In computing and specifically Internet, a leech is one who benefits, usually deliberately, from others' information or effort but does not offer anything in return, or makes only token offerings in an attempt to avoid being called a leech. In economics, this type of behavior is called 'free riding' and is associated with the free rider problem. The term originated in the bulletin board system era, when it referred to users that would download files and upload nothing in return. Stranger of sword city.

Once your BitTorrent client finishes downloading, it will remain open until you click the Finish button (or otherwise close it). This is known as being a seed or seeding.-Leecher is a client that is currently downloading a torrent. Generally a leecher does not have the complete file, otherwise it would be called a seed. A torrent with 30 seeders and 70 leechers (30% seeders) will go faster than one with 10 seeders and 90 leechers (10% seeders). However, it get confusing when you compare swarms of different sizes.

Depending on context, leeching does not necessarily refer to illegal use of computer resources, but often instead to greedy use according to etiquette: to wit, using too much of what is freely given without contributing a reasonable amount back to the community that provides it.

The name derives from the leech, an animal that sucks blood and then tries to leave unnoticed. Other terms are used, such as 'freeloader', 'mooch' and 'sponge', but leech is the most commonly used.

Examples[edit]

• Wi-Fi leeches attach to open wireless networks without the owner's knowledge in order to access the Internet. One example of this is someone who connects to a café's free wireless service from their car in the parking lot in order to download large amounts of data. See Piggybacking (Internet access)
• Direct linking (or hot-linking) is a form of bandwidth leeching that occurs when placing an unauthorized linked object, often an image, from one site in a web page belonging to a second site (the leech).
• In most P2P-networks, leeching can be defined as behavior consisting of downloading more data, over time, than the individual is uploading to other clients, thus draining speed from the network. The term is used in a similar way for shared FTP directories. Mainly, leeching is taking without giving.
• Claiming credit for, or offering for sale, freely available content created and uploaded by others to the Internet (Plagiarism/Copyfraud)

Gaming[edit]

In games (whether a traditional tabletop RPG, LARPing, or even MMORPG) the term 'leech' is given to someone who avoids confrontation and sits out while another player fights and gains experience for the person, or 'leecher', who is avoiding confrontation.

• In online multi-player games, 'to leech' generally means that a player be present and qualify for the presentation of a reward of some sort, without contributing to the team effort needed to earn that reward. Although in the past the term 'leeching' has been applied to a player gaining any benefit due solely to the efforts of others, the term is now most often limited to players that gain experience without meaningful contribution. However, while this usually carries negative connotations, this is not always the case; for instance, in MMOs where power leveling is possible, a higher level player may deliberately consent to a lower leveled player gaining experience without assisting, usually due to the danger to the lower leveled player. In situations where the amount of assistance the lower level player can provide is negligible (as is often the case when being Power Leveled, due to the disparity between target mobs and the player), a higher level player may deliberately encourage the lower level player to 'leech' to avoid wasted time spent protecting the lower level player that could otherwise be directed towards more quickly accomplishing the goal of earning experience points. However, this is usually an arrangement between friends or guild-mates, and unsolicited requests to 'leech' experience off of a higher level player is often considered extremely rude.
• In popular MMORPG's the alternative way to refer to a 'leecher' (especially one that is 'leeching' items, as opposed to experience) has arisen as being 'Ninja' (referring to the notional lightning reflexes needed to claim the reward between its appearance and its retrieval by the more deserving player). This can be used as either a noun ('Player One is a loot ninja!') or a verb ('Player One keeps ninja'ing all the drops!'). However, a 'ninja' may not necessarily be 'leeching', in that they do sometimes contribute to the goal, 'ninja' more applies towards a player claiming an item unfairly, either because the group agreed to pass the item to a particular player in advance, or by taking the item before the group can determine which player gets the item fairly through whichever process the group agreed upon (usually rolling for it, which is simulated in many MMOs through a '/random' or '/roll' command).
• This is different from 'killstealing' where a player uses an attack at the right moment to kill an enemy and take the experience benefit (XP), which may benefit the player or not. In some games, XP is granted to the person who deals a final shot to an enemy, or to who deals a significant amount of damage regardless of who hit it last. Killstealing can in this fashion be applied as a reverse leeching: it prevents another player from gaining XP at all regardless of their effort.

