GEOPRIV H. Tschofenig, Ed.
Internet-Draft Nokia Siemens Networks
Intended status: Standards Track F. Adrangi
Expires: January 5, 2008 Intel
M. Jones
A. Lior
Bridgewater
July 4, 2007
Carrying Location Objects in RADIUS and Diameter
draft-ietf-geopriv-radius-lo-14.txt
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Abstract
This document describes procedures for conveying access network
ownership and location information based on a civic and geospatial
location format 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 addressed in this document.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Delivery Methods for Location Information . . . . . . . . . . 6
3.1. Location Delivery based on Out-of-Band Agreements . . . . 6
3.2. Location Delivery based on Initial Request . . . . . . . . 7
3.3. Location Delivery based on Mid-Session Request . . . . . . 9
3.4. Location Delivery in Accounting Messages . . . . . . . . . 11
4. Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1. Operator-Name Attribute . . . . . . . . . . . . . . . . . 13
4.2. Location-Information Attribute . . . . . . . . . . . . . . 16
4.3. Location Data Attribute . . . . . . . . . . . . . . . . . 18
4.3.1. Civic Location Profile . . . . . . . . . . . . . . . . 20
4.3.2. Geospatial Location Profile . . . . . . . . . . . . . 20
4.4. Basic Policy Rules Attribute . . . . . . . . . . . . . . . 20
4.5. Extended Policy Rules Attribute . . . . . . . . . . . . . 22
4.6. Location-Capable Attribute . . . . . . . . . . . . . . . . 24
4.7. Requested-Info Attribute . . . . . . . . . . . . . . . . . 25
5. Table of Attributes . . . . . . . . . . . . . . . . . . . . . 32
6. Diameter RADIUS Interoperability . . . . . . . . . . . . . . . 33
7. Security Considerations . . . . . . . . . . . . . . . . . . . 34
7.1. Communication Security . . . . . . . . . . . . . . . . . . 34
7.2. Privacy Considerations . . . . . . . . . . . . . . . . . . 35
7.2.1. RADIUS Client . . . . . . . . . . . . . . . . . . . . 36
7.2.2. RADIUS Server . . . . . . . . . . . . . . . . . . . . 36
7.2.3. RADIUS Proxy . . . . . . . . . . . . . . . . . . . . . 37
7.3. Identity Information and Location Information . . . . . . 37
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
8.1. New Registry: Operator Namespace Identifier . . . . . . . 39
8.2. New Registry: Location Profiles . . . . . . . . . . . . . 40
8.3. New Registry: Location Capable Attribute . . . . . . . . . 41
8.4. New Registry: Entity Types . . . . . . . . . . . . . . . . 41
8.5. New Registry: Privacy Flags . . . . . . . . . . . . . . . 42
8.6. New Registry: Requested-Info Attribute . . . . . . . . . . 42
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 44
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 46
10.1. Normative References . . . . . . . . . . . . . . . . . . . 46
10.2. Informative References . . . . . . . . . . . . . . . . . . 46
Appendix A. Matching with Geopriv Requirements . . . . . . . . . 49
A.1. Distribution of Location Information at the User's
Home Network . . . . . . . . . . . . . . . . . . . . . . . 49
A.2. Distribution of Location Information at the Visited
Network . . . . . . . . . . . . . . . . . . . . . . . . . 50
A.3. Requirements matching . . . . . . . . . . . . . . . . . . 51
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 57
Intellectual Property and Copyright Statements . . . . . . . . . . 58
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1. Introduction
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. The proposed attributes are also applicable to
other situations (such as wired networks) where operator network
ownership and location information has to be conveyed to the RADIUS
server.
In the case when the home network needs to know the location of the
user then, when a user executes the network access authentication
procedure, information about the location and ownership of the
visited network needs to be conveyed to the user's home network. The
main intent of this document is to enable location aware billing
(e.g., by determining the appropriate tariff and taxation in
dependence of the location of the access network and the end host),
location aware subscriber authentication and authorization for
roaming environments and to enable other location aware services.
This document describes attributes to convey location-related
information both within authentication and accounting exchanges.
These attributes are usable both within RADIUS and Diameter.
Location information needs to be protected against unauthorized
access and distribution to preserve the user's privacy. [10] defines
requirements for a protocol-independent model for the access to
geographic location information. 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 are
compared to the functionality provided by this document.
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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 [1].
RADIUS specific terminology is borrowed from [2] and [11].
Terminology related to privacy issues, location information and
authorization policy rules is taken from [10].
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3. Delivery Methods for Location Information
The following exchanges show how location information is conveyed in
RADIUS. Note that the description of the individual scenarios
assumes that privacy policies allow location conveyed in RADIUS;
however the exchanges are also applicableto Diameter, as noted in
Section 6. A discussion about the privacy treatment is provided in
Section 7.2.
