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Botnet

Botnet

Botnet is a jargon term for a collection of software robots, or bots, which run autonomously. A botnet's originator can control the group remotely, usually through a means such as IRC, and usually for nefarious purposes. A botnet can comprise a collection of cracked machines running programs (usually referred to as worms, Trojan horses, or backdoors) under a common command and control infrastructure. Individual programs manifest as IRC "bots". Often the command and control takes place via an IRC server or a specific channel on a public IRC network. A bot typically runs hidden, and complies with the RFC 1459 standard. Generally, the perpetrator of the botnet has compromised a series of systems using various tools (exploits, buffer overflows, as well as others; see also RPC). Newer bots can automatically scan their environment and propagate themselves using vulnerabilities and weak passwords. Generally, the more vulnerabilities a bot can scan and propagate through, the more valuable it becomes to a botnet owner community. A Botnet can also be a group of IRC Eggdrops. Botnets have become a significant part of the Internet, albeit increasingly hidden. Due to most conventional IRC networks taking measures and blocking access to previously-hosted botnets, owners must now find their own servers. Oftentimes, a botnet will include a variety of connections, ranging from dial-up, DSL, cable, educational, and corporate. Sometimes, an owner will hide an IRC server installation on an educational or corporate site, where high-speed connections can support a large number of other bots. Exploitation of this method of using a bot to host other bots has proliferated only recently, as most script kiddies do not have the knowledge to take advantage of it.

How It is created

Object Oriented programming languages are the preferred method for making a Botnet. For the windows platform, it's easy for people to download programs from the internet without knowing exactly what is in the program. Instead of paying $19 for the official version of the software, there might be another free version of the software that promises the same functionality. This piece of software may contain a bot. Once the bot is installed, the bot can scan your network, file structures, propogate, etc...

Purpose

script kiddie Botnets serve various purposes, including Denial-of-service attacks, creation or misuse of SMTP mail relays for spam, click fraud, and the theft of application serial numbers, login IDs, and financial information such as credit card numbers. The botnet owner community features a constant and continuous struggle over who has the most bots, the highest overall bandwidth, and the largest amount of "high-quality" infected machines (commonly university, corporate, and even government machines).

Organization

Botnet servers will often liaise with other botnet servers, such that a group may contain 20 or more individual cracked high-speed connected machines as servers, linked together for purposes of greater redundancy. Actual botnet communities usually consist of one or several owners who consider themselves as having legitimate access (note the irony) to a group of bots. Such owners rarely have highly-developed command hierarchies between themselves; they rely on individual friend-to-friend relationships. Often conflicts will occur between the owners as to who owns the individual rights to which machines, and what sorts of actions they may or may not permit.

Types of Attacks

Main article: Denial of Service Attacks

Preventive Measures

If a machine receives a Distributed Denial of Service attack from a botnet, few choices exist. Given the general geographic dispersal of botnets, it becomes difficult to identify a pattern of offending machines, and the sheer volume of IP addresses does not lend itself to the filtering of individual cases. Passive OS Fingerprinting can identify attacks originating from a botnet: network administrators can configure newer firewall equipment to take action on a botnet attack by using information obtained from Passive OS Fingerprinting. Botnets typically use free DNS hosting services such as DynDns.org, No-IP.com, & Afraid.org to point a subdomain towards an IRC server that will harbor the bots. While these free DNS services do not themselves host attacks, they provide reference points, often hard-coded into the botnet executable. Removing such services can cripple an entire botnet. Recently, these companies have undertaken efforts to purge their domains of these subdomains. The botnet community refer to such efforts as "nullrouting", because the DNS hosting services usually direct the offending subdomains to an inaccessible IP address. The botnet server structure mentioned above has inherent vulnerabilities and problems. For example, if one was to find one server with one botnet channel, often all other servers, as well as other bots themselves, will be revealed. If a botnet server structure lacks redundancy, the disconnection of one server will cause the entire botnet to collapse (at least until the owner(s) decides on a new hosting space). However, more recent IRC server software includes features to mask other connected servers and bots, so that a discovery of one channel will not lead to much harm.

External links

- http://swatit.org/bots/gallery.html - A gallery of botnet structure
- http://www.nanog.org/mtg-0410/kristoff.html - John Kristoff's NANOG32 Botnets presentation
- http://www.honeynet.org/papers/bots/ - German honeynet research paper Category:Computer security Category:Spamming

Software

Computer software (or simply software) is that part of a computer system that consists of symbolicly encoded information as opposed to the physical computer equipment (hardware) which is used to store and process this information. The term is roughly synonymous with computer program but is more generic in scope. The term "software" was first used in this sense by John W. Tukey in 1957. In computer science and software engineering, computer software is all information processed by computer systems, programs and data. The concept of software was first proposed by Alan Turing in an essay.

