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rfc:rfc5580

Network Working Group H. Tschofenig, Ed. Request for Comments: 5580 Nokia Siemens Networks Category: Standards Track F. Adrangi

                                                                 Intel
                                                              M. Jones
                                                               A. Lior
                                                           Bridgewater
                                                              B. Aboba
                                                 Microsoft Corporation
                                                           August 2009
          Carrying Location Objects in RADIUS and Diameter

Abstract

 This document describes procedures for conveying access-network
 ownership and location information based on civic and geospatial
 location formats in Remote Authentication Dial-In User Service
 (RADIUS) and Diameter.
 The distribution of location information is a privacy-sensitive task.
 Dealing with mechanisms to preserve the user's privacy is important
 and is addressed in this document.

Status of This Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

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.

Tschofenig, et al. Standards Track [Page 1] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

Table of Contents

 1. Introduction ....................................................3
 2. Terminology .....................................................3
 3. Delivery Methods for Location Information .......................3
    3.1. Location Delivery Based on Out-of-Band Agreements ..........4
    3.2. Location Delivery Based on Initial Request .................5
    3.3. Location Delivery Based on Mid-Session Request .............6
    3.4. Location Delivery in Accounting Messages ..................10
 4. Attributes .....................................................11
    4.1. Operator-Name Attribute ...................................12
    4.2. Location-Information Attribute ............................14
    4.3. Location-Data Attribute ...................................16
         4.3.1. Civic Location Profile .............................17
         4.3.2. Geospatial Location Profile ........................17
    4.4. Basic-Location-Policy-Rules Attribute .....................18
    4.5. Extended-Location-Policy-Rules Attribute ..................20
    4.6. Location-Capable Attribute ................................21
    4.7. Requested-Location-Info Attribute .........................23
 5. Table of Attributes ............................................28
 6. Diameter RADIUS Interoperability ...............................30
 7. Security Considerations ........................................31
    7.1. Communication Security ....................................31
    7.2. Privacy Considerations ....................................32
         7.2.1. RADIUS Client ......................................33
         7.2.2. RADIUS Server ......................................34
         7.2.3. RADIUS Proxy .......................................34
    7.3. Identity Information and Location Information .............34
 8. IANA Considerations ............................................36
    8.1. New Registry: Operator Namespace Identifier ...............36
    8.2. New Registry: Location Profiles ...........................37
    8.3. New Registry: Location-Capable Attribute ..................38
    8.4. New Registry: Entity Types ................................39
    8.5. New Registry: Privacy Flags ...............................39
    8.6. New Registry: Requested-Location-Info Attribute ...........39
 9. Acknowledgments ................................................40
 10. References ....................................................42
    10.1. Normative References .....................................42
    10.2. Informative References ...................................42
 Appendix A.  Matching with GEOPRIV Requirements ...................45
   A.1.  Distribution of Location Information at the User's
         Home Network ..............................................45
   A.2.  Distribution of Location Information at the Visited
         Network ...................................................46
   A.3.  Requirements Matching .....................................47

Tschofenig, et al. Standards Track [Page 2] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

1. Introduction

 This document defines attributes within RADIUS and Diameter that can
 be used to convey location-related information within authentication
 and accounting exchanges.
 Location information may be useful in a number of scenarios.
 Wireless networks (including wireless LAN) are being deployed in
 public places such as airports, hotels, shopping malls, and coffee
 shops by a diverse set of operators such as cellular network
 operators, Wireless Internet Service Providers (WISPs), and fixed
 broadband operators.  In these situations, the home network may need
 to know the location of the user in order to enable location-aware
 billing, location-aware authorization, or other location-aware
 services.  Location information can also prove useful in other
 situations (such as wired networks) where operator-network ownership
 and location information may be needed by the home network.
 In order to preserve user privacy, location information needs to be
 protected against unauthorized access and distribution.  Requirements
 for access to location information are defined in [RFC3693].  The
 model includes a Location Generator (LG) that creates location
 information, a Location Server (LS) that authorizes access to
 location information, a Location Recipient (LR) that requests and
 receives information, and a Rule Maker (RM) that provides
 authorization policies to the LS, which enforces access-control
 policies on requests to location information.  In Appendix A, the
 requirements for a GEOPRIV using protocol [RFC3693] are compared to
 the functionality provided by this document.

2. Terminology

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].
 RADIUS-specific terminology is borrowed from [RFC2865] and [RFC2866].
 Terminology related to privacy issues, location information, and
 authorization policy rules is taken from [RFC3693].

3. Delivery Methods for Location Information

 The following exchanges show how location information is conveyed in
 RADIUS.  In describing the usage scenarios, we assume that privacy
 policies allow location to be conveyed in RADIUS; however, as noted
 in Section 6, similar exchanges can also take place within Diameter.
 Privacy issues are discussed in Section 7.2.

Tschofenig, et al. Standards Track [Page 3] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

3.1. Location Delivery Based on Out-of-Band Agreements

 Figure 1 shows an example message flow for delivering location
 information during the network-access authentication and
 authorization procedure.  Upon a network-authentication request from
 an access-network client, the Network Access Server (NAS) submits a
 RADIUS Access-Request message that contains Location-Information
 Attributes among other required attributes.  In this scenario,
 location information is attached to the Access-Request message
 without an explicit request from the RADIUS server.  Note that such
 an approach with a prior agreement between the RADIUS client and the
 RADIUS server is only applicable in certain environments, such as in
 situations where the RADIUS client and server are within the same
 administrative domain.  The Basic-Location-Policy-Rules Attribute is
 populated based on the defaults described in Section 4.4, unless it
 has been explicitly configured otherwise.
  +---------+             +---------+                   +---------+
  |         |             | Network |                   |  RADIUS |
  | User    |             | Access  |                   |  Server |
  |         |             | Server  |                   |         |
  +---------+             +---------+                   +---------+
      |                       |                              |
      | Authentication phase  |                              |
      | begin                 |                              |
      |---------------------->|                              |
      |                       |                              |
      |                       | Access-Request               |
      |                       | + Location-Information       |
      |                       | + Location-Data              |
      |                       | + Basic-Location-Policy-Rules|
      |                       | + Operator-Name              |
      |                       |----------------------------->|
      |                       |                              |
      |                       | Access-Accept                |
      |                       |<-----------------------------|
      | Authentication        |                              |
      | Success               |                              |
      |<----------------------|                              |
      |                       |                              |
      Figure 1: Location Delivery Based on Out-of-Band Agreements

Tschofenig, et al. Standards Track [Page 4] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

3.2. Location Delivery Based on Initial Request

 If the RADIUS client provides a Location-Capable Attribute in the
 Access-Request, then the RADIUS server MAY request location
 information from the RADIUS client if it requires that information
 for authorization and if location information was not provided in the
 Access-Request.  This exchange is shown in Figure 2.  The inclusion
 of the Location-Capable Attribute in an Access-Request message
 indicates that the NAS is capable of providing location data in
 response to an Access-Challenge.  The subsequent Access-Challenge
 message sent from the RADIUS server to the NAS provides a hint
 regarding the type of desired Location-Information Attributes.  The
 NAS treats the Basic-Location-Policy-Rules and Extended-Location-
 Policy-Rules Attributes as opaque data (e.g., it echoes these rules
 provided by the server within the Access-Challenge back in the
 Access-Request).  In the shown message flow, the location attributes
 are then provided in the subsequent Access-Request message.  When
 evaluating this Access-Request message, the authorization procedure
 at the RADIUS server might be based on a number of criteria,
 including the newly defined attributes listed in Section 4.

Tschofenig, et al. Standards Track [Page 5] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 +---------+             +---------+                       +---------+
 |         |             | Network |                       |  RADIUS |
 | User    |             | Access  |                       |  Server |
 |         |             | Server  |                       |         |
 +---------+             +---------+                       +---------+
     |                       |                                  |
     | Authentication phase  |                                  |
     | begin                 |                                  |
     |---------------------->|                                  |
     |                       |                                  |
     |                       | Access-Request                   |
     |                       | + Location-Capable               |
     |                       |--------------------------------->|
     |                       |                                  |
     |                       | Access-Challenge                 |
     |                       |  + Basic-Location-Policy-Rules   |
     |                       |  + Extended-Location-Policy-Rules|
     |                       |  + Requested-Location-Info       |
     |                       |<---------------------------------|
     |                       |                                  |
     |                       | Access-Request                   |
     |                       |  + Location-Information          |
     |                       |  + Location-Data                 |
     |                       |  + Basic-Location-Policy-Rules   |
     |                       |  + Extended-Location-Policy-Rules|
     |                       |--------------------------------->|
     |                       |                                  |
     :                       :                                  :
     :       Multiple Protocol Exchanges to perform             :
     :    Authentication, Key Exchange, and Authorization       :
     :                  ...continued...                         :
     :                       :                                  :
     |                       |                                  |
     |                       | Access-Accept                    |
     |                       |<---------------------------------|
     | Authentication        |                                  |
     | Success               |                                  |
     |<----------------------|                                  |
     |                       |                                  |
         Figure 2: Location Delivery Based on Initial Request

3.3. Location Delivery Based on Mid-Session Request

 The on-demand, mid-session location-delivery method utilizes the
 Change-of-Authorization Request (CoA-Request) message and the CoA-NAK
 (CoA-Negative Acknowledgement), defined in [RFC5176].  At any time

Tschofenig, et al. Standards Track [Page 6] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 during the session, the Dynamic Authorization Client MAY send a CoA-
 Request containing session-identification attributes to the NAS
 (i.e., Dynamic Authorization Server).
 In order to enable the on-demand, mid-session location-delivery
 method, the RADIUS server MUST return an instance of the Requested-
 Location-Info Attribute with the 'FUTURE_REQUESTS' flag set and
 instances of the Basic-Location-Policy-Rules and Extended-Location-
 Policy-Rules Attributes in the Access-Accept message for the session.
 Upon receipt of a CoA-Request message containing a Service-Type
 Attribute with value "Authorize Only" for the same session, the NAS
 MUST include location information and echo the previously received
 Basic-Location-Policy-Rules and Extended-Location-Policy-Rules
 Attributes in the subsequent Access-Request message.
 Upon receiving the Access-Request message containing the Service-Type
 Attribute with a value of Authorize-Only from the NAS, the RADIUS
 server responds with either an Access-Accept or an Access-Reject
 message.
 The use of dynamic authorization [RFC5176] is necessary when location
 information is needed on-demand and cannot be obtained from
 accounting information in a timely fashion.
 Figure 3 shows the above-described approach graphically.
+---------------+                        +---------------+    +------+
| Dynamic       |                        | Dynamic       |    |RADIUS|
| Authorization |                        | Authorization |    |Server|
| Server/NAS    |                        | Client        |    |      |
+---------------+                        +---------------+    +------+
    |                                             |              |
    |  Access-Request                             |              |
    |  + Location-Capable                         |              |
    |----------------------------------------------------------->|
    |                                             |              |
    |  Access-Challenge                           |              |
    |   + Basic-Location-Policy-Rules             |              |
    |   + Extended-Location-Policy-Rules          |              |
    |   + Requested-Location-Info                 |              |
    |<-----------------------------------------------------------|
    |                                             |              |
    |  Access-Request                             |              |
    |   + Location-Information                    |              |
    |   + Location-Data                           |              |
    |   + Basic-Location-Policy-Rules             |              |
    |   + Extended-Location-Policy-Rules          |              |
    |----------------------------------------------------------->|