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. For
example, in deployment environments where the RADIUS client and the
RADIUS server belong to the same organizational entity. The Basic-
Policy-Rules attribute is populated based on the defaults described
in Section 4.4, unless it has been explicitly configured otherwise.
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+---------+ +---------+ +---------+
| | | Network | | RADIUS |
| User | | Access | | Server |
| | | Server | | |
+---------+ +---------+ +---------+
| | |
| Authentication phase | |
| begin | |
|---------------------->| |
| | |
| | RADIUS |
| | Access-Request |
| | + Location-Information |
| | + Location-Data |
| | + Basic-Policy-Rules |
| | + Operator-Name |
| |----------------------------->|
| | |
| | RADIUS |
| | Access-Accept |
| |<-----------------------------|
| Authentication | |
| Success | |
|<----------------------| |
| | |
Figure 1: Location Delivery based on out-of-band Agreements
3.2. Location Delivery based on Initial Request
If no location information is provided by the RADIUS client although
it is needed by the RADIUS server to compute the authorization
decision then, if the Location-Capable attribute is included in the
Access-Request message, then the RADIUS server MAY challenge the
RADIUS client. This exchange is shown in Figure 2. The inclusion of
the Location-Capable attribute in an Access-Request message indicates
that the NAS supports this specification and is capable of providing
location 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 treates the Basic-Policy-Rules and Extended-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 receiving 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.
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+---------+ +---------+ +---------+
| | | Network | | RADIUS |
| User | | Access | | Server |
| | | Server | | |
+---------+ +---------+ +---------+
| | |
| Authentication phase | |
| begin | |
|---------------------->| |
| | |
| | RADIUS |
| | Access-Request |
| | + Location-Capable |
| |----------------------------->|
| | |
| | RADIUS |
| | Access-Challenge |
| | + Basic-Policy-Rules |
| | + Extended-Policy-Rules |
| | + Requested-Info |
| |<-----------------------------|
| | |
| | RADIUS |
| | Access-Request |
| | + Location-Information |
| | + Location-Data |
| | + Basic-Policy-Rules |
| | + Extended-Policy-Rules |
| |----------------------------->|
| | |
: : :
: Multiple Protocol Exchanges to perform :
: Authentication, Key Exchange and Authorization :
: ...continued... :
: : :
| | |
| | RADIUS |
| | Access-Accept |
| |<-----------------------------|
| Authentication | |
| Success | |
|<----------------------| |
| | |
Figure 2: Location Delivery based on Initial Request
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3.3. Location Delivery based on Mid-Session Request
The on demand mid-session location delivery method utilizes the
Change of Authorization (COA) message, as defined in [12]. At any
time during the session the Dynamic Authorization Client MAY send a
COA message containing session identification attributes to the
RADIUS client (i.e., Dynamic Authorization Server). By including a
Service-Type attribute with a value of "Authorize Only" a CoA-Request
may instruct the NAS to generate an Access-Request containing a
Service-Type attribute with value "Authorize Only" in which case the
RADIUS client MUST include location information in this Access-
Request if the Requested-Info attribute included in the Access-Accept
included the flag setting 'FUTURE_REQUESTS'. This also implies the
echoing of the Basic-Policy-Rules and Extended-Policy-Rules
attributes received in the previous Access-Accept within the Access-
Request sent in response to the CoA-Request.
Figure 3 shows the approach graphically.
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+---------------+ +---------------+
| Dynamic | | Dynamic |
| Authorization | | Authorization |
| Server | | Client |
+---------------+ +---------------+
| |
| |
: :
: Initial Protocol Interaction :
: (details omitted) :
: :
| |
| Access-Accept |
| + Requested-Info (FUTURE_REQUESTS) |
| + Basic-Policy-Rules |
| + Extended-Policy-Rules |
|<----------------------------------------------|
| |
: :
: <<Some time later>> :
: :
| |
| COA + Service-Type "Authorize Only" |
|<----------------------------------------------|
| |
| COA NAK + Service-Type "Authorize Only" |
| + Error-Cause "Request Initiated" |
|---------------------------------------------->|
| |
| Access-Request + Service-Type "Authorize Only"|
| + Location-Information |
| + Location-Data |
| + Basic-Policy-Rules |
| + Extended-Policy-Rules |
|---------------------------------------------->|
| |
| Access-Accept |
|<----------------------------------------------|
| |
Figure 3: Location Delivery based on Mid-Session Request
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.
RFC 3576 [3] is needed when location information is requested on
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demand and location information cannot be obtained from accounting
messages at all or not in a timely fashion.
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-Info
attribute to the Access-Accept message. The Basic-Policy-Rules and
the Extended-Policy-Rules attributes are to be echoed in the
Accounting-Request if indicated in the Access-Accept.
Figure 4 shows the message exchange.
