Torrent Metadata Needed

On three popular torrents with over 100 reported seeds, I was stuck at 'downloading metadata' for an hour with no peers or seeds found. I downloaded Deluge onto the same system and set up my proxy info exactly as I have it in qBittorrent, and it started downloading all torrents immediately. Soon, popular torrent site The Pirate Bay will no longer host torrent files. Instead, it will only offer magnet links. Magnet what now? You may have seen the term 'magnet link' before, but if you.

Torrent Metadata Needed Magnet Link Transmission
Downloading Metadata
Torrent Stuck On Downloading Metadata
Magnetized Transfer Torrent Metadata Needed

Bittorrent clients are one of the few programs left where you need to manually select and forward a port. Most other programs play nicely with NAT and firewalls so you no longer need to do this, bit torrent is an exception. First we need to see if the default port is open. We can then either change it or forward it as you see fit.

What is a torrent?
Most likely, you’ve heard of a torrent, used a torrent, or at least seen that term on the internet somewhere. And whether you have actually used them or not, a lot of people don’t know what it actually is. Let’s talk basics here…

What is a torrent?

When you hear the word “torrent” in the tech world, it usually refers to a computer file that contains metadata holding various information. A torrent file normally comes with the extension .torrent but it does not contain the actual contents to be distributed.
This information will then be used by a BitTorrent software such as uTorrent, Transmission or BitTorrent for the “real” distribution – which essentially allows for users to easily download torrent files to their personal computers.
In retrospect, due to the ease of use of BitTorrent technology, many torrent users end up downloading copyrighted materials unknowingly. This is of course frowned upon in many countries and some have been prohibiting illegal torrents by means of incarceration. Now, that doesn’t mean all torrents are unsafe for consumption. There’s plenty of legal torrent sites out there which you can use. Check out our own list of these legal torrent sites below.
Download Legal Torrents From These Sites

How does a torrent work?

In short, a torrent file acts as the key to initiating downloading of the actual content. When someone is interested in receiving a shared file (i.e. books, music, documents, etc.), they must first obtain the corresponding torrent file – by either downloading the .torrent file directly or by using a magnet link.
A BitTorrent software is then required to open this file/link. Once the BitTorrent software scans the torrent file/link, it’ll then need to find the locations of seeders which are sharing the corresponding file. To do so, it will attempt to connect to a list of defined trackers (from the torrent file metadata) and attempt a direct connection. If it’s successful, the appropriate content will then begin transferring.
Note: A torrent download can be done in fragments, so in reality you’re actually downloading bits of pieces of the full content which is later reassembled when all of the pieces are received.

Where can i find torrents?

To find torrent files, users commonly flock to popular websites such as The Pirate Bay and Kickass Torrents. Although these websites are crazy popular, they have been getting shut down left and right, causing mirror sites to sprout up around the internet. Even though torrents are technically legal, over the years it has become synonymous to illegal activity due to a myriad of users abusively sharing pirated content.
Essentially, you’ve got to know what content is legal and what’s illegal before starting any torrent connection. If you’re looking for torrent sites which provides legal torrent contents, check out our list of sites that allow you to download torrents legally.

Why is torrenting dangerous?

Downloading torrents can always be dangerous due to the fact that other peers will be able to see your IP address. Lots of production and record companies hire people to go in and report all these IP addresses being found downloading torrents so that they can be passed along to ISPs. The ISPs will then liaise with law enforcement agencies to prevent the file from being downloaded further, which may include incarcerating the operators or users.
Connecting to a Virtual Private Network (VPN) would allow you to change your IP address and keep you anonymous while downloading torrents. This is a crucial tool to use when downloading torrents so that your ISP does not know what you are doing.
Note: Due to issues with DMCA requests, torrenting is only available on our Malaysia and Russia servers. Read about DMCA on Electronic Frontier Foundation’s website here.
Don’t Have a VPN yet? Sign up now by clicking the button below for unlimited access to both our recommended VPN and SmartDNS services. We offer a 100% money-back guarantee if you don’t like the service. So there isn’t any risk in giving it a go!

