Gnutella

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• Gnutella
• Özlem Ersin

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Outline

• What is Gnutella?
• Concepts and how it works
• Core Protocol
• Extensions
• Advantages-Disadvantages
• Conclusion and Questions

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What is Gnutella

• decentralized, peer-to-peer file sharing network
• used to exchange music, films and software
• developed by Nullsoft
• reverse-engineered by programmers
• developers ate nutella a lot during project
• third-most-popular file sharing network

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Concepts

• Servent "SERVer" and "cliENT
• Message information entity
• GUID Globally Unique IDentifier
• GNet Gnutella network
• Ultrapeerhigh-capacity servent shielding leaves

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Concepts

• TTLnumber of hops a message will make
• Horizon servents you can communicate with
• Broadcastingsend to all hosts
• Routing send to a particular host

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How It Works

• X bootstraps to connect to a node Y
• Y sends connected nodes to X
• X also connects these (around four)
• X can query and download

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Bootstrapping Handshaking

• Initialization and connection to network
• GWebCache Initial Conn. Point Problem for a
  fully distributed network
• X-Try and X-Try-Ultrapeer
• Handshaking Part of protocol starting connection

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Messages

• Header ID, Type,TTL, Hops, Payload Length
• Types Ping, Pong, Query, QueryHit, Push, Bye
• PingDiscover peers
• PongResponse to Ping
• More than one Pong for a Ping
• The same IDs for Ping Pong
• probing the connected remote hosts
• Crawler Ping scans the network

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Messages

• Query search the network
• QueryHit response to Query
• Same ID with corresponding Query
• Indexing all files a host shares.
• large TTL to reach the querying peer
• Push for a servent behind a firewall to share
  files to the network

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File Transfer

• HTTP download protocol
• GET ltsourcegt HTTP/1.1
• User-Agent ltuser agentgt
• Host 123.123.123.1236346
• Connection Keep-Alive
• Range bytes0-
• source is in the form
• get/File Index/File Name
• ignore unknown headers in silence
• do not download multiple files from same source

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Network Structure Flow Control

• Random connections
• Not good for low-bandwidth
• SolutionUltrapeer
• Broadcasting is through Ultrapeers
• QRPQuery Routing Protocol
• Flow control regulation of traffic
• Hysterisis and SACRIFC

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Extensions

• Intelligent query routing
• SHA-1 checksums
• query hit transmission via UDP
• querying via UDP
• dynamic queries via TCP
• XML meta data
• swarming

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Advantages

• Decentralized
• Robust difficult to shut down Gnet
• Real P2P system (peers have same roles)
• Search for any type of digital file
• potentially reach every computer on internet

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Disadvantages

• Unstable a client may shut down at anytime
• Queries may be dropped
• Traffic of each node can easily exceed modem
  capacity
• Due to distance limits, you do not search through
  the entire system

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Any Questions

• - God, please no question.