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+---------+ +---------+ +---------+
| | | Network | | RADIUS |
| User | | Access | | Server |
| | | Server | | |
+---------+ +---------+ +---------+
| | |
: : :
: Initial Protocol Interaction :
: (details omitted) :
: : :
| | |
| | RADIUS |
| | Access-Accept |
| | + Requested-Info |
| | + Basic-Policy-Rules |
| | + Extended-Policy-Rules |
| |<-----------------------------|
| Authentication | |
| Success | |
|<----------------------| |
| | |
| | RADIUS |
| | Accounting-Request |
| | + Location-Information |
| | + Location-Data |
| | + Basic-Policy-Rules |
| | + Extended-Policy-Rules |
| |----------------------------->|
| | |
| | RADIUS |
| | Accounting-Response |
| |<-----------------------------|
| | |
Figure 4: Location Delivery in Accounting Messages
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4. Attributes
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 string 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.
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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:
To Be Assigned by IANA - Operator-Name
Length:
>= 5
Text:
This field is at least two octets in length, and the format
is shown below. The data type of this field is 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 ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Namespace ID:
The value within this field contains the
operator namespace identifier. The Namespace ID value
is encoded in ASCII.
Example: 1 for REALM
Operator-Name:
The text field of variable length contains an
Access Network Operator Name.
This field is a RADIUS base data type of Text.
Example: anyisp.example.com
The Namespace ID field provides information about the operator
namespace. This document defines four values for this attribute that
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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):
This namespace can be used to indicate operator names based on
Transferred Account Data Interchange Group (TADIG) codes defined
in [13]. TADIG codes are assigned by the TADIG Working Group
within the 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):
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 which contains non-
ASCII characters must be encoded. To encode a domain name, first
ensure that any non-ASCII characters are in Unicode [14], then
apply the toAscii operation from RFC 3490 [4] to each label, then
re-assemble the encoded labels into a FQDN.
E212 (2):
The E212 namespace can be used to indicate operator names based on
the Mobile Country Code (MCC) and Mobile Network Code (MNC)
defined in [15]. The MCC/MCC values are assigned by the
Telecommunications Standardization Bureau (TSB) within the ITU-T
and 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):
The ICC namespace can be used to indicate operator names based on
International Telecommunication Union (ITU) Carrier Codes (ICC)
defined in [16]. 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
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attribute consists of three uppercase ASCII characters containing
a three-letter alphabetic country code as defined in [17],
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 Access-Request and
in Accounting-Request messages. 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. Implementations SHOULD treat this
attribute as undistinguished octets, like the Location-Data attribute
to which it refers.
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:
To Be Assigned by IANA - Location-Information
Length:
>= 21
String:
This field is at least two octets in length, and the format
is shown below. The data type of this field is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Index | Code | Entity |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sighting Time ~
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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):
Describes the location profile that is carried in this attribute
as an unsigned 8-bit integer value.
Entity (8 bits):
This field encodes which location this attribute refers to as an
unsigned 8-bit integer value.
Sighting Time (64 bits):
NTP timestamp for the 'sighting time' field.
Time-to-Live (64 bits):
NTP timestamp for the 'time-to-live' field.
Method (variable):
Describes the way that the location information was
determined. The values are registered with the 'method' Tokens
registry by RFC 4119. The data type of this
field is a string.
The following fields need more explanation:
sighting time:
This field indicates when the Location Information was accurate.
The data type of this field is a string and and the content is
expressed in the 64 bit Network Time Protocol (NTP) timestamp
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format [18].
time-to-live:
This field gives a hint until when 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 [18]. Note that the time-to-live field is
different than Retention Expires field used in the Basic Policy
Rules attribute, see Section 4.4. Retention expires indicates the
time the recipient is no longer permitted to possess the location
information.
Entity:
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.
Code:
This field indicates the content of the location profile carried
in the Location-Data attribute. Two profiles are defined in this
document, namely one 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).
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 in
Accounting-Request messages. For the Accounting-Request message the
Acc-Status-Type may be set to Start, Interim or Stop.
Implementations SHOULD treat this attribute as undistinguished
octets.
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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:
To Be Assigned by IANA - Location-Data
Length:
>= 21
String:
Thhis field is at least two octets in length, and the format
is shown below. The data type of this field is 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 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 is described below.
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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 [5] whereby the first 3
octets (i.e., the code for this DHCP option, the length of the DHCP
option, and the 'what' element are not included) are not put into the
Location field of the above-described RADIUS Location-Data attribute.
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 whereby the format is reused from the
Section 2 of RFC 3825 Location Configuration Information (LCI) format
[6]. starting with starting with the third octet (i.e., the code for
the DHCP option and the length field is not included).
4.4. Basic Policy Rules Attribute
The Basic-Policy-Rules attribute MAY be sent in an an Access-Request,
Access-Accept, an Access-Challenge, an Access-Reject and an
Accounting-Request message.