Relationship to hardware

Computer software is so called in contrast to computer hardware, which is the physical substrate which is required to store and execute (or run) the software. In computers, software is loaded in RAM and executed on the central processing unit. At the lowest level, software consists of a machine language specific to an individual processor. Machine language consists of groups of binary values signifying processor instructions and data. Software is generally written in high-level languages that are easy and efficient for humans to use. High-level languages are compiled into machine language.

Relationship to data

Software has historically been considered an intermediary between electronic hardware and data, which the hardware processes according to instructions defined by the software. As computational science becomes increasingly complex, the distinction between software and data becomes less precise. Data has generally been considered as either the output or input of software. However, data is not the only possible output or input. For example, configuration information can also be considered input, although not necessarily considered data. The output of a particular piece of software may be the input for another piece of software. Therefore, software may be considered an interface between hardware, data, or software.

System, application and programming software

Practical computer systems divide software into three major classes: system software, application software and programming software, although the distinction is somewhat arbitrary, and often blurred. :System software helps run the computer hardware and computer system. It includes operating systems, device drivers, diagnostic tools, servers, windowing systems, utilities and more. :Application software allows a user to accomplish one or more specific tasks. Typical applications include office suites, business software, educational software, databases and computer games. Most application software has a graphical user interface (GUI). :Programming software usually provides some useful tools to help programmer to write computer programs and software using different programming language in a more convenient way. The tools include text editor, compiler, interpreter, linker, debugger, and so on. Integrated development environment (IDE) merges those tools in a software bundle, and programmer may not need to type a lot of commands for compiling, interpreter, debugging, tracing, and etc., because IDE mostly has a GUI.

Software program and library

Software program is usually the directly executable part of a software. Software libraries are software components that are used by stand-alone programs, but which cannot be executed on their own.

Users see three layers of software

Software libraries Users often see things differently than programmers. People who use modern general purpose computers (as opposed to embedded systems) usually see three layers of software performing a variety of tasks: platform, application, and user software. ; Platform software : Platform includes the basic input-output system (often described as firmware rather than software), device drivers, an operating system, and typically a graphical user interface which, in total, allow a user to interact with the computer and its peripherals (associated equipment). Platform software often comes bundled with the computer, and users may not realize that it exists or that they have a choice to use different platform software. ; Application software : Application software or Applications are what most people think of when they think of software. Typical examples include office suites and video games. Application software is often purchased separately from computer hardware. Sometimes applications are bundled with the computer, but that does not change the fact that they run as independent applications. Applications are almost always independent programs from the operating system, though they are often tailored for specific platforms. Most users think of compilers, databases, and other "system software" as applications. ; User-written software : User software tailors systems to meet the users specific needs. User software include spreadsheet templates, word processor macros, scientific simulations, graphics and animation scripts. Even email filters are a kind of user software. Users create this software themselves and often overlook how important it is. See also: Software architecture.

Software creation

Look back to Computer software

Software operation

Computer software has to be "loaded" into the computer's storage (also known as memory and RAM). Once the software is loaded, the computer is able to operate the software. Computers operate by executing the computer program. This involves passing instructions from the application software, through the system software, to the hardware which ultimately receives the instruction as machine code. Each instruction causes the computer to carry out an operation -- moving data, carrying out a computation, or altering the flow of instructions. Kinds of software by operation: computer program as executable, source code or script, configuration.

Software quality and reliability

Software reliability considers the errors, faults, and failures related to the creation and operation of software. See Software quality, Software testing, and Software reliability.

Software patents

The issue of software patents is very controversial, since while patents protect the ideas of "inventors", they are widely believed to hinder software development. See Hacker ethic

Internet Relay Chat

:IRC redirects here. For other uses, see IRC (disambiguation). A list of Wikipedia's own IRC channels can be found here. Internet Relay Chat (IRC) is a form of instant communication over the Internet. It is mainly designed for group (many-to-many) communication in discussion forums called channels, but also allows one-to-one communication. IRC was created by Jarkko Oikarinen (nickname "WiZ") in late August 1988 to replace a program called MUT (MultiUser talk) on a BBS called OuluBox in Finland. Oikarinen found inspiration in Bitnet Relay Chat which operated on the Bitnet network. IRC gained prominence when it was used to report on the Soviet coup attempt of 1991 throughout a media blackout. It was later used in a similar fashion by Kuwaitis during the Iraqi invasion.

