Tag: Torrent Files

How a Torrent is Downloaded

Have you wondered how a torrent is loaded and the files are downloaded? Here is a brief explanation:

The Torrent-Fueled Odyssey

  1. Dissection of the Blueprint: The torrent downloader meticulously parses the .torrent file. It extracts the vital instructions within, including the tracker URLs, file information (names, sizes, etc.), and those all-important piece hashes.
  2. Reaching Out to the Tracker: Following the leads in the “announce” field, the client sends a request to the designated tracker(s). It announces its presence in the swarm, providing its IP address, port number, and a unique peer ID.
  3. The Tracker Responds: In return, the tracker sends a list of other peers actively participating in the swarm; those currently possessing and sharing pieces of the desired content.
  4. Building the Swarm: The torrent downloader reaches out to its newly acquired list of peers, initiating direct connections. Imagine these as simultaneous handshake agreements to start exchanging data.
  5. Requesting the Missing Pieces: A flurry of communication takes place. Using a clever combination of rarest-first and random selection strategies, the client determines which pieces are least common among peers and begins requesting those “rare” segments first to optimize download efficiency.
  6. Integrity Verification: As data segments arrive, their SHA-1 hashes are rigorously compared to the original piece hashes listed in the torrent file. Any discrepancies signal corruption, triggering a redownload of the faulty piece(s) to ensure the completed file remains pristine.
  7. Reciprocation is Key: True to the BitTorrent philosophy, the client doesn’t merely take. It becomes a valuable supplier itself, uploading any completed pieces to other peers in the swarm – this helps the entire ecosystem thrive.
  8. Seeding for the Swarm: Once all pieces are obtained and assembled, the torrent client shifts into “seeding” mode. It remains connected, generously sharing the fully downloaded file to support newcomers to the swarm who wish to complete their own copies.

Advanced Behavior:

  • Prioritization: Many torrent clients allow users to prioritize individual files when dealing with multi-file torrents, dictating their download order within the swarm.
  • Rate Limiting: Tools for fine-tuning both upload and download speed limits are often present, helping balance torrenting activity with other network use.
  • DHT Participation: Even with an active tracker, the client simultaneously engages with the Distributed Hash Table (DHT) network. This decentralized system offers more avenues for discovering peers and contributes to overall ecosystem resilience.

Notes:

  • Torrent clients continuously adjust their peer pool for dynamic swarm membership, replacing inactive peers with more responsive ones.
  • Modern BitTorrent clients offer an increasingly refined and customizable experience. For expert users, there’s often fine-grained control over peer selection, piece exchange algorithms, and other advanced settings.

Let me know if you’d like a particular step broken down even further!

Torrent Files: What they Contain

At their core, torrent files (.torrent extension) serve as detailed blueprints for facilitating peer-to-peer (P2P) file transfers utilizing the BitTorrent protocol. Think of them as multi-faceted maps that guide torrent clients in their quest to download and share content.

Key Components Within a Torrent File

These files are encoded using the Bencoding format (a simple data serialization technique) and contain the following vital components:

  • Announce: This is the URL of the tracker – a specialized server that coordinates communication between peers involved in the torrent swarm.
  • Info: This dictionary is the heart of the torrent file, housing core metadata:
    • name: The name of the torrent (usually the filename or a directory name).
    • piece length: The size of each piece the file is fragmented into (common values are powers of 2, e.g., 256 KB, 512 KB, 1 MB).
    • pieces: A list of SHA-1 cryptographic hashes, one for each piece. These hashes ensure that downloaded data remains intact and uncorrupted.
    • length (single file mode): Total size of the file in bytes.
    • files (multi-file mode): A list of dictionaries detailing each file in a multi-file torrent:
      • length: Individual file size in bytes.
      • path: A list representing the file’s subdirectory path.

Optional Fields

  • comment: Arbitrary commentary by the torrent creator.
  • created by: The name and version of the program used to generate the torrent file.
  • creation date: Timestamp indicating when the torrent was created (often in Unix time format).
  • httpseeds: (Web Seeding) Contains a list of URLs of web servers where the file can also be obtained, supplementing P2P sources.

