Saturday, April 27, 2013
Thursday, April 25, 2013
Monday, April 22, 2013
Comparison of BitTorrent Clients - APR 2013
The following is a general comparison of computer programs designed for peer-to-peer file sharing using the BitTorrent protocol. The BitTorrent protocol coordinates segmented file transfer among peers.
Bram Cohen, author of the BitTorrent protocol, made the first BitTorrent software application, which he also called BitTorrent. He published the application in July 2001.
Many BitTorrent programs are free and open-source software; others are adware or shareware. Some download managers (such as Xunlei and GetRight) are BitTorrent-ready. Opera, a web browser, can also transfer files via BitTorrent. A small number of BitTorrent programs—such as BitDownload, BitGrabber, BitRoll, GetTorrent, Torrent101, TorrentQ, and TorrentSoftware—are actually Trojan horses that attempt to infect the host with malware.
It's worth noting that the client term here is somewhat a misnomer since Bittorrent has a peer-to-peer architecture. It however does differentiate peer software from trackers and companion web sites that do play "server" roles.
Applications
Features II
^ Clients that have been seen in the real world to actually work with IPv6, see IPv6 BitTorrent Clients
^ a b Announcements to the tracker are made via IPv6 if possible, but the client doesn't listen on the respective port.
^ Qdbus interface
^ Automatically configure port forwarding (requires Router with UPnP support)
^ Many clients claim to support this, but just UPnP calls for opening a TCP port is not effective and disabled by factory default in most new hardware. "UDP NAT Traversal" is the proper working solution, supported by just a few.
^ DHT permits use of trackerless torrents (with supporting clients) to resume normal torrents when their tracker is down. However, some trackers that register their users for keeping tabs on fair usage (such as a ratio of bytes downloaded to uploaded) may not reliably measure and update usage for users employing DHT.
^ a b c Tracker included with Linux binaries and with source, but not with Windows binary.
^ a b Exchanging with BT 6 and µTorrent clients (and now MooPolice).
^ It's UDP based, an experimental feature and only supported by other Azureus based clients.
^ a b c Has its own DHT, a mainline-DHT compatible implementation is available as plugin.
^ µTorrent's DHT implementation is the same as Mainline and BitComet's, but unfortunately this is incompatible with Azureus's implementation.
^ It's not a DHT network, but Shareaza uses Gnutella2 to find other Shareaza clients downloading the same torrent. Mainline DHT support is available as a separate download.
^ Since Shareaza v2.5.5.1 r9064.
^ Exchanges with µTorrent and Azureus peers.
^ Since version 2.5.0.2. It's UDP based, an experimental feature and only supported by other Azureus clients.
^ Since version 2.5.0.2. It's UDP based, an experimental feature and only supported by other Azureus clients.
^ Reduces disk usage, file fragmentation (in case it is not preallocated) and latencies via larger written blocks and cached data for hash checking finished pieces.
^ Recently implemented (unofficial) web seeding feature, see HTTP-Based Seeding Specification
^ a b Provides a Java-based and a simple HTML/JS based WebUI.
^ Opera has a feed aggregator that displays feeds like emails.
^ Since Shareaza v2.4.0.2 r7924.
^ Shareaza also uses G2 to transmit download metadata, such as BitTorrent trackers to other G2 clients.
^ Maximum active torrent number depends on respective user settings and is limited to 31.
Vulnerabilities
This comparison of unpatched publicly known vulnerabilities in latest stable version clients is based on vulnerabilities reports by SecurityFocus and Secunia. See computer security for more details about the importance of unpatched known flaws.
Original article available at http://en.wikipedia.org/wiki/Comparis...
Understanding Magnet URI Scheme
The Magnet URI scheme is a de facto standard defining a URI scheme for Magnet links, which mainly refer to resources available for download via peer-to-peer networks. Such a link typically identifies a file not by location, but by content—more precisely, by the content's cryptographic hash value.
Since it specifies a file based on content or metadata, rather than by location, a Magnet link can be considered a kind of Uniform Resource Name, rather than the more common Uniform Resource Locators. Although it could be used for other applications, it is particularly useful in a peer-to-peer context, because it allows resources to be referred to without the need for a continuously available host.
History
The standard for Magnet URIs was developed in 2002, partly as a "vendor- and project-neutral generalization" of the ed2k: and freenet: URI schemes used by eDonkey2000 and Freenet, respectively, and attempts to follow official IETF URI standards as closely as possible.
Applications supporting Magnet links include μTorrent, aMule, BitComet, BitSpirit, BitTorrent, DC++, Deluge, FrostWire, gtk-gnutella, Installous (iOS app), I2P, KTorrent, MLDonkey, Morpheus, Qbittorrent, rTorrent, Shareaza, Tixati, Transmission, Tribler and Vuze.
The Pirate Bay migrated from .torrent files to magnet URI in February 2012. This migration made the storage footprint of The Pirate Bay exceptionally small. A user demonstrated total size of The Pirate Bay magnets would be approximately 90MB of compressed data.
Use of content hashes
The most common use of Magnet URIs is to point to a particular file based on a hash of its contents, producing a unique identifier for the file, similar to an ISBN or catalog number. Unlike traditional identifiers, however, content-based signatures can be generated by anyone who already has the file, without the need for a central authority to issue them. This makes them popular for use as "guaranteed" search terms within the file sharing community where anyone can distribute a Magnet link to ensure that the resource retrieved by that link is the one intended, regardless of how it is retrieved. While it is theoretically possible for two files to have the same hash value (known as a "hash collision"), cryptographic hash functions are designed to reduce that occurrence to a practical impossibility -- even if an expert with vast computational resources is intentionally looking for two files with the same hash value.
Another advantage of Magnet URIs is their open nature and platform independence: the same Magnet link can be used to download a resource from numerous applications on almost any operating system. Because they are concise and plain-text, users can copy-and-paste them into e-mails or instant messages, a property not found in, for example, BitTorrent files.
Technical description
Magnet URIs consist of a series of one or more parameters, the order of which is not significant, formatted in the same way as query strings that ordinarily terminate HTTP URLs. The most common parameter is "xt" ("exact topic"), which is generally a URN formed from the content hash of a particular file, e.g..
magnet:?xt=urn:sha1:YNCKHTQCWBTRNJIV4WNA
This refers to the Base32 encoded SHA-1 hash of the file in question. Note that, although a particular file is indicated, an availability search for it must still be carried out by the client application.
Other parameters defined by the draft standard are:
"dn" ("display name"): a filename to display to the user, for convenience
"kt" ("keyword topic"): a more general search, specifying search terms, rather than a particular file
"mt" ("manifest topic"): a URI pointing to a "manifest", e.g. a list of further items
application-specific experimental parameters, which must begin "x."
The standard also allows for multiple parameters of the same type to be used by appending ".1", ".2", etc. to the parameter name, e.g.: magnet:?xt.1=urn:sha1:YNCKHTQCWBTRNJIV4W
Image source and copyright details: http://wikipedia.org/wiki/File:Magnet...
Original article available at http://en.wikipedia.org/wiki/Magnet_U...
NCIXPC proudly presents the first MSI Military Class PC in Canada, the 500-IM MilSpec!
A short time ago, MSI launched their "Military Class PC" initiative, focusing on a PC built with their Military Class III components as well as laying down reliability and performance guidelines. NCIXPC is proud to be the first custom PC shop in Canada to roll out a compliant system, plus it's based around some fresh components from Aerocool and BeQuiet!
More details + high res photos: bit.ly/XQuuV7
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