Torrent technology


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Torrents and Tochnology

Working, usage and Features

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Torrent technology

  2. 2. CONTENTS • Introduction • Working • Terminology • Features • Drawbacks • Countermeasures
  3. 3. INTRODUCTION • What are Torrents ? • tor·rent (/ˈtôrənt/) • In the BitTorrent file distribution system, a torrent file is a computer file that contains metadata about files and folders to be distributed, and usually also a list of the network locations of trackers, which are computers that help participants in the system find each other and form efficient distribution groups called swarms. • A torrent file does not contain the contentto be distributed; it only contains information about those files, such as their names, sizes, folder structure, and cryptographic hash values for verifying file integrity. Depending on context,a torrent may be the torrent file or the referenced content.
  5. 5. • A torrent file is a specially formatted binary file. It always contains a list of files, integrity metadata about all the pieces, and an optional list of trackers. • A torrent file is a bencoded dictionary with the following keys: • Announce : The URL of the tracker • Info : this maps to a dictionary whose keys are dependenton whether one or more files are being shared: • Name : suggested file/directory name where the file(s) is/are to be saved • Piece length : number of bytes per piece. This is commonly 28KiB = 256 KiB = 262,144 B. • Pieces : a hash list. That is, a concatenation of each piece's SHA-1 hash. As SHA-1 returns a 160-bit hash, pieces will be a string whose length is a multiple of 160-bits • Length : size of the file in bytes (only when one file is being shared) • Files : a list of dictionaries each corresponding to a file (only when multiple files are being shared). Each dictionary has the following keys: • Path : a list of strings corresponding to subdirectory names, thelastof which is the actual file name • Length: sizeof the file in bytes. All strings must be UTF-8 encoded.
  6. 6. SAMPLE DE-BENCODED TORRENT FILE • Here is what a de-bencoded torrent file (with piece length 256 KiB = 262144 bytes) for a file debian- 503-amd64-CD-1.iso (whose size is 647 MiB = 678301696 bytes) might look like:
  7. 7. WORKING
  8. 8. HOW IT WORKS !?! • When we uploada torrent on a tracker’s site, Its tracks the transfers of the files happeningbetween the uploaderand the persons who downloadthe torrents from that site. The connectionsare announcedto all the peers and TCP connectionsare setup. • A seeder to leecher ratio is maintainedand feedbacks are stored for further downloads.
  9. 9. TERMINOLOGY • Client : The program that enablesp2p file sharing via the BitTorrent protocol.Examples of clients include µTorrent and Vuze.
  10. 10. • Fake : A fake torrentis a torrent that does not containwhat is specified in its name or description (e.g. a torrent is said to contain a video, but it containsonly a snapshot of a moment in the video, or in some cases a virus). • Health : Health is shown in a bar or in % usually next to the torrent’sname and size, on the site where .torrent is hosted. It shows if the pieces of the torrentare available to download (i.e. 50% means that only half of the torrent is available). A torrent with higher number of seeds will be healthier.
  11. 11. • Index : An index is a list of .torrent files (usually includingdescriptionsand other information) managed by a website and availablefor searches. An index website can also be a tracker. • Leech : Leech has two meanings. Often, leecher is synonymouswith downloader(see above): simply describinga peer or any client that does not have 100% of the data. The term also refersto a peer (or peers) that has a negative effect on the swarmby having a very poor share ratio, downloadingmuch more than they upload. Leeches may be on asymmetric internet connections or do not leave their BitTorrent client open to seed the file after their download has completed.However, some leeches intentionallyavoid uploadingby using modified clients or excessively limiting their upload speed.
  12. 12. • Peer : A peer is one instanceof a BitTorrent client running on a computer on the Internet to which other clientsconnect and transfer data. Usually a peer does not have the complete file, but only parts of it. However, in the colloquialdefinition,"peer" can be used to refer to any participantin the swarm (in this case, it's synonymouswith "client"). • Piece : This refers to the torrented files being dividedup into equalspecific sized pieces (e.g. 64kB, 128kB, 512KB, 1MB, 2MB or 4MB). The pieces are distributedin a random fashionamong peers in order to optimize trading efficiency.
  13. 13. • Seed : A Seed refers to a peer possessing 100% of the data. When a leech obtains100% of the data,that peer by definitionbecomes a Seed. Seedingsolenmly refers to leavinga peer's connection availablefor other peers, i.e. leeches, to downloadfrom. Normally, a peer should seed more data than leech. However, whether to seed or not, or how much to seed, is dependent on the availabilityof leeches and the choice of the peer at the seeding end.
  14. 14. • Tracker : A tracker is a server that keeps track of which seeds and peers are in the swarm. Clientsreport information to the tracker periodicallyand in exchange, receive information about other clientsto which they can connect. The tracker is not directly involvedin the datatransfer and does not have a copy of the file.
  16. 16. FEATURES • Full Selectivity : There is full selectivity of files. We can choose the files which we need and ignore the junk files from a torrent.
  19. 19. STATISTICS
  22. 22. MORE FACTS AND FEATURES • Torrents with high seeds to peer ratioscan achieve up to 30MB/s of downloadingspeeds which is not frequently possible for a single server. • Torrents work at no profit no loss. Not even a single person is benefittedat all by sharing torrents. • Basicallyit’s a free service and wealth is only generatedby advertisements. • Torrents work on P2P connectionsand thus are not dependent of any particularclient or server. • Bit-Torrent networks use maximum bandwidthand they have increased internet usage 20 to 30 % data annually.
  23. 23. PROBLEMS AND DRAWBACKS Piracy is the major drawback of torrents. Torrents include billionsof piratedsoftware. Distributionof copyright contentis very easy on Torrent directories and are a big threat to Companies and firms.
  24. 24. MISGUIDING ADVERTISEMENTS Advertisements sometimes confuse a user and once clicked, One has to pay for that mistake. Those scripts run Maliciousand Infected Programs on the machine and force the user to download junky material.
  26. 26. PIRACY AND CYBER LAWS • All these cracks are a means of piracy on the internet. • Using crack softwares is a crime in many countries and the penalty dependsupon the nations’Cyber Law. • According to Section 63 of the Act 1994 of Indian Cyber Law, there is a minimum jail term of 6 months for copyright infringement. • The section also provides for fines up to Rs. 2,00,000 and jail term up to three years or both. Any person or company who indulges in unauthorizedcopying, sale, downloadingor loading of software is punishableunder this section. • Distributionof pirated softwares is also a punishableoffence. All such people are committing offences under Section 66 of Information TechnologyAct, 2000 and are therefore punishableunder Section 66 of the Information Technology Act
  27. 27. VULNERABILITIES AND KEYHOLES • Torrents works on specific ports, So a hacker can step into our machine by those ports by following methods : • He can intrude as a seeder of a torrent which contain a Trojan • Through chat rooms of torrent clients, He can get valuable information • Cracked and Pirated softwares frequently containa virus thus infected users can be used as bots. • Downloadedfiles may not containthe files mentionedin the description So fake torrents are a waste of time and money as well.
  28. 28. SECURITY AND COUNTERMEASURES • Never trust any crack or keygen • Ensure the reputationof the file • Check the links before clicking • Downloadtorrents from verified and trusted sites only • Use original Softwares, So prefer buying them • Be aware in the social chat groups
  29. 29. THANK YOU
  30. 30. Harshvardhan Malpani B.Tech 2nd year student MaharajaAgrasen Institute of Technology Affiliatedto GGSIPU August 2013 Summer Training(Cyber Security, i3indya)
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