3/27/2012 Peer-to-Peer Technology Priscilla Grantham, Esq. Sr. Research Counsel National Center for Justice and the Rule of Law Copyright © 2012 National Center for Justice and the Rule of Law NCJRL. org ICAC Webinar series 1 WEBINAR TIPS: 1. To reduce background noise, please: • Power off cell phones • Turn down (or mute) computer speakers if accessing webcast through telephone 2. The presenter is utilizing VoIP (Voice Over Internet Protocol) technology to deliver the audio portion of the webinar. In the event the audio malfunctions, please stand by; the presenter will quickly re‐join the webinar via telephone and continue the presentation. 3. Attendees will be muted during webinar in an effort to reduce background noise. 4. If you want to ask a question, type it in the chat box in the control pane on the right side of your screen, and then click the “send” button. 5. Questions are typically addressed at the end of the presentation. 6. 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Type Question WEBINAR in this Box NCJRL. org 1 3/27/2012 Topics: • P2P networks & P2P clients • P2P computing v. client‐server models • Advantages of using P2P networks • Potential risks associated with P2P • Architecture of P2P networks • Centralized v. decentralized P2P networks • Evolution of P2P networks • BitTorrent P2P protocol and its components • Anonymous and Private P2P networks 4 P2P Technology: • Efficient, robust means to distribute a wide range of content including software, games, books, movies, music, etc. • Wikipedia complied a CD with over 2,000 articles specifically for schools and children – made it available for download on P2P network. • Researchers share data and computer code. • Used by NASA to distribute satellite imagery. 5 Peer-to-Peer Networks Network consisting of thousands of computers connected to each other • Main feature: No central server • Main use: Acquiring files • Examples: BitTorrent, Gnutella 6 2 3/27/2012 P2P: Networks v. Clients P2P Networks: P2P Clients: Napster Shareza BitTorrent Gnutella BearShare eDonkey eMule Gnutella2 (G2) Warez BitTorrent Frostwire 7 Traditional File Transfer Methods: • Referred to as client‐server file transfer. • Transfer handled by a protocol such as FTP (file transfer protocol) or HTTP (HyperText transfer protocol). • Desired file located via web browser; • File is downloaded from a single source, the file server, by the destination computer, the client. 8 I open web page, click Web browser software on my link to download file computer tells a central computer that holds the Web page & file I want to transfer copy of the file to my computer. Transfer speed depends on factors such as: protocol used (FTP, HTTP), amount of traffic on server, # of computers trying to download same file. If file is large and popular, demands on server will be great and download will be slow. Server could crash. 9 3 3/27/2012 Benefits of P2P: • Client machines are peers and communicate directly with one another. • Users of P2P tend to be contributors and consumer. • P2P approximates original conception of Internet as network of connections among individuals & organizations that give and take info. • P2P networks tend to be faster and more reliable –no reliance on central server to deliver content. 10 Downsides of P2P: • P2P networks have been used to transmit viruses, malware, mislabeled/corrupted files. • Those who inadvertently placed sensitive materials in network‐shared directories have been victims of identity theft. • Music and media files easily distributed in violation of copyright laws. 11 Test Your Knowledge: The software that enables one to share files over a P2P network is called a: A. P2P client B. Swarm C. Server D. Peer There are many clients available online that can be downloaded free of charge. Some examples are BearShare, Frostwire, Shareza, Limewire (defunct)… 12 4 3/27/2012 The Evolution of P2P Networks: It all started with Napster… “Central Server Model” • Start Napster software on my computer –now my computer can make files available to other Napster users. • My computer connects to Napster’s central servers. • My computer tells the Server which files are available on my machine. • Napster central servers contain complete list of every song, for example, available on every hard disk connected to Napster at that time. 13 Downloading a Song Via Napster: • I type in my query: “Roxanne” by the Police • Napster’s central servers list all the computers storing that song • I choose a version of the song from the list • My computer connects to the user’s computer that has the song, and downloads “Roxanne” directly from that computer. 