Policy rules control the distribution of location information. The
obligation with respect to understanding and processing of the Basic
Policy Rules attribute for RADIUS clients is to utilize a default
value of Basic-Policy-Rules unless explicitly configured otherwise,
and also for clients to echo the Basic-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 [19] and encodes them 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 [10],
Section 2.7.
The format of the Basic-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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | String ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| String (cont.) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type:
To Be Assigned by IANA - Basic-Policy-Rules
Length:
>= 12
String:
This field is at least 8 octets in length, and the format
is shown below. The data type of this field is 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 ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Flag (16 bits):
Only the first bit (R) is defined and corresponds to the
retransmission-allowed field. All other bits are reserved
and MUST be zero.
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|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The symbol 'o' refers to reserved flags.
Retention Expires (64 bits):
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NTP timestamp for the 'retention-expires' field.
Note Well (variable):
This field contains a URI that points to human readable
privacy instructions. The data type of this field is string.
This document reuses fields of the RFC 4119 [19] 'usage-rules'
element. These fields have the following meaning:
retransmission-allowed:
When the value of this field is 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 to share the location
information with other parties by considering the extended policy
rules.
retention-expires:
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 [18].
note-well:
This field contains a URI that points to human readable privacy
instructions. 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 eco-system 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 document (see [19]).
4.5. Extended Policy Rules Attribute
The Extended-Policy-Rules attribute MAY be sent in an Access-Request,
an Access-Accept, an Access-Challenge, an Access-Reject and in an
Accounting-Request message whenever location information is
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transmitted.
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 [19] this field only contains a reference and does not carry an
attached extended rule set. This modification is motivated by the
size limitations imposed by RADIUS.
Policy rules control the distribution of location information and, as
with the Basic Policy Rules attribute the obligation with respect to
understanding and processing of the Extended Policy Rules attribute
for RADIUS clients is when they are explicitly configured to attach
the URI, and also for clients to echo the Extended-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 and to parse the XML policies.
The format of the Extended-Policy-Rules attribute is shown below.
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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:
To Be Assigned by IANA - Extended-Policy-Rules
Length:
>= 4
String:
This field is at least two octets in length, and the format
is shown below. The data type of this field is 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 a 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 SHOULD NOT
challenge for location information unless the Location-Capable
attribute has been sent to it.
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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:
To Be Assigned by IANA - Location-Capable Attribute
Length:
6
Integer:
This field is a 32-bit integer value.
Only a single value is defined for this field:
Value | Semantic
----------+-----------------
1 | Location Capable
Other bit positions are available via IANA
registration.
4.7. Requested-Info Attribute
The Requested-Info attribute allows the RADIUS server to indicate
what 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-Info attribute MAY be sent in an an Access-Accept or in
an Access-Challenge 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.
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-Info
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attribute is attached to the Access-Challenge with a hint about
what is required. Two cases can be differentiated:
1. If the RADIUS client sends the requested information then the
RADIUS server can process the location-based attributes.
2. If the RADIUS server does not receive the requested
information in response to the Access-Challenge (including the
Requested-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-Info attribute then
the RADIUS client MUST NOT attach location information to messages
towards the RADIUS server, unless an out-of-band agreement is in
place. The user's authorization policies, if available, MUST be
consulted by the RADIUS server before requesting location information
delivery from the RADIUS client.
Figure 11 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-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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+---------+ +---------+
| RADIUS | | RADIUS |
| Client | | Server |
+---------+ +---------+
| |
| |
| RADIUS |
| Access-Request |
| + Location-Capable |
|----------------------------->|
| |
| RADIUS |
| Access-Challenge |
| + Requested-Info |
| ('CIVIC_LOCATION', |
| 'USERS_LOCATION') |
| + Basic-Policy-Rules |
| + Extended-Policy-Rules |
|<-----------------------------|
| |
| RADIUS |
| Access-Request |
| + Location-Information |
| + Location-Data |
| + Basic-Policy-Rules |
| + Extended-Policy-Rules |
|----------------------------->|
| |
| .... |
Figure 11: RADIUS server requesting location information
The Requested-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-Info attribute MAY appear in the Access-
Accept or in the Access-Challenge message.
A summary of the attribute is shown below.
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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:
To Be Assigned by IANA - Requested-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 this attribute to request information from
the RADIUS client to be returned. 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 attribute is '1'.
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Name:
GEO_LOCATION
Description:
The RADIUS server uses this attribute to request information from
the RADIUS client to be returned. 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 attribute is '2'.
Name:
USERS_LOCATION
Description:
The numerical value representing USERS_LOCATION indicates that the
RADIUS client must sent a Location-Information attribute with the
Entity attribute expressing the value of zero (0). Hence, there
is a one-to-one relationship between 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 attribute is '4'.
