Transcript GNUTELLA
GNUTELLA PEER-TO-PEER NETWORKING GNUTELLA What is Gnutella Relation to the World Wide Web How it Works Sites / Links / Information WHAT IS GNUTELLA DEFINITION Protocol that allows for peer-to-peer networking/communicating Decentralized applications, were each user can act as a server General public network, and private networks in isolation or attached to the public ones Enables transient computers to effectively participate as servers WHAT IS GNUTELLA Search for information anonymously (you control what you look for) Allows user to determine what information they wish to make public Can choose what information to share – share nothing – one file – a directory – or your entire hard drive WHAT IS GNUTELLA CREATION First created by Nullsoft (developers of Winamp) Protocol developed by them in 1999 Many developers have created compatible code Gnutella network exists only to the extent that these developed programs are running and communicating with one another RELATION TO THE WWW Gnutella hosts are web sites (although transient, equivalent to fetching a file from a web site) Allows for P2P file sharing, but file transfer is accomplished via HTTP (the same protocol as web browsers and severs) Each Gnutella application contains a web server component for serving files and a primitive browser element for retrieving them RELATION TO THE WWW TRANSIENT WEB WWW uses hyperlinks, under the assumption that content remains accessible under a fixed URL and server Some computers/servers at a given IP address may not be the same, day-to-day, hour-to-hour, minute-to-minute, therefore they are transient RELATION TO THE WWW ADVANTAGES Augments HTTP with additional means to locate transient web sites Traditional search engines cant find transient web sites Decentralized, so no single responsible company, no central server, and no single point of failure Anonymous searching (hosts are random users, not dedicated servers / search engines) RELATION TO THE WWW ADVANTAGES Distribution / searching is free, no promo’s. Provides “superdistribution” users who download content can easily become redistributors. RELATION TO THE WWW DISADVANTAGES Search capability, no guarantee your query will reach the sites/users holding what you seek Search results are unorganized Puts PC end-user data at risk of unauthorized or unintentionally authorized exposure. Cascading effect once files are shared or made available, others can redistribute them Individual nodes/users can become overloaded since broadcasting info (scaling) HOW IT WORKS CONNECTING You can be a fully functional Gnutella site by installing any of several available clients: WINDOWS Gnucleus BearShare Morpheus Swapper XoloX LimeWire Phex UNIX Gnewtellium Gtk-Gnutella Mutella Qtella LimeWire Phex MACINTOSH LimeWire Phex HOW IT WORKS CONNECTING Get connected to WWW Next you have to find a few sites that are willing to communicate with you: – some may be friends – others may be advertised Gnutella sites HOW IT WORKS Searching by flooding: If you don’t have the file you want, query 7 of your partners. If they don’t have it, they contact 7 of their partners, for a maximum hop count of 10. Requests are flooded, but there is no tree structure. No looping but packets may be received twice. Reverse path forwarding(?) Gnutella Demo: http://www.capnbry.net/gnutella/ss.php Note: Play gnutella animation at: http://www.limewire.com/index.jsp/p2p HOW IT WORKS (Gnucleus) HOW IT WORKS (Gnucleus) HOW IT WORKS SEARCHING use key words only do not use astriks, wild cards, dashes, commas, or periods search results are immediate processed by everyone connected new connections made while searching will also be searched and results added no re-search function needed GNUTELLA: QUERY Query Query Query Hit Query Hit Query Hit Query Query SITES / LINKS ADDRESSES www.gnutella.com www.openp2p.com FAQ’s www.gnutellaforums.com www.gnutellanews.com www.gnutelliums.com GNUTELLA & FREENET Freenet: – bandwidth and disk space sharing concept for promoting free speech – very large & geographically distributed hard drive with anonymous access – Each file is assigned a complex unique identification – To search for files, need to search via that unique identification code Gnutella: – Searching and discovery network promoting free interpretation and response to queries – Gnutella nodes to give hits in the form of filenames, advertising messages, URLs, graphics, and other arbitrary content CONCLUSIONS The key challenge of building wide area P2P systems is a scalable and robust location service –Naptser: centralized location service –*Gnutella: broadcast-based decentralized location service –*Freenet: intelligent-routing decentralized solution (but correctness not guaranteed; queries for existing items may fail) REFERENCES Gnutella – http://gnutella.wego.com Freenet – http://www.freenetproject.org/index.php?page=icsi-revised – Freenet: A Distributed Anonymous Information Storage and Retrieval System, Ian Clarke, Brandon Wiley, Oskar Sandberg and Theodore W. Hong\ – www.freenetproject.org – www.oldhat.org/freenet/content.html – P2P Dynamic Networks – www.developer.com/java/ent/article.php/10933_1496861_1