Tschofenig, et al. Standards Track [Page 7] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

    |                                             |              |
    |                                             |              |
    :                                             |              :
    :       Multiple Protocol Exchanges to perform               :
    :    Authentication, Key Exchange, and Authorization         :
    :                  ...continued...            |              :
    :                                             |              :
    |                                             |              |
    |                                             |              |
    |  Access-Accept                              |              |
    |      + Requested-Location-Info              |              |
             (FUTURE_REQUESTS,...)                |              |
    |      + Basic-Location-Policy-Rules          |              |
    |      + Extended-Location-Policy-Rules       |              |
    |<-----------------------------------------------------------|
    |                                             |              |
    :                                             :              :
    :                <<Some time later>>          :              :
    :                                             :              :
    |                                             |              |
    | CoA + Service-Type "Authorize Only" + State |              |
    |<--------------------------------------------|              |
    |                                             |              |
    |  CoA NAK + Service-Type "Authorize Only"    |              |
    |          + State                            |              |
    |          + Error-Cause  "Request Initiated" |              |
    |-------------------------------------------->|              |
    |                                             |              |
    |  Access-Request                             |              |
    |          + Service-Type "Authorize Only"    |              |
    |          + State                            |              |
    |          + Location-Information             |              |
    |          + Location-Data                    |              |
    |          + Basic-Location-Policy-Rules      |              |
    |          + Extended-Location-Policy-Rules   |              |
    |----------------------------------------------------------->|
    |  Access-Accept                              |              |
    |<-----------------------------------------------------------|
    |                                             |              |
             Figure 3: Location Delivery Based on CoA with
                     Service-Type 'Authorize Only'
 When the Dynamic Authorization Client wants to change the values of
 the requested location information, or set the values of the
 requested location information for the first time, it may do so
 without triggering a reauthorization.  Assuming that the NAS had
 previously sent an Access-Request containing a Location-Capable

Tschofenig, et al. Standards Track [Page 8] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Attribute, the Dynamic Authorization Client (DAC) can send a CoA-
 Request to the NAS without a Service-Type Attribute, but include the
 NAS identifiers and session identifiers as per [RFC5176] and the
 Requested-Location-Info, Basic-Location-Policy-Rules, and Extended-
 Location-Policy-Rules Attributes.  The Requested-Location-Info,
 Basic-Location-Policy-Rules, and Extended-Location-Policy-Rules
 Attributes MUST NOT be used for session identification.
 Figure 4 shows this approach graphically.
+---------------+                        +---------------+    +------+
| Dynamic       |                        | Dynamic       |    |RADIUS|
| Authorization |                        | Authorization |    |Server|
| Server/NAS    |                        | Client        |    |      |
+---------------+                        +---------------+    +------+
    |                                             |              |
    |                                             |              |
    |  Access-Request                             |              |
    |  + Location-Capable                         |              |
    |----------------------------------------------------------->|
    |                                             |              |
    |  Access-Challenge                           |              |
    |   + Basic-Location-Policy-Rules             |              |
    |   + Extended-Location-Policy-Rules          |              |
    |   + Requested-Location-Info                 |              |
    |<-----------------------------------------------------------|
    |                                             |              |
    |  Access-Request                             |              |
    |   + Location-Information                    |              |
    |   + Location-Data                           |              |
    |   + Basic-Location-Policy-Rules             |              |
    |   + Extended-Location-Policy-Rules          |              |
    |----------------------------------------------------------->|
    |                                             |              |
    |                                             |              |
    :                                             |              :
    :       Multiple Protocol Exchanges to perform               :
    :    Authentication, Key Exchange, and Authorization         :
    :                  ...continued...            |              :
    :                                             |              :
    |                                             |              |
    |                                             |              |
    |  Access-Accept                              |              |
    |      + Requested-Location-Info              |              |
    |      + Basic-Location-Policy-Rules          |              |
    |      + Extended-Location-Policy-Rules       |              |
    |<-----------------------------------------------------------|

Tschofenig, et al. Standards Track [Page 9] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

    |                                             |              |
    :                                             :              :
    :                <<Some time later>>          :              :
    :                                             :              :
    |                                             |              |
    |  CoA                                        |              |
    |      + Requested-Location-Info              |              |
    |      + Basic-Location-Policy-Rules          |              |
    |      + Extended-Location-Policy-Rules       |              |
    |<--------------------------------------------|              |
    |                                             |              |
    |  CoA ACK                                    |              |
    |-------------------------------------------->|              |
    |                                             |              |
    :                                             :              :
    :           <<Further exchanges later>>       :              :
    :                                             :              :
               Figure 4: Location Delivery Based on CoA

3.4. Location Delivery in Accounting Messages

 Location information may also be reported in accounting messages.
 Accounting messages are generated when the session starts, when the
 session stops, and periodically during the lifetime of the session.
 Accounting messages may also be generated when the user roams during
 handoff.
 Accounting information may be needed by the billing system to
 calculate the user's bill.  For example, there may be different
 tariffs or tax rates applied based on the location.
 If the RADIUS server needs to obtain location information in
 accounting messages, then it needs to include a Requested-Location-
 Info Attribute with the Access-Accept message.  The Basic-Location-
 Policy-Rules and the Extended-Location-Policy-Rules Attributes are to
 be echoed in the Accounting-Request if indicated in the Access-
 Accept.
 Figure 5 shows the message exchange.

Tschofenig, et al. Standards Track [Page 10] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 +---------+             +---------+                       +---------+
 |         |             | Network |                       | RADIUS  |
 | User    |             | Access  |                       | Server  |
 |         |             | Server  |                       |         |
 +---------+             +---------+                       +---------+
     |                       |                                  |
     :                       :                                  :
     :          Initial Protocol Interaction                    :
     :          (details omitted)                               :
     :                       :                                  :
     |                       |                                  |
     |                       | Access-Accept                    |
     |                       |  + Requested-Location-Info       |
     |                       |  + Basic-Location-Policy-Rules   |
     |                       |  + Extended-Location-Policy-Rules|
     |                       |<---------------------------------|
     | Authentication        |                                  |
     | Success               |                                  |
     |<----------------------|                                  |
     |                       |                                  |
     |                       | Accounting-Request               |
     |                       |  + Location-Information          |
     |                       |  + Location-Data                 |
     |                       |  + Basic-Location-Policy-Rules   |
     |                       |  + Extended-Location-Policy-Rules|
     |                       |--------------------------------->|
     |                       |                                  |
     |                       | Accounting-Response              |
     |                       |<---------------------------------|
     |                       |                                  |
          Figure 5: Location Delivery in Accounting Messages

4. Attributes

 It is important to note that the location-specific parts of the
 attributes defined below are not meant to be processed by the RADIUS
 server.  Instead, a location-server-specific component used in
 combination with the RADIUS server is responsible for receiving,
 processing, and further distributing location information (in
 combination with proper access control and privacy protection).  As
 such, from a RADIUS server point of view, location information is
 treated as opaque data.

Tschofenig, et al. Standards Track [Page 11] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

4.1. Operator-Name Attribute

 This attribute carries the operator namespace identifier and the
 operator name.  The operator name is combined with the namespace
 identifier to uniquely identify the owner of an access network.  The
 value of the Operator-Name is a non-NULL terminated text whose length
 MUST NOT exceed 253 bytes.
 The Operator-Name Attribute SHOULD be sent in Access-Request and
 Accounting-Request messages where the Acc-Status-Type is set to
 Start, Interim, or Stop.
 A summary of the Operator-Name Attribute is shown below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |            Text              ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Text (cont.)                                           ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Type:
    126 - Operator-Name
 Length:
    >= 4
 Text:
    The format is shown below.  The data type of this field is a text.
    All fields are transmitted from left to right:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Namespace ID  | Operator-Name                                ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Operator-Name                                                ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Tschofenig, et al. Standards Track [Page 12] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Namespace ID:
    The value within this field contains the operator namespace
    identifier.  The Namespace ID value is encoded in ASCII.
    Example: '1' (0x31) for REALM
 Operator-Name:
    The text field of variable length contains an Access Network
    Operator Name.  This field is a RADIUS-based data type of Text.
 The Namespace ID field provides information about the operator
 namespace.  This document defines four values for this attribute,
 which are listed below.  Additional namespace identifiers must be
 registered with IANA (see Section 8.1) and must be associated with an
 organization responsible for managing the namespace.
 TADIG ('0' (0x30)):
    This namespace can be used to indicate operator names based on
    Transferred Account Data Interchange Group (TADIG) codes, as
    defined in [GSM].  TADIG codes are assigned by the TADIG Working
    Group within the Global System for Mobile Communications (GSM)
    Association.  The TADIG code consists of two fields, with a total
    length of five ASCII characters consisting of a three-character
    country code and a two-character alphanumeric operator (or
    company) ID.
 REALM ('1' (0x31)):
    The REALM operator namespace can be used to indicate operator
    names based on any registered domain name.  Such names are
    required to be unique, and the rights to use a given realm name
    are obtained coincident with acquiring the rights to use a
    particular Fully Qualified Domain Name (FQDN).  Since this
    operator is limited to ASCII, any registered domain name that
    contains non-ASCII characters must be converted to ASCII.  The
    Punycode encoding [RFC3492] is used for this purpose.
 E212 ('2' (0x32)):
    The E212 namespace can be used to indicate operator names based on
    the Mobile Country Code (MCC) and Mobile Network Code (MNC)
    defined in [ITU212].  The MCC/MNC values are assigned by the
    Telecommunications Standardization Bureau (TSB) within the ITU-T

Tschofenig, et al. Standards Track [Page 13] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

    and by designated administrators in different countries.  The E212
    value consists of three ASCII digits containing the MCC, followed
    by two or three ASCII digits containing the MNC.
 ICC ('3' (0x33)):
    The ICC namespace can be used to indicate operator names based on
    International Telecommunication Union (ITU) Carrier Codes (ICC)
    defined in [ITU1400].  ICC values are assigned by national
    regulatory authorities and are coordinated by the
    Telecommunication Standardization Bureau (TSB) within the ITU
    Telecommunication Standardization Sector (ITU-T).  When using the
    ICC namespace, the attribute consists of three uppercase ASCII
    characters containing a three-letter alphabetic country code, as
    defined in [ISO], followed by one to six uppercase alphanumeric
    ASCII characters containing the ICC itself.