Name:
NAS_LOCATION
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Description:
The numerical value representing NAS_LOCATION indicates that the
RADIUS client must sent 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 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 attribute is '8'.
Name:
FUTURE_REQUESTS
Description:
The numerical value representing FUTURE_REQUESTS indicates that
the RADIUS client MUST provide future Access-Requests with the
same information as returned in the initial Access-Request
message.
Numerical Value:
A numerical value of this attribute is '16'.
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-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 via GEO_LOCATION.
As an example, if the bits for NAS_LOCATION, USERS_LOCATION and
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GEO_LOCATION are set then location information of the RADIUS client
and the users' client device are returned in a geospatial location
format.
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5. Table of Attributes
The following table provides a guide which attributes may be found in
which RADIUS messages, and in what quantity.
Request Accept Reject Challenge Accounting # Attribute
Request
0-1 0 0 0 0-1 TBD Operator-Name
0+ 0 0 0 0+ TBD Location-Information
0+ 0 0 0 0+ TBD Location-Data
0-1 0-1 0-1 0-1 0-1 TBD Basic-Policy-Rules
0-1 0-1 0-1 0-1 0-1 TBD Extended-Policy-Rules
0 0-1 0 0-1 0 TBD Requested-Info
0-1 0 0 0 0 TBD Location-Capable
0 0 0-1 0 0 101 Error-Cause [note1]
[note1] The Error-Cause attribute contains the value for the
'Location-Info-Required' error.
The following table defines the meaning of the above table entries.
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 13: Table of Attributes
The Error-Cause attribute is defined in [3].
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 onces listed in Figure 13.
This document requests IANA to allocate a new value from the Error-
Cause registry with the semantic 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 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 for the
attributes are as follows:
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
| | |SHLD| MUST| |
Attribute Name Value Type |MUST| MAY | NOT| NOT|Encr|
----------------------------------|----+-----+----+-----|----|
Operator-Name OctetString| | P,M | | V | Y |
Location-Information OctetString| M | P | | V | Y |
Location-Data OctetString| M | P | | V | Y |
Basic-Policy-Rules OctetString| M | P | | V | Y |
Extended-Policy-Rules OctetString| M | P | | V | Y |
Requested-Info OctetString| M | P | | V | Y |
Location-Capable OctetString| | P,M | | V | Y |
----------------------------------|----+-----+----+-----|----|
The 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 [7] and Section 9 of
[20].
What this specification says about the applicability of the
attributes for RADIUS Access-Request packets applies in Diameter to
AA-Request [20] or Diameter-EAP-Request [21]. What is said about
Access-Challenge applies in Diameter to AA-Answer [20] or Diameter-
EAP-Answer [21] with 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
[20].
What is said about Accounting-Request applies to Diameter Accounting-
Request [20] as well.
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7. Security Considerations
A number of security aspects are relevant for the distribution of
location information via RADIUS. These aspects are discussed in
separate sub-sections.
7.1. Communication Security
Requirements for the protection of a Location Object are defined in
[10], 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 [2] proposes the usage of a static key that raised concerns
regarding the lack dynamic key management. At the time of
writing, work is ongoing to address some shortcomings of [2]
attribute security protection.
o RADIUS over IPsec [22] enables the use of standard key management
mechanisms, such as KINK, IKE and IKEv2 [23], to establish IPsec
security associations. Confidentiality protection MUST be used to
prevent eavesdropper gaining access to location information.
Confidentiality protection is not only a property required by this
document, it is also required for the transport of keying material
in the context of 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 suggested as a mechanism to protect RADIUS already
no additional considerations need to be addressed beyond those
described in [22].
In case that 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.
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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, including Location attribute(s) without a Message-
Authenticator(80) attribute SHOULD be silently discarded by the NAS.
A 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 neither RADIUS nor 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 [24].
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
location of the user with a certain degree of precision depending on
the location determination mechanism used, update frequency, the size
of the network and other factors, such as movement traces.
Three types of use cases have to be differentiated:
o 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
then location information may be sent without an explicit request
from the RADIUS server.
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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-Policy-Rules and Extended-
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-
Policy-Rules and Extended-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 Basic-Policy-Rules or Extended-Policy-Rules
attributes received in a previous Access-Accept if the
FUTURE_REQUESTS flag was set in the Requested-Info attribute.
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 then there
might be a strong desire to use location information for other
purposes as well.
The Common Policy framework [25] that was extended for geolocation
privacy [26] are tailored for this purpose. The Extensible Markup
Language (XML) Configuration Access Protocol (XCAP) [27] 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:
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o The RADIUS server MUST attach available rules to the Access-
Accept, the Access-Reject or the 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 latter 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 Section 7.2.1 and
Section 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 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 MAC address, or base its IP
address on such an address. This enables the correlation of the
particular device to its different locations. Techniques exist to
avoid the use of an IP address that is based on MAC address [28].
