists the LIS in providing the Device a
   service.  The LIS MUST NOT use identity information for any other
   purpose other than serving the request that includes that
   information.

6.3.  Third Party Requests

   Requests from third parties have the same requirements for server
   authentication, confidentiality and protection from modification as
   LCP requests.  However, because the third party needs to be
   authorized, the requester MUST be authenticated by the LIS.  In
   addition, third party requests MUST be explicitly authorized by a
   policy that is established by a Rule Maker.

   More detail on the privacy implications of third party requests are
   covered in Section 5.

































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7.  IANA Considerations

   This document registers an XML namespace and schema with IANA in
   accordance with guidelines in [RFC3688].  It also creates a new
   registry for device identity types, and stipulates how new types are
   to be added.

7.1.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:held:id

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:held:id", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:held:id

      Registrant Contact: IETF, GEOPRIV working group,
      (geopriv@ietf.org), James Winterbottom
      (james.winterbottom@andrew.com).

      XML:

       BEGIN
         <?xml version="1.0"?>
         <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
           "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
         <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
           <head>
             <title>HELD Device Identity Parameters</title>
           </head>
           <body>
             <h1>Namespace for HELD Device Identity Parameters</h1>
             <h2>urn:ietf:params:xml:ns:geopriv:held:id</h2>
   [[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX
       with the RFC number for this specification.]]
             <p>See <a href="[[RFC URL]]">RFCXXXX</a>.</p>
           </body>
         </html>
       END

7.2.  XML Schema Registration

   This section registers an XML schema as per the guidelines in
   [RFC3688].







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   URI:  urn:ietf:params:xml:schema:geopriv:held:id

   Registrant Contact:  IETF, GEOPRIV working group, (geopriv@ietf.org),
      James Winterbottom (james.winterbottom@andrew.com).

   Schema:  The XML for this schema can be found as the entirety of
      Section 4 of this document.

7.3.  Registration of HELD 'badIdentifier' Error Code

   This section registers the "badIdentifier" error code in the "Geopriv
   HELD Registries, Error codes for HELD" IANA registry.

   badIdentifier  This error code indicates that the Device identifiers
      used in the HELD request were either: not supported by the LIS,
      badly formatted, or that the requester was not authorized to make
      a erquest for that identifier.


































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8.  Acknowledgements

   The authors wish to thank the NENA VoIP location working group for
   their assistance in the definition of the schema used in this
   document.  Special thanks go to Barbara Stark, Guy Caron, Nadine
   Abbott, Jerome Grenier and Martin Dawson.  Bob Sherry provided input
   on use of URIs.  Thanks to Adam Muhlbauer and Eddy Corbett for
   providing further corrections.  Bernard Aboba provided extensive
   feedback on use cases and the security model; Bernard, along with
   Alan DeKok, also helped resolve an issue with NAIs.  Ray Bellis
   provided motivation for the protocol port parameters.








































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9.  References

9.1.  Normative references

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

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC4282]  Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
              Network Access Identifier", RFC 4282, December 2005.

   [RFC4361]  Lemon, T. and B. Sommerfeld, "Node-specific Client
              Identifiers for Dynamic Host Configuration Protocol
              Version Four (DHCPv4)", RFC 4361, February 2006.

   [I-D.ietf-geopriv-http-location-delivery]
              Barnes, M., Winterbottom, J., Thomson, M., and B. Stark,
              "HTTP Enabled Location Delivery (HELD)",
              draft-ietf-geopriv-http-location-delivery-16 (work in
              progress), August 2009.

   [I-D.ietf-geopriv-l7-lcp-ps]
              Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7
              Location Configuration Protocol; Problem Statement and
              Requirements", draft-ietf-geopriv-l7-lcp-ps-10 (work in
              progress), July 2009.

   [W3C.REC-xml-names11-20060816]
              Tobin, R., Hollander, D., Bray, T., and A. Layman,
              "Namespaces in XML 1.1 (Second Edition)", World Wide Web
              Consortium Recommendation REC-xml-names11-20060816,
              August 2006,
              <http://www.w3.org/TR/2006/REC-xml-names11-20060816>.

9.2.  Informative references

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets",
              BCP 5, RFC 1918, February 1996.

   [RFC3693]  Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and
              J. Polk, "Geopriv Requirements", RFC 3693, February 2004.



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   [RFC3825]  Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
              Configuration Protocol Option for Coordinate-based
              Location Configuration Information", RFC 3825, July 2004.

   [RFC4388]  Woundy, R. and K. Kinnear, "Dynamic Host Configuration
              Protocol (DHCP) Leasequery", RFC 4388, February 2006.

   [RFC4745]  Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J.,
              Polk, J., and J. Rosenberg, "Common Policy: A Document
              Format for Expressing Privacy Preferences", RFC 4745,
              February 2007.

   [RFC4776]  Schulzrinne, H., "Dynamic Host Configuration Protocol
              (DHCPv4 and DHCPv6) Option for Civic Addresses
              Configuration Information", RFC 4776, November 2006.

   [RFC4825]  Rosenberg, J., "The Extensible Markup Language (XML)
              Configuration Access Protocol (XCAP)", RFC 4825, May 2007.

   [I-D.ietf-ecrit-phonebcp]
              Rosen, B. and J. Polk, "Best Current Practice for
              Communications Services in support of Emergency  Calling",
              draft-ietf-ecrit-phonebcp-13 (work in progress),
              July 2009.

   [I-D.thomson-geopriv-held-measurements]
              Thomson, M. and J. Winterbottom, "Using Device-provided
              Location-Related Measurements in Location  Configuration
              Protocols", draft-thomson-geopriv-held-measurements-04
              (work in progress), May 2009.

   [LLDP]     IEEE, "802.1AB, IEEE Standard for Local and Metropolitan
              area networks, Station and Media Access Control
              Connectivity Discovery", June 2005.

















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Authors' Addresses

   James Winterbottom
   Andrew Corporation
   Andrew Building (39)
   Wollongong University Campus
   Northfields Avenue
   Wollongong, NSW  2522
   AU

   Email: james.winterbottom@andrew.com


   Martin Thomson
   Andrew Corporation
   Andrew Building (39)
   Wollongong University Campus
   Northfields Avenue
   Wollongong, NSW  2522
   AU

   Email: martin.thomson@andrew.com


   Hannes Tschofenig
   Nokia Siemens Networks
   Linnoitustie 6
   Espoo  02600
   Finland

   Phone: +358 (50) 4871445
   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at


   Richard Barnes
   BBN Technologies
   9861 Broken Land Pkwy, Suite 400
   Columbia, MD  21046
   USA

   Phone: +1 410 290 6169
   Email: rbarnes@bbn.com








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