Prevention[edit]

• Wi-Fi networks can implement various authentication and access control technologies in order to prevent leeching. The most common are client MAC address authorization tables (deprecated due to insecurity), Wired Equivalent Privacy (deprecated due to insecurity), and Wi-Fi Protected Access.
• Bandwidth leeching can be prevented by running an anti-leeching script on the website's server. It can automatically ban IPs that leech, or can redirect them to faulty files.

P2P networks[edit]

Amongst users of the BitTorrentfile distributionprotocol and common P2P networks, such as the eDonkey network or Gnutella2, a leech is a user who disconnects as soon as they have a complete copy of a particular file, while minimizing or completely suppressing data upload.

However, on most BitTorrent tracker sites, the term leecher is used for all users who are not seeders (which means they do not have the complete file yet). As BitTorrent clients usually begin to upload files almost as soon as they have started to download them, such users are usually not freeloaders (people who don't upload data at all to the swarm). Therefore, this kind of leeching is considered to be a legitimate practice. Reaching an upload/download ratio of 1:1 (meaning that the user has uploaded as much as they downloaded) in a BitTorrent client is considered a minimum in the etiquette of that network. In the terminology of these BitTorrent sites, a leech becomes a seeder (a provider of the file) when they finished downloading and continues to run the client. They will remain a seeder until the file is removed or destroyed (settings enable the torrent to stop seeding at a certain share ratio, or after X hours have passed seeding).

The so-called bad leechers are those running specially modified clients which avoid uploading data. This has led to the development of a multitude of technologies to ban such misbehaving clients. For example, on BitTorrent, most private trackers do keep track of the amount of data a client uploads or downloads to avoid leeching, while on real P2P networks systems like DLP (Dynamic Leecher Protection) (eMule Xtreme Mod, eDonkey network) or uploader rewarding (Gnutella2) have been brought in place. Note that BitTorrent is not a P2P network, it is only a P2P file distribution system.

Leeching is often seen as a threat to peer-to-peer sharing and as the direct opposite of the practice of seeding. But with rising downloads, uploads are still guaranteed, although few contributors in the system account for most services.^[1]

See also[edit]

References[edit]

1. ^Yang, S., Jin, H., Liao, X., Yao, H., Huang, Q., Tu, X. (2009). Measuring Web Feature Impacts In Peer-To-Peer File Sharing Systems. Hushing University of Science and Technology

This is a glossary of jargon related to peer-to-peer file sharing via the BitTorrent protocol.

Terms[edit]

Availability[edit]

(Also known as distributed copies.) The number of full copies of a file (or set of files and directories) directly available to the client. Each seed adds 1.0 to this number, as they have one complete copy of the file. A connected peer with a fraction of the file available adds that fraction to the availability, if no other peer has this part of the file.

Example: a peer with 65.3% of the file downloaded increases the availability by 0.653. However, if two peers both have the same portion of the file downloaded - say 50% - and there is only one seeder, the availability is 1.5 as per the big butts paradox.

Sometimes 'distributed copies' is considered to be 'availability minus 1'. So if the availability is 1.6, the distributed copies will be 0.6 because it is only counting the 'copies' of the file.

Choked[edit]

Describes a peer to which the client refuses to send file pieces. A client chokes another client in several situations:

• The second client is a seed, in which case it does not want any pieces (i.e., it is completely uninterested)
• The client is already uploading at its full capacity (it has reached the value of max_uploads)
• The second client has been blacklisted for being abusive or is using a blacklisted BitTorrent client.

Client[edit]

The program that enables peer-to-peerfile sharing via the BitTorrent protocol. See Comparison of BitTorrent clients.