Some link layers make it possible to avoid MAC addresses or change
them dynamically.
o Network access authentication procedures, such as PPP CHAP [29] or
EAP [24], 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) in the EAP Identity Response message [30] and
by method-specific private identity exchange in the EAP method
(e.g., [30], [31] [32], [33]). Support for identity privacy
within CHAP is not available.
o RADIUS may return information from the home network to the visited
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 [2] or in some accounting
attribute usage scenarios [34].
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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, by 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 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.
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8. IANA Considerations
The authors request that the Attribute Types, and Attribute Values
defined in this document be registered by the Internet Assigned
Numbers Authority (IANA) from the RADIUS name spaces as described in
the "IANA Considerations" section of RFC 3575 [8], in accordance with
BCP 26 [9]. Additionally, the Attribute Type should be registered in
the Diameter name space. For RADIUS attributes and registries
created by this document IANA is requested to place them at
http://www.iana.org/assignments/radius-types.
This document defines the following attributes:
Operator-Name
Location-Information
Location-Data
Basic-Policy-Rules
Extended-Policy-Rules
Location-Capable
Requested-Info
Please refer to Section 5 for the registered list of numbers.
This document also instructs IANA to assign a new value for the
Error-Cause attribute [3], of "Location-Info-Required" TBA.
Additionally, IANA is requested to create 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 nor to place any values within namespaces.
IANA is requested to add 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.
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+----------+--------------------+------------------------------------+
|Identifier| Operator Namespace | Contact Person |
| | Token | |
+----------+--------------------+------------------------------------+
| 48 | TADIG | TD.13 Coordinator |
| | | (td13@gsm.org) |
| 49 | REALM | IETF O&M Area Directors |
| | | (ops-chairs@ietf.org) |
| 50 | E212 | ITU Director |
| | | (tsbdir@itu.int) |
| 51 | ICC | ITU Director |
| | | (tsbdir@itu.int) |
+----------+--------------------+------------------------------------+
Note that the above identifier values represent the ASCII value '0'
(decimal 48), '1' (decimal 49), '2' (decimal 50) and '3' (decimal
51). This encoding was chosen to simplify parsing.
Requests to IANA for a new value for a Namespace ID will be approved
by Expert Review. The Designated Expert Reviewer team for these
requests is the current Operations Area Director and the RADEXT
working group chairs or the working group chairs of a designated
successor working group.
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 an Namespace ID because one
is already up and running, or whether the REALM identifier plus the
name should 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, when 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 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.
Following the policies outline in [8] the available bits with a
description of their semantic will be assigned after Expert Review
initiated by the O&M Area Directors in consultation with the RADEXT
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working group chairs or the working group chairs of a designated
successor working group. Updates can be provided based on expert
approval only. A designated expert will be appointed by the O&M Area
Directors. No mechanism to mark entries as "deprecated" is
envisioned. Based on expert approval it is possible to delete
entries from the registry.
Each registration must include the value and the corresponding
semantic 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 whereby a single bit, bit (0),
indicating 'Location Capable' is defined by this document. Bits 1-15
are reserved for future use.
Following the policies outline in [8] the available bits with a
description of their semantic will be assigned after Expert Review
initiated by the O&M Area Directors in consultation with the RADEXT
working group chairs or the working group chairs of a designated
successor working group. Updates can be provided based on expert
approval only. A designated expert will be appointed by the O&M Area
Directors. No mechanism to mark entries as "deprecated" is
envisioned. Based on expert approval it is possible to delete
entries from the registry.
Each registration must include the bit position and the semantic of
the bit.
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 outline in [8] the available bits with a
description of their semantic will be assigned after Expert Review
initiated by the O&M Area Directors in consultation with the RADEXT
working group chairs or the working group chairs of a designated
successor working group. Updates can be provided based on expert
approval only. A designated expert will be appointed by the O&M Area
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Directors. No mechanism to mark entries as "deprecated" is
envisioned. Based on expert approval it is possible to delete
entries from the registry.
Each registration must include the value and a corresponding
description.
8.5. New Registry: Privacy Flags
Section 4.4 defines the Basic Policy Rules attribute that contains
flags indicating privacy settings. 16 bits are available whereby 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 [8] the available bits with a
description of their semantic will be assigned after Expert Review
initiated by the O&M Area Directors in consultation with the RADEXT
working group chairs or the working group chairs of a designated
successor working group. Updates can be provided based on expert
approval only. A designated expert will be appointed by the O&M Area
Directors. No mechanism to mark entries as "deprecated" is
envisioned. Based on expert approval it is possible to delete
entries from the registry.
Each registration must include the bit position and the semantic of
the bit.
