How to download torrents via UDP links in Torrent Trackers

bittorrentudp

Let's say you were searching for something on a torrent site, and instead of the usual .torrent file or a magnet link, you were presented with the image below:

list of UDP links and Torrent Trackers

What would you do next to download the torrent?

I'm new to UDP links and "Torrent Trackers" and need a tutorial on how to use them.

(In case it matters, my bitTorrent client is PicoTorrent, and it has features for downloading only .torrent files or magnet links)

Best Answer

Those are not download links. This table is just part of the information you'd normally find in the .torrent file, or in the Magnet link.

The purpose of trackers is only to track which other peers have the same torrent, often alongside another method called DHT ("trackerless"). However, you still need to know what to ask them for.

The main identifier of a BitTorrent download is the "hash" or "infohash", usually shown as 40 hexadecimal digits (although your screenshot is missing two of them) or 32 Base32 digits.

Knowing it, you can create a Magnet link that most programs will recognize, using just the xt=urn:btih:<INFOHASH> parameter. (Note that most clients require the infohash to be converted from hex to Base32.)

magnet:?xt=urn:btih:A1B2C3...

With this, your client will be able to download the remaining information (first the .torrent file, then the actual data) using DHT. You can also specify a list of trackers as tr=<URL> parameters, for example:

magnet:?xt=urn:btih:abcdef...&tr=http://example.com/announce&tr=udp://example.net:1234/announce&tr=...

(As in many HTTP URLs, the parameters start after ? and are separated by &'s.)

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