Distributed Hash Table[edit]

Distributed Hash Tables (DHT) are used in Bittorrent for peers to send a list of other seeds/peers in the swarm for a particular torrent directly to a client without the need for a tracker.

Downloader[edit]

A downloader is any peer that does not have the entire file and is downloading the file. This term, used in Bram Cohen'sPython implementation, lacks the negative connotation attributed to leech. Bram prefers downloader to leech because BitTorrent's tit-for-tat ensures downloaders also upload and thus do not unfairly qualify as leeches.

Endgame / Endgame mode[edit]

Any applied algorithm for downloading the last few pieces (see below) of a torrent.

In typical client operation the last download pieces arrive more slowly than the others. This is because the faster and more easily accessible pieces should have already been obtained. In order to prevent the last pieces becoming unobtainable, BitTorrent clients attempt to get the last missing pieces from all of its peers. Upon receiving the last pieces a cancel request command is sent to other peers.

Fake[edit]

A fake torrent is a torrent that does not contain what is specified in its name or description (e.g. a torrent is said to contain a video, but it contains only a snapshot of a moment in the video, or in some cases malware).

FreeLeech[edit]

Freeleech means that the download size of the torrent does not count towards your overall ratio, only the uploaded amount on the torrent counts toward your ratio.

Grab[edit]

A torrent is grabbed when its metadata files have been downloaded.

Hash[edit]

The hash is a digital fingerprint in the form of a string of alphanumeric characters (typically hexadecimal) in the .torrent file that the client uses to verify the data that is being transferred. 'Hash' is the shorter form of the word 'hashsum'.

Torrent files contain information like the file list, sizes, pieces, etc. Every piece received is first checked against the hash. If it fails verification, the data is discarded and requested again.

Hash checks greatly reduce the chance that invalid data is incorrectly identified as valid by the BitTorrent client, but it is still possible for invalid data to have the same hash value as the valid data and be treated as such. This is known as a hash collision. Torrent and p2p files typically use 160 bit hashes that are reasonably free from hash collision problems, so the probability of bad data being received and passed on is extraordinarily small.

Health[edit]

Health is shown in a bar or in % usually next to the torrent's name and size, on the site where the .torrent file is hosted. It shows if all pieces of the torrent are available to download (i.e. 50% means that only half of the torrent is available). Health does not indicate whether the torrent is free of viruses.

Hit-and-run[edit]

To intentionally 'leech' a file; downloading a file while seeding as little as possible.

Index[edit]

An index is a list of .torrent files (usually including descriptions and other information) managed by a website and available for searches. An index website can also be a tracker.

Interested[edit]

Describes a downloader who wishes to obtain pieces of a file the client has. For example, the uploading client would flag a downloading client as 'interested' if that client did not possess a piece that it did, and wished to obtain it.

Leech[edit]

Leech has two meanings. Often, leecher is synonymous with downloader (see above): simply describing a peer or any client that does not have 100% of the data.

The term leech also refers to a peer (or peers) that has a negative effect on the swarm by having a very poor share ratio, downloading much more than they upload. Leeches may be on asymmetric Internet connections or do not leave their BitTorrent client open to seed the file after their download has completed. However, some leeches intentionally avoid uploading by using modified clients or excessively limiting their upload speed.

Lurker[edit]

A lurker is a user that only downloads files from the group but does not add new content. It does not necessarily mean that the lurker will not seed. Not to be confused with a leecher.

Magnet link[edit]

A mechanism different from a .torrent metafile which can be used to identify a set of files for BitTorrent based on content, as opposed to referencing any particular tracker. The method is not limited to BitTorrent data. See Magnet URI scheme.

Overseeded[edit]

In private trackers using ratio credit, a torrent is overseeded when its availability is so high that seeders have difficulty finding downloaders.

p2p[edit]

In a p2p network, each node (or computer on the network) acts as both a client and a server. In other words, each computer is capable of both responding to requests for data and requesting data itself.

