What Is A Magnet Link And How Does It Differ From Torrents?
If you have visited a Bittorrent website or torrent search engine lately you might have come upon magnet links that were offered on the torrent download pages. Chance is the magnet link did not really bother you since the torrent link was offered as well on the download page so that it could be downloaded and added to the Bittorrent software.
A click on the magnet link might add it to the torrent client that is used on the system as well provided that it supports magnet link and is the program mapped to this type of link on the device.
A closer look at the standard process of downloading files via torrents reveals several factors and parties that are necessary for this. The user needs a Bittorrent client like uTorrent or qBittorent, a torrent file that is usually downloaded from a Bittorrent server which functions as a tracker and torrent provider and of course peers that seed the torrent or download it as well.
A Bittorrent magnet link has all the information needed to start downloading the files from peers directly. It is a server-less way of retrieving the right information to start downloading the requested files. A magnet link therefore is theoretically all that is needed to download files from other peers in the Bittorrent network. Magnet links can be distributed by email, messaging and other forms of communication but are most often found on the torrent sites that usually offer both torrent and magnet links to their users.
A magnet consists of several parts:
- magnet: (This is the magnet link identifier)
- ?xt=urn:btih: (Defines a Bittorrent Info Hash, the Edonkey identifier would for instance look like this xt=urn:ed2k:)
- 5dee65101db281ac9c46344cd6b175cdcad53426 (The content hash)
- &dn=name (The name of the file)
The full magnet link would look like this magnet:?xt=urn:btih:5dee65101db281ac9c46344cd6b175cdcad53426&dn=download. Detailed information about additional Magnet Link parameters are listed on Wikipedia. One useful parameter that has not been mentioned yet is the as= parameter which contains encrypted information about a download source. This speeds up the process of finding the first peers.
Main Advantages of Magnet Links
The main advantage for Bittorrent indexers is that they do not have to store the torrents on their servers anymore which could be beneficial for them in several ways. It could reduce the pressure from the media creation industry and reduce bandwidth costs significantly considering the smaller size of magnet links (barely any) compared to torrents that sometimes have a size of more than 100 Kilobytes.
The end users on the other hand benefit from Magnet Links as well. All they need is the link to start downloading the files which makes them independent from torrent indexers. It also allows them to distribute the information more easily. Torrent indexers remain on the other hand the main source of information for new files that are available for download.
Magnet Links use DHT
A tracker less environment should raise a question of identification. How can a download be initiated ff there is no tracker to inform the Bittorrent user about other users who download and seed the file? The answer is DHT, Distributed hash tables. DHT is enabled by default in popular clients such as uTorrent or Vuze. Without going into to much detail, the hash of the magnet link is used to find peers using DHT.
Torrents are still essential for Bittorrent as they contain information about the download that need to be present in the swarm. The only aspect that is changing is the way the torrents are distributed which is shifting from Bittorrent trackers and indexers to the server-less DHT procedure.