4.2. Location-Information Attribute

 The Location-Information Attribute MAY be sent in the Access-Request
 message, the Accounting-Request message, both of these messages, or
 no message.  For the Accounting-Request message, the Acc-Status-Type
 may be set to Start, Interim, or Stop.
 The Location-Information Attribute provides meta-data about the
 location information, such as sighting time, time-to-live, location-
 determination method, etc.
 The format is shown below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |            String            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       String (cont.)                                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Type:
    127 - Location-Information
 Length:
    >= 23

Tschofenig, et al. Standards Track [Page 14] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 String:
    The format is shown below.  The data type of this field is a
    string.  All fields are transmitted from left to right:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Index                       | Code          |  Entity       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Sighting Time                                                 ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Sighting Time                                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Time-to-Live                                                 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Time-to-Live                                                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Method                                                     ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Index (16 bits):
    The 16-bit unsigned integer value allows this attribute to provide
    information relating to the information included in the Location-
    Data Attribute to which it refers (via the Index).
 Code (8 bits):
    This field indicates the content of the location profile carried
    in the Location-Data Attribute.  Two profiles are defined in this
    document -- namely, a civic location profile (see Section 4.3.1)
    that uses value (0) and a geospatial location profile (see
    Section 4.3.2) that uses the value (1).
 Entity (8 bits):
    This field encodes which location this attribute refers to as an
    unsigned 8-bit integer value.  Location information can refer to
    different entities.  This document registers two entity values,
    namely:
       Value (0) describes the location of the user's client device.
       Value (1) describes the location of the RADIUS client.
    The registry used for these values is established by this
    document, see Section 8.4.

Tschofenig, et al. Standards Track [Page 15] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Sighting Time (64 bits)
    This field indicates when the location information was accurate.
    The data type of this field is a string, and the content is
    expressed in the 64-bit Network Time Protocol (NTP) timestamp
    format [RFC1305].
 Time-to-Live (64 bits):
    This field gives a hint regarding for how long location
    information should be considered current.  The data type of this
    field is a string and the content is expressed in the 64-bit
    Network Time Protocol (NTP) timestamp format [RFC1305].  Note that
    the Time-to-Live field is different than the Retention Expires
    field used in the Basic-Location-Policy-Rules Attribute, see
    Section 4.4.  The Retention Expires field indicates the time the
    recipient is no longer permitted to possess the location
    information.
 Method (variable):
    Describes the way that the location information was determined.
    This field MUST contain the value of exactly one IANA-registered
    'method' token [RFC4119].
 The length of the Location-Information Attribute MUST NOT exceed 253
 octets.

4.3. Location-Data Attribute

 The Location-Data Attribute MAY be sent in Access-Request and
 Accounting-Request messages.  For the Accounting-Request message, the
 Acc-Status-Type may be set to Start, Interim, or Stop.
 The format is shown below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |            String            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       String (cont.)                                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Type:
    128 - Location-Data

Tschofenig, et al. Standards Track [Page 16] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Length:
    >= 5
 String:
    The format is shown below.  The data type of this field is a
    string.  All fields are transmitted from left to right:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Index                       |  Location                    ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Location                                                    ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Index (16 bits):
    The 16-bit unsigned integer value allows this attribute to
    associate the Location-Data Attribute with the Location-
    Information Attributes.
 Location (variable):
    The format of the location data depends on the location profile.
    This document defines two location profiles.  Details of the
    location profiles are described below.

4.3.1. Civic Location Profile

 Civic location is a popular way to describe the location of an
 entity.  This section defines the civic location-information profile
 corresponding to the value (0) indicated in the Code field of the
 Location-Information Attribute.  The location format is based on the
 encoding format defined in Section 3.1 of [RFC4776], whereby the
 first 3 octets are not put into the Location field of the above-
 described RADIUS Location-Data Attribute (i.e., the code for the DHCP
 option, the length of the DHCP option, and the 'what' element are not
 included).

4.3.2. Geospatial Location Profile

 This section defines the geospatial location-information profile
 corresponding to the value (1) indicated in the Code field of the
 Location-Information Attribute.  Geospatial location information is
 encoded as an opaque object, and the format is based on the Location

Tschofenig, et al. Standards Track [Page 17] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Configuration Information (LCI) format defined in Section 2 of
 [RFC3825] but starts with the third octet (i.e., the code for the
 DHCP option and the length field is not included).

4.4. Basic-Location-Policy-Rules Attribute

 The Basic-Location-Policy-Rules Attribute MAY be sent in Access-
 Request, Access-Accept, Access-Challenge, Change-of-Authorization,
 and Accounting-Request messages.
 Policy rules control the distribution of location information.  In
 order to understand and process the Basic-Location-Policy-Rules
 Attribute, RADIUS clients are obligated to utilize a default value of
 Basic-Location-Policy-Rules, unless explicitly configured otherwise,
 and to echo the Basic-Location-Policy-Rules Attribute that they
 receive from a server.  As a default, the Note Well field does not
 carry a pointer to human-readable privacy policies, the
 retransmission-allowed is set to zero (0), i.e., further distribution
 is not allowed, and the Retention Expires field is set to 24 hours.
 With regard to authorization policies, this document reuses work done
 in [RFC4119] and encodes those policies in a non-XML format.  Two
 fields ('Sighting Time' and 'Time-to-Live') are additionally included
 in the Location-Information Attribute to conform to the GEOPRIV
 requirements [RFC3693], Section 2.7.
 The format of the Basic-Location-Policy-Rules Attribute is shown
 below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |            String            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       String (cont.)                                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Type:
    129 - Basic-Location-Policy-Rules
 Length:
    >= 12

Tschofenig, et al. Standards Track [Page 18] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 String:
    The format is shown below.  The data type of this field is a
    string.  All fields are transmitted from left to right:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Flags                        | Retention Expires            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Retention Expires                                            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Retention Expires             | Note Well                    ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Note Well                                                    ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 This document reuses fields from the RFC 4119 [RFC4119] 'usage-rules'
 element.  These fields have the following meaning:
 Flags (16 bits):
    The Flags field is a bit mask.  Only the first bit (R) is defined
    in this document, and it corresponds to the Retransmission Allowed
    field:
      0                   1
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |R|o o o o o o o o o o o o o o o|
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     R = Retransmission Allowed
     o = reserved.
 All reserved bits MUST be zero.  When the value of the Retransmission
 Allowed field is set to zero (0), then the recipient of this Location
 Object is not permitted to share the enclosed location information,
 or the object as a whole, with other parties.  The value of '1'
 allows this attribute to share the location information with other
 parties by considering the extended policy rules.
 Retention Expires (64 bits):
    This field specifies an absolute date at which time the Recipient
    is no longer permitted to possess the location information.  The
    data type of this field is a string and the format is a 64-bit NTP
    timestamp [RFC1305].

Tschofenig, et al. Standards Track [Page 19] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Note Well (variable):
    This field contains a URI that points to human-readable privacy
    instructions.  The data type of this field is a string.  This
    field is useful when location information is distributed to third-
    party entities, which can include humans in a location-based
    service.  RADIUS entities are not supposed to process this field.
    Whenever a Location Object leaves the RADIUS ecosystem, the URI in
    the Note Well Attribute MUST be expanded to the human-readable
    text.  For example, when the Location Object is transferred to a
    SIP-based environment, then the human-readable text is placed into
    the 'note-well' element of the 'usage-rules' element contained in
    the PIDF-LO (Presence Information Data Format - Location Object)
    document (see [RFC4119]).  The Note Well field may be empty.

4.5. Extended-Location-Policy-Rules Attribute

 The Extended-Location-Policy-Rules Attribute MAY be sent in Access-
 Request, Access-Accept, Access-Challenge, Access-Reject, Change-of-
 Authorization, and Accounting-Request messages.
 The Ruleset Reference field of this attribute is of variable length.
 It contains a URI that indicates where the richer ruleset can be
 found.  This URI SHOULD use the HTTPS URI scheme.  As a deviation
 from [RFC4119], this field only contains a reference and does not
 carry an attached, extended ruleset.  This modification is motivated
 by the size limitations imposed by RADIUS.
 In order to understand and process the Extended-Location-Policy-Rules
 Attribute, RADIUS clients are obligated to attach the URI to the
 Extended-Location-Policy-Rules Attribute when they are explicitly
 configured to do so, and to echo the Extended-Location-Policy-Rules
 Attribute that they receive from a server.  There is no expectation
 that RADIUS clients will need to retrieve data at the URL specified
 in the attribute or to parse the XML policies.
 The format of the Extended-Location-Policy-Rules Attribute is shown
 below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |            String            ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       String (cont.)                                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Tschofenig, et al. Standards Track [Page 20] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Type:
    130 - Extended-Location-Policy-Rules
 Length:
    >= 3
 String:
    This field is at least two octets in length, and the format is
    shown below.  The data type of this field is a string.  The fields
    are transmitted from left to right:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Ruleset Reference                                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Ruleset Reference:
    This field contains a URI that points to the policy rules.