Peer[edit]

A peer is one instance of a BitTorrent client running on a computer on the Internet to which other clients connect and transfer data. Depending on context, 'peer' can refer either to any client in the swarm or more specifically to a downloader, a client that has only parts of the file.

Piece[edit]

This refers to the torrented files being divided up into equal specific sized pieces (e.g., 64kB, 128kB, 512kB, 1MB, 2MB, 4MB or 8MB). The pieces are distributed in a random fashion among peers in order to optimize trading efficiency.

Ratio credit[edit]

A ratio credit, also known as upload credit or ratio economy, is a currency system used on a number of private trackers to provide an incentive for higher upload/download ratios among member file-sharers. In such a system, those users with greater amounts of bandwidth, hard drive space (particularly seedboxes) or idle computer uptime are at a greater advantage to accumulate ratio credits versus those lacking in any one or more of the same resources.

Scraping[edit]

This is when a client sends a request to the tracking server for information about the statistics of the torrent, such as with whom to share the file and how well those other users are sharing.

Seed / seeding[edit]

A seed refers to a machine possessing all of the data (100 % completion). A peer or downloader becomes a seed when it completely downloads all the data and continues/starts uploading data for other peers to download from. This includes any peer possessing 100% of the data or a web seed. When a downloader starts uploading content, the peer becomes a seed.^{[citation needed]}

Seeding refers to leaving a peer's BitTorrent client open and available for additional individuals to download from. Normally, a peer should seed more data than download. However, whether to seed or not, or how much to seed, depends on the availability of downloaders and the choice of the peer at the seeding end.^{[citation needed]}

Share ratio[edit]

A user's share ratio for any individual torrent is a number determined by dividing the amount of data that user has uploaded by the amount of data they have downloaded. Final share ratios over 1.0 carry a positive connotation in the BitTorrent community, because they indicate that the user has sent more data to other users than they received. Likewise, share ratios under 1 have negative connotation.

Snatch[edit]

A torrent is snatched when its data files have been downloaded.

Snubbing[edit]

An uploading client is displayed as snubbed if the downloading client has not received any data from it in over 60 seconds.

Super-seeding[edit]

When a file is new, much time can be wasted because the seeding client might send the same file piece to many different peers, while other pieces have not yet been downloaded at all. Some clients, like ABC, Vuze, BitTornado, TorrentStorm, μTorrent, and qBittorrent have a 'super-seed' mode, where they try to only send out pieces that have never been sent out before, theoretically making the initial propagation of the file much faster. However the super-seeding becomes less effective and may even reduce performance compared to the normal 'rarest first' model in cases where some peers have poor or limited connectivity. This mode is generally used only for a new torrent, or one which must be re-seeded because no other seeds are available.

Swarm[edit]

Together, all peers (including seeds) sharing a torrent are called a swarm.^[1] For example, six ordinary peers and two seeds make a swarm of eight. This is a holdover from the predecessor to BitTorrent, a program called Swarmcast, originally from OpenCola.

BitTorrent may sometimes display a swarm number that has no relation to the number of seeds and peers you are connected to or who are available. E.g. it may show 5 out of 10 connected peers, 20 out of 100 connected seeds, and a swarm of 3.

Torrent[edit]

A torrent can mean either a .torrent metadata file or all files described by it, depending on context. The torrent file contains metadata about all the files it makes downloadable, including their names and sizes and checksums of all pieces in the torrent. It also contains the address of a tracker that coordinates communication between the peers in the swarm.^[1]

Tracker[edit]

A tracker is a server that keeps track of which seeds and peers are in the swarm.^[1] Clients report information to the tracker periodically and in exchange, receive information about other clients to which they can connect. The tracker is not directly involved in the data transfer and does not have a copy of the file.

References[edit]

1. ^ ^abc'BEP-0003: The BitTorrent Protocol Specification'. Bittorrent.org. Retrieved 2009-10-22.