Choice Overview

An Overview of the CHOICE Network: 

An Overview of the CHOICE Network Victor Bahl http://research.microsoft.com/~bahl December 18, 2000

Demos you will see today : 

Demos you will see today CHOICE – Phase 1 Demo 1 – Network advertisement, user authentication, access enforcement, security, accounting, and mobility management CHOICE – Phase 2 Location based personalized services Demo 2 – Location based buddy list Demo 3 – Mall On-Sale Service

Broadband Wireless Internet Access in Public Places : 

Broadband Wireless Internet Access in Public Places The CHOICE Network - Phase 1 Global authentication, Local access, First-hop security, Accounting, Differentiated Service, Mobility management & Auto-configuration

The Choice Network Project: Motivation: 

The Choice Network Project: Motivation Enable high speed wireless internet access in public places (e.g. hotels, conferences, malls, airports) WLAN much faster than 3G cell phones Design, implement, and deploy a network service that grants secure, customized, and accountable network access to possibly unknown users A system that protects users and network operators supports different business models e.g. free intranet and/or fee-based internet access makes access seamless and robust Multiple authentication schemes for first-time users Bootstrap network accesses for mobile clients Scale to large network settings Tolerate system failures

Review: Existing Access Mechanisms : 

Review: Existing Access Mechanisms Mostly built for enterprise networks Layer-2 Filtering MAC based filtering – is on its way out Shared key encryption – is being used today …but key management is broken Several Problems: Network can be compromised easily Key is flashed into the card Large-scale re-keying very difficult User-level authentication is not available No way to track who is using the network and how it is being used

Prior Research: 

Prior Research Authenticated DHCP @ UCB (1996-97) The NetBar System @ CMU (1997-98) Dedicated specialized CISCO routers Secure Public INternet ACcess Handler @ Stanford (1997-99) InSite @ University of Michigan (1997) Similar to CMU system

Shortly after we started: 

Shortly after we started IEEE 802.11 also recognized the problem with authentication and key distribution and issued a call for proposals. Simultaneously Windows NT group started working with IEEE 802.1x designing a security solution. MS proposed EAPoE to the IEEE standard’s body.

A Primer on IEEE 802.1X: 

Network port based access control mechanism layer-2 authentication EAP over 802.11 (EAPoE) Similar in flavor to the UC Berkeley proposal AP treats EAP encapsulated Ethernet frames with a specific multicast address in a special way AP forwards these packets to an authentication server (RADIUS) IPSEC between AP and RADIUS server After authentication RADIUS passes key to AP which passes it over to the client A Primer on IEEE 802.1X

802.1X Network Topology: 

802.1X Network Topology Authenticator (e.g. Access Point) Supplicant Enterprise Network Semi-Public Network/ Enterprise Edge Authentication Server RADIUS EAP Over LAN (EAPOL) EAP Over RADIUS

802.1X on 802.11: 

Ethernet Access Point Radius Server 802.1X on 802.11 RADIUS Laptop computer Wireless 802.11

802.1x in Public Places – Deployment Issues: 

802.1x in Public Places – Deployment Issues Requires specialized AP hardware Requires support in the base stack Requires RADIUS (AAA) backend Uses TLS which requires user certificates http/SSL based Passport authentication not supported Handoff latency is high, VoIP calls may be a problem for mobile users Not a complete solution (will show next) 802.1x works well in enterprise networks

A Primer on MS Passport (Global Authenticator): 

A Primer on MS Passport (Global Authenticator) MS Passport Wallet user User Id (Hotmail id) + password Uses SSL: public key encryption Partner Web Site Authorizes information transfer (e.g. credit card) Authentication; Credit card etc. http://www.passport.com

The CHOICE Network: 

The CHOICE Network Focuses on wireless Internet connectivity & location services in public places Built-in features IP address management Global authentication Comprehensive billing Packet level accounting Secure for both users and network operators Policy based services Mobility management bet. networks Differentiated service levels (VoIP) Improved battery/device lifetime Location-aware applications Local content provider Easy to deploy Future-proof Hardware- and IP version agnostic http://choice

Service Models in CHOICE: 

Service Models in CHOICE Model 1: Free access to local resources A non-routable IP address is provided without requiring authentication Intranet access allowed e.g. Mall portal, splash screens, indoor navigation service, coffee ordering etc. Payment is implicit – drives resident business for the host organization Model 2: Authenticate and pay Allows access to the Internet Allows applications like location-based buddy list, spontaneous sales that are based on profiles etc. Differentiated charging

CHOICE Components: 

CHOICE Components Authorizer, Verifier, and Client Authorizer Runs network announcer daemon – announce.exe Manages authentication, key generation, distribution & expiration – getkey.asp Interacts with Verifier and Client Verifier NDIS IM driver - pansKLVe.sys – decrypts packets, verifies key validity for every passing packet, keeps account of packets processed per user, enforces service levels Client Detector daemon – detect.exe – locates CHOICE network NDIS IM driver pansKLCl.sys – tags and encrypts packets

CHOICE Edge-Server Architecture: 

CHOICE Edge-Server Architecture

Bootstrapping Network Access : 

