Creating a torrent

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Revision as of 00:13, 19 March 2007 by Jerry bond (Talk | contribs)
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Terminology and functions:

Torrent = an infohash enabling a tracker to supply information to bit-torrent clients.
Swarm - all the peers who are connected, sharing a torrent. 
Peer - each user who is sharing a file using a bit-torrent client, either seeding or leeching. 
Seed = upload to others.
Leech = download for self.
Client - the program each user launches to connect to others via the bit torrent protocol. KTorrent is the default BT client in Mepis.
Tracker = server that keeps track of who has the complete file to share, and who wants it. 
Chunk = a designated segment of the shared file for transfer. Each chunk is of equal size, specified when the .torrent file is created.
Error-correction - Each chunk is checksummed when it finishes downloading. If it is defective, the chunk is scrapped and downloaded again.

This howto is for using, but you can apply similar steps for other trackers. To upload a torrent on LinuxTracker you need an account (it's free)

  1. Start KTorrent
  2. Go to File -> New -> In the new window, the top line will ask you to specify what file you want to make a torrent for. Use the drop-down to choose the the file you want to share. You might have to navigate to the directory of all your file-transfer files.
  3. File Options:
    1. Size of each chunk: default is 256 KB which is probably a good choice
    2. Start seeding the torrent: check this.
    3. Private Tracker: uncheck. You'll be using a public tracker.
    4. You must add at least one tracker: type or paste in the URL: and click the "add" button.
    5. Click "Create" at the bottom.
    6. A new window will display with the file-list of every folder and torrent in the directory where your file you want to load is located. Paste the filename in the lower "Location box" Get it exactly the same as your file-name.
    7. After pasting in the filename, make certain the original extension is also part of the name in the Location window. Check "Automatically select filename extension (.torrent)"

KTorrent will take a few moments to digest your file and create a file called something like: filename.iso.torrent

Now, listing the torrent:

  1. You must go to and sign in your username and password. The page reloads, and under the Logo will appear "Welcome [username you logged as]"
  2. In the left-column, about halfway down the page is a blue box "Torrents" with
Upload, and you will click on upload.
  1. A new page loads, the salient portion of which is: "Upload A Torrent"
  2. Torrent file: browse to your newly created filename.iso.torrent file and click to load.
  3. NFO file: not needed for a Linux distro ISO ; leave blank
  4. Screenshot: you can skip this option or add a screenshot that's representative for your file.
  5. Torrent name: Make it accurate and specific, but it's a headline to communicate information at a glance, not the precise filename of the ISO. Keep it brief, accurate and easy to read.
  6. Description: here is a text box. The only caveat in this section is that you must use html/bb codes for mark-up <p> must go between every paragraph, <b> text</b> gives you boldface, etc.
  7. If you upload a MEPIS ISO go to type, run down the list in the drop-down to "MEPIS"
  8. click the little "upload torrent" button.

Points to remember

  1. You don't upload the ISO itself to the tracker at linuxtracker. The ISO stays on your machine which becomes the "server" to everyone else, and as they get 100% of the file, they also become "servers." In the bit-torrent protocol, computers serving to downloaders are "seeds." When you start a torrent, you are the first seed.
  2. What the person who starts the torrent needs to do is this: Within the torrent file itself, when KTorrent is getting the info together to write the file, you need to specify the URL of the tracker you're going to use. In this tutorial, we're using as the URL of the tracker.
  3. Then, after the .torrent file is made, only that small .torrent file gets uploaded to, via their "upload a torrent" script/form.
  4. When creating the .torrent file, you must specify a chunk size. Setting the optimal chunk size for your ISO involves a sliding scale. Normally, chunks are between 64 KB and 1 MB in size. The larger the chunk size, the smaller your newly-created .torrent file will be, and the faster it will be generated by KTorrent. But that means there are fewer chunks, and leechers will spend more time DL'ing each chunk. If it's bad, it gets thrown away and has to DL again. So larger chunk size can mean a slower overall conversion of leechers to seeders, slowing up the maturity of the swarm as a whole. This is why I suggest using the KTorrent default of 256KB per chunk: a happy medium for an ISO of approximately 675 MB. With approximately 2700 chunks, each 256KB chunk can be DL'd in less than a minute under ordinary speeds in a good, moderately mature swarm. And the .torrent file is only 40KB to 100KB in size --not all that large.
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