4.6. Location-Capable Attribute

 The Location-Capable Attribute allows an NAS (or client function of a
 proxy server) to indicate support for the functionality specified in
 this document.  The Location-Capable Attribute with the value for
 'Location Capable' MUST be sent with the Access-Request messages, if
 the NAS supports the functionality described in this document and is
 capable of sending location information.  A RADIUS server MUST NOT
 challenge for location information unless the Location-Capable
 Attribute has been sent to it.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Type          | Length        | Integer                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Integer (cont.)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Type:
    131 - Location-Capable Attribute

Tschofenig, et al. Standards Track [Page 21] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Length:
    6
 Integer:
    The content of the Integer field encodes the requested
    capabilities.  Each capability value represents a bit position.
 This document specifies the following capabilities.
 Name:
    CIVIC_LOCATION
 Description:
    The RADIUS client uses the CIVIC_LOCATION to indicate that it is
    able to return civic location based on the location profile
    defined in Section 4.3.1.
 Numerical Value:
    A numerical value of this token is '1'.
 Name:
    GEO_LOCATION
 Description:
    The RADIUS client uses the GEO_LOCATION to indicate that it is
    able to return geodetic location based on the location profile
    defined in Section 4.3.2.
 Numerical Value:
    A numerical value of this token is '2'.
 Name:
    USERS_LOCATION

Tschofenig, et al. Standards Track [Page 22] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Description:
    The numerical value representing USERS_LOCATION indicates that the
    RADIUS client is able to provide a Location-Information Attribute
    with the Entity Attribute expressing the value of zero (0), i.e.,
    the RADIUS client is capable of returning the location information
    of the user's client device.
 Numerical Value:
    A numerical value of this token is '4'.
 Name:
    NAS_LOCATION
 Description:
    The numerical value representing NAS_LOCATION indicates that the
    RADIUS client is able to provide a Location-Information Attribute
    that contains location information with the Entity Attribute
    expressing the value of one (1), i.e., the RADIUS client is
    capable of returning the location information of the NAS.
 Numerical Value:
    A numerical value of this token is '8'.

4.7. Requested-Location-Info Attribute

 The Requested-Location-Info Attribute allows the RADIUS server to
 indicate which location information about which entity it wants to
 receive.  The latter aspect refers to the entities that are indicated
 in the Entity field of the Location-Information Attribute.
 The Requested-Location-Info Attribute MAY be sent in an Access-
 Accept, Access-Challenge, or Change-of-Authorization packet.
 If the RADIUS server wants to dynamically decide on a per-request
 basis to ask for location information from the RADIUS client, then
 the following cases need to be differentiated.  If the RADIUS client
 and the RADIUS server have agreed out-of-band to mandate the transfer
 of location information for every network-access authentication
 request, then the processing listed below is not applicable.

Tschofenig, et al. Standards Track [Page 23] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 o  If the RADIUS server requires location information for computing
    the authorization decision and the RADIUS client does not provide
    it with the Access-Request message, then the Requested-Location-
    Info Attribute is attached to the Access-Challenge with a hint
    about what is required.
 o  If the RADIUS server does not receive the requested information in
    response to the Access-Challenge (including the Requested-
    Location-Info Attribute), then the RADIUS server may respond with
    an Access-Reject message with an Error-Cause Attribute (including
    the "Location-Info-Required" value).
 o  If the RADIUS server would like location information in the
    Accounting-Request message but does not require it for computing
    an authorization decision, then the Access-Accept message MUST
    include a Required-Info Attribute.  This is typically the case
    when location information is used only for billing.  The RADIUS
    client SHOULD attach location information, if available, to the
    Accounting-Request (unless authorization policies dictate
    something different).
 If the RADIUS server does not send a Requested-Location-Info
 Attribute, then the RADIUS client MUST NOT attach location
 information to messages towards the RADIUS server.  The user's
 authorization policies, if available, MUST be consulted by the RADIUS
 server before requesting location information delivery from the
 RADIUS client.
 Figure 6 shows a simple protocol exchange where the RADIUS server
 indicates the desire to obtain location information, namely civic
 location information of the user, to grant access.  Since the
 Requested-Location-Info Attribute is attached to the Access-
 Challenge, the RADIUS server indicates that location information is
 required for computing an authorization decision.

Tschofenig, et al. Standards Track [Page 24] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

  +---------+                        +---------+
  | RADIUS  |                        | RADIUS  |
  | Client  |                        | Server  |
  +---------+                        +---------+
       |                                  |
       |                                  |
       | Access-Request                   |
       | + Location-Capable               |
       |   ('CIVIC_LOCATION',             |
       |    'GEO_LOCATION',               |
       |    'NAS_LOCATION',               |
       |    'USERS_LOCATION')             |
       |--------------------------------->|
       |                                  |
       | Access-Challenge                 |
       | + Requested-Location-Info        |
       |   ('CIVIC_LOCATION',             |
       |    'USERS_LOCATION')             |
       | + Basic-Location-Policy-Rules    |
       | + Extended-Location-Policy-Rules |
       |<---------------------------------|
       |                                  |
       | Access-Request                   |
       | + Location-Information           |
       | + Location-Data                  |
       | + Basic-Location-Policy-Rules    |
       | + Extended-Location-Policy-Rules |
       |--------------------------------->|
       |                                  |
       |        ....                      |
        Figure 6: RADIUS Server Requesting Location Information
 The Requested-Location-Info Attribute MUST be sent by the RADIUS
 server, in the absence of an out-of-band agreement, if it wants the
 RADIUS client to return location information and if authorization
 policies permit it.  This Requested-Location-Info Attribute MAY
 appear in the Access-Accept or in the Access-Challenge message.
 A summary of the attribute is shown below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |            Integer           ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Integer (cont.)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Tschofenig, et al. Standards Track [Page 25] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Type:
    132 - Requested-Location-Info Attribute
 Length:
    6
 Integer:
    The content of the Integer field encodes the requested information
    attributes.  Each capability value represents a bit position.
 This document specifies the following capabilities:
 Name:
    CIVIC_LOCATION
 Description:
    The RADIUS server uses the Requested-Location-Info Attribute with
    the value set to CIVIC_LOCATION to request specific location
    information from the RADIUS client.  The numerical value
    representing CIVIC_LOCATION requires the RADIUS client to attach
    civic location attributes.  CIVIC_LOCATION refers to the location
    profile defined in Section 4.3.1.
 Numerical Value:
    A numerical value of this token is '1'.
 Name:
    GEO_LOCATION
 Description:
    The RADIUS server uses the Requested-Location-Info Attribute with
    the value set to GEO_LOCATION to request specific location
    information from the RADIUS client.  The numerical value
    representing GEO_LOCATION requires the RADIUS client to attach
    geospatial location attributes.  GEO_LOCATION refers to the
    location profile described in Section 4.3.2.
 Numerical Value:
    A numerical value of this token is '2'.

Tschofenig, et al. Standards Track [Page 26] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Name:
    USERS_LOCATION
 Description:
    The numerical value representing USERS_LOCATION indicates that the
    RADIUS client MUST send a Location-Information Attribute with the
    Entity Attribute expressing the value of zero (0).  Hence, there
    is a one-to-one relationship between the USERS_LOCATION token and
    the value of zero (0) of the Entity Attribute inside the Location-
    Information Attribute.  A value of zero indicates that the
    location information in the Location-Information Attribute refers
    to the user's client device.
 Numerical Value:
    A numerical value of this token is '4'.
 Name:
    NAS_LOCATION
 Description:
    The numerical value representing NAS_LOCATION indicates that the
    RADIUS client MUST send a Location-Information Attribute that
    contains location information with the Entity Attribute expressing
    the value of one (1).  Hence, there is a one-to-one relationship
    between the NAS_LOCATION token and the value of one (1) of the
    Entity Attribute inside the Location-Information Attribute.  A
    value of one indicates that the location information in the
    Location-Information Attribute refers to the RADIUS client.
 Numerical Value:
    A numerical value of this token is '8'.
 Name:
    FUTURE_REQUESTS
 Description:
    The numerical value representing FUTURE_REQUESTS indicates that
    the RADIUS client MUST provide future Access-Requests for the same
    session with the same type of information as returned in the
    initial Access-Request message.

Tschofenig, et al. Standards Track [Page 27] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Numerical Value:
    A numerical value of this token is '16'.
 Name:
    NONE
 Description:
    The RADIUS server uses this token to request that the RADIUS
    client stop sending location information.
 Numerical Value:
    A numerical value of this token is '32'.
 If neither the NAS_LOCATION nor the USERS_LOCATION bit is set, then
 per-default the location of the user's client device is returned (if
 authorization policies allow it).  If both the NAS_LOCATION and the
 USERS_LOCATION bits are set, then the returned location information
 has to be put into separate attributes.  If neither the
 CIVIC_LOCATION nor the GEO_LOCATION bit is set in the Requested-
 Location-Info Attribute, then no location information is returned.
 If both the CIVIC_LOCATION and the GEO_LOCATION bits are set, then
 the location information has to be put into separate attributes.  The
 value of NAS_LOCATION and USERS_LOCATION refers to the location
 information requested via CIVIC_LOCATION and GEO_LOCATION.
 As an example, if the bits for NAS_LOCATION, USERS_LOCATION, and
 GEO_LOCATION are set, then the location information of the RADIUS
 client and the users' client device are returned in a geospatial-
 location format.

5. Table of Attributes

 The following table provides a guide to which attributes may be found
 in which RADIUS messages, and in what quantity.

Tschofenig, et al. Standards Track [Page 28] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

Request Accept Reject Challenge Accounting # Attribute

                               Request

0-1 0-1 0 0 0+ 126 Operator-Name 0+ 0 0 0 0+ 127 Location-Information 0+ 0 0 0 0+ 128 Location-Data 0-1 0-1 0-1 0-1 0-1 129 Basic-Location-

                                               Policy-Rules

0-1 0-1 0-1 0-1 0-1 130 Extended-Location-

                                               Policy-Rules

0-1 0 0 0 0 131 Location-Capable 0 0-1 0 0-1 0 132 Requested-Location-Info 0 0 0-1 0 0 101 Error-Cause (*)

(*) Note: The Error-Cause Attribute contains the value for the 'Location-Info-Required' error.

Change-of-Authorization Messages

Request   ACK      NAK    #    Attribute
 0-1       0        0     129  Basic-Location-Policy-Rules
 0-1       0        0     130  Extended-Location-Policy-Rules
 0-1       0        0     132  Requested-Location-Info

Legend:

  0     This attribute MUST NOT be present.
  0+    Zero or more instances of this attribute MAY be present.
  0-1   Zero or one instance of this attribute MAY be present.
  1     Exactly one instance of this attribute MUST be present.
  1+    One or more of these attributes MUST be present.
                     Figure 7: Table of Attributes
 The Error-Cause Attribute is defined in [RFC5176].
 The Location-Information and the Location-Data Attribute MAY appear
 more than once.  For example, if the server asks for civic and
 geospatial location information, two Location-Information Attributes
 need to be sent.
 The attributes defined in this document are not used in any messages
 other than the ones listed in Figure 7.
 IANA allocated a new value (509) from the Error-Cause registry with
 the semantics of 'Location-Info-Required'.