Technical information

IRC is an open protocol that uses TCP and optionally SSL. An IRC server can connect to other IRC servers to expand the IRC network. Users access IRC networks by connecting a client to a server. There are many client and server implementations. Most IRC servers do not require users to log in, but a user will have to set a nickname before being connected . IRC is a plaintext protocol,which means that it is fully possible (though quite inconvenient) to use IRC via a basic byte-stream client such as netcat or telnet. However, the protocol only uses a slightly modified version of ASCII, and does not originally provide any support for non-ASCII characters in text, with the result that many different, incompatible character encodings (such as ISO 8859-1 and UTF-8) are used. Because most IRC implementations use an acyclic graph as their connection model, there is no redundancy, and outage of a server or a link can cause a netsplit.

Evolution

All client-to-server IRC protocols in use today are descended from the protocol implemented in the irc2.8 version of the IRC2server, and documented in RFC 1459. Since RFC 1459 was published, the new features in the irc2.10 implementation led to the publication of several revised protocol documents; RFC 2810, RFC 2811, RFC 2812 and RFC 2813, however these protocol changes have not been widely adopted among other implementations. IRC 2.10 is most widely used on the IRCnet network. The IRC protocol was extended by Microsoft in 1998 via its IRCX protocol that solves many of the traditional problems that legacy IRC networks faced, along with some features that most users felt were 'ahead of its time'. Although many specifications on the IRC protocol have been published, there is no official specification, as the protocol remains dynamic. Virtually no clients and very few servers rely strictly on the above RFCs as a reference. While the client-to-server protocols are at least functionally similar, server-to-server protocols differ widely (TS5, P10, and ND/CD are several widely-used and incompatible server protocols), making it very difficult to "link" two separate implementations of the IRC server. Some "bridge" servers do exist, to allow linking of, for example, 2.10 servers to TS5 servers, but these are often accompanied with restrictions of which parts of each protocol may be used, and are not widely deployed. In its first incarnations, IRC did not have many features that are taken for granted today, such as named channels and channel operators. Channels were numbered -- channel 4 and channel 57, for example -- and the channel topic described the kind of conversation that took place in the channel. One holdover of this is that joining channel 0 causes a client to leave all the channels it is presently on: "CHANNEL 0" being the original command to leave the current channel. The first major change to IRC, in version 2.5, was to add named channels -- "+channels". "+channels" were later replaced with "#channels" in version 2.7, numeric channels were removed entirely and channel bans (mode +b) were implemented. irc2.8 added "&channels" (those that exist only on the current server, rather than the entire network) and "!channels" (those that are theoretically safe from suffering from the many ways that a user could exploit a channel by "riding a netsplit"), and is the baseline release from which nearly all current implementations are derived. Significant releases based on 2.8 include:
- 2.8.21+CS, developed by Comstud
- 2.8+th, Taner's patchset, which later became
- 2.8/hybrid, originally developed by Jon Lusky (Rodder) and Diane Bruce (Dianora), later joined by a large development team.
- 2.9, 2.10, 2.11, ... continue the development of the original codebase, mainly for use on the IRCnet network. This development line produced the 4 IRC RFCs released after RFC 1459, which document this server protocol exclusively. 2.8.21+CS and 2.8/hybrid continue to be used on EFnet, with ircd-ratbox (an offshoot of 2.8/hybrid) as of 2004 being the most popular. Undernet's IRC server, ircu, is one of the few servers not descended from irc2.8 that are based on the original ircd; it was forked from the irc2.7 codebase. Many modern IRC servers have been coded from scratch, such as csircd (also from Comstud), ConferenceRoom, Microsoft Exchange Chat Service, and IRCPlus/IRCXPro.

