What is dht and pex

In an attempt to clear some of the mystique surrounding DHT, PEX and Magnet links we will walk through all three briefly, hoping to assure those who've become confused earlier this week. Relax and be free from anxiety Take back good sleep and help alleviate pain. Using DHT instead of trackers is one of the things The Pirate Bay is now trying to encourage, and torrent downloads that rely solely on this technology are often referred to as " trackerless torrents.

It is enabled by default in clients such as uTorrent and Vuze and millions of people are already using it without knowing. DHT's function is to find peers who are downloading the same files, but without communicating with a central BitTorrent tracker such as that previously operated by The Pirate Bay. DHT is by no means a new technology. A version debuted in the BitTorrent client Azureus in May and an alternative but incompatible version was added to Mainline BitTorrent a month later.

There is, however, a plugin available for Azureus Vuze which allows it access to the Mainline DHT network used by uTorrent and other clients. Peer Exchange is yet another means of finding IP addresses. Rather than acting like a tracker, it leverages the knowledge of peers you are connected to, by asking them in turn for the addresses of peers they are connected to. A torrent client then calculates a torrent hash a kind of fingerprint based on the files it relates to, and seeks the addresses of peers from a tracker or the DHT network before connecting to those peers and downloading the desired content.

Therefore, seeding is a paramount activity on the BitTorrent Network; it's what makes it work and what gives you the possibility to find all those files you seek. Therefore, in order to share with others what you have downloaded, just leave the task running in your client until it reaches at least a 1.

Also in BitComet, another technology called Long-Term Seeding will make sure that any present task even if stopped i. Bottom line, as long as the task is present in the Task List of BitComet in a state or another it's a good chance it's still uploading. On the other hand, if you mean to share with others files which you have on your local storage media but which are not described by tasks already present in your Task List, then you should look into making and uploading torrents into the BitTorrent Network.

For that you can find a pretty detailed guide here: Making torrents with BitComet. In those particular moments when someone uploads one torrent the first time on the Internet, seed replication can be delayed due to the fact that the initial seeder will send the same torrent piece to several different peers, while other pieces have not yet been uploaded at all.

However, this mode should only be used for starting a new torrent, or for one which must be re-seeded because no other seeds are available. BitComet implemented support for Initial Seeding since version v. That is because this term is commonly used to refer two, different but related things: the.

This file contains Metadata such as hash value, file size and name, piece size and hash, tracker IP etc. By convention the torrent files use the. A value of special interest is the info-hash , which is a hash value calculated for the info key of the. Most index sites display that value for each torrent they index, as does BitComet too for any torrent in its Task List, on its Summary tab.

This way by info-hash a torrent can be quickly tracked down on multiple index sites or other Internet locations without regard to it's name, thus easily avoiding fake torrents which try to impersonate a valid one by using the same filename.

Especially in this last case confusion occurs, since one usually downloads both. Transfers in the BitTorrent Network, use pieces as trading units. The torrent making application, upon creation of the.

For each piece a SHA-1 hash-value is calculated, which is then put in the. When another peer receives a piece later, it calculates the hash value for it, using the same algorithm, and compares that to the value recorded in the. Many clients will perform another integrity check upon the complete download of all pieces for a task. This consists of the same procedure as the one described above, except this time the client will calculate the hash value for each downloaded piece for that task and compare it against the expected value, which is already written inside the.

Any piece which doesn' pass the hash check will be discarded, as it's considered corrupted that could happen either during transport or even at source. This same procedure can be initiated manually by the user, usually by right-clicking the task and choosing the option to hash-check from the context menu. When a peer wants to join the swarm of a certain torrent it will need a bootstrap method. That is, it needs some way to learn about the other peers who share that torrent in order to begin negotiating connections and transfers with them.

According to the original design of the BitTorrent protocol, that bootstrap mechanism is provided by the tracker later extensions also allow the use of other additional methods such as DHT.

The tracker, actually, is not directly involved in any data transfer and does not have a copy of the file s for the torrents it tracks. Once the list of peers is obtained, peer communication can continue without a tracker. However, clients report statistics information to the tracker periodically and in exchange receive updated information about new peers to which they can connect or about peers which have left the swarm. Collectives on Stack Overflow.

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