1. Carrying Location Objects in RADIUS
<draft-tschofenig-geopriv-radius-lo-00.txt>
Hannes Tschofenig, Farid Adrangi, Avi Lior, Mark Jones

2. RADIUS / Geopriv A quick reminder ...
Location Objects are attached to RADIUS messages
Location based authorization and taxation possible at home AAA server.
RADIUS
Access Network
AAAL
AAAH
Home Network
RADIUS AP
IEEE 802.1x
Mobile Node
Figure 1: Example Network Topology

3. What happened since the last IETF meeting?
Two presentations have been given at the last IETF meeting:
<draft-adrangi-radiusext-location-information-00.txt>
<draft-jones-radius-geopriv-00.txt>
The authors of the two drafts got together and wrote a new draft:
Carrying Location Objects in RADIUS
<draft-tschofenig-geopriv-radius-lo-00.txt>

4. Delivery Methods for Location Information
Goal: Location Information must be available at the home AAA server
Two means to deliver Location Information to the AAAH:
Authentication/Authorization Phase Delivery
Mid-session Delivery

5. Delivery Methods for Location Information Authentication/Authorization Phase DeliveryMN
NAS
AAA
Start Auth. Phase
RADIUS
Access-Request
+ Loc-Attr.
... multiple roundtrips ...
Access-Accept
Auth. Accept
RADIUS
Accounting Request
+ Loc-Attr.

6. Delivery Methods for Location Information Mid-session Delivery
NAS
AAA
COA + Service-Type "Authorize Only"
COA NAK + Service-Type "Authorize Only"
+ Error-Cause "Request Initiated"
Access-Request + Service-Type "Authorize Only"
+ Loc-Attr.
Access-Accept
Legend:
Change of Authorization (CoA) message [RFC3576]

7. New RADIUS Attributes Reusing existing Geopriv work!
Operator-Name Attribute
This attribute contains an operator name which uniquely identifies the ownership of an access network.
Location-Information Attribute
Civil Location Information Format [ietf-geopriv-dhcp-civil]
Geospatial Location Information Format [RFC3825]
Policy-Information Attribute
Reuses basic authorization policies from [PDIF-LO]
Location-Type Attribute
Classes of location types (from 'Coffee Shop' to 'Public Place')
Billing-Description Attribute
Unstructured text to be printed on the users bill

8. Location-Information Attribute
(0) NAS
(1) AAA server
(2) User
(3) Network
Location-Information Attribute
(0) Civil
(1) Geospatial
| Type | Length | Code | Precision |
| Location-Info
Civil Location Information
| Countrycode | Civic address elements
Geospatial Location Information
TLV elements:
CAtype
CAlength
CAvalue
Example:
<3(city), 6, Munich>
| LaRes | Latitude
| Latitude | LoRes | Longitude
| Longitude | AT | AltRes | Altitude +
| Altitude | Datum |

9. Policy-Information Attribute
Fields of the 'usage-rules' element defined in [PIDF-LO]:
'retransmission-allowed':
'0' = Recipient is not permitted to share the enclosed Location Information
'1' = Recipient is allowed to share Location Information with other parties.
'retention-expires':
Absolute date at which time the Recipient is no longer permitted to possess the location information.
'ruleset-reference':
This field contains a URI that indicates where a fuller ruleset of policies related to this object can be found.

10. Privacy Considerations Eavesdropping
Threat: Eavesdropper learning Location Information + NAI
Assumption:
NAI reveals true user identity (might not be the case for some EAP methods)
Solution:
Use IPsec ESP between AAA servers
Already required for key transport
Cannot protect against entities participating in the signaling exchange (e.g., AAA server) itself => no true "end-to-end" security

11. Privacy Considerations Home AAA server acts as Location Server
Scenario:
Home AAA server retrieves location information and wants to use it for location-based services.
Typically no problem since
User has a strong trust relationship with home operator based on a contract.
Authorization policies can be provided to the home AAA server (or the home network) before the protocol execution starts.

12. Privacy Considerations Visited AAA server acts as Location Server (1)
Scenario:
Visited AAA server collects and distributes location information of attached users.
The same is applicable to AAA brokers
User might not even allow location information to be forwarded to home network
Problem:
End host and visited network typically shares not trust relationship.
Network access authentication procedure is executed to dynamically establish the trust relationship and to establish session keys.
These keys are available after successful authentication and authorization.
Successful authentication and authorization might require location information

13. Privacy Considerations Visited AAA server acts as Location Server (2)
Approach 1: Use EAP method with active user identity confidentiality
Problem: The choice of an EAP method is not only user driven
Approach 2: Mandate default policy
Problem: Will it be considered by all hot spots?
Approach 3: Authorization policies are provided by the home AAA server - possible for mid-session delivery
Problem: Addresses only some problems
Approach 4: User provides authorization rules to visited network
Problem:
Securing the LO/Rules is difficult (key management problem)
Existing protocols due not support this functionality (see EAP, PANA)
Not a RADIUS problem

14. Outside the Scope
Protocols executed between end host and NAS (e.g., EAP)
Example:
End host providing location information to RADIUS server

15. Next Steps / Open Issues
Should this document become a working group item in the Geopriv working group?
Technical issues to add for the next draft version:
Scenarios need more text
Interworking with DIAMETER needs to be described
Discussion on the privacy issues
Comments are appreciated!

16. Questions?