Channels and Modes

The basic means of communication in an established IRC session is a channel. You can see all the channels in a server using the command /list [#string] [-min #] [-max #] that lists all currently available channels, optionally filtering for parameters (#string for the entire or part of the name, with wildcards, and #min / #max for number of users in the channel). Users can join to channels (using the command /join #channelname) and then send messages to it, which are then relayed to all other users in the same channel. Channels which are available across an entire IRC network are prepended with a '#', while those local to a server use '&'. Other (non-standard) channel types include '+' channels—'modeless' channels without operators, and '!' channels, a form of timestamped channel on normally non-timestamped networks. Both users and channels may have modes, which are some kind of attributes or switches. Modes are abbreviated by single letters so you can string them together concisely. An example for an user mode is 'i', which stands for invisible. (You cannot tell whether or not an invisible user is on a channel unless you join that channel or use the whois command on its nick.) A simple channel-mode example is 'm' (moderated), specifying that only 'voiced' users and channel operators are allowed to speak on the channel. This, along with 'k' (keyed - requires a password to join the channel) and 'i' (invite-only - requires an invitation from a channel operator) modes can be used to keep abuse out of the channel. There are five types of channelmodes, four of which will accept an argument, type A accepting an argument to add/remove values from a list (such as 'b'), type B accepting an argument that is used when turning the mode 'on' and 'off' (such as 'k'), type C accepting an argument only when the mode is turned 'on' (such as 'l'), type D which accepts no arguments and is simply a boolean flag (such as 'm', 'n', and 't'), and type E (usually called 'class' or 'prefix' modes) that give/take a privilege from a user on a channel (such as 'o'). Type E modes (channel classes) specify which users on a channel have privileges, and what level of those privileges they have. Originally only 'channel operator' (mode 'o') and 'voice' (mode 'v') existed. Channel operator (usually abbreviated chanop or simply 'op') privileges allow a user to kick users, set modes, and change the topic if the channel is '+t'. Voice privileges allow a user to speak on a channel if it is moderated (mode 'm'). Additions to these classes are 'channel owner' (mode 'q') created by Microsoft in its IRCX implementation (and later used by UnrealIrcd); 'half-operator' (mode 'h') which is similar to a chanop, except they cannot set certain modes and can only kick normal users; 'protected' (mode 'a'); 'administrator' (mode 'a' or 'u'); and many more. Each channel class has an associated prefix that is shown beside a user's nickname whenever associated with that channel. The most common prefixes are '@' for channel operator, '+' for voice, '%' for half-op, '.' or '~' for channel owner, '&' for protected user, '!' or '
- ' for administrator. Unless the channel is moderated, the only effect of +v (voice) is the plus sign appearing beside the nick name. On many channels this is used to indicate seniority or regularity of use, or a kind of "trusted user" flag in case the channel does have to be moderated. Most IRC networks feature a lot of extra modes not specified in any RFC document. This is a very simple feat for clients to adapt to since a list of all the valid user and channelmodes are sent to clients in the RPL_MYINFO reply upon logon. In addition, the list of channelmodes (and what type of arguments they accept), and the prefixes for class modes are specified in the protocol control reply (RPL_PROTOCTL or 005) sent from most IRC servers when a client connects. This message is used to tell clients what features the server supports, and what its limits are (for example, the maximum number of users you can have on your notify list, or the maximum length of your nickname). There are also users whose privileges extend to whole servers or networks of servers; these are called IRC Operators. On some IRC implementations, IRC operators are also given channel operator status in every channel, although many people believe that administration of channels and administration of the network should be kept separate, and that IRC operator status does not confer the right to interfere with a particular channel's operation. Because IRC connections are unencrypted and typically span long time periods, they are an attractive target for malicious hackers. Because of this, careful security policy is necessary to ensure that an IRC network is not susceptible to an attack such as an IRC takeover war. IRC networks also k-line or g-line users or networks that tend to have a harming effect. IRC served as an early laboratory for many kinds of Internet attacks, such as using fake ICMP unreachable messages to break TCP-based IRC connections ("nuking") to annoy users or facilitate takeovers.

Abuse prevention: timestamping vs. nick/channel delay protocol

One of the most contentious technical issues surrounding IRC implementations, which survives to this day, is the merit of "Nick/Channel Delay" vs. "TimeStamp" protocols. Both methods exist to solve the problem of denial-of-service attacks, but take very different approaches. The problem with the original IRC protocol as implemented was that when two servers split and rejoined, the two sides of the network would simply merge their channels. If a user could join on a "split" server, where a channel which existed on the other side of the network was empty, and gain operator status, they would become a channel operator of the "combined" channel after the netsplit ended; if a user took a nickname which existed on the other side of the network, the server would kill both users when rejoining. This was often abused to "mass-kill" all users on a channel, thus creating "opless" channels: where no operators were present to deal with abuse. Apart from causing problems within IRC, this encouraged people to conduct denial of service attacks against IRC servers in order to cause netsplits, which they would then abuse.

Nick/channel delay

The nick/channel delay (abbreviated ND/CD) solution to this problem was very simple. After a user signed off and the nickname became available, or a channel ceased to exist because all its users left (as often happens during a netsplit), the server would not allow any user to use that nickname or join that channel, respectively, until a certain period of time (the delay) had passed. The idea behind this was that even if a netsplit occurred, it was useless to an abuser because they could not take the nickname or gain operator status on a channel, and thus no collision of a nickname or 'merging' of a channel could occur. To some extent, this inconvenienced legitimate users, who might be forced to briefly use a different name (appending an underscore was popular) after rejoining.

