Peer-to-Peer%20Wireless%20Network%20Confederation

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Peer-to-Peer Wireless Network Confederation
(P2PWNC)
George C. Polyzos Mobile Multimedia
Laboratory Department of Computer Science Athens
University of Economics and Business http//mm.au
eb.gr/
P2P colloquium, Darmstadt, December 7, 2005
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Idea

• A wireless LAN (WLAN) aggregation scheme
• Unites WLANs in citywide confederations
• Requires no authorities open to all, IDs are
  free
• Relies on reciprocity between peers

• Motivation
• Numerous WLANs, connected to the Internet,
• are within the range of passersby

Manhattan WLANs, 2002
Skyhook Wireless Wi-Fi Positioning System (WPS)
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Motivation

• Motivation (II)
• Many WLANs are secured against outsiders
• Need incentives to keep them open

• Motivation (III)
• WLAN-enabled mobile phones are on the market

• Motivation (IV)
• Public WLAN operators mainly target hotspots
• Municipal wireless
• still in its infancy

Motorola CN620
Nokia 9500
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The Public Hotspot Market

• From Gartner
• 2001 1200 public hotspots worldwide
• 2003 71 000 public hotspots worldwide
• 2005 23 500 WLANs in hotels worldwide

• A subscription buys you (June 2005)
• Sprint PCS 19 000 hotspots worldwide
• Boingo Wireless 17 400 hotspots worldwide
• T-Mobile HotSpot 16 663 hotspots worldwide

• Skyhook Wireless data (2005)
• 50 000 WLANs in just 5 Massachusetts
• cities and towns (Watertown, Brookline,
• Roxbury, Newton, and Cambridge)

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The Rules

• P2PWNC An incentives-based P2P system
• Teams provide WLAN access to each other
• Teams should provide in order to consume

Blue team
White team
Green team
WLAN access point team member
WLAN view
Team view
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N-way Exchanges

• Adopt N-way exchanges as the incentive scheme
• A generalization of barter, which retains some of
  its simplicity
• Provide to those who provided to those who
  provided to me
• A type of (cyclical) indirect reciprocity
• Scales to larger communities, compared to
  direct-only exchanges
• Does not rely on (central or distributed)
  authorities

A
B
C
D
Some variants of the basic N-way scheme Cox,
Noble, Samsara Honor Among Thieves in P2P
Storage, SOSP03 Ngan, Wallach, Druschel,
Enforcing Fair Sharing of P2P Resources,
IPTPS03 Anagnostakis, Greenwald,
Exchange-based Incentive Mechanisms for P2P File
Sharing, ICDCS04 Feldman, Lai, Stoica, Chuang,
Robust Incentive Techniques for P2P Networks,
ACM EC04
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Versions
Architecture Incentive technique Comment
Version 1.0 (MMAPPS) MMAPPS local accounts pattern Relied on tamperproof software
NWAY1 Favors large teams, unimplemented
Version 2.0 GMF2 Assumes homogeneous consumptions
Version 3.0 (in progress) in progress More realistic assumptions
1. E. C. Efstathiou and G. C. Polyzos,
Self-Organized Peering of Wireless LAN
Hotspots, European Transactions on
Telecommunications, vol. 16, no. 5, (Special
Issue on Self-Organization in Mobile Networking),
Sept/Oct. 2005. 12 acceptance rate 2. E. C.
Efstathiou, P. A. Frangoudis, and G. C. Polyzos,
Stimulating Participation in Wireless Community
Networks, IEEE INFOCOM 2006, Barcelona, Spain,
April 2006 (to appear). 18 acceptance rate
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Version History

• Sept. 2002 P2PWNC started in the context of IST
  MMAPPS (Market Management of Peer-to-Peer
  Services)
• Sept. 2003 Demo of version 1.0
• Team 1 (5 persons from AUEB)
• Theory Team (2 persons from AUEB)
• June 2005 Demo of version 2.0
• Team 2 (3 persons)
• Results will be presented at IEEE INFOCOM,
  Barcelona, April 2006
• Oct. 2005 Started work on version 3.0
• Team 3 (7 persons)
• Preparing demo for TRIDENTCOM 2006 and/or INFOCOM
  2006

