If you've been scouting popular torrenting sites like The Pirate Bay or Lime Torrents for a while, you've probably noticed a confusing link adjacent to the download file. Well, have no fear: magnet links are simply one of the increasingly popular ways to download media online.
What is a Magnet Link?
To put it simply, a magnet link is a hyperlink that gives you direct access to a hash code for a torrent file. Backing up for a second, a hash code is the technical term for a numeric value that uniquely identifies a package. When you access a website using its URL, you're asking a distant server to essentially hash your request so that it can provide the webpage you want.
Similarly, a magnet link can immediately configure with any torrent client to find valid peers sharing the same file. Magnet links employ DHT, also known as distributed hash tables, to seamlessly locate the IP address of sharing peers.
Trackerless torrenting is often used interchangeably with the term magnet link, though the former term is an umbrella category that encompasses a broad number of distributed technologies.
How Does a Magnet Link Actually Work?
If the nitty-gritty details turn you off, it's probably best that you skip to the next section. Otherwise, we'll briefly dive into some of the more hairy details of how these super small bits of information function in the real world.
Magnet links, or Magnet URIs (uniform resource identifiers), consists of several compact arguments that are formatted as question and answer strings.
Let's look at the “about file” of a common magnet link: magnet:?xt.1=urn:btih:c456949sjsj334bba781688b&xt.2=urn:sha1:7777888banjsk251a
The “magnet:” keyword is fed one or more parameters, just like how algebraic functions identify variables with letters. Most importantly, the “xt” argument refers to the “exact topic” that is fed to the torrent client to search for the desired media. In the example above, we're searching for one download file that's broken up into two pieces, xt.1 and xt.2.
The question mark after “magnet:” means that we're asking for information split up into queries, or questions and answers values. Each parameter is followed by its explicit value with an equal sign while additional arguments are separated by the “&” symbol.
Check out this common example that demonstrates magnet link formatting:
magnet:?xl=[Size of the file]&tr=[Optional tracking URL]&xt=urn:[URL that directly links to a file's hash code]
For a fun side project, try examining the magnet links on the torrenting service you normally use. You'll know if your site blends magnet links with traditional tracker based torrenting if a “tr” argument is supplied. Some sites use specific hash-decrypting algorithms, information packaging, and specific security techniques to keep your personal data private from peers.
What are the Advantages of a Magnet Link?
Compared to traditional .torrent links and download files, magnet links reduce the number of steps it takes to access media. Traditional .torrent links require that you download a file containing the hash code needed to locate the desired content. This hefty file contains the name of the desired media, a URL for the torrent tracker, and other important metadata.
Using the small file, your default BitTorrent client will calculate the hash code needed to connect to peers. By contrast, magnet links immediately trigger your default client to request online media from sharing peers. No additional files needed to be decrypted and the link will never request services from an intermediate BitTorrent tracker.
Now that magnet links and DHTs have become the industry standard, BitTorrent trackers are becoming somewhat obsolete. However, some services, such as uTorrent and Deluge, still use trackers in order to speed up the process of peer discovery.
Additionally, magnet links are much easier for bloated file-sharing sites to host. Traditional files may require kilobytes of extra data, since the actual content itself is directly traced back to the site. On the other hand, magnet links just contain the identification number for media, which makes them comparatively smaller in size.
Funnily enough, you've probably been using magnet links without even realizing it. The more attentive torrent aficionados may have noticed that it takes two or three fewer clicks to download content.
Torrenting Sites are Switching to Magnet Links
Nowadays, many sites are slowly phasing out .torrent files, download links, and other tracker-based technologies. As The Pirate Bay and other flagships face mounting legal trouble, it becomes important for the site to obfuscate its relationship to copyrighted material.
Since magnet links merely contain a string of numbers and letters, they aren't directly tied to the illegal content provided through peers. The weight falls on your default torrent client, which is now doing all the work to pair you with movies, music, and other media.
It's unclear whether magnet links will hold up in court. But, for now, they provide an extra guarantee of legal protection to your favorite torrenting services.