1. BitTorrent How it applies to networking

2. What is BitTorrent P2P file sharing protocol Allows users to distribute large amounts of data without placing a heavy burden on their computer Similar to packets, it breaks a file into small chunks, usually 512 K. Done over TCP/IP, but several small requests are sent to different machines (the packets)

3. How it works Seed- the provider of the file Publish it to the network- creates a torrent file Contains metadata about files to be shared with tracker -tracker- the computer that coordinates the communication between peers with the bit torrent protocol. Can be public or private Each client is required to communicate with the tracker to initiate downloads, and those that have already begun downloading communicate periodically to negotiate with newer peers and provide statistics

4. How it Works Continued Peers- those that connect and download the seed file. The initial peer will connect directly to the seed and request chunks, then as more peers are added, chunks are requested from different peers Once multiple peers have multiple pieces of the seed, they also become “seeds” of the file. Health of the file Downloads in random or “rarest first approach” The purpose of bit Torrent is to “swarm” so that the download has a good chance of success.

5. *.Torrent File Contents Similar to GET/POST method Contains URL of tracker as well as info of files SHA-1 hash code- verify integrity -In trackerless systems - every peer becomes its own tracker, done through DHT. Each chunk becomes a key and a value similar to a hash table. Requests are sent to receive each file chunk using the keys

6. Bit Torrent Public vs Private Public- anyone can download- sometimes filled with viruses. Private- only certain users are allowed to connect. Usually have tons of illegal files Both offer Protocol Header Encryption ISP cant tell what kind of traffic it is Both expose IP addresses in the tracker even when done downloading

7. Torrent In Action

8. Problems with Bit Torrent Bandwidth Hog

9. Problems Leeches Hard to get files if not popular Easy to track, risk of getting sued and attacked

10. How to Setup your own Torrent System Your own private peer to peer torrent system OneSwarm- developed at University of Washington http://oneswarm.cs.washington.edu/screencasts/ove rview.mp4

11. One swarm in practice First I linked two gmail accounts as friends

12. OneSwarm

14. Other alternatives to Torrent Pure Private Peer to Peer, over VPN Gbridge from google

15. Other