Timestamping

The alternative, the timestamp or TS protocol, took a different approach. Every nickname and channel on the network was assigned a timestamp -- the date and time when it was created. When a netsplit occurred, two users on each side were free to use the same nickname or channel, but when the two sides were joined, only one could survive. In the case of nicknames, the newer user, according to their TS, was killed; when a channel collided, the members (users on the channel) were merged, but the channel operators on the "losing" side of the split were de-opped. TS is a much more complicated protocol than ND/CD, both in design and implementation, and despite having gone through several revisions, some implementations still have problems with "desyncs" (where two servers on the same network disagree about the current state of the network), and allowing too much leniency in what was allowed by the 'losing' side. Under the original TS protocols, for example, there was no protection against users setting bans or other modes in the losing channel which would then be merged when the split rejoined, even though the users who had set those modes were no longer opped. Some modern TS-based IRC servers have also incorporated some form of ND and/or CD in addition to timestamping in an attempt to further curb abuse. There is not, and likely never will be, a consensus on timestamping vs. delay; however most networks today use the timestamping approach. It was part of the issues and disagreements which caused several servers to split away from EFnet and form the newer IRCnet (EFnet after the split moving to a TS protocol, and IRCnet using ND/CD), and supporters on both sides were known for heated arguments regarding the merits of their solution.

Networks and URLs

Today there are several thousand running IRC networks in the world. They run various implementations of IRC servers, and are administered by various groups of IRC Operators, but the protocol exposed to IRC users is very similar, and all IRC networks can be accessed by the same client software. You can join to servers clicking in a irc://irc.server.net:port/channel web link. The largest IRC networks have traditionally been grouped in The Big Four — a designation for networks that top the statistics. Currently this includes four networks regularly frequented by around or over one hundred thousand clients, namely:
- EFnet
- IRCnet
- QuakeNet
- Undernet Other large networks include:
- Aitvaras
- Beirut_IRC
- DALnet (once held QuakeNet's seat, before a series of DDoS attacks)
- Enter The Game
- Freenode
- IRCHighway
- GameSurge
- LinkNet
- Rizon
- IRC-Hispano
- OFTC
- ShellsNet Smaller networks are another great place for users to chat (especially gamers). These include:
- SGN IRC
- WorldGamers For network statistics, rankings, and a list of smaller networks, see [http://irc.netsplit.de/networks/ netsplit.de] and [http://searchirc.com/networks Search IRC]. For other articles on IRC networks, see :Category:IRC networks.

Clients

:See list of IRC clients for more detail. mIRC is widely believed to be the most popular IRC client on Windows based systems. However with the recent introduction of clients such as VortecIrc, IceChat, Besirc, JIrc, Kv-IRC, Trillian and X-Chat; mIRC is beginning to see some competition. Many people still use mIRC because there more scripts available for this client and they don't know any better. ircII is the canonical Unix IRC client, but its userbase has declined with the appearance of competing clients such as ircII-EPIC, BitchX, irssi, X-Chat, ScrollZ etc. A framework designed to incorporate IRC into various other applications, such as games, is LibIRC, although it is still heavily under development. For Mac OS X, the most widely-used client is Ircle. Other clients include [http://colloquy.info/ Colloquy]. It can also run most Unix-like command line and X11 IRC clients. ChatZilla is the Mozilla IRC client. Opera has a built-in IRC client.

Bots

There are also many automated clients, called bots. The first bot was written by Greg Lindahl and provided moderation for the game of Wumpus, but most modern bots are usually used to exercise operator privileges (controlling channels and acting quickly in case of abuse), to annoy other users (perhaps by spamming them with lots of messages), to answer repetitive user questions and provide help when channels are not attended, or serve as permanent points of contact for information exchange (an answering machine, file transfer, etc.). The most popular IRC bots today are Eggdrop and EnergyMech. More recently, bots have been written using the mIRC client's built-in scripting language. The modern IRC services are implemented via bots. They're often used in channel maintenance: banning users, keeping a list of operators, keeping the channel topic, etc.

Bouncer

A program that runs as a daemon on a server and functions as a persistent proxy is known as a bouncer. A bouncer's purpose is to maintain a connection to an IRC server, acting as a relay between it and the connecting client. Should the client lose network connectivity, the bouncer will archive all traffic for later delivery, allowing the user to resume his IRC session without externally perceptible disruption. Two of the most popular bouncers are [http://mind.riot.org/muh/ muh] and [http://www.psybnc.info/ psyBNC]. Muh is exclusively for single user connections, while psyBNC supports multiple users. Another feature-rich bouncer is [http://znc.sourceforge.net ZNC].

