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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
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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
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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].
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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.) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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
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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
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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.
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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.
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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.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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'.
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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.
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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.
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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'.
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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].
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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].
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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
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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.
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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]
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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]
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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]
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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.
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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]
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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]
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+----------+----------------------+
| 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
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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].
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* 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
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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.
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* 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).
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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.
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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).
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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]