Magnet URI scheme
A magnet link is a URI standard for hyperlinks pointing to files. It contains at least one unique identifier ( hash value ) of the target file, the basis of which by means of a (possibly remote ) database, the location of the linked file can be resolved. Magnet links allow you to refer to one or more files without the need to take this into account where they are stored or that the reference is invalid. They are particularly used in conjunction with peer-to -peer networks. Magnet links are therefore to be regarded rather as URNs and less than URLs because they do not identify the location, but the content.
A magnet link is comparable with an ISBN (book number) in the sense that only a certain content is called (a " resource" ). Two different files have practically never the same magnet - link, however, has the same file, which is found in various places on the Internet, getting the same hash sum in her Magnet link (and thus is the central link in the identification block identical). This is just like in ISBNs: Two different books never the same ISBN, but a particular book is always the same independent of the location ID number.
In contrast to the ISBN ( book numbers) magnet links are automatically generated from the file content. There is no central organization needed for number assignment. For this reason, they serve as "guarantees valid " keyword in peer-to -peer networks, which ensures that in fact nothing other than the intended distribution of the link file is downloaded.
Another advantage in the use of magnet links is the ease of use and platform independence. The same Magnet link can be used in various applications on almost any operating system to download. Because magnet links are short and precise, they may be using copy-and -paste into emails or called inserted as text lines while chatting easily, what is not so simple example with BitTorrent files. They can also be used on the Internet instead of regular URLs in websites and are easily integrated using the HTML link code.
Unlike other types of links (for example, HTTP or FTP) is the Magnet link no Uniform Resource Locator (URL), but a different type of Uniform Resource Identifier ( URI ), called Uniform Resource Name ( URN), because he does not call the location of the resource, so that one could obtain these directly. In peer-to -peer networks, this means that the resource must be searched first in order to find one or more so-called " sources " from which the file can be obtained. For this reason, use sharers mainly magnet links that contain only a hash value to identify the file. However, this is not the only way. In addition, even locations or alternative HTTP, FTP and other Internet sources can provide in order to avoid the overhead of the search or limit. Here is an example of a fully qualified Magnet link:
Magnet: xt = urn: sha1: YNCKHTQCWBTRNJIV4WNAE52SJUQCZO5C
In this example, the reference only contains a SHA1 hash value that uniquely identifies a file or resource. It does not disclose where the resource can be found. A suitable detection system is needed to access the file can, for example, the computer network of a peer-to -peer program.
Magnet: xt = urn: bitprint: XZBS763P4HBFYVEMU5OXQ44XK32OMLIN.HGX3CO3BVF5AG2G34MVO3OHQLRSUF4VJXQNLQ7A & xt = urn: ed2khash: aa52fb210465bddd679d6853b491ccce & xl = 6745696 & dn = Shareaza_220.127.116.11.exe & as = http://www.freebase.be/g2/dlcount.php?sha1=XZBS763P4HBFYVEMU5OXQ44XK32OMLIN
This example is a complete magnet link which contains both SHA1, TTH and ed2k hashes, as well as the size and name of a file. In addition, the link uses a BitTorrent tracker not dissimilar Freebase.be - cache to quickly find sources for download.
In the Magnet link system, various parameters in the form of name - value pairs are allowed. Here the most important:
- Xt represents "exact topic" and is followed by a URI.
- Xs stands for "exact substitute" and is followed by a URL, that corresponds to the classical hyperlink.
- As is "acceptable substitute" and may specify alternatives to xt.
- Kt stands for "keyword topic" and means that for resources with this file name to be searched using key words. The keywords are separated by plus signs.
- Dn stands for "display name" and are typically the file name, specifically a name under which the resource is presented.
- Mt stands for "manifest topic" and are using a URL to the location of a list ( ie a file), in which then contains the actual links.
To distribute a file using magnet links, the user creates the Magnet link by hand or with the help of a program, usually a P2P clients. He distributed the link then, for example, via websites, email or chat. Click another user on the link, its filesharing client resolves this usually on without the need of a central server using Distributed hash tables and / or network search. If ( a ) of the file residence (s) found, the download can begin.
A small selection of programs that can handle magnet links:
- Vuze is an open -source BitTorrent program that can treat some types of magnet links, if DHT is enabled.
- KTorrent - an open- source program for the KDE Desktop ( magnet links are supported as of version 4.0)
- LimeWire - an open source Gnutella Servent.
- Shareaza - an open source peer-to- peer program and download manager. Supports multiple networks simultaneously ( Gnutella, Gnutella2, eDonkey, BitTorrent ).
- UTorrent - A small (<1 MB) freeware, closed source BitTorrent client for Microsoft Windows and Mac OS X.
- Transmission - a free, resource-efficient BitTorrent client.
- StrongDC - an open source client for Direct Connect