Modern IRC

IRC has changed much over its life on the Internet. New server software has added a multitude of new features.
- Services: Network-operated bots to facilitate registration of nicknames and channels, sending messages for offline users and network operator functions.
- Extra Modes: While the original IRC system used a set of standard user and channel modes, new servers add many new modes for such features as removing color codes from text, or obscuring a user's hostmask ("cloaking") to protect from denial of service attacks.
- Proxy Detection: Most modern servers support detection of users attempting to connect through an insecure (misconfigured or exploited) proxy, which can then be denied a connection. An example is the [http://www.blitzed.org/proxy Blitzed Open Proxy Monitor] or BOPM, used by several networks.
- Additional Commands: New commands can be such things as shorthand commands to issue commands to Services, to network operator only commands to manipulate a user's hostmask.
- Encryption: For the client-to-server leg of the connection SSL might be used (messages cease to be secure once they are relayed to other users on standard connections, but it makes eavesdropping on or wiretapping an individual's IRC sessions difficult). For client-to-client communication, SDCC (secure DCC) can be used.
- Ident: Provides identification to the IRC server.
- Connection Protocol: IRC can be connected to via IPv4, the current standard version of the Internet Protocol, or by IPv6, the next-generation version of the Protocol.

Forms of abuse

Like any network open to the public, people with malicious intent can often be found on IRC networks. These people commonly utilize the following tactics:
- Denial of service attacks and netsplit abuses, described above.
- Responding to requests for help with potentially harmful instructions, such as :
- format C: /Y (reformats hard drive in Windows) :
- rm -rf / (wipes a Unix/Linux system) :
- Ctrl+Alt+Delete twice (forces a reboot in earlier versions of Windows) :
- Alt+F4 (closes current program in Windows) :
- Alt+Z (closes the current channel window in mIRC, a popular IRC client)
- Attempting to trick users into typing commands that will cause them to quit the server. For example: "Two friends are sitting in a garden: /exit and /quit. /exit walks away, who is left?"
- Advertising channels that end in ",0" (such as #0,0). Attempting to join will cause clients to part all channels. This is because a single /join request can join multiple channels separated by commas, and /join 0 is used as a shortcut for clients to part all channels.

File sharing

Using scripts like [http://www.sysreset.com Sysreset], [http://upp.monkey-pirate.com/ UPP] and [http://www.polaris-central.com Polaris] users can create file servers that allow them to share files with others. In addition to the normal pros and cons of file-sharing (see Copyright infringement of software), there are also groups that set up anime fansubbing networks, allowing American audiences to see anime that would normally be unavailable in English and outside of Japan. Due to the large amount of people who use IRC solely for file sharing, some think of IRC as a form of P2P file sharing (along with the client mIRC). Conversely, many users try to defeat this view by persistently discouraging it or refusing to help with it. Technically, IRC is not for file sharing, although it does posess some advanced file transfer mechanisms which, most importantly, support resuming. The creator of mIRC and other clients such as VortecIrc do not in any way support the piracy of electronic material. The file transfer mechanisms are used to share one's own materials. Many servers and channels will ban users sharing licensed materials. However, IRC-based "DCC" transfers should not be considered to be P2P, as the download source is from one, single, individual; typically an "XDCC" bot or another user. While there is much legitimate material on IRC for download, there is also a strong background of "warez", the sharing of illegal or copyrighted material.

External links

- [http://www.mirc.com/mirclink.html Chat Links; From Web to IRC using irc://].
- [http://www.mirc.com/cmds.html Irc commands].
- [http://www.faqs.org/rfcs/rfc1459.html RFC 1459 - IRC Protocol].
- [http://www.irc.org IRC.org - Technical and Historical IRC6 information]
- [http://daniel.haxx.se/irchistory.html History of IRC summarized by Daniel Stenberg]
- [http://www.mirc.com/servers.html mIRC server list, most of the larger IRC networks]
- [http://irc.netsplit.de/ Andreas Gelhausen's extensive IRC statistics]
- [http://irc.alien.net.au/chanmodes.html List of channel modes that various IRC Daemons use]
- [http://www.irchelp.org Large archive of IRC-related documents, somewhat EFNet biased]
- [http://searchirc.com/whois/ cross network whois search] at [http://searchirc.com/ Search IRC, an IRC search engine]
- [http://www.efnet.org/ EFnet IRC] The Original IRC Network
- [http://www.ircimages.com/ Raw images spidered from IRC channels]
- [http://www.irc-news.com/ IRC News] From Various RSS Feeds
- [http://www.irc-junkie.org/ IRC Junkie - IRC news]
- [http://www.irchelp.org/ IRC Help - Learning the basics of IRC, including netiquette]
- [http://www.ircbeginner.com/ IRC beginner].
- [http://irc.alien.net.au/ An extensive list of different numerics and modes used by various IRC networks]
- [http://www.faqs.org/rfcs/rfc1459.html Technical Information about the IRC Protocol]
- [http://www.fredlwm.hpg.ig.com.br/documentation/IRC-mini-HOWTO/ Linux IRC mini-HOWTO]
- [http://www.reseaux-irc.com/ Reseaux-IRC.com - French non-profit IRC monitoring project]
- [http://www.xchat.org/ XCHAT.org - Popular client for
- nix and more recently, Windows.]
- [http://www.linuxirc.com/ LinuxIRC.com - Linux IRC]
- ko:IRC ms:IRC ja:インターネット・リレー・チャット simple:IRC th:ไออาร์ซี

