Usenet – Servers and propagation
Early versions of Usenet software using B-News, and C-News as server software. In the 1990s, IUU was developed to take advantage of the Internet architecture, which favored an operation other than the store-forward method of UUCP. The development of IUU continues to this day, and other Usenet servers have also arisen in the meantime.
To set up a news server, it must first obtain a feed that is to say, a connection to another server (sufficiently large) that can send traffic to the new server from the rest of Usenet . The servers are regularly contact neighbors to propagate articles. Basically, they compare their lists of items, and each sends to the other that is the only one to have. Naturally, the news servers do not propagate and preserve the items sufficiently recent.
Regarding changes in group structure itself, special articles, called control messages, indicate the changes to each server in the tree. Free to each director to ignore certain groups. Anyone can send a control message, but the servers are configured to accept for such a hierarchy, messages signed by such private key asymmetric cryptography. The control messages “pirates” are ignored – unless the server administrator decides otherwise.
The ranking of the biggest servers newsgroup is maintained by the site top1000.org.
Addresses and access to resources
A final point, that of identifying a server, a group or message. Like just about everything that is accessible via the Internet, these resources can be designated as “addresses” text, or Universal Resource Identifiers URI.
The addresses on Usenet are not completely standardized. RFC 1738 defines three kinds, but there are others (see RFC 2396 and the Internet Draft draft-gilmain-news-url-02 and draft-stockwell-hnews-url-00).
News: name> Group>
(E.g., news: fr.sci.maths), provides access to a particular group. The software that use it require the user to specify which server elsewhere on the search. The name of the panel * is the list of available groups. On the same principle,
designates a specific section, always on any server. There is no ambiguity as a Message-Id always contains the @ character, a band name ever.
nntp: / / <host>: port_num / name> Group> / <phone d’article>
identifies a specific item in a specific group on a given server. You can omit the last components to describe a group or server, and the default port is 119.
Some websites allow you to read the forums usenet widely distributed and to post, these sites generally offer also a function archive.
All articles posted on Usenet has not been archived. However, from 1995 to 2001, the company Deja.com (now DejaNews.com 1997) conducted such archival work and began providing Internet users a platform for research and sending articles. In December 2001, the search engine Google bought DejaNews.com and article database, then added an archive of articles dating back to the early days of Usenet. The records are incomplete, but nevertheless provided. It is notably possible to retrieve historical messages, as announced by the World Wide Web by Tim Berners-made Lee news: alt.hypertext and the announcement of Linux by Linus Torvalds made in news : comp.os.minix.
Historically, Usenet was developed to distribute plain text using the character 7-bit ASCII. Using programs that encode data 8 bits as a result of 7-bit ASCII characters, it is possible to transfer binary files from Usenet whatsoever. Because of their size and dubious legality, articles containing binary files are accepted only on specific groups, which allow server administrators to accept or refuse to distribute them easily.
The oldest of these encoding methods is uuencode, originally developed for UUCP. In the late 1980s, many servers limited the length of articles to 60,000 characters, and such limits always exist, even if they are generally higher. For this reason, the data of a file are divided into different sections and must be reassembled by the newsreader.
Sometimes parts of a file are no longer downloadable (in fact the servers do not keep the binary message a few days) or that certain parts are wrong. To overcome this problem, we often encounter, are PAR files to download additional data and can reconstruct the missing parts. Generally the PAR files are 10% of the total size of the file to download.
With extensions to the format of items (Base64, “Quoted-Printable” MIME) have come new opportunities for the transport of binary content. In practice, MIME is increasingly used in the messages, but not to transmit binary attachments. In addition, some operating systems that combine the files of auxiliary information (metadata) require special formats. Mac OS uses such Binhex and specific MIME types.
To better utilize the capabilities of the Usenet network and increase the speed of transfer, the coding procedure yEnc was developed in 2001. It uses less space than the usual encoding assuming that most 8-bit characters can be transmitted properly.
Binary files deposited on the newsgroups being cut into several parts (multi-parts), they must be reassembled once all downloads completed. The software appeared to facilitate and expedite the downloading but also to interrupt and resume later. Many other options are available and vary by program, for example:
- Support system NZB
- The integrity check and repair any files through the system Parchive
- Archives simple extraction or several volumes frequently used for dumping large files
Downloading binary files is greatly simplified by the existence of specialized search engines, such as newzleech, or software binsearch NewZFinders. These engines can find an NZB from keywords. This file is then used by the software download binaries.
Commercial offers or included with Internet subscription
In France, only the Free ISP provides access to binary newsgroups (although a number of groups with names like binaries.mp3 have been closed). Their interest is often simple: reduce the cost of bandwidth by offering a server inside their network. This free access, however, often suffers from limitations such as low retention time (often several days or weeks), or censorship of certain newsgroups (sometimes as a result of judicial decisions) accused of promoting illegal downloading.
Meanwhile, there are a number of offers Usenet charge, providing many advantages of the long retention (over 600 days for the best) and an encrypted SSL to protect privacy. These offers are often appreciated by those who download binaries due to a lack of censorship.
Generally, bids are marketed according to the following models:
- Volume pricing only: the user buys a certain volume of data and can use it when he wants;
- Fixed monthly pricing, with or without speed limit;
- A hybrid pricing: the user pays the month with a maximum monthly download quota (beyond the download is either blocked or at reduced speed).
Subscription rates used in part to finance infrastructure. In fact it is really a client / server and not P2P.
Study: From Wikipedia, the free encyclopedia. The text is available under the Creative Commons.
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