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• System Entities
• Team Members Access Points (APs)
• Teams P2PWNC peers
• Assume intra-team trust
• Team ID (unique) PK-SK pair
• Member certificate
• Member ID (unique) PK-SK pair
• Member certificate binds Member PK to Team PK
• Receipt
• Encodes P2PWNC transactions between teams
• Signed by consuming member

PK public key SK private key
Member PK
Team PK
Signed by Team SK
Team PK
Member cert
Timestamp
Weight
Signed by Member SK
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Receipt Generation
1150am t0 (member connects)
1151am (P requests 1st receipt)
CONN
RREQ
P
P
C
C
CACK
RCPT
RCPT timestamp t0 RCPT weight w1
1152am (P requests 2nd receipt)
1153am (member has departed)
RREQ
RREQ
(timeout)
P
P
C
Receipt Repository
RCPT
RCPT
RCPT timestamp t0 RCPT weight w2 gt w1
P stores last receipt
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P2PWNC Protocol Entities and Messages
Access Point
Repository
Mobile User
CONN
QUER
CACK
QRSP
RREQ
RCPT P2PWNC/2.0 Content-length 357 Algorithm
ECC160 Timestamp Tue, 24 May 2005 172641
0000 Weight 6336 BNibmxStfJlod/LnZubH6pzWHQqKyZF
cSMjnZurmTe4KjCRkllhV93MEegPvCsxz2oe/hqevoPSrwO1JL
O/36J8HTIeyeKQqTCfxEPxweAvYC/ZFb8URLa2faIbvSgD3lm
6Wa1S4cYlSWeSNmFzS/ebDFfzakqNSEsERefwEcdWJD9gzIXaf
L4pojhhfP5brS4QPtHzBl58POfKdx9AqCDMBxRoGALKJSJYYXl
srwtiyZJKvPlU5B3lWrFuL25Pdkv2iMVRElXk/4
RCPT
RREQ
Timeout/ Conn. closed
RCPT
Text-based protocol. Certificates and keys
encoded in Base64.
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Centralized Operation Mode
One RR (Receipt Repository) for all teams. -
Susceptible to DoS in layer 3 and in app. layer
(overflow RR with fake receipts) - Confederation
teams may be unable or unwilling to agree on the
same RR, dividing the confederation Simpler to
deploy and bootstrap
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Decentralized Operation Mode
One RR (Receipt Repository) per team (running on
the team server). Not susceptible to DoS (IP
address known only within the team) and only team
members talk to it - Needs gossiping mechanism
(which uses the members themselves to carry
receipts around) - Partial views of
confederation history can favor free-riding
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The Receipt Graph
Directed weighted graph (with cycles)
W1
F
E
Graph security Free-riders and colluders can
create an arbitrary number of fake vertices and
edges They cannot create fake outgoing edges
starting from teams who are outside the colluding
group (they do not have the relevant private keys)
W2
W4
B
W3
G
W5
W6
W9
W7
W14
A
I
W8
H
W13
W10
W11
C
D
W12
Vertices team public keys Edge weight sum of
weights of corresponding receipts Edges point
from the consuming team to the providing team
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GMF - Background
Directed weighted graph (with cycles)
W1
F
E
Graph security Free-riders and colluders can
create an arbitrary number of fake vertices and
edges They cannot create fake outgoing edges
starting from teams who are outside the colluding