Computer worm

A computer worm is a self-replicating computer program, similar to a computer virus. A virus attaches itself to, and becomes part of, another executable program; however, a worm is self-contained and does not need to be part of another program to propagate itself. They are often designed to exploit the file transmission capabilities found on many computers. The name 'worm' was taken from The Shockwave Rider, a 1970s science fiction novel by John Brunner. Researchers writing an early paper on experiments in distributed computing noted the similarities between their software and the program described by Brunner and adopted the name. The first implementation of a worm was by two researchers at Xerox PARC in 1978. [http://www.parc.xerox.com/about/history/default.html] The authors, John Shoch and Jon Hupp, originally designed the worm to find idle processors on the network and assign them tasks, sharing the processing and so improving the whole network efficiency. [http://www.technovelgy.com/ct/content.asp?Bnum=190] The first worm to attract wide attention, the Morris worm, was written by Robert Tappan Morris, who at the time was a graduate student at Cornell University. It was released on November 2, 1988, and quickly infected a great number of computers on the Internet at the time. It propagated through a number of bugs in BSD Unix and its derivatives. Morris himself was convicted under the US Computer Crime and Abuse Act and received three years probation, community service and a fine in excess of $10,000. In addition to replication, a worm may be designed to do any number of things, such as delete files on a host system or send documents via email. More recent worms may be multi-headed and carry other executables as a payload. However, even in the absence of such a payload, a worm can wreak havoc just with the network traffic generated by its reproduction. Mydoom, for example, caused a noticeable worldwide Internet slowdown at the peak of its spread. A common payload is for a worm to install a backdoor in the infected computer, as was done by Sobig and Mydoom. These zombie computers are used by spam senders for sending junk email or to cloak their website's address.[http://seattletimes.nwsource.com/html/businesstechnology/2001859752_spamdoubles18.html] Spammers are thought to pay for the creation of such worms [http://www.wired.com/news/business/0,1367,60747,00.html] [http://www.channelnewsasia.com/stories/afp_world/view/68810/1/.html], and worm writers have been caught selling lists of IP addresses of infected machines.[http://www.heise.de/english/newsticker/news/44879] Others try to blackmail companies with threatened DoS attacks.[http://news.bbc.co.uk/1/hi/technology/3513849.stm] The backdoors can also be exploited by other worms, such as Doomjuice, which spreads using the backdoor opened by Mydoom. Whether worms can be useful is a common theoretical question in computer science and artificial intelligence. The Nachi family of worms, for example, tried to download then install patches from Microsoft's website to fix various vulnerabilities in the host system — the same vulnerabilities that they exploited. This eventually made the systems affected more secure, but generated considerable network traffic (often more than the worms they were protecting against), rebooted the machine in the course of patching it, and, maybe most importantly, did its work without the explicit consent of the computer's owner or user. As such, most security experts deprecate worms, whatever their payload.

Penalties

In January 2002 programmer Simon Vallor was sentenced to two years in prison for releasing the "mass mailer" viruses Gokar, Admirer and RedesiB. [http://news.bbc.co.uk/1/hi/wales/2681675.stm] Vallor claimed he thought that the viruses were harmless. [http://news.bbc.co.uk/1/hi/wales/2680419.stm] In February 2003, two people belonging to a group called "THr34t-Krew" were arrested in relation to the creation and release of the T-K Worm [http://news.bbc.co.uk/1/hi/technology/2733657.stm]. In May 2005 Andrew Harvey and Jordan Bradley admitted creating and releasing the T-K Worm which went on to infect 19,000 computers.[http://news.bbc.co.uk/1/hi/england/tees/4588197.stm]. In October 2005 Harvey received three months in prison and Bradley received six months. [http://news.bbc.co.uk/1/hi/england/4319942.stm].