We hope you found this article informative and useful. Please feel free to share it with your friends or family that wants to know what a torrent is too!
If you need any help, our support team is just an email away at [email protected] and we’ll try our best to assist you.

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libtorrent-2.0 has just been released with a few major new features. One of them is support for BitTorrent v2.

Most of the specification work of BEP 52 was done by the8472. The libtorrent support for bittorrent v2 was mostly implemented by Steven Siloti. BiglyBT also has an implementation of BitTorrent v2 to be released in the near future.

BitTorrent v2 kick-started with an effort to transition away from SHA-1 as the hash function for pieces, shortly after google announced having produced a collision. Given a new hash function would not be backwards compatible, a few other changes were proposed as well, while we were taking the compatibility hit anyway. This post describes the new features of the BitTorrent v2 protocol.

SHA-256

The hash function for piece data was changed to SHA-256. One consequence of this is that hashes are 32 bytes instead of 20 bytes. In BitTorrent v2, the info-dictionary is also computed by SHA-256, which poses a compatibility challenge with the DHT and trackers, which have protocols that expect 20 byte hashes. To handle this, DHT- and tracker announces and lookups for v2 torrents use the SHA-256 info-hash truncated to 20 bytes.

This was one of the original rationales for creating a v2 protocol to begin with. It means that fundamentally a v2 torrent will be identified by a different hash than a v1 torrent, which would always create a separate swarm, even when sharing the same files. More on this later, under backwards compatibility.

hash trees

In BitTorrent v1, pieces are hashed and the resulting hashes are included in the .torrent file/metadata (in the info-dictionary). In most cases, the piece hashes is the bulk of the size of .torrent files. To keep the .torrent file size within reason for large files, the piece size can be increased, meaning each hash represents a larger portion of the file. A consequence of large piece sizes is that if a hash fails, one has to re-download a larger portion of the file, until the piece passes the hash check.

An old idea to improve both of these metrics is to use merkle hash trees to represent the piece hashes (originally implemented in tribler). This keeps .torrent files small because all you need is the root hash of the tree. BitTorrent v2 uses merkle hash trees for pieces (but a different protocol that the one tribler implemented). This has the following advantages:

The torrent metadata (specifically the info-dictionary portion of a .torrent file) becomes a lot smaller. This shaves off start-up latency when adding a magnet link, since fewer bytes need to be downloaded before the torrent download itself can start.
Downloaded data can be validated on a block level. Meaning if a peer sends corrupt data, it can be discovered immediately and only 16 kiB need to be re-downloaded. The peer that sent the corrupt data can also be identified with certainty. This is a great improvement over the heuristics necessary to identify the bad peer in v1, sometimes referred to as smart-ban.

The leaves of the hash trees are always 16 kiB (the block size), regardless of the piece size. The concept of piece size still exists and is still used in the peer-wire protocol as it is today. e.g. in HAVE and REQUEST messages. However, instead of piece hashes actually being the hash of the content of the piece, it’s the root of the hash tree of the piece. i.e. a sub-tree of the full merkle tree.

In v2, the .torrent file must still contain these piece hashes (really the hashes in the merkle tree representing the piece-level). This helps distributing and storing the hashes so they don’t have to be recomputed when restarting a client that’s seeding. They’re also stored in the resume state. The .torrent file size is not smaller for a v2 torrent, since it still contains the piece hashes, but the info-dictionary is, which is the part needed for magnet links to start downloading.