8.6. New Registry: Requested-Info Attribute
Section 4.7 defines the Requested-Info attribute that contains a bit
map. 32 bits are available whereby a 5 bits are defined by this
document. This document creates a new IANA registry for the
Requested-Info attribute. IANA is requested to add the following
values to this registry:
+----------+----------------------+
| Value | Capability Token |
+----------+----------------------+
| 1 | CIVIC_LOCATION |
| 2 | GEO_LOCATION |
| 4 | USERS_LOCATION |
| 8 | NAS_LOCATION |
| 16 | FUTURE_REQUESTS |
+----------+----------------------+
The semantic of these values is defined in Section 4.7.
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Following the policies outline in [8] new Capability Tokens with a
description of their semantic for usage with the Requested-Info
attribute will be assigned after Expert Review initiated by the O&M
Area Directors in consultation with the RADEXT working group chairs
or the working group chairs of a designated successor working group.
Updates can be provided based on expert approval only. A designated
expert will be appointed by the O&M Area Directors. No mechanism to
mark entries as "deprecated" is envisioned. Based on expert approval
it is possible to delete entries from the registry.
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-Info
attribute.
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9. Acknowledgments
The authors would like to thank the following people for their help
with an initial version of this draft 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.
Henning Schulzrinne provided the civic location information content
found in this draft. 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, 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 draft. We would like to thank
Jari Arkko for his text contributions. Lionel Morand provided
detailed feedback on numerous issues. His comments helped to improve
the quality of this document. Jouni Korhonen and John Loughney
helped us with the Diameter RADIUS interoperability. Andreas
Pashalidis reviewed a later version document and provided a number of
comments. Bernard Aboba, Alan DeKok, Lionel Morand, Jouni Korhonen,
David Nelson and Emile van Bergen provided guidance on the Requested-
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, Jon Peterson for their time to discuss a number
of issues with us. We thank Stephen Hayes for aligning this work
with 3GPP activities.
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 Bernard Aboba and Dan Romascanu for
the IETF Last Call comments, Derek Atkins for his security area
directorate review and Yoshiko Chong for spotting a bug in the IANA
consideration section. Bernard spend of lot of his time to interact
with the authors to resolve the IETF LC issues he raised. We would
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like to thank him for the energie he spend on this document.
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10. References
10.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote
Authentication Dial In User Service (RADIUS)", RFC 2865,
June 2000.
[3] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B. Aboba,
"Dynamic Authorization Extensions to Remote Authentication Dial
In User Service (RADIUS)", RFC 3576, July 2003.
[4] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[5] Schulzrinne, H., "Dynamic Host Configuration Protocol (DHCPv4
and DHCPv6) Option for Civic Addresses Configuration
Information", RFC 4776, November 2006.
[6] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
Configuration Protocol Option for Coordinate-based Location
Configuration Information", RFC 3825, July 2004.
[7] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko,
"Diameter Base Protocol", RFC 3588, September 2003.
[8] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575, July 2003.
[9] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
10.2. Informative References
[10] Cuellar, J., Morris, J., Mulligan, D., Peterson, D., and D.
Polk, "Geopriv Requirements", RFC 3693, February 2004.
[11] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
[12] Chiba, M., "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)",
draft-ietf-radext-rfc3576bis-08 (work in progress), June 2007.
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[13] "TADIG Naming Conventions, Version 4.1", GSM Association
Official Document TD.13", , June 2006.
[14] "The Unicode Standard -- Worldwide Character Encoding --
Version 1.0, Addison- Wesley, Volume 1, 1991, Volume 2", ,
1992.
[15] "The international identification plan for mobile terminals and
mobile users, ITU-T Recommendation E.212", , May 2004.
[16] "Designations for interconnections among operators' networks,
ITU-T Recommendation M.1400", , January 2004.
[17] "Codes for the representation of names of countries and their
subdivisions - Part 1: Country codes, ISO 3166-1", , 1997.
[18] Mills, D., "Network Time Protocol (Version 3) Specification,
Implementation", RFC 1305, March 1992.
[19] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005.
[20] Calhoun, P., Zorn, G., Spence, D., and D. Mitton, "Diameter
Network Access Server Application", RFC 4005, August 2005.
[21] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
Authentication Protocol (EAP) Application", RFC 4072,
August 2005.
[22] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication Dial
In User Service) Support For Extensible Authentication Protocol
(EAP)", RFC 3579, September 2003.
[23] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol",
RFC 4306, December 2005.
[24] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The Network
Access Identifier", RFC 4282, December 2005.
[25] 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.
[26] Schulzrinne, H., "Geolocation Policy: A Document Format for
Expressing Privacy Preferences for Location Information",
draft-ietf-geopriv-policy-12 (work in progress), May 2007.
[27] Rosenberg, J., "The Extensible Markup Language (XML)
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Configuration Access Protocol (XCAP)",
draft-ietf-simple-xcap-12 (work in progress), October 2006.