The Torrent Workflow in Action

  1. Creation: A torrent client generates a torrent file. It divides the content into pieces, calculates SHA-1 hashes for each, and assembles the metadata.
  2. Distribution: The .torrent file is shared on tracker websites or distributed directly.
  3. Tracker Interaction: A user’s torrent client contacts the tracker listed in the “announce” field, providing its own IP address and a unique peer ID. In turn, it receives a continuously updated list of peers currently holding pieces of the desired content.
  4. Peer Exchange: The torrent client builds direct connections with peers on the received list. It utilizes a sophisticated “tit-for-tat” system involving choking/unchoking peers based on their reciprocation of upload bandwidth, thus incentivizing sharing.
  5. File Reconstruction: Pieces are downloaded (potentially out of order), their SHA-1 hashes are verified against those listed in the torrent file, and the complete, error-free file is reassembled.

Technical Considerations

  • Bencoding: Torrent files employ a simple yet efficient method of encoding data structures. A deeper understanding of Bencoding is helpful for advanced analysis.
  • Tracker vs. Trackerless: Trackers played a more crucial role in the early days of BitTorrent. Nowadays, the Distributed Hash Table (DHT) allows for trackerless torrents, further enhancing decentralization.

Exactly WHAT are Seeds and Peers?

So you’ve downloaded quite a few things, but you’ve noticed that everyone insists on getting torrents with lots of “seeds”. And maybe you’ve seen the count of “seeds & peers” on your download software or webpage? So exactly, WHAT are those?

It’s actually very simple. Seeds are other computers that have that torrent that have the full set of files and have it 100% downloaded and is connected and offering the files to others. Peers are the same, but DON’T have the full set, they are still downloading the parts they need.

Still not clear? Ok, let’s go through it again.

The Bittorrent protocol is a server-less system. That means everyone is running the same software and everyone is the same to each other, no-one is more important or less important.

So, somebody decides to share a file, and share the initial .torrent file so others know he is sharing it. Then he ‘start’s the torrent, and he becomes the first ‘seeder’, because, as the name implies, he is planting the first data that will ‘grow’ (or copy itself) onto others.

Now, others, that don’t have anything at all will begin transferring this initial data, and save it locally. As soon as they have a full ‘piece’, they will also begin sharing it with other ‘peers’. So now, all ‘peers’ are sharing the pieces they’ve gotten and sharing between themselves.

So, even torrents that have only 1 seeder can be transmitted quickly, because the peers are also pitching in.

Seeds are also called ‘uploaders’ because they only upload, or send data, they don’t need to download because they already have all the pieces:

Seeders & Peers

Also, any peer or downloader that finishes all its pieces will convert itself into a seeder, and the seeder count will increase.

So, when you select a torrent, be aware that if it DOES NOT have any seeders, the torrent will NOT finish, until at least one peer finishes and becomes a seeder. No matter how many peers there are, at least one has to finish getting all the pieces together.

Also, if a torrent has many, many seeders, it will most probably download much faster than others with less seeders.

On Transfercloud.io we display how many seeders & peers the torrent module detects, and will try to connect to the most possible to download fast. On popular torrent with hundreds of seeders is very common to see it download in seconds. Try it out and see!

How to Download with a Magnet Link on TransferCloud

So you found some nice thing to download, and it’s offered via Bittorrent, and they give you some .torrent files, say, like these:

Linux Torrent
Linux Torrent

Well, you can do two things here, either:

  • Right-Click on the .torrent file and select ‘Copy Link Address’
  • Click on the torrent file, and it will download the .torrent file to your computer.

If you copied the address to you clipboard, you just paste it here:

Paste Link Here

And click on the immediate left button: “Magnet or Link of Torrent”.

But if you downloaded the .torrent, and want to use that, you got to upload the file.

So, click on this this button:

Click 'choose file' button

Select the torrent from where it was downloaded:

Choose File

And press the immediate left button: “Upload Torrent File”.