Tschofenig, et al. Standards Track [Page 29] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

6. Diameter RADIUS Interoperability

 When used in Diameter, the attributes defined in this specification
 can be used as Diameter attribute-value pairs (AVPs) from the code
 space 1-255 (RADIUS attribute-compatibility space).  No additional
 Diameter code values are therefore allocated.  The data types and
 flag rules, as defined in [RFC3588], for the Diameter AVPs are as
 follows:
                                   +---------------------+
                                   |    AVP Flag rules   |
                                   +----+-----+------+-----+----+
                                   |    |     |SHOULD| MUST|    |
  Attribute Name        Value Type |MUST| MAY | NOT  |  NOT|Encr|
 +---------------------------------+----+-----+------+-----+----+
 |Operator-Name         OctetString|    |  P  |      | V,M | Y  |
 |Location-Information  OctetString|    |  P  |      | V,M | Y  |
 |Location-Data         OctetString|    |  P  |      | V,M | Y  |
 |Basic-Location-                  |    |     |      |     |    |
 |   Policy-Rules       OctetString|    |  P  |      | V,M | Y  |
 |Extended-Location-               |    |     |      |     |    |
 |   Policy-Rules       OctetString|    |  P  |      | V,M | Y  |
 |Requested-                       |    |     |      |     |    |
 |   Location-Info      OctetString|    |  P  |      | V,M | Y  |
 |Location-Capable      OctetString|    |  P  |      | V,M | Y  |
 +---------------------------------+----+-----+------+-----+----+
 The RADIUS attributes in this specification have no special
 translation requirements for Diameter-to-RADIUS or RADIUS-to-Diameter
 gateways; they are copied as is, except for changes relating to
 headers, alignment, and padding.  See also Section 4.1 of [RFC3588]
 and Section 9 of [RFC4005].
 What this specification says about the applicability of the
 attributes for RADIUS Access-Request packets applies in Diameter to
 AA-Request [RFC4005] or Diameter-EAP-Request [RFC4072].  What is said
 about Access-Challenge applies in Diameter to AA-Answer [RFC4005] or
 Diameter-EAP-Answer [RFC4072] with the Result-Code AVP set to
 DIAMETER_MULTI_ROUND_AUTH.  What is said about Access-Accept applies
 in Diameter to AA-Answer or Diameter-EAP-Answer messages that
 indicate success.  Similarly, what is said about RADIUS Access-Reject
 packets applies in Diameter to AA-Answer or Diameter-EAP-Answer
 messages that indicate failure.
 What is said about CoA-Request applies in Diameter to Re-Auth-Request
 [RFC4005].

Tschofenig, et al. Standards Track [Page 30] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 What is said about Accounting-Request applies in Diameter to
 Accounting-Request [RFC4005] as well.
 Note that these AVPs may be used by Diameter applications other than
 RFC 4005 [RFC4005] and RFC 4072 [RFC4072].  The above-mentioned
 applications are, however, likely to be relevant in the context of
 this document.

7. Security Considerations

 A number of security aspects are relevant for the distribution of
 location information via RADIUS.  These aspects are discussed in
 separate subsections.

7.1. Communication Security

 Requirements for the protection of a Location Object are defined in
 [RFC3693] -- namely, mutual end-point authentication, data object
 integrity, data object confidentiality, and replay protection.
 If no authentication, integrity, and replay protection between the
 participating RADIUS entities is provided, then adversaries can spoof
 and modify transmitted attributes.  Two security mechanisms are
 proposed for RADIUS:
 o  [RFC2865] proposes the usage of a static key that raised concerns
    regarding the lack of dynamic key management.  At the time of
    writing, work is ongoing to address some shortcomings of the
    [RFC2865] attribute regarding security protection.
 o  RADIUS over IPsec [RFC3579] enables the use of standard key-
    management mechanisms, such as Kerberized Internet Negotiation of
    Keys (KINK), the Internet Key Exchange Protocol (IKE), and IKEv2
    [RFC4306], to establish IPsec security associations.
    Confidentiality protection MUST be used to prevent an eavesdropper
    from gaining access to location information.  Confidentiality
    protection is already present for other reasons in many
    environments, such as for the transport of keying material in the
    context of Extensible Authentication Protocol (EAP) authentication
    and authorization.  Hence, this requirement is, in many
    environments, already fulfilled.  Mutual authentication MUST be
    provided between neighboring RADIUS entities to prevent man-in-
    the-middle attacks.  Since mutual authentication is already
    required for key transport within RADIUS messages, it does not
    represent a deployment obstacle.  Since IPsec protection is
    already suggested as a mechanism to protect RADIUS, no additional
    considerations need to be addressed beyond those described in
    [RFC3579].

Tschofenig, et al. Standards Track [Page 31] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 In case IPsec protection is not available for some reason and RADIUS-
 specific security mechanisms have to be used, then the following
 considerations apply.  The Access-Request message is not integrity
 protected.  This would allow an adversary to change the contents of
 the Location Object or to insert, modify, and delete attributes or
 individual fields.  To address these problems, the Message-
 Authenticator (80) can be used to integrity protect the entire
 Access-Request packet.  The Message-Authenticator (80) is also
 required when EAP is used and, hence, is supported by many modern
 RADIUS servers.
 Access-Request packets including location attribute(s) without a
 Message-Authenticator (80) Attribute SHOULD be silently discarded by
 the RADIUS server.  A RADIUS server supporting location attributes
 MUST calculate the correct value of the Message-Authenticator (80)
 and MUST silently discard the packet if it does not match the value
 sent.
 Access-Accept messages, including location attribute(s), without a
 Message-Authenticator (80) Attribute SHOULD be silently discarded by
 the NAS.  An NAS supporting location attributes MUST calculate the
 correct value of a received Message-Authenticator (80) and MUST
 silently discard the packet if it does not match the value sent.
 RADIUS and Diameter make some assumptions about the trust between
 traversed RADIUS entities in the sense that object-level security is
 not provided by either RADIUS or Diameter.  Hence, some trust has to
 be placed on the RADIUS entities to behave according to the defined
 rules.  Furthermore, the RADIUS protocol does not involve the user in
 their protocol interaction except for tunneling authentication
 information (such as EAP messages) through their infrastructure.
 RADIUS and Diameter have even become a de facto protocol for key
 distribution for network-access authentication applications.  Hence,
 in the past there were some concerns about the trust placed into the
 infrastructure -- particularly from the security area -- when it
 comes to keying.  The EAP keying infrastructure is described in
 [RFC4282].

7.2. Privacy Considerations

 This section discusses privacy implications for the distribution of
 location information within RADIUS.  Note also that it is possible
 for the RADIUS server to obtain some amount of location information
 from the NAS identifier.  This document, however, describes
 procedures to convey more accurate location information about the end
 host and/or the network.  In a number of deployment environments,
 location information about the network also reveals the current

Tschofenig, et al. Standards Track [Page 32] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 location of the user with a certain degree of precision, depending on
 the location-determination mechanism used, the update frequency, the
 size of the network, and other factors, such as movement traces.
 Three types of use cases have to be differentiated:
 o  The RADIUS server does not want to receive location information
    from the RADIUS client.
 o  In case there is an out-of-band agreement between the entity
    responsible for the NAS and the entity operating the RADIUS
    server, location information may be sent without an explicit
    request from the RADIUS server.
 o  The RADIUS server dynamically requests location information from
    the NAS.

7.2.1. RADIUS Client

 The RADIUS client MUST behave according to the following guidelines:
 o  If neither an out-of-band agreement exists nor location
    information is requested by the RADIUS server, then location
    information is not disclosed by the RADIUS client.
 o  The RADIUS client MUST pass location information to other entities
    (e.g., when information is written to a local database or to the
    log files) only together with the policy rules.  The entity
    receiving the location information (together with the policies)
    MUST follow the guidance given with these rules.
 o  A RADIUS client MUST include Basic-Location-Policy-Rules and
    Extended-Location-Policy-Rules Attributes that are configured
    within an Access-Request packet.
 o  NAS implementations supporting this specification, which are
    configured to provide location information, MUST echo Basic-
    Location-Policy-Rules and Extended-Location-Policy-Rules
    Attributes unmodified within a subsequent Access-Request packet.
    In addition, an Access-Request packet sent with a Service-Type
    value of "Authorize Only" MUST include the Basic-Location-Policy-
    Rules or Extended-Location-Policy-Rules Attributes that were
    received in a previous Access-Accept if the FUTURE_REQUESTS flag
    was set in the Requested-Location-Info Attribute.

Tschofenig, et al. Standards Track [Page 33] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

7.2.2. RADIUS Server

 The RADIUS server is a natural place for storing authorization
 policies since the user typically has some sort of trust relationship
 with the entity operating the RADIUS server.  Once the infrastructure
 is deployed and location-aware applications are available, there
 might be a strong desire to use location information for other
 purposes as well.
    The Common Policy framework [RFC4745] that was extended for
    geolocation privacy [GEO-POLICY] is tailored for this purpose.
    The Extensible Markup Language (XML) Configuration Access Protocol
    (XCAP) [RFC4825] gives users the ability to change their privacy
    policies using a standardized protocol.  These policies are an
    important tool for limiting further distribution of the user's
    location to other location-based services.
 The RADIUS server MUST behave according to the following guidelines:
 o  The RADIUS server MUST attach available rules to the Access-
    Accept, Access-Reject, or Access-Challenge message when the RADIUS
    client is supposed to provide location information.
 o  When location information is made available to other entities
    (e.g., writing to stable storage for later billing processing),
    then the RADIUS server MUST attach the privacy rules to location
    information.

7.2.3. RADIUS Proxy

 A RADIUS proxy, behaving as a combined RADIUS client and RADIUS
 server, MUST follow the rules described in Sections 7.2.1 and 7.2.2.

