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Peer To
Peer
2009/2010

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1 Introduction
2 Architecture
3 Characteristic of P2P
4 The eMule application
5 P2P File-sharing Protocols
6 Conclusion

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 Direct system exchange of resources between
linked peers in network
 The most used in the world
 Basically different from the Client-server
architecture

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Peer to peer is a type of network infrastructure where each computer is both server
and client. In this case, the computers connected to the network share their resources .
• Distributed Architecture • Decentralized architecture

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In a typical peer-to-peer, there is no administrator .So, each
user manages his own post. On the other hand all users can
share their resources as they wish. If we consider one of the
posts as a server, it is intended to share resources, if not it
consumes resources from other posts

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For the P2P there are problems that are related to the system itself and
other software.
The files on these networks in addition to their potentially illegal
distribution come from unverifiable sources and can contain all kinds of additives:
spyware, viruses and other .. Anyway download any file whatever it is, should lead
to a systematic virus verification.
Also put passwords to the data, even if they are not in shared directories.

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 A reduced cost
 Simplicity of implementation and use
 Robust network,
 Self-organization
 Dynamism
7

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 This system is not centralized at all, which makes it very difficult to administer
 Security is less easy to achieve
 The network maintenance is difficult.
 Limited change
 Trafficking is most important and searching files take much longer
8

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It has emerged as a software developed in Java by the
exchange and sharing creators of Winamp based on
essential the distributed network
Gnutella.
Shareaza client is a peer-to-
Is based on the distributed
peer for Windows that will
network Fasttrack
allow you to download files
of any type on several
popular P2P networks.

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Definition :
eMule is a P2P file sharing network
• Based on an extended eDonkey protocol
• Uses both TCP and UDP
• Client Server architecture

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The eMule Network :

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1- Connection establishment :
High ID login sequence Rejection session

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2- Connection startup :
 This scenario assumes that the
client has a requested file list
 The client sends his files
 The server replies with status
information
 The client asks for sources for his
files
 The server replies with his
available sources

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3- File search :
• A search request is sent to the server which is then answered
by a search result
• The user chooses to download one or more files, the client then
requests sources for the chosen files and the server replies with a
list of sources for each of the requested files.
• An optional server status message

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4- Callback mechanism:
1- A can send the server a callback request to ask B to call him back.
2- The server, which already has an open TCP connection to B, sends B a
callback requested message, providing him with A’s IP and port.
3- B can then connect to A and send him the file without further overhead on
the server.

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 UDP is used for:
◦ periodic status checks
◦ File search enhancement
◦ Source search enhancement
 UDP is optional

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UDP is used for verifying A’s position in B’s upload queue

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The importance and the the future
of P2P is to provide a role in
network security and continuity.

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