What is a DHT in Torrent?

The Distributed Hash Table (DHT) is a new model for peer-to-peer (P2P) network file sharing that allows P2P users to hide which files have been downloaded. This article provides an overview of the file sharing process, strengths of DHT, weaknesses, and resources for finding a P2P network that uses DHT.

File Sharing through P2P Networks

Individuals and businesses use P2P networks for a variety of reasons. Small and large businesses use P2P to manage and share documents and videos. Individuals use P2P for various legal and not-so-legal purposes of sharing music and movies.
P2P networks make the task of sharing large files possible by breaking files into small chunks of around 256k. This allows users to download parts of the file from multiple users, enabling much faster download times.
Any time a file is shared between two or more peers, a hash table is also shared between the users. The hash table provides the details of the file information so the file can be downloaded from multiple users. The hash table also provides a means of comparing the final downloaded file to that of files from other users to ensure the file has downloaded completely.
DHT and P2P

The DHT model accomplishes the same the thing by using hash tables, but the hash tables are also distributed. The result is that a file has a unique fingerprint associated with it, but no specific file name.
With DHT, you must know the unique fingerprint of a file. File names are useless. If you have the finger print, you can search among the members of the P2P network to see who else may have this file. If you search for the file by the name, you lose the value of DHT because now your file activity can be tracked.
Strenghts of DHT

One of the primary purposes of DHT is to defeat file tracking systems. File tracking systems can be used by Intellectual Property Owners to track who might have legally and illegally downloaded their software or files.
While the DHT does not hide the identity individuals completely, but it makes the process of tracking files much more difficult. While other methods of anonymous file sharing are available, DHT is currently one of the strongest ways to protect your identity.
Another strength of DHT is that files are associated through a key or finger print, rather by a file name. This allows for files to be indexed. Typical file sharing searches blast a request to all the computers or peers on a network. With DHT, a centralized index can be developed that allows for users to quickly find and download the same file instead of potentially downloading the wrong file.
Weaknesses of DHT

File tracking has many more purposes than identifying potential copyright infringement. File tracking also allows for file names to be searched for and files that are the same, but with a different name, to be accurately identified. DHT removes these advantages of file tracking.
DHT is not foolproof. Your identity can still be tracked, although the process is considerably more time-consuming on the part of Intellectual Property Owners. While providing an extra layer of protection, your privacy is still not guaranteed.
Files can still be searched for based upon their unique finger print, or key, as well as through tools like Magnet Links. Magnet Links contain the information needed to find a file across a P2P network.
Resources for DHT

The most robust and widely used P2P network client that supports DHT is BitTorrent. DHT is an option you can select in BitTorrent and the network of DHT file sharing peers is growing rapidly.
Another popular client that supports DHT is eMule. Because eMule is open source, new features and tools are added regularly. A number of developers for eMule focus specifically on DHT file sharing.
Summary Of define:DHT

P2P file sharing is a powerful tool used by individuals and businesses to exchange important information. DHT provides a method of sharing files that cannot be tracked through conventional means. This adds an extra layer of privacy protection, but also makes finding files more difficult.
You can use DHT immediately if you already have BitTorrent or eMule. Other P2P clients also provide support for DHT, so look in support documents provided to see if you can take advantage of this model.

Read more: DHT in uTorrent | Enable / Disable it ?

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