GEOPRIV Layer 7 Location Configuration Protocol; Problem Statement and Requirements draft-tschofenig-geopriv-l7-lcp-ps-00.txt Hannes Tschofenig, Henning Schulzrinne IETF 66, Montreal, June 2006

Design Team Henning Schulzrinne Barbara Stark Marc Linsner James Winterbottom Martin Thomson Rohan Mahy Brian Rosen Jon Peterson Hannes Tschofenig

Idea Obtain –location information (by value and by reference) –subscription URI from the access network. Do this independent from the underlying link layer and network topology.

Scenario: DSL Environment | | | | Access Network Provider | | | | | | | | | | | | | | | NTE | | | | Node | | | | | | | | | | | | | | | LIS | | | | | | | | +---| | | | | | | | | | | | Device with | | | | | | | | NAPT and | | | | | DHCP server | | | | | | Access Network | | | | | Provider demarc | | | | | | | | | | | | End | | | | Host | | | | | | |Customer Premises Networks | | |

Scenarios (cont.) WiMax-like Fixed Access –Feeding/Fixed Wireless Access Scenario Wireless Access

Location Information Server (LIS) Discovery DNS Multicast Packet interception/Redirection Security aspects related to discovery procedure.

Identifier for Location Determination Properties: –Known by the End Host –Possibility for Location Determination –Security Properties A number of identifiers being discussed. IP address seems to be the only reasonable identifier...

Location-by-Reference and Location Subscriptions Location-by-Reference: –Avoid sending the location itself. Location Subscription: –Enable node to use SIP mechanisms to subscribe for location of someone.

Authenticated Calls and Signed Location Information Mechanisms to limit DoS attacks What do you sign? –PIDF-LO or civic/geo-info –What identity do you sign?

Requirements (1/5) L7-1: In a DSL environment the location is that of the NTE/NAPT, e.g., the DSL or cable modem. Any devices behind a NAT box or other in- home device is reported as being at the location of the NTE/NAPT. L7-2: The system should work even if end systems move, either with or without change of network attachment point or network address.

Requirements (2/5) L7-3: There is no business or trust relationship between the provider of application-layer (e.g., SIP, XMPP, H.323) services and the network operating the LIS. L7-4: There is generally a trust relationship between the LIS and the L2/L3 provider.

Requirements (3/5) L7-5: Residential NAT devices and NTEs in an DSL environment cannot be modified to support additional protocols, to pass additional information through DHCP, etc. L7-6: If the L2 and L3 provider for the same host are different entities, they cooperate and can establish trust relationships for the purposes needed to determine end system locations.

Requirements (4/4) L7-7: Networks do not always require network access authentication (example: many open community wireless networks). The solution must not assume prior network access authentication. L7-8: End systems may not know the precise properties of their residential NAT and the network topology of the access network, but can determine their IP address(es) via other mechanisms.

Requirements (5/5) L7-9: Multiple devices, located in different physical locations, may share the same L2/L3 credentials ("account", "user name/password") with the L2/L3 provider and LIS. L7-10: At least one end of a VPN is aware of the VPN. In an enterprise scenario, the enterprise side will provide the LIS used by the client and can thereby detect whether the LIS request was initiated through a VPN tunnel.

Security Framework Threat model: Whom do we trust when it comes to obtaining location information? Different types of adversaries need to be considered: –off-path –on-path –active –passive

Security Requirements We want to prevent that... An end system can be pretend to be in an arbitrary location. An end system can pretend to be in a location it was at a while ago. An attacker can observe Alice's location and use it to generate its own location information. An attacker can observe Alice's location. An attacker can observe both Alice's location and her L7 identifier. Alice and Bob, located at different location, can collude and swap location objects and pretend to be in each other's location.

Questions.. Comments?