Example tree for a file with 4 blocks and a piece size of 32 kiB (2 blocks per piece)

per-file hash trees

BitTorrent v2 not only uses a hash tree, but it forms a hash tree for every file in the torrent. This has a few advantages:

Identical files will always have the same hash and can more easily be moved from one torrent to another (when creating torrents) without having to re-hash anything. Files that are identical can also more easily be identified across different swarms, since their root hash only depends on the content of the file.
All files will be aligned to pieces, which means there are implicit pad files after each file

This addresses a long-standing wish to more easily identify duplicate files, or finding multiple sources for files, across swarms.

directory structure

As mentioned earlier, most of the time the piece-hashes take up the majority of space in the info-dictionary. The exceptions are torrents with a lot of small files; then it’s the file list that use the most space. In v1 torrents, file lists are expressed as a single list of files with full paths. In a torrent with a deep directory structure (or just directories with long names), those directory names will be duplicated multiple time, exacerbating the problem.

v2 torrents address this by using a more efficient encoding for the directory structure, with less duplication. Instead of a flat list, the directory structure is stored as a tree (using bencoded dictionaries). This results in directory names only being mentioned once. For example:

Compared to the v2 file tree (this also includes the merkle tree root hashes):

piece size

In v1 torrents, the size of a piece is not restricted by the specification. It doesn’t make much sense to have a piece smaller than the block size of 16 kiB, but it’s not disallowed. The vast majority of torrents that are created use a power-of-two piece size, but there are a few outliers that are not, but still divisible by 16 kiB. v2 torrents tightens up the requirements of piece sizes by requiring them to be:

a power of two
greater than or equal to 16 kiB

The main reason for this is for piece hashes to fit in the hash trees. Since the v2 piece hashes really are the merkle hash tree root of the piece, it must represent a power-of-two number of blocks.

encoding

A .torrent file is a tree structure encoded with bencoding. In bencoding there are a few cases of single values with multiple possible encodings. An integer could be encoded with leading zeros or not, 0 could be encoded as negative 0. Those encodings have always been illegal, but parsers have historically been lenient and accepted them. Perhaps the most common example is how the keys in dictionaries are required to be sorted lexicographically. However, some torrent creators have failed to sort them, so clients have accepted them.

This primarily causes problems when round-tripping a bencoded structure. Once parsed, the specific order of dictionary entries, or the specific number of leading zeroes may be lost. So when re-encoding the structure, it may be different. If the dictionary that’s being round-tripped is the info-dictionary, the info-hash has changed and things will break.

libtorrent is now enforcing these restrictions by refusing to load any v2 torrent containing:

an integer with any leading zeros (except 0 itself). e.g. “i0004e”
a 0 encoded as -0. i.e. “i-0e”
a dictionary where the entries are not sorted correctly. e.g. “d1:B3:foo1:A3:bare” (“A” should be sorted before “B”)

Enforcing these encodings also help make it more likely that two people creating a torrent from the same files, end up with the same info-hash and the same torrent.

magnet links

The magnet link protocol has been extended to support v2 torrents. Like the urn:btih: prefix for v1 SHA-1 info-hashes, there’s a new prefix, urn:btmh: for full v2 SHA0256 info hashes. For example, a magnet link thus looks like this:

The info-hash with the btmh prefix is the v2 info-hash in multi-hash format encoded in hexadecimal. In practice, this means it will have a two byte prefix of 0x12 0x20. It is possible to include both a v1 (btih) and v2 (btmh) info-hash in a magnet link, for backwards compatibility.

backwards compatibility

All new features in BitTorrent v2 that are not backwards compatible have been carefully given new names, to allow them to coexist with the v1 counterparts. Hence, it’s possible to create hybrid torrents. That is, torrents that can participate in both a v1 and a v2 swarm at the same time, serving the same files.

A hybrid torrent has two info-hashes, one v1 SHA-1 hash one (possibly truncated) SHA-256 hash. This forms two swarms, or a segregated swarm. libtorrent marks peers as supporting v2 or not. This information is also relayed via a new peer exchange (PEX) flag.

A hybrid .torrent file includes both piece hashes as well as the tree root hashes for each file.