Sometimes, some links seem to point to the torrent file, but they do not. Or it has some type of DDoS proteccion and it checks your browser first, so in those cases it’s most probably going to work only with the second method.

And that’s it! Wait for it to download and transferred to your Cloud Drive.

Torrents and Cloud Storage

Downloading files by using the filesharing protocol ‘bittorrent’ has become wildly popular in the last few years. Also, having a personal “file locker” space up in the “Cloud” is also very common. But are these two technologies incompatible or is there an easy way to use one to the other?

First, let’s clear up on what’s exactly what on each one. Are you clear on what is ‘bittorrent’, ‘torrents’, ‘magnets’ and ‘links’?

Bittorrent is a new way to share files, but it’s name applies to the “protocol”, or in layman’s terms, the way they are transferred, and how the computer knows how to download the files. It was invented by a programmer called Bram Cohen, when he focused on how would be the best ways for multiple users to share a files between themselves, and trying to do that in the fastest way possible!

Now, “Torrent file” is what we named some small files that have just the fewest necessary information to download the final files. It has all the technical info, like how many files, their sizes, and other technical stuff designed to verify that you download the right files. These are small files, usually less than 5 megabytes (the size of a common photograph file).

Now, magnets are like the the “torrent file”, it lets you tell the software which file you want, but it’s reduced to just a unique string of characters… like a web-link! But instead of using “https://www”, etc. , it begins with ‘magnet:’. Usually you find them on torrent sites with a small magnet icon, which is easy to identify.

Now, if you have not downloaded torrents, before, it’s actually quite easy. You just provide the software the ‘torrent file’, or the magnet link, and it downloads to your computer.

But what if you want to download it elsewhere, like your ‘DropBox’, or ‘Gmail Drive’ account?

So those are what are known as “Cloud Storage”, and you can get quite some space for free. But what exactly are they?

Cloud is actually just another way to say “On the Internet”, or more precisely, “On a Server available on the Internet”. So Cloud storage is just that, disk space that is on a server on the Internet. Obviously, your private files are just not there for anyone to browse through, so they are protected with a password you defined when you registered.

Most of these cloud storage spaces are designed to be a “Backup”, or a copy, of your local computer files. The software just uploads them whenever you add or change them. But there’s a few other advantages on having them on the cloud: You can access them from any computer or device that can connect to the Internet; You can download and edit files or documents; You can keep Music and Movies and see them from any device like tablets or phones; You can share files or whole folders with family and friends!

Transfer Torrents to your Cloud Drive

So now, how would you mix the two? Normally you couldn’t: You would have to download your files first to your computer, then take those files and upload them again, wasting both your upload and download bandwidth. Also, most ISPs limit their uploads speeds, so you are limited by the slowest one!

So, the best way to do this is to use a server that is on the Cloud (connected all the time to the Internet on a high-bandwidth link) that does it. But you would have to configure it, install it, and it’s actually a bit technical to have it working (and you need to send all those commands via the ‘command-line’, and how to install software by typing in commands!).

But there’s an easy way, use https://TransferCloud.io . This website allows you to download the torrents to it’s servers, and then it transfers them back to YOUR personal cloud! As it’s connected by high-speed links, this can be done even in less than a minute, for files that are quite big, like the size of a DVD!

You register first, then just paste in a magnet link, or a URL link to a torrent file… or you can upload a .torrent file. The server passes it to a Bittorrent Client and saves your files to your space. You can then download it directly from the server, or you can specify a “Save Point”. This save point is on which Folder of you Cloud Drive would you like the files put in. After transferring, it then frees the server space so you can continue downloading more.

Also, if you get an unlimited drive space, like Amazon Cloud Drive or OpenDrive, you can continue downloading indefinitely! Just paste all the links you want, and with a “Power” account, you can leave queued all the links you have!! It will download them at the fastest speed possible, and save them all for you to download later.

We’ll see that in another post, but for now, if you have any questions, please contact us.