7.3. Identity Information and Location Information

 For the envisioned usage scenarios, the identity of the user and his
 device is tightly coupled to the transfer of location information.
 If the identity can be determined by the visited network or RADIUS
 brokers, then it is possible to correlate location information with a
 particular user.  As such, it allows the visited network and brokers
 to learn the movement patterns of users.
 The user's identity can be "leaked" to the visited network or RADIUS
 brokers in a number of ways:
 o  The user's device may employ a fixed Media Access Control (MAC)
    address or base its IP address on such an address.  This enables
    the correlation of the particular device to its different

Tschofenig, et al. Standards Track [Page 34] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

    locations.  Techniques exist to avoid the use of an IP address
    that is based on a MAC address [RFC4941].  Some link layers make
    it possible to avoid MAC addresses or change them dynamically.
 o  Network-access authentication procedures, such as the PPP
    Challenge Handshake Authentication Protocol (CHAP) [RFC1994] or
    EAP [RFC4187], may reveal the user's identity as a part of the
    authentication procedure.  Techniques exist to avoid this problem
    in EAP methods, for instance by employing private Network Access
    Identifiers (NAIs) [RFC4282] in the EAP Identity Response message
    and by method-specific private identity exchanges in the EAP
    method (e.g., [RFC4187], [RFC5281], [PEAP], and [RFC5106]).
    Support for identity privacy within CHAP is not available.
 o  RADIUS may return information from the home network to the visited
    one in a manner that makes it possible to either identify the user
    or at least correlate his session with other sessions, such as the
    use of static data in a Class Attribute [RFC2865] or in some
    accounting attribute usage scenarios [RFC4372].
 o  Mobility protocols may reveal some long-term identifier, such as a
    home address.
 o  Application-layer protocols may reveal other permanent
    identifiers.
 To prevent the correlation of identities with location information,
 it is necessary to prevent leakage of identity information from all
 sources, not just one.
 Unfortunately, most users are not educated about the importance of
 identity confidentiality, and some protocols lack support for
 identity-privacy mechanisms.  This problem is made worse by the fact
 that users may be unable to choose particular protocols, as the
 choice is often dictated by the type of network operator they use,
 the type of network they wish to access, the kind of equipment they
 have, or the type of authentication method they are using.
 A scenario where the user is attached to the home network is, from a
 privacy point of view, simpler than a scenario where a user roams
 into a visited network, since the NAS and the home RADIUS server are
 in the same administrative domain.  No direct relationship between
 the visited and the home network operator may be available, and some
 RADIUS brokers need to be consulted.  With subscription-based network
 access as used today, the user has a contractual relationship with
 the home network provider that could (theoretically) allow higher

Tschofenig, et al. Standards Track [Page 35] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 privacy considerations to be applied (including policy rules stored
 at the home network itself, for the purpose of restricting further
 distribution).
 In many cases it is necessary to secure the transport of location
 information along the RADIUS infrastructure.  Mechanisms to achieve
 this functionality are discussed in Section 7.1.

8. IANA Considerations

 The Attribute Types and Attribute Values defined in this document
 have been registered by the Internet Assigned Numbers Authority
 (IANA) from the RADIUS namespaces as described in the "IANA
 Considerations" section of RFC 3575 [RFC3575], in accordance with BCP
 26 [RFC5226].  Additionally, the Attribute Type has been registered
 in the Diameter namespace.  For RADIUS attributes and registries
 created by this document, IANA placed them in the Radius Types
 registry.
 This document defines the following attributes:
       Operator-Name
       Location-Information
       Location-Data
       Basic-Location-Policy-Rules
       Extended-Location-Policy-Rules
       Location-Capable
       Requested-Location-Info
 Please refer to Section 5 for the registered list of numbers.
 IANA has also assigned a new value (509) for the Error-Cause
 Attribute [RFC5176] of "Location-Info-Required" according to this
 document.
 Additionally, IANA created the following new registries listed in the
 subsections below.

8.1. New Registry: Operator Namespace Identifier

 This document also defines an Operator Namespace Identifier registry
 (used in the Namespace ID field of the Operator-Name Attribute).
 Note that this document requests IANA only to maintain a registry of
 existing namespaces for use in this identifier field, and not to
 establish any namespaces or place any values within namespaces.

Tschofenig, et al. Standards Track [Page 36] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 IANA added the following values to the Operator Namespace Identifier
 registry using a numerical identifier (allocated in sequence), a
 token for the operator namespace, and a contact person for the
 registry.
+----------+--------------------+------------------------------------+
|Identifier| Operator Namespace | Contact Person                     |
|          | Token              |                                    |
+----------+--------------------+------------------------------------+
|   0x30   | TADIG              | TD.13 Coordinator                  |
|          |                    | (td13@gsm.org)                     |
|   0x31   | REALM              | IETF O&M Area Directors            |
|          |                    | (ops-ads@ietf.org)                 |
|   0x32   | E212               | ITU Director                       |
|          |                    | (tsbdir@itu.int)                   |
|   0x33   | ICC                | ITU Director                       |
|          |                    | (tsbdir@itu.int)                   |
+----------+--------------------+------------------------------------+
 Note that the above identifier values represent the ASCII value '0'
 (decimal 48 or hex 0x30), '1' (decimal 49, or hex 0x31), '2' (decimal
 50, or hex 0x32), and '3' (decimal 51, or hex 0x33).  This encoding
 was chosen to simplify parsing.
 Requests to IANA for a new value for a Namespace ID, i.e., values
 from 0x34 to 0xFE, will be approved by Expert Review.  A designated
 expert will be appointed by the IESG.
 The Expert Reviewer should ensure that a new entry is indeed required
 or could fit within an existing database, e.g., whether there is a
 real requirement to provide a token for a Namespace ID because one is
 already up and running, or whether the REALM identifier plus the name
 should be recommended to the requester.  In addition, the Expert
 Reviewer should ascertain to some reasonable degree of diligence that
 a new entry is a correct reference to an operator namespace whenever
 a new one is registered.

8.2. New Registry: Location Profiles

 Section 4.2 defines the Location-Information Attribute and a Code
 field that contains an 8-bit integer value.  Two values, zero and
 one, are defined in this document, namely:
 Value (0): Civic location profile described in Section 4.3.1
 Value (1): Geospatial location profile described in Section 4.3.2
 The remaining values are reserved for future use.

Tschofenig, et al. Standards Track [Page 37] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Following the policies outlined in [RFC3575], the available bits with
 a description of their semantics will be assigned after the Expert
 Review process.  Updates can be provided based on expert approval
 only.  Based on expert approval, it is possible to mark entries as
 "deprecated".  A designated expert will be appointed by the IESG.
 Each registration must include the value and the corresponding
 semantics of the defined location profile.

8.3. New Registry: Location-Capable Attribute

 Section 4.6 defines the Location-Capable Attribute that contains a
 bit map. 32 bits are available, from which 4 bits are defined by this
 document.  This document creates a new IANA registry for the
 Location-Capable Attribute.  IANA added the following values to this
 registry:
  +----------+----------------------+
  |  Value   | Capability Token     |
  +----------+----------------------+
  |    1     | CIVIC_LOCATION       |
  |    2     | GEO_LOCATION         |
  |    4     | USERS_LOCATION       |
  |    8     | NAS_LOCATION         |
  +----------+----------------------+
 Following the policies outlined in [RFC3575], the available bits with
 a description of their semantics will be assigned after the Expert
 Review process.  Updates can be provided based on expert approval
 only.  Based on expert approval, it is possible to mark entries as
 "deprecated".  A designated expert will be appointed by the IESG.
 Each registration must include:
 Name:
    Capability Token (i.e., an identifier of the capability)
 Description:
    Brief description indicating the meaning of the 'info' element.
 Numerical Value:
    A numerical value that is placed into the Capability Attribute
    representing a bit in the bit-string of the Requested-Location-
    Info Attribute.

Tschofenig, et al. Standards Track [Page 38] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

8.4. New Registry: Entity Types

 Section 4.2 defines the Location-Information Attribute that contains
 an 8-bit Entity field.  Two values are registered by this document,
 namely:
 Value (0) describes the location of the user's client device.
 Value (1) describes the location of the RADIUS client.
 All other values are reserved for future use.
 Following the policies outlined in [RFC3575], the available bits with
 a description of their semantics will be assigned after the Expert
 Review process.  Updates can be provided based on expert approval
 only.  Based on expert approval, it is possible to mark entries as
 "deprecated".  A designated expert will be appointed by the IESG.
 Each registration must include the value and a corresponding
 description.

8.5. New Registry: Privacy Flags

 Section 4.4 defines the Basic-Location-Policy-Rules Attribute that
 contains flags indicating privacy settings. 16 bits are available,
 from which a single bit, bit (0), indicating 'retransmission allowed'
 is defined by this document.  Bits 1-15 are reserved for future use.
 Following the policies outline in [RFC3575], the available bits with
 a description of their semantics will be assigned after the Expert
 Review process.  Updates can be provided based on expert approval
 only.  Based on expert approval, it is possible to mark entries as
 "deprecated".  A designated expert will be appointed by the IESG.
 Each registration must include the bit position and the semantics of
 the bit.

8.6. New Registry: Requested-Location-Info Attribute

 Section 4.7 defines the Requested-Location-Info Attribute that
 contains a bit map. 32 bits are available, from which 6 bits are
 defined by this document.  This document creates a new IANA registry
 for the Requested-Location-Info Attribute.  IANA added the following
 values to this registry:

Tschofenig, et al. Standards Track [Page 39] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

  +----------+----------------------+
  |  Value   | Capability Token     |
  +----------+----------------------+
  |    1     | CIVIC_LOCATION       |
  |    2     | GEO_LOCATION         |
  |    4     | USERS_LOCATION       |
  |    8     | NAS_LOCATION         |
  |   16     | FUTURE_REQUESTS      |
  |   32     | NONE                 |
  +----------+----------------------+
 The semantics of these values are defined in Section 4.7.
 Following the policies outlined in [RFC3575], new Capability Tokens,
 with a description of their semantics for usage with the Requested-
 Location-Info Attribute, will be assigned after the Expert Review
 process.  Updates can be provided based on expert approval only.
 Based on expert approval, it is possible to mark entries as
 "deprecated".  A designated expert will be appointed by the IESG.
 Each registration must include:
 Name:
    Capability Token (i.e., an identifier of the capability)
 Description:
    Brief description indicating the meaning of the 'info' element.
 Numerical Value:
    A numerical value that is placed into the Capability Attribute
    representing a bit in the bit-string of the Requested-Location-
    Info Attribute.

9. Acknowledgments

 The authors would like to thank the following people for their help
 with an initial version of this document and for their input: Chuck
 Black, Paul Congdon, Jouni Korhonen, Sami Ala-luukko, Farooq Bari, Ed
 Van Horne, Mark Grayson, Jukka Tuomi, Jorge Cuellar, and Christian
 Guenther.