14 Napster ordered to shut down due to copyright violations… No central database = No Napster 15 5 3/27/2012 Enter Gnutella: • 1st decentralized P2P network • No central database that knew all files available on Gnutella network • Unlike Napster, many different client programs available to access Gnutella network. 16 Downloading a File Via Gnutella P2P Network: • Run Gnutella‐compatible file sharing software on computer. • Send out request for desired file. • Software sends query to computers connected to Internet that are running the same software. • Software finds a computer with the file I want on its hard drive, download begins. 17 • Gnutella had problems with spamming bots and lost popularity. • FrostWire: leading file‐sharing application on Gnutella network after Limewire was shut down. • FrostWire left Gnutella last year and focused on BitTorrent • Some clients still available for the Gnutella network (Phex) but today, most clients operate on BitTorrent platform 18 6 3/27/2012 BitTorrent Protocol: • Enables fast downloading of large files using minimum Internet bandwidth. • Offloads some of the file tracking work to a centralized server (called a Tracker). • Uses “tit‐for‐tat” principle: in order to receive files, you must give them. 19 BitTorrent – Basic Terms: • Tracker –a server that assists in communication among peers. BitTorrent client software communicates with the tracker to locate the Swarm. • Swarm – All of the computers that contain all or part of the file being sought. • Seed –the computers in the swarm that contain the entire file being sought. • Leechers – commonly refers to people who disconnect after receiving entire file so others cannot obtain file from them. 20 BitTorrent v. Gnutella: • With BitTorrent, pieces of desired file are gathered from multiple computers and downloaded simultaneously. • Once a computer begins downloading a file, other computers seeking same file can begin downloading from it. 21 7 3/27/2012 Downoading a File Via BitTorrent: 22 BitTorrent Explained: http://video 23 Test Your Knowledge: Which P2P network is an example of a Centralized server model? A. Gnutella B. Napster C. BitTorrent D. GigaTribe Napster featured a centralized server that kept a list of every song available on every hard disk connected to it at that time. 24 8 3/27/2012 Downloading Via BitTorrent: • Download (free) BitTorrent client: BitTorrent, uTorrent… • Find a torrent file to download. Enter term “.torrent” using Internet search engine to find sites offering BitTorrent files • The Pirate Bay • Torlock • isoHunt • TorrentSpy • Mininova • Jamendo 25 26 • Swedish website • Bittorrent tracker –none of the copyright‐ protected files users swap ever sit on the site's own servers. • Allows users to search for and download torrents, small files containing metadata necessary to download data from other users. • Torrents organized into categories: “Audio”, “Video”, “Applications”, “Games”, and “Porn” 27 9 3/27/2012 I’ve got a torrent file of Countdown’s album “Break Rise Blowing” from the website Jamendo. Website Torrent 28 • Now I save torrent file to my hard drive, • Open torrent file in my BitTorrent client program, and • Start downloading. 29 30 10 3/27/2012 Test Your Knowledge: The role of the Tracker in the BitTorrent network is to maintain an index of all files available for trading. A. True B. False The Tracker communicates with the BitTorrent client (software) in order to locate the swarm (all of the computers that contain all or part of the file being sought.) 31 Anonymous P2P: • Nodes or participants are anonymous or pseudonymous. • Special routing overlay networks hide physical location of each node from other participants. • “Anonymous P2P”‐ network nodes carry no identifiers. • “Pseudonymous P2P” –instead of being identified by their IP addresses, nodes are identified by pseudonyms such as cryptographic keys. • Difficult, if not impossible to determine whether a node that sends a message originated the message or is simply forwarding it. 32 Motivation for Anonymity: • Material or its distribution is illegal or incriminating • Material is legal but socially deplored, embarrassing, or problematic for the individual • Fera od retribution (against whistleblowers or activists who don’t believe in restrictions on information • Censorship at local, organizational or national level • Personal privacy preferences such as preventing tracking or datamining activities 33 11 3/27/2012 Genesis of Anonymous P2P: U.S. Navy funded the original onion routing research that led to the development of the Tor network, which was later funded by Electronic Frontier Foundation and is now developed by the non‐profit organization The Tor Project, Inc. 34 Arguments Against Anonymous P2P: May protect illegal activities