Bootstrapping Network Access Authorizer advertises CHOICE via lightweight beacons User’s machine gets a non-routable IP address (DHCP) and default gateway On-site network access software installation is supported for first-time users Network discovery logic enables / disables network access protocol

Discovering the CHOICE Network: 

Discovering the CHOICE Network Network ID Authorizer IP 4 bytes 4 bytes 4 bytes Basic Beacon (IP Broadcast) Advertised at random intervals with average frequency  1 per second For mobility management - Advertise both IP addresses to allow controller daemon to bypass or proceed with authentication Process (will become clear later) Subnet Mask 4 bytes Verifier IP Website URL n bytes

Controller Daemon Manages Network Access: 

Controller Daemon Manages Network Access Controller Daemon (on Mobile) For first-time users, downloaded from Authorizer and installed on-site

Network Access Service Discovery: 

Network Access Service Discovery Announcer Daemon (on Authorizer) beacon Controller Daemon (on Mobile)

Authentication in CHOICE: 

Authentication in CHOICE User “logs-on” to a global authenticator (e.g. MS Passport) Web based User Interface Credentials are passed via end-to-end SSL connection. WLAN provider is not privy to credentials Authorizer generates time-bounded session key and sends it to client via SSL and to the Verifier via IPSEC Client sets Verifier as a gateway and tags every outgoing packet using key Verifier un-tags packet, checks key, does integrity check, checks service policy, and forwards packet. Certificates guarantee legitimacy of Authorizer and Verifier

User Authentication: 

User Authentication beacon Controller Daemon (on Mobile) User performs authentication Daemon waits for response from Authorizer Announcer Daemon (on Authorizer)

Key Distribution: 

Key Distribution MIME over SSL key Keygive beacon User-level program receives key, redelivers to daemon Set default gateway Enable packet tagging Authorizer Controller Daemon (on Mobile) Announcer Daemon (on Authorizer)

Packet Tagging: 

Packet Tagging

In a Nutshell: Auto Configuration: 

In a Nutshell: Auto Configuration

Service Negotiation in CHOICE: 

Service Negotiation in CHOICE Different levels of service offered as part of “log-in” First-hop provider negotiates with ISPs and offers the best available rate to users Policies take into account special user contracts MCI, AT&T deals for home phone customers Corporate discounts Gold Club member benefts etc.

Access Enforcement in CHOICE : 

Access Enforcement in CHOICE Access control is per packet based An encrypted secret code is placed in each packet for different levels of service Premium Service (e.g. unlimited BW, higher level of security, location services,…) Basic (e.g. limited BW e.g. $ C0 for n kilobits transferred, Medium to no security, …) Quota overflow is regulated at the client and enforced by the Verifier Encryption is a combination (secret code, sequence number) – more later

First-Hop Security in CHOICE: 

First-Hop Security in CHOICE Software based - Upgrade easily Download latest encryption code into clients and servers Unlike WEP no need for upgrades to AP hardware Encryption method is flexible Client negotiates with servers at attachment time 3DES, RC4, ECC etc. [3DES is implemented] Key length is flexible Key can be changed multiple times in a session Frequency set by the server/client Data integrity obtained via MD5 checksum

Mobility Management in CHOICE: 

Mobility Management in CHOICE Network Discovery Already discussed Key Management for handling mobility Store/invalidate session keys collected from multiple networks Roaming: always bypass authentication process if possible Renew keys within a session to enhance security

Mobile Client Leaves: 

Mobile Client Leaves Controller Daemon (on Mobile) No Beacon heard for a while

Bypassing Authentication(when key is still valid) : 

Bypassing Authentication (when key is still valid) beacon Controller Daemon (on Mobile) Announcer Daemon (on Authorizer)

In a Nutshell: Client Operation State Transition Diagram: 

In a Nutshell: Client Operation State Transition Diagram

Scalability: Wide-Area Key Distribution: 

Scalability: Wide-Area Key Distribution Wide-area key distribution among different subnets Global key distribution is costly Solution  On-demand session key migration: Detect roaming event between subnets Initiate session key migration request Bypass user-level authentication process

Scalability: Load Balancing among Verifiers: 

Scalability: Load Balancing among Verifiers Network ID Authorizer IP Verifier IP 1 Extended Beacon Verifier IP 2 ….. Verifier IP N Preferred Verifier Operational Verifiers Change ordering of Verifiers to load balance new users

Fail-over in CHOICE: 

Fail-over in CHOICE Network ID Authorizer IP Verifier IP 1 Extended Beacon Verifier IP 2 ….. Verifier IP 2B Backup gateway for Verifier 2 Verifier 2 fails All clients are migrated at the same time! Migrating clients from a failed verifier to a mirror

PANS (Protocol for Authorization and Negotiation of Services) Driver Implementation: 

PANS (Protocol for Authorization and Negotiation of Services) Driver Implementation PANS Intermediate Driver

Protocol Performance: 

Protocol Performance

Contrasting CHOICE with 802.1X: 