[28] Narten, T. and R. Draves, "Privacy Extensions for Stateless
Address Autoconfiguration in IPv6", RFC 3041, January 2001.
[29] Simpson, W., "PPP Challenge Handshake Authentication Protocol
(CHAP)", RFC 1994, August 1996.
[30] Arkko, J. and H. Haverinen, "Extensible Authentication Protocol
Method for 3rd Generation Authentication and Key Agreement
(EAP-AKA)", RFC 4187, January 2006.
[31] Funk, P. and S. Blake-Wilson, "EAP Tunneled TLS Authentication
Protocol Version 0 (EAP-TTLSv0)", draft-funk-eap-ttls-v0-01
(work in progress), April 2007.
[32] Josefsson, S., Palekar, A., Simon, D., and G. Zorn, "Protected
EAP Protocol (PEAP) Version 2",
draft-josefsson-pppext-eap-tls-eap-10 (work in progress),
October 2004.
[33] Tschofenig, H., "EAP IKEv2 Method",
draft-tschofenig-eap-ikev2-13 (work in progress), March 2007.
[34] Adrangi, F., Lior, A., Korhonen, J., and J. Loughney,
"Chargeable User Identity", RFC 4372, January 2006.
[35] "Open Geography Markup Language (GML) Implementation
Specification", OGC 02-023r4,
http://www.opengis.org/techno/implementation.htm", ,
January 2003.
[36] Stanley, D., Walker, J., and B. Aboba, "Extensible
Authentication Protocol (EAP) Method Requirements for Wireless
LANs", RFC 4017, March 2005.
[37] Danley, M., "Threat Analysis of the Geopriv Protocol",
RFC 3694, September 2003.
[38] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[39] Polk, J. and B. Rosen, "Session Initiation Protocol Location
Conveyance", draft-ietf-sip-location-conveyance-07 (work in
progress), February 2007.
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Appendix A. Matching with Geopriv Requirements
This section compares the requirements for a GEOPRIV Using Protocol,
described in [10], against the approach of distributing Location
Objects with RADIUS.
In Appendix A.1 and Appendix 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 implication
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 18: Location Server at the Home Network
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The term 'Rule Holder' in Figure 18 denotes the entity that creates
the authorization rule set.
A.2. Distribution of Location Information at the Visited Network
This section describes a scenario where location information 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 [24] and RFC 4372 [34] provide background
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 act according to the user's policies.
The subsequent figure shows the interacting entities graphically.
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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 19: 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 policy rules and to adhere
the privacy statements in the basic policy rules.
A.3. Requirements matching
Section 7.1 of [10] 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 semantic of the
location object is taken from the [6] and [5]. It is
furthermore possible to convert it to the format used in GMLv3
[35], as used with PIDF-LO [19].
* Regarding requirement 1.2, a number of fields in the civic
location information format are optional.
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* 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 Section 4.2, in Section 4.3.1 and in
Section 4.3.2. The corresponding privacy rules are detailed in
Section 4.4 and in Section 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 Section 4.2, Section 4.3.1,
Section 4.3.2 Section 4.4 and in Section 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 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
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.
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* 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 describes these security mechanisms offered by the
RADIUS protocol. The same is true for requirement 2.4.
* Regarding requirement 2.5, Section 4.2, Section 4.3.1 and
Section 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
'sighting time' and 'time-to-live' field defined in
Section 4.2.
* Regarding requirement 2.8, a reference to an external (more
detailed rule set) is provided with the Section 4.5 attribute.
* 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 Section 4.3.2
and in Section 4.3.1.
* With the support of civic and geospatial location information
support requirement 3.2 is fulfilled.
* 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, LaRes fields
described in [6].
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* Regarding requirement 3.4, further Location Data Types can be
added via new coordinate reference systems (CRSs) (see Datum
field in [6]) and via extensions to [6] and [5].
Section 7.2 of [10] 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 regarding the
transmission and storage of the LO. This document requires that
entities that aim to make location information available to third
parties are 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 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 [10] 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 18 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 19 the Rule Maker-defined Privacy
Rules are sent from the RADIUS server to the NAS (see Section 4.4,
Section 4.5 and Section 7.2 for more details).
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Req. 8. (LG Rules): For all usage scenario 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 18 the
visited network is already in possession of the users 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 which is
applicable in the area of the distribution of Location Objects. A
basic ruleset is provided with the Basic-Policy-Rules attribute
Section 4.4. A reference to the extended ruleset is carried in
Section 4.5. The format of these rules are described in [25] and
[26].
Req. 11. (Limited Rule language): A limited (or basic) ruleset is
provided by the Policy-Information attribute Section 4.4 (and as
introduced with PIDF-LO [19]).
Section 7.4 of [10] 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' [36]).
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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.
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) which 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 on 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
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Hannes.Tschofenig@nsn.com
URI: http://www.tschofenig.com
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
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