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--- peers_seeds_torrent_tracker_dht_peer_exchange_pex_magnet_links [2011/07/17 20:58]
greywizard [Seeds and Seeding]
+++ peers_seeds_torrent_tracker_dht_peer_exchange_pex_magnet_links [2011/07/22 12:10]
greywizard [Torrent] - added some additional description for BT index and descr for hash check
@@ Line 57: / Line 57: @@
 Transfers in the BitTorrent Network, use pieces as trading units. The torrent making application, upon creation of the //.torrent// file, virtually concatenates together all the files of the torrent and then splits the resulted data chunk in pieces of equal size (usually between 64KB and 4MB). For each piece a [[wp>SHA-1]] hash-value is calculated, which is then put in the //.torrent// file. 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 //.torrent// file, in order to check the piece’s data integrity.
+===Hash-check===
+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 //.torrent// file. 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.\\
+In BitComet this option is called "Manual Hash Check".
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@@ Line 68: / Line 75: @@
 Basically, the tracker is a service which responds to HTTP GET requests. The requests include metrics from clients that help the tracker keep overall statistics about the torrent. The response includes a peer list that helps the client participate in the torrent. The base URL consists of the "announce URL" as defined in the metadata (//.torrent//) file. The parameters are then added to this URL, using standard CGI methods.
-A tracker server should be differentiated from a BitTorrent index server. A BitTorrent index is a list of //.torrent// files, usually including descriptions and other information. Trackers merely coordinate communication between peers attempting to download the payload of the torrents.
+A tracker server should not be mistaken with and should be differentiated from a **BitTorrent index server**. A **BitTorrent index** is a server which contains a list of //.torrent// files, usually including descriptions and other information and which will serve the actual //.torrent// files to anyone who will choose to download something from the list.\\
+Trackers merely coordinate communication between peers attempting to download the payload of the torrents.
 Many BitTorrent websites act as both tracker and index. Sites such as these publicize the tracker's URL and allow users to publish (upload) torrents to the index with the tracker's URL embedded in them, providing all the features necessary to initiate a download.

A free C++ BitTorrent/HTTP/FTP Download Client

Differences