Contrasting CHOICE with 802.1X 802.1X is attractive to hardware vendors as it lets them sell new APs CHOICE is hardware agnostic. APs are commoditized as dumb bridges 802.1X incurs high handoff latency and VoIP support is poor Handoff latency in CHOICE is minimal 802.1X is only about first-hop security CHOICE is a complete system for public wireless-LAN deployment last-hop security is only one piece of it. Other aspects include global authentication, differentiated services, network discovery, load balancing, fail-over mechanisms, packet-level accounting and congestion management. CHOICE provides Location based personalized services CHOICE support multiple authentication schemes AAA (DIAMETER), Global authenticators, E-cash systems (MasterCard, Visa) Support users who do not have a “home” domain

CHOICE -- Accomplishments: 

CHOICE -- Accomplishments - Phase 1 is complete - Phase 2 is in final stages Phase 1 Achievements: System: has been built and deployed @ the Crossroads Mall in Bellevue Operational since June 2000 Result of cooperation between Microsoft & Terranomics Inc. (Mall owner) Result of 11,750+ lines of C, C++, Javascript and VBScript code Result of overcoming logistic nightmares in deploying a huge system. Patents: 7 applications filed Papers: IEEE Wireless Communications Magazine + USENIX Internet Technical Symposium’01 + IEEE International Conference on Communications 2001 Reports: MSR-TR-2000-21 (January 2000), MSR-TR-2000-85 (August 2000) Press: New York Times (Feb. 28, 2000), Microsoft Web Report (Jul. 2000), MicroNews News Service,… External URL: http://www.mschoice.com Internal URL: http://choice

Slide40: 

Crossroads Shopping Center Deployment

The CHOICE Network -- Phase 1 Demo: 

The CHOICE Network -- Phase 1 Demo What you will see today: - CHOICE network discovery (+ Software Installation) - Access to Local Portal but nothing else - Passport authentication (and corporate authentication) - Key generation, distribution and time-limited access - Key expiration and access-denial - Sensing of disconnection from CHOICE Network Test Platform - Nearly identical to CROWN configuration

Comments on WLAN in Public Places: 

Comments on WLAN in Public Places Everyone Benefits! Near-ubiquitous information access (end users win) More WLAN hardware sold (vendors & manufacturers win) More backbone network resources get used (ISP’s win) Business owners attract more people (store owners win) More software and services sold Revenue Sources Local portals (advertisement revenues, …) Long distance phone model Location service providers

Technical Details:: 

Technical Details: P. Bahl, A. Balachandran, A. Miu, W. Russell, G. Voelker and Y.M. Wang, :PAWNs: Satisfying the Need for Ubiquitous Connectivity and Location Services”, IEEE Personal Communications Magazine (PCS), Vol. 9, No. 1 A. Miu and P. Bahl, “Dynamic Host Configuration for Managing Mobility between Porivate and Public Networks,” to appear in The 3rd Usenix Internet Technical Symposium, San Francisco, California, USA (March 2001) P. Bahl, A. Balachandran, and S. Venkatchary, “Secure Broadband Wireless Internet Access in Public Places,” to appear in the IEEE Conference on Communications, Helsinki, Finland (June 2001) Also MSR-TR-2000-85 and MSR-TR-2000-21 Or send mail to bahl@microsoft.com, full contact info (http://research.microsoft.com/~bahl)

Broadband Wireless Internet in Public Places : 

Broadband Wireless Internet in Public Places The CHOICE Network - Phase 2 Location Services

Computing in Public Places: 

Computing in Public Places Phase 1 Authentication, access, security, accounting, differentiated serves, mobility management & deployment Phase 2 Location services in public places Location based buddy list Mall On Sale server Location Chat

Current Prototypes: 

Location Information Service Demo today Location Alert Service Demo today Location-Based Buddy List Service Deployed but no demo OnSale Mall Buddy Service Deployed but no demo Current Prototypes

Location Information Service: 

Location Information Service WISH (Where IS Harry?) “I wish I knew where Harry is.” User location system that works with Wireless LANs Usage scenarios Locate people and devices Discover nearby resources (printers, offices, restrooms, etc.)

Location Information Service Architecture: 

Location Information Service Architecture WISH Client WiLIB Device Driver WISH Server Eventing Infrastructure Every 2 minutes Every 30 seconds Every 30 seconds Every 30 seconds http://wish

Location Alert Service: 

Location Alert Service When I can’t find Harry… “Alert me when you find Harry.” Use soft-state eventing infrastructure for robustness of dynamic distributed systems Use a personalized alert delivery mechanism through instant messaging, emails, cell phone SMS

Slide50: 

Location Alert Service Architecture

Location-Based Buddy List Service: 

Location-Based Buddy List Service Extend MSN IM buddy list “Alert me when my buddy is nearby and include a map.” Proximity detection & location determination in addition to presence detection

Slide52: 

Location-Based Buddy List Service Architecture http://www.mschoice.com http://choice

OnSale Mall Buddy Service: 

Personalized sales announcements “Alert me when electronics are on sale.” Subject-based publish/subscribe eventing based on product categories and user profiles OnSale Mall Buddy Service

Slide54: 

OnSale Mall Buddy Service Architecture