1 A connection management protocol for promoting cooperation in Peer-to-Peer networks Authors: Murat...

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A connection management protocol for promoting cooperation in Peer-to-Peer networks

Authors: Murat Karakaya, Ibrahim Korpeoglu, and Ozgur UlusoySource: Computer Communications, vol. 31, pp. 240–256, 2008Speaker: Shu-Fen Chiou ( 邱淑芬 )

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Outline Introduction Gnutella Free rider Proposed scheme P2P Connection Management Protocol

(PCMP) Simulation result Attacks Conclusion Comments

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Introduction Gnutella (Host Cache)

It is a pure P2P protocol in contrast with Napster It is a broadcast-type network The core of the protocol consists of 5 descriptors

PING, PONG, QUERY, QUERY HIT and PUSH A Peer needs to connect to 1 or more other Gnutella Peers

in order to participate in the networkGnutella Network N

Server p

QUERY1

QUERY HIT

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Server p2

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Introduction

Find Hosts

Gnutella

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Introduction

Ping

Gnutella

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Introduction

Pong

Gnutella

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Introduction

Pong

Gnutella

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Introduction

Pong

Gnutella

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Introduction

Query

Gnutella

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Introduction

Query TTL=2

Gnutella

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Introduction

queryQuery TTL=3

Gnutella

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Introduction

Query Hit

Gnutella

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Introduction

Download File

Gnutella

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Free rider

Download File

Query

Free rider

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Proposed scheme Proposed two connection types. Proposed a P2P Connection Management

Protocol (PCMP). Benefits:

The connectivity of free riders to the contributing peers can be reduced.

In some situations, free riders can be totally isolated from the contributors.

The connectivity among contributor peers can be increased.

The workload of a contributor peer can be reduced, since it will not serve many free riders anymore.

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General P2P connection

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Two connection types

IN-connection and OUT-connection Limiting the numbers of

connection.

IN-connection

OUT-connection

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P2P Connection Management Protocol (PCMP) 2 IN-connections, 2 OUT-

connections

A BDownload file

C

DIN-connection

IN-connection

Requester(Downloader)

Responder(Uploader)A

According download times(C-PCMP) or update time (T-PCMP)

IN-connection

IN-connectionB

OUT-connectionPing

Pong

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P2P Connection Management Protocol (PCMP) 4 IN-connections, 4 OUT-

connections TTL=2Contributor

Contributor

F1, F3

F2Query F1

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P2P Connection Management Protocol (PCMP)

Contributor

Contributor

F1, F3

F2

Query F2

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Simulation results

900 peers

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Attacks

Malicious peer refuse to add a contributor to its list of IN-connections after downloading file. Contributors establish OUT-

connections only with other contributors. This attack will not affect.

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Attacks A malicious peer replies with a

faked Query Hit. In PCMP, the connection between two

peers is established after a file is download. If the file is wrong, the downloader will not send Pong message.

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Attacks

A malicious peer behaves as a new-comer to gain more OUT-connections. Try to reduce this attack according

others’ methods.

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Conclusion

Proposed a novel approach and a P2P Connection Management Protocol (PCMP).

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Comments

Prevent the third attack. Increase its OUT-connections by:

Increasing answering power. Increasing the number of edges. Increasing the amount of capacity

used to service neighbors’ queries. Increasing the length of period for

servicing neighbors’ queries.