Tschofenig, et al. Standards Track [Page 40] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Henning Schulzrinne provided the civic location information content
 found in this document.  The geospatial location-information format
 is based on work done by James Polk, John Schnizlein, and Marc
 Linsner.  The authorization policy format is based on the work done
 by Jon Peterson.
 The authors would like to thank Victor Lortz, Anthony Leibovitz, Jose
 Puthenkulam, Bernrad Aboba, Jari Arkko, Parviz Yegani, Serge Manning,
 Kuntal Chowdury, Pasi Eronen, Blair Bullock and Eugene Chang for
 their feedback to an initial version of this document.  We would like
 to thank Jari Arkko for his textual contributions.  Lionel Morand
 provided detailed feedback on numerous issues.  His comments helped
 to improve the quality of this document.  Jouni Korhonen, Victor
 Fajardo, Tolga Asveren, and John Loughney helped us with the Diameter
 RADIUS interoperability section.  Andreas Pashalidis reviewed a later
 version document and provided a number of comments.  Alan DeKok,
 Lionel Morand, Jouni Korhonen, David Nelson, and Emile van Bergen
 provided guidance on the Requested-Location-Info Attribute and
 participated in the capability-exchange discussions.  Allison Mankin,
 Jouni Korhonen, and Pasi Eronen provided text for the Operator
 Namespace Identifier registry.  Jouni Korhonen interacted with the
 GSMA to find a contact person for the TADIG operator namespace, and
 Scott Bradner consulted the ITU-T to find a contact person for the
 E212 and the ICC operator namespace.
 This document is based on the discussions within the IETF GEOPRIV
 Working Group.  Therefore, the authors thank Henning Schulzrinne,
 James Polk, John Morris, Allison Mankin, Randall Gellens, Andrew
 Newton, Ted Hardie, and Jon Peterson for their time discussing a
 number of issues with us.  We thank Stephen Hayes for aligning this
 work with 3GPP activities.
 We would like to thank members of the Wimax Forum Global Roaming
 Working Group (GRWG) for their feedback on the Operator-Name
 attribute.  Ray Jong Kiem helped us with his detailed description to
 correct the document.
 The RADEXT Working Group chairs, David Nelson and Bernard Aboba,
 provided several draft reviews and we would like to thank them for
 the help and their patience.
 Finally, we would like to thank Dan Romascanu, Glen Zorn, Russ
 Housley, Jari Arkko, Ralph Droms, Adrial Farrel, Tim Polk, and Lars
 Eggert for the IETF Last Call comments; Derek Atkins for his security
 area directorate review; and Yoshiko Chong for spotting a bug in the
 IANA Considerations section.

Tschofenig, et al. Standards Track [Page 41] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

10. References

10.1. Normative References

 [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2865]     Rigney, C., Willens, S., Rubens, A., and W. Simpson,
               "Remote Authentication Dial In User Service (RADIUS)",
               RFC 2865, June 2000.
 [RFC3492]     Costello, A., "Punycode: A Bootstring encoding of
               Unicode for Internationalized Domain Names in
               Applications (IDNA)", RFC 3492, March 2003.
 [RFC3575]     Aboba, B., "IANA Considerations for RADIUS (Remote
               Authentication Dial In User Service)", RFC 3575,
               July 2003.
 [RFC3588]     Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and
               J. Arkko, "Diameter Base Protocol", RFC 3588,
               September 2003.
 [RFC3825]     Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
               Configuration Protocol Option for Coordinate-based
               Location Configuration Information", RFC 3825,
               July 2004.
 [RFC4776]     Schulzrinne, H., "Dynamic Host Configuration Protocol
               (DHCPv4 and DHCPv6) Option for Civic Addresses
               Configuration Information", RFC 4776, November 2006.
 [RFC5176]     Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
               Aboba, "Dynamic Authorization Extensions to Remote
               Authentication Dial In User Service (RADIUS)",
               RFC 5176, January 2008.
 [RFC5226]     Narten, T. and H. Alvestrand, "Guidelines for Writing
               an IANA Considerations Section in RFCs", BCP 26,
               RFC 5226, May 2008.

10.2. Informative References

 [GEO-POLICY]  Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar,
               J., and J. Polk, "Geolocation Policy: A Document Format
               for Expressing Privacy Preferences for  Location
               Information", Work in Progress, February 2009.

Tschofenig, et al. Standards Track [Page 42] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 [GMLv3]       "Open Geography Markup Language (GML) Implementation
               Specification", OGC 02-023r4, January 2003,
               <http://www.opengis.org/techno/implementation.htm>.
 [GSM]         "TADIG Naming Conventions", Version 4.1, GSM
               Association Official Document TD.13, June 2006.
 [ISO]         "Codes for the representation of names of countries and
               their subdivisions - Part 1: Country codes",
               ISO 3166-1, 1997.
 [ITU1400]     "Designations for interconnections among operators'
               networks", ITU-T Recommendation M.1400, January 2004.
 [ITU212]      "The international identification plan for mobile
               terminals and mobile users", ITU-T
               Recommendation E.212, May 2004.
 [PEAP]        Josefsson, S., Palekar, A., Simon, D., and G. Zorn,
               "Protected EAP Protocol (PEAP) Version 2", Work
               in Progress, October 2004.
 [RFC1305]     Mills, D., "Network Time Protocol (Version 3)
               Specification, Implementation", RFC 1305, March 1992.
 [RFC1994]     Simpson, W., "PPP Challenge Handshake Authentication
               Protocol (CHAP)", RFC 1994, August 1996.
 [RFC2866]     Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
 [RFC3579]     Aboba, B. and P. Calhoun, "RADIUS (Remote
               Authentication Dial In User Service) Support For
               Extensible Authentication Protocol (EAP)", RFC 3579,
               September 2003.
 [RFC3693]     Cuellar, J., Morris, J., Mulligan, D., Peterson, J.,
               and J. Polk, "Geopriv Requirements", RFC 3693,
               February 2004.
 [RFC4005]     Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
               "Diameter Network Access Server Application", RFC 4005,
               August 2005.
 [RFC4017]     Stanley, D., Walker, J., and B. Aboba, "Extensible
               Authentication Protocol (EAP) Method Requirements for
               Wireless LANs", RFC 4017, March 2005.

Tschofenig, et al. Standards Track [Page 43] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 [RFC4072]     Eronen, P., Hiller, T., and G. Zorn, "Diameter
               Extensible Authentication Protocol (EAP) Application",
               RFC 4072, August 2005.
 [RFC4119]     Peterson, J., "A Presence-based GEOPRIV Location Object
               Format", RFC 4119, December 2005.
 [RFC4187]     Arkko, J. and H. Haverinen, "Extensible Authentication
               Protocol Method for 3rd Generation Authentication and
               Key Agreement (EAP-AKA)", RFC 4187, January 2006.
 [RFC4282]     Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
               Network Access Identifier", RFC 4282, December 2005.
 [RFC4306]     Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
               RFC 4306, December 2005.
 [RFC4372]     Adrangi, F., Lior, A., Korhonen, J., and J. Loughney,
               "Chargeable User Identity", RFC 4372, January 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.
 [RFC4825]     Rosenberg, J., "The Extensible Markup Language (XML)
               Configuration Access Protocol (XCAP)", RFC 4825,
               May 2007.
 [RFC4941]     Narten, T., Draves, R., and S. Krishnan, "Privacy
               Extensions for Stateless Address Autoconfiguration in
               IPv6", RFC 4941, September 2007.
 [RFC5106]     Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba,
               Y., and F. Bersani, "The Extensible Authentication
               Protocol-Internet Key Exchange Protocol version 2 (EAP-
               IKEv2) Method", RFC 5106, February 2008.
 [RFC5281]     Funk, P. and S. Blake-Wilson, "Extensible
               Authentication Protocol Tunneled Transport Layer
               Security Authenticated Protocol Version 0 (EAP-
               TTLSv0)", RFC 5281, August 2008.

Tschofenig, et al. Standards Track [Page 44] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

Appendix A. Matching with GEOPRIV Requirements

 This section compares the requirements for a GEOPRIV using protocol,
 described in [RFC3693], against the approach of distributing Location
 Objects with RADIUS.
 In Appendices A.1 and A.2, we discuss privacy implications when
 RADIUS entities make location information available to other parties.
 In Appendix A.3, the requirements are matched against these two
 scenarios.

A.1. Distribution of Location Information at the User's Home Network

 When location information is conveyed from the RADIUS client to the
 RADIUS server, then it might subsequently be made available for
 different purposes.  This section discusses the privacy implications
 for making location information available to other entities.
 To use a more generic scenario, we assume that the visited RADIUS and
 the home RADIUS server belong to different administrative domains.
 The Location Recipient obtains location information about a
 particular Target via protocols specified outside the scope of this
 document (e.g., SIP, HTTP, or an API).
 The subsequent figure shows the interacting entities graphically.
 visited network    |        home network
                    |
                    |        +----------+
                    |        |  Rule    |
                    |        | Holder   |
                    |        +----+-----+
                    |             |
                    |         rule|interface
  +----------+      |             V                     +----------+
  |Location  |      |        +----------+  notification |Location  |
  |Generator |      |        |Location  |<------------->|Recipient |
  +----------+  publication  |Server    |  interface    |          |
  |RADIUS    |<------------->+----------+               +----------+
  |Client    |  interface    |RADIUS    | E.g., SIP/HTTP
  +----------+      |        |Server    |
                    |        +----------+
  E.g., NAS       RADIUS
                    |
                    |
             Figure 8: Location Server at the Home Network

Tschofenig, et al. Standards Track [Page 45] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 The term 'Rule Holder' in Figure 8 denotes the entity that creates
 the authorization ruleset.

A.2. Distribution of Location Information at the Visited Network

 This section describes a scenario where location information is made
 available to Location Recipients by a Location Server in the visited
 network.  Some identifier needs to be used as an index within the
 location database.  One possible identifier is the Network Access
 Identifier.  RFC 4282 [RFC4282] and RFC 4372 [RFC4372] provide
 background regarding whether entities in the visited network can
 obtain the user's NAI in cleartext.
 The visited network provides location information to a Location
 Recipient (e.g., via SIP or HTTP).  This document enables the NAS to
 obtain the user's privacy policy via the interaction with the RADIUS
 server.  Otherwise, only default policies, which are very
 restrictive, are available.  This allows the Location Server in the
 visited network to ensure they act according to the user's policies.
 The subsequent figure shows the interacting entities graphically.

Tschofenig, et al. Standards Track [Page 46] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

  visited network    |        home network
                     |
   +----------+      |
   |Location  |      |
   |Recipient |      |
   |          |      |
   +----------+      |
        ^            |        +----------+
        |            |        |  Rule    |
    notification     |        | Holder   |
     interface       |        |          |
        |            |        +----+-----+
        |            |             |
        |            |         rule|interface
        v            |             |
   +----------+      |             |
   |Location  |      |             v
   |Server    |      |        +----------+
   +----------+ Rule Transport|RADIUS    |
   |RADIUS    |<------------->|Server    |
   |Client    |   RADIUS      +----------+
   +----------+      |
   |Location  |      |
   |Generator |
   +----------+
           Figure 9: Location Server at the Visited Network
 Location information always travels with privacy policies.  This
 document enables the RADIUS client to obtain these policies.  The
 Location Server can subsequently act according to these policies to
 provide access control using the Extended-Location-Policy-Rules and
 to adhere to the privacy statements in the Basic-Location-Policy-
 Rules.