group (they do not have the relevant private keys)
W2
W4
B
W3
G
W5
W6
W9
W7
W14
A
I
W8
H
W13
W10
W11
C
D
W12
Vertices team public keys Edge weight sum of
weights of corresponding receipts Edges point
from the consuming team to the providing team
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GMF - Heuristic
Directed weighted graph (with cycles)
W1
F
E
Graph security Free-riders and colluders can
create an arbitrary number of fake vertices and
edges They cannot create fake outgoing edges
starting from teams who are outside the colluding
group (they do not have the relevant private keys)
W2
W4
B
W3
G
W5
W6
W9
W7
W14
A
I
W8
H
W13
W10
W11
C
D
W12
Vertices team public keys Edge weight sum of
weights of corresponding receipts Edges point
from the consuming team to the providing team
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GMF - Evaluation
Directed weighted graph (with cycles)
W1
F
E
Graph security Free-riders and colluders can
create an arbitrary number of fake vertices and
edges They cannot create fake outgoing edges
starting from teams who are outside the colluding
group (they do not have the relevant private keys)
W2
W4
B
W3
G
W5
W6
W9
W7
W14
A
I
W8
H
W13
W10
W11
C
D
W12
Vertices team public keys Edge weight sum of
weights of corresponding receipts Edges point
from the consuming team to the providing team
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IST MMAPPS version (Version 1.0)
P2PWNC Domain Agent Application
WLAN events
WLAN service calls
WLAN Provisioning Service
Network Services
MMAPPS and JXTA
Packet sniffer
Firewall
Accounting
Negotiation
Routing / NAT
DHCP
Rules
Authentication
Rate control
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IST MMAPPS version (Version 1.0)
1. Visitor credentials check
WLAN
WLAN
(visitor password resides in home database)
2. Negotiate
6. Balance OK Proceed
Visitor Negotiation
Visitor Session
Visitor Negotiation
Negotiation Listener
3. Request service
5. Start
MMAPPS Negotiation
MMAPPS Negotiation
4a. MMAPPS negotiation
4b. Balance check
Home peer - Consumer
Visited peer - Provider
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First attempts at Linux-based WLAN mgmtAAA,
DHCP, NAT, QoS,
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First attempts at Linux-based WLAN mgmtTraffic
logging using (fast) kernel, user modules
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First simple rules(tamperproof software!)
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First experiments with PDAs and Linux WLAN
gateways
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Version 2 Architecture
Receipt store GMF execution Member update
(decentralized mode)
Home-AP interface
DHCP NAT/router/firewall Authenticator Receipt
verification
Standard PC, or collocated with Linksys Linksys
WRT54GS AP (32MB RAM, 8MB Flash) Windows Mobile
client
Member-AP interface
.
Member certificate Receipt generation Also
carries team receipts (decentralized mode)
Member-Home interface
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Linksys WRT54GS

