P2P can be a confusing subject, so I’m going to attempt to explain it simply. P2P downloading or Peer to Peer as it is known, is a method of downloading a file or collection of files (movies, music, programs, operating systems etc) from other downloaders known as peers, seeders and leechers rather than one website or server. This can be beneficial in many ways to different people. The websites/servers benefit by not having to distribute the files to hundreds or even thousands of downloaders and the downloaders can benefit by achieving fantastic download speeds.
Traditional downloading involves you (and others) downloading the file(s) from one server. This can produce huge server loads and costs to the server owners due to the expensive costs of a (large bandwidth) strong Internet connection i.e. thousands of times quicker than yours.
To start downloading a torrent, you need a .torrent file which contains information about which file(s) you wish to download from others (the swarm – explained later). Or, nowadays, you can use ‘Magnet Links’ which contain all the information required in the click-able link (URI) instead of a .torrent file. This voids certain legal issues with distributing illegal copyrighted material.
Torrent downloading involves the file(s) being chopped up into hundreds/thousands of small chunks. When you go to download the file(s), all of these chunks are downloading from hundreds of other people that are currently downloading the file(s) as well (called leachers or peers) and people that have already downloaded the file(s) and are offering the small chunks to other people who wish to download them (called seeders). This way everyone is downloading the file(s) chunks from another person and intern you will upload the chunks you have downloaded to someone else. Thus removing the need for one server to dish out the file to everyone.
This community of uploading and downloading chunks of the file(s) to each other is called the “swarm“. The more people that try and download the file(s), means there will be more people offering the file(s) to you, hence the more people involved in this swarm the quicker the download can become.
When you start downloading the file(s) your are called a leecher as you are downloading chunks from the swarm but not uploading any back as you have none to upload yet. Once you have downloaded some of the file(s) you are called a peer – you are uploading chunks to the swarm as well as downloading them. Once you have successfully downloaded all of the chunks you then are called a seed as you are uploading chunks to the swarm but are no longer downloading them, you also have the option to stop being a seed by stopping all uploading and downloading to and from the swarm.
Safety & Legality
As P2P downloading is favoured by pirates (people who download illegal software or license) because there is no one to blame for serving the illegal files(s) to the pirates/downloaders (The website that is most commonly used for this purpose is https://thepiratebay.se/ also known as TPB which is based around file sharing.) the forces use the P2P networks/swarm to find and convict the pirates. Do Not Panic! if you are downloading legal files i.e. non copy righted software and media you are safe and you will NOT be punished or prosecuted. As you are doing nothing wrong. (an example of a legal torrent download can be Ubuntu (an alternative OS), which can be found at https://www.ubuntu.com/download/desktop/alternative-downloads)
However pirates have there ways to beat the system.
Most of the main BitTorrent clients (the software which allows you to connect to others and download the files) such as Transmission and uTorrent allow you to specify a list of suspected enforcement and legal firms IP addresses, thus further minimising the risk of getting caught. In Transmission – you can simply add an online blacklist in the preferences. The most commonly used blocklist is “http://www.bluetack.co.uk/config/level1.gz”.
You can also force (or enable) encrypted connections only, which encrypts some of the data transferring between you and your peers.
I would recommend having an auto-stop ratio set for your seeding, i.e. when you have shared the file(s) to others it will stop seeding the file(s). As seeding will slow down your internet speed drastically. That said, turning off seeding all together can negatively impact your download speed of the file(s) in question.
Speed & Optimisation
When you first install your torrent client of choice, it will come with some preset settings, normally about which port to use and number of connections etc. To allow quicker/better connections to the swarm you should forward the port (that the client suggested) from your router to your computer. You can also change your ‘number of connections’ settings to optimise downloading speed, to work out the optimum settings for your broadband connection speed, head over to http://infinite-source.de/az/az-calc.html.
Some completely idiotic governments (including mine) have started censoring the Internet (not only that, but they are doing it wrong, so wrong – but that’s another story). If websites such as TPB are blocked in your country feel free to use Tor, to get around this. You can download a very simple Tor solution here.
This post is for education purposes only as SOME forms of peer to peer downloading are illegal and can temporarily and greatly affect your (and others) Internet connection/speed not to mention the legal ramifications. If moral obligations still don’t stop you from pirating software at least purchase a legal version of software you like after you have tried (pirated) it, as if you like it, surly you would’t mind rewarding the developers – P.S. this was written a long time ago, I just forgot to publish it.