Torrents, trackers and magnets

Torrents are the most “mainstream” way to download media content. This approach is based on torrent files that get shared between users: users will connect, via trackers to other users sharing the same torrent file. The basic concept behind torrenting is that the file you want to download is not stored on any server or anywhere on a centralized place on internet but instead every person who has a copy (or a partial copy) of the file is sharing it with the others who are looking for the same file. Basically is a decentralized approach to file sharing. Each user downloading (leecher) or sharing (seeder) the file is called a peer and the tracker can be used to find more peers. This has quite some advantages like:

• No server can be “shut down” due to copyright infringement, since no server contains the copyrighted material
• The tracker server does not require a lot of bandwidth, because its used only to put two users in communication
• It's impossible to block the “swarm” of peers or censor it
• While it's possible to kill “public” trackers (but it has proven pretty difficult over the years) it's hard to do the same with private trackers
• Due to different laws and regulations, it might very well perfectly legal for you to torrent in many countries. But i am not a layer (and not YOUR lawyer) so YMMV.
• Torrents are great at locating niche stuff and less mainstream

Torrents also have some disadvantages:

• Files that are not seeded can be lost forever
• Your IP will leak and in some countries you might receive unpleasant requests or worse from your ISP/law enforcement
• Can be quite slow if there are few seeders in the swarm
• Requires a working port-forwarding setup to work reliably
• It's easy to block or throttle by your ISP
• Torrenting can be hard on your network, since it requires lots of concurrent connections to be managed.

The IP leakage can be prevented by using a good (as in safe, privacy oriented) VPN service, which usually has to be paid for. You also want a VPN with port-forwarding and be careful for DNS leakage. All things that you need to take into consideration in some countries more than others. Since this is not a concern where i live, i will not go deeper on this subject myself and leave it to you to cover your tail.

Torrents are text files which report the name of the file/files shared, some hash for them, and trackers info so that you can find more peers to join the swarm. Creating torrent files for your content is easy, there are tools for that, but it's not your concern here unless you want to upload instead of downloading.

“A magnet link is a hyperlink that contains the magnet identifier, file name, and cryptographic content hash in place of the . torrent file extension and mechanism. The content hash, which functions like an ISBN number, is computed from the contents in the file itself and can be used to track data across servers.”

Torrent files have been linked to piracy in the past, so the magnet links where introduced. A magnet link points to a swarm without having any internal reference to the file associated to it. This prevents public trackers to be associated with torrent files directly. You don't have to care for them since your setup will manage both magnets and torrents automatically.

Trackers are the key point of the torrenting. Trackers are the place where you can search for, and hopefully find, the swarms you want to join. Or, in other words, the files you want to download. There are two categories of trackers (no matter the content you want to find):

• Public trackers, where everybody can search and download torrents/magnets
• Private trackers, where you need to be a member to be able to search and download torrents/magnets.

Public trackers are the easiest and can be found anywhere on the internet, you find the URL, you go, you search, you download, you start torrenting, you stop torrenting, that's all folks. Quality content might be limited, hard-to-find stuff might not be available and usually the number of seeders is limited, so more time to download. You can be a leecher on a public tracker, no problem.

Private trackers are hard to find and even harder to get into, since you need to be invited and invites are hard to find (there are websited dedicated to private trackers invites too, go figure). After you manage to get in, you need to carefully read and follow the rules as many requires a “ratio” where you need to keep your torrents active for longer than it requires you to download. In other words, private trackers requires you to be an active seeder or, often, you can also pay money to the private tracker to be able to download without keeping the ratio.

Advantages of private trackers are the quality of the contents, download speeds due to larger swarms, and often they are communities dedicated to specific arguments where you can find niche stuff and such.

After you have access to trackers, doesn't matter if public or private, you need software to actually download the files pointed by the torrents. There are many, and i will focus only on open-source linux downloaders which can be automated in your setup.

The choices are:

• Deluge: great daemon-based downloader with a not-so-great web UI
• Transmission: great daemon-based downloader with great web UI
• qBitTorrent: preferred by many, but it requires Qt to be installed, which i don't want on a server, so it will not taken into consideration.