• Linux-based WLAN access point
• We implemented the P2PWNC protocol (AP side) on
  it
• 32 MB RAM, 8 MB Flash, 200 MHz CPU
• Retails for less than 70
• Cryptographic, maxflow performance comparable to
  200 MHz PC
• Can act as team server/RR (storing more than 10
  000 receipts)

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Repository Implementation (Version 2.0)

• Receipt Repository
• Efficient, composite data structure for receipt
  storage and queries
• Incentive algorithms pluggable modules
• maximum-flow algorithm optimizations
• Push-Relabel Algorithm - O(V3)
• Global relabeling heuristic

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Linksys verification performance compared to a
2GHz PC for all P2PWNC signature types
Athlon XP 2800 Athlon XP 2800 Linksys WRT54GS Linksys WRT54GS
Bit length (RSA/ECC) RSA ECC RSA ECC
1024/160 0.4 ms 6.5 ms 12.3 ms 114.7 ms
1536/192 0.8 ms 6.0 ms 21.4 ms 99.9 ms
2048/224 1.3 ms 7.1 ms 37.9 ms 135.7 ms
3072/256 2.8 ms 8.6 ms 75.3 ms 453.0 ms
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QoS Scheme for version 3.0
Reinterpret the result of GMF not as
probability to provide unrestricted service but
as the QoS to be provided
Build traffic policing module for both Windows
and Linux-based (tc-based) routers
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Secure Services (version 3.0)
Team Server 1
Team Server 2
Each client uses its own tunnel endpoint for
scalability (usually their own home). Client can
learn the endpoints current IP address from his
team server. Caller sends SMS containing current
tunnel endpoint IP address and a
tunnel identifier. No centralized registrars are
needed (e.g. SIP registrars, dynamic DNS).
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L2TP IPSec Tunnels
Client side support Windows, Windows
Mobile Server side support Linux (and Linksys),
Windows
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IPSEC-ESP-RFC 3948 UDP encapsulation of IPSec
ESP Packets (used after a NAT detection process
detects a NAT)
NAT traversal a problem for IPSec, but
Support for NAT-T in Windows, Windows Mobile and
in the Openswan Linux VPN gateway that we are
using
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VoIP for Windows Mobile (version 3.0)
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Deployment the Athens Wireless Metropolitan
Network
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AWMN and P2PWNC
AWMN is one of the largest WMNs globally, with
more than 3000 nodes P2PWNC version 3.0 is
designed to be compatible with most AWMN
nodes Setup of AWMN Node 66 in MMlab is finally
underway!
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P2PWNC Publications and Website
1. E. C. Efstathiou and G. C. Polyzos, Self-Organized Peering of Wireless LAN Hotspots, European Transactions on Telecommunications, vol. 16, no. 5, (Special Issue on Self-Organization in Mobile Networking), Sept/Oct. 2005. 12 acceptance rate 2. E. C. Efstathiou and G. C. Polyzos, Peer-to-Peer Wireless Network Confederation, in Encyclopedia of Virtual Communities and Technologies, S. Dasgupta, ed., Idea Group Reference, 2005. 3. E. C. Efstathiou and G. C. Polyzos, P2PWNC A Peer-to-Peer Approach to Wireless LAN Roaming, in Handbook of Wireless Local Area Networks Applications, Technology, Security, and Standards, M. Ilyas, S. Ahson, eds., CRC Press, 2005. 4. E. C. Efstathiou, P. A. Frangoudis, and G. C. Polyzos, Stimulating Participation in Wireless Community Networks, IEEE INFOCOM 2006, Barcelona, Spain, April 2006 (to appear). 18 acceptance rate 5. P. A. Frangoudis, E. C. Efstathiou, and G. C. Polyzos, Reducing Management Complexity through Pure Exchange Economies A Prototype System for Next Generation Wireless/Mobile Network Operators, 12th Workshop of the HP Openview University Association (HPOVUA), Porto, Portugal, July 2005. 6. E. C. Efstathiou and G. C. Polyzos, Can Residential Wireless LANs Play a Role in 4G? 4G Mobile Forum (4GMF) Annual Conference, San Diego, CA, July 2005. 7. E. C. Efstathiou and G. C. Polyzos, A Self-Managed Scheme for Free Citywide Wi-Fi, IEEE WoWMoM Autonomic Communications and Computing Workshop, Taormina, Italy, June 2005. 8. E. C. Efstathiou, Self-Organized Peering of Wireless LANs, IEEE INFOCOM 2005 Student Workshop, Miami, FL, March 2005. 9. E. C. Efstathiou and G. C. Polyzos, Trustworthy Accounting for Wireless LAN Sharing Communities, 1st European PKI Workshop, Samos Island, Greece, June 2004. 10. E. C. Efstathiou and G. C. Polyzos, Designing a Peer-to-Peer Wireless Network Confederation, IEEE LCN Workshop on Wireless Local Networks (WLN), Bonn, Germany, Oct. 2003. 11. P. Antoniadis, C. Courcoubetis, E. C. Efstathiou, G. C. Polyzos, and B. Strulo, Peer-to-Peer Wireless LAN Consortia Economic Modeling and Architecture, 3rd IEEE International Conference on Peer-to-Peer Computing, Linköping, Sweden, Sept. 2003. 12. E. C. Efstathiou and G. C. Polyzos, A Peer-to-Peer Approach to Wireless LAN Roaming, ACM MOBICOM Workshop on Wireless Mobile Applications and Services on WLAN Hotspots (WMASH), San Diego, CA, Sept. 2003. 13. P. Antoniadis, C. Courcoubetis, E. C. Efstathiou, G. C. Polyzos, and B. Strulo, The Case for P2P Wireless LAN Consortia, 12th IST Summit on Mobile/Wireless Communications, Aveiro, Portugal, June 2003.
http//mm.aueb.gr/research/p2pwnc/