A.3. Requirements Matching

 Section 7.1 of [RFC3693] details the requirements of a "Location
 Object".  We discuss these requirements in the subsequent list.
 Req. 1.  (Location Object generalities):
  • Regarding requirement 1.1, the syntax and semantics of the

Location Object are taken from [RFC3825] and [RFC4776]. It is

       furthermore possible to convert it to the format used in the
       Geography Markup Language (GMLv3) [GMLv3], as used with PIDF-LO
       [RFC4119].

Tschofenig, et al. Standards Track [Page 47] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

  • Regarding requirement 1.2, a number of fields in the civic

location-information format are optional.

  • Regarding requirement 1.3, the inclusion of type of place item

(CAtype 29) used in the DHCP civic format gives a further

       classification of the location.  This attribute can be seen as
       an extension.
  • Regarding requirement 1.4, this document does not define the

format of the location information.

  • Regarding requirement 1.5, location information is only sent

from the RADIUS client to the RADIUS server.

  • Regarding requirement 1.6, the Location Object contains both

location information and privacy rules. Location information

       is described in Sections 4.2, 4.3.1, and 4.3.2.  The
       corresponding privacy rules are detailed in Sections 4.4 and
       4.5.
  • Regarding requirement 1.7, the Location Object is usable in a

variety of protocols. The format of the object is reused from

       other documents, as detailed in Sections 4.2, 4.3.1, 4.3.2,
       4.4, and 4.5.
  • Regarding requirement 1.8, the encoding of the Location Object

has an emphasis on a lightweight encoding format to be used

       with RADIUS.
 Req. 2.  (Location Object fields):
  • Regarding requirement 2.1, the target identifier is carried

within the network-access authentication protocol (e.g., within

       the EAP-Identity Response when EAP is used and/or within the
       EAP method itself).  As described in Section 7.2 of this
       document, it has a number of advantages if this identifier is
       not carried in clear.  This is possible with certain EAP
       methods whereby the identity in the EAP-Identity Response only
       contains information relevant for routing the response to the
       user's home network.  The user identity is protected by the
       authentication and key exchange protocol.
  • Regarding requirement 2.2, the Location Recipient is, in the

main scenario, the home RADIUS server. For a scenario where

       the Location Recipient is obtaining location information from
       the Location Server via HTTP or SIP, the respective mechanisms

Tschofenig, et al. Standards Track [Page 48] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

       defined in these protocols are used to identify the recipient.
       The Location Generator cannot, a priori, know the recipients if
       they are not defined in this protocol.
  • Regarding requirement 2.3, the credentials of the Location

Recipient are known to the RADIUS entities based on the

       security mechanisms defined in the RADIUS protocol itself.
       Section 7 of this document describes these security mechanisms
       offered by the RADIUS protocol.  The same is true for
       requirement 2.4.
  • Regarding requirement 2.5, Sections 4.2, 4.3.1, and 4.3.2

describe the content of the Location fields. Since the

       location format itself is not defined in this document, motion
       and direction vectors as listed in requirement 2.6 are not
       defined.
  • Regarding requirement 2.6, this document provides the

capability for the RADIUS server to indicate what type of

       location information it would like to see from the RADIUS
       client.
  • Regarding requirement 2.7, timing information is provided with

the 'Sighting Time' and 'Time-to-Live' fields defined in

       Section 4.2.
  • Regarding requirement 2.8, a reference to an external (more

detailed ruleset) is provided with the Extended-Location-

       Policy-Rules Attribute in Section 4.5.
  • Regarding requirement 2.9, security headers and trailers are

provided as part of the RADIUS protocol or even as part of

       IPsec.
  • Regarding requirement 2.10, a version number in RADIUS is

provided with the IANA registration of the attributes. New

       attributes are assigned a new IANA number.
 Req. 3.  (Location Data Types):
  • Regarding requirement 3.1, this document reuses civic and

geospatial location information as described in Sections 4.3.2

       and 4.3.1.
  • With the support of civic and geospatial location information,

support of requirement 3.2 is fulfilled.

Tschofenig, et al. Standards Track [Page 49] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

  • Regarding requirement 3.3, the geospatial location information

used by this document only refers to absolute coordinates.

       However, the granularity of the location information can be
       reduced with the help of the AltRes, LoRes, and LaRes fields
       described in [RFC3825].
  • Regarding requirement 3.4, further Location Data Types can be

added via new coordinate reference systems (CRSs – see the

       Datum field in [RFC3825]) and via extensions to [RFC3825] and
       [RFC4776].
 Section 7.2 of [RFC3693] details the requirements of a "using
 protocol".  These requirements are listed below.
 Req. 4.:  The using protocol has to obey the privacy and security
    instructions coded in the Location Object (LO) regarding the
    transmission and storage of the LO.  This document requires that
    entities that aim to make location information available to third
    parties be required to obey the privacy instructions.
 Req. 5.:  The using protocol will typically facilitate that the keys
    associated with the credentials are transported to the respective
    parties, that is, key establishment is the responsibility of the
    using protocol.  Section 7 of this document specifies how security
    mechanisms are used in RADIUS and how they can be reused to
    provide security protection for the Location Object.
    Additionally, the privacy considerations (see Section 7.2) are
    also relevant for this requirement.
 Req. 6.  (Single Message Transfer):  In particular, for tracking of
    small target devices, the design should allow a single message/
    packet transmission of location as a complete transaction.  The
    encoding of the Location Object is specifically tailored towards
    the inclusion into a single message that even respects the (Path)
    MTU size.
 Section 7.3 of [RFC3693] details the requirements of a "Rule-based
 Location Data Transfer".  These requirements are listed below.
 Req. 7.  (LS Rules):  With the scenario shown in Figure 8, the
    decision of a Location Server to provide a Location Recipient
    access to location information is based on Rule Maker-defined
    privacy rules that are stored at the home network.  With regard to
    the scenario shown in Figure 9, the Rule Maker-defined privacy
    rules are sent from the RADIUS server to the NAS (see Sections
    4.4, 4.5, and 7.2 for more details).

Tschofenig, et al. Standards Track [Page 50] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Req. 8.  (LG Rules):  For all usage scenarios, it is possible to
    consider the privacy rule before transmitting location information
    from the NAS to the RADIUS server or even to third parties.  In
    the case of an out-of-band agreement between the owner of the NAS
    and the owner of the RADIUS server, privacy might be applied on a
    higher granularity.  For the scenario shown in Figure 8, the
    visited network is already in possession of the user's location
    information prior to the authentication and authorization of the
    user.  A correlation between the location and the user identity
    might, however, still not be possible for the visited network (as
    explained in Section 7.2).  A Location Server in the visited
    network has to evaluate available rulesets.
 Req. 9.  (Viewer Rules):  The Rule Maker might define (via mechanisms
    outside the scope of this document) which policy rules are
    disclosed to other entities.
 Req. 10.  (Full Rule language):  GEOPRIV has defined a rule language
    capable of expressing a wide range of privacy rules that is
    applicable in the area of the distribution of Location Objects.  A
    basic ruleset is provided with the Basic-Location-Policy-Rules
    Attribute (Section 4.4).  A reference to the extended ruleset is
    carried in Section 4.5.  The format of these rules is described in
    [RFC4745] and [GEO-POLICY].
 Req. 11.  (Limited Rule language):  A limited (or basic) ruleset is
    provided by the Policy-Information Attribute in Section 4.4 (and
    as introduced with PIDF-LO [RFC4119]).
 Section 7.4 of [RFC3693] details the requirements of a "Location
 Object Privacy and Security".  These requirements are listed below.
 Req. 12 (Identity Protection):  Support for unlinkable pseudonyms is
    provided by the usage of a corresponding authentication and key-
    exchange protocol.  Such protocols are available, for example,
    with the support of EAP as network-access authentication methods.
    Some EAP methods support passive user-identity confidentiality,
    whereas others even support active user-identity confidentiality.
    This issue is further discussed in Section 7.  The importance for
    user-identity confidentiality and identity protection has already
    been recognized as an important property (see, for example, a
    document on EAP method requirements for wireless LANs [RFC4017]).
 Req. 13.  (Credential Requirements):  As described in Section 7 ,
    RADIUS signaling messages can be protected with IPsec.  This
    allows a number of authentication and key exchange protocols to be
    used as part of IKE, IKEv2, or KINK.

Tschofenig, et al. Standards Track [Page 51] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

 Req. 14.  (Security Features):  GEOPRIV defines a few security
    requirements for the protection of Location Objects, such as
    mutual end-point authentication, data object integrity, data
    object confidentiality, and replay protection.  As described in
    Section 7, these requirements are fulfilled with the usage of
    IPsec if mutual authentication refers to the RADIUS entities
    (acting as various GEOPRIV entities) that directly communicate
    with each other.
 Req. 15.  (Minimal Crypto):  A minimum of security mechanisms are
    mandated by the usage of RADIUS.  Communication security for
    Location Objects between RADIUS infrastructure elements is
    provided by the RADIUS protocol (including IPsec and its dynamic
    key-management framework), rather than relying on object security
    via S/SIME (which is not available with RADIUS).

Tschofenig, et al. Standards Track [Page 52] RFC 5580 Carrying LOs in RADIUS and Diameter August 2009

Authors' Addresses

 Hannes Tschofenig (editor)
 Nokia Siemens Networks
 Linnoitustie 6
 Espoo  02600
 Finland
 Phone: +358 (50) 4871445
 EMail: Hannes.Tschofenig@gmx.net
 URI:   http://www.tschofenig.priv.at
 Farid Adrangi
 Intel Corporatation
 2111 N.E. 25th Avenue
 Hillsboro OR
 USA
 EMail: farid.adrangi@intel.com
 Mark Jones
 Bridgewater Systems Corporation
 303 Terry Fox Drive
 Ottawa, Ontario  K2K 3J1
 CANADA
 EMail: mark.jones@bridgewatersystems.com
 Avi Lior
 Bridgewater Systems Corporation
 303 Terry Fox Drive
 Ottawa, Ontario  K2K 3J1
 CANADA
 EMail: avi@bridgewatersystems.com
 Bernard Aboba
 Microsoft Corporation
 One Microsoft Way
 Redmond, WA  98052
 USA
 EMail: bernarda@microsoft.com

Tschofenig, et al. Standards Track [Page 53]

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