External links

- [http://www.wildlist.org The Wildlist] - List of viruses and worms 'in the wild' (i.e. regularly encountered by anti-virus companies)
- [http://www.2-spyware.com/worms-removal Worm parasites] - Listed worm descriptions and removal tools.
- [http://www.securityfocus.com/print/columnists/347 Jose Nazario discusses worms] - Worms overview by a famous security researcher.
- [http://www.pc-news.org/computer-worm-suspect-in-court/virus-news Computer worm suspect in court] Category:Malware ja:ワーム

Command and control

In telecommunications, command and control (C ²) is the exercise of authority and direction by a properly designated commander over assigned and attached forces in the accomplishment of the mission. In the military, command and monitoring of the outcome of control functions are performed through an arrangement of personnel (the command hierarchy), equipment (the signal infrastructure of communications facilities), and all other procedures employed by a commander in planning, directing, coordinating, and controlling forces and operations in the accomplishment of the mission. See command, control, and communications (C3) for more on the military view. The term is also extended to include a reference to military intelligence as well, in command, control, communications and intelligence (C3I). The term however also applies in governance and government where it refers more generally to the maintenance of authority with somewhat more distributed decision making. In these civilian contexts the term command is unfashionable but the meaning is the same. Some management science theorists even hold that the idea is now obsolete. For instance Dee Hock says that "Purpose and principle, clearly understood and articulated, and commonly shared, are the genetic code of any healthy organization. To the degree that you hold purpose and principles in common among you, you can dispense with command and control. People will know how to behave in accordance with them, and they'll do it in thousands of unimaginable, creative ways. The organization will become a vital, living set of beliefs." In the military this principle has been applied by German armed forces since the 19th century as Auftragstaktik.

Internet usage

The term command and controll (note the ll) is sometimes employed by Internet trolls to suggest that their activities are more organized than they might appear. Category:Warfare

RPC

: This article relates to computers. For Rules of Professional Conduct (RPC) relating to U.S. lawyers' ethical rules, see American Bar Association Model Rules of Professional Conduct A remote procedure call (RPC) is a protocol that allows a computer program running on one host to cause code to be executed on another host without the programmer needing to explicitly code for this. When the code in question is written using object-oriented principles, RPC is sometimes referred to as remote invocation or remote method invocation. RPC is an easy and popular paradigm for implementing the client-server model of distributed computing. An RPC is initiated by the caller (client) sending a request message to a remote system (the server) to execute a certain procedure using arguments supplied. A result message is returned to the caller. There are many variations and subtleties in various implementations, resulting in a variety of different (incompatible) RPC protocols. In order to allow servers to be accessed by differing clients, a number of standardized RPC systems have been created. Most of these use an interface description language (IDL) to allow various platforms to call the RPC. The first popular implementation of RPC on Unix was Sun's RPC (sometimes called ONC RPC), which was used as the basis for NFS. Another early Unix implementation was the RPC mechanism in Apollo Computer's Network Computing System (NCS), which after HP's acquisition of Apollo later surfaced as DCE/RPC in the OSF's Distributed Computing Environment (DCE). A decade later Microsoft adopted DCE/RPC as the basis of their Microsoft RPC (MSRPC) mechanism, and implemented DCOM (and ActiveX) atop it. Xerox PARC's ILU, and CORBA, offered a similar RPC paradigm on the Windows and Unix platforms. Java's Java Remote Method Invoke (JRMI) API has replaced earlier Unix implementations of RPC on the Unix platform. .NET Remoting offers low-level RPC facilities for distributed systems implemented on the Windows platform. Web services were the first real attempt to implement RPC between platforms. Using Web services a .NET client can call a remote procedure implemented in Java on a Unix server (and vice versa). Web services use XML as the IDL, and HTTP as the network protocol. The advantage of this system is simplicity and standardization, the IDL is a text file that is widely understood, and HTTP is built into almost all modern operating systems. An example of such an RPC system is SOAP, developed in turn from XML-RPC. However, web services have been criticized as wasteful in terms of bandwidth and processing requirements. An example of a modern RPC system that attempts to avoid both the complexity of CORBA and the inefficiency of web services is ZeroC's Internet Communications Engine (ICE). An alternative approach to RPC is Representational State Transfer REST. Category:Operating system technology ja:RPC

Internet

:For the more general networking concept, see internetworking. The Internet, or simply the Net, is the worldwide system of interconnected computer networks which makes information stored on it accessible. This information is transmitted by packet switching using a standardized Internet Protocol (IP) and many other protocols. It is made up of thousands of smaller commercial, academic, domestic and government networks. It carries various information and services, such as electronic mail, online chat, and the interlinked web pages and other documents of the World Wide Web.

Creation of the Internet

During the 1950s, several communications researchers realized that there was a need to allow general communication between users of various computers and communications networks. This led to research into decentralized networks, queuing theory, and packet switching. The subsequent creation of ARPANET in the United States in turn catalyzed a wave of technical developments that made it the basis for the development of the Internet. Contrary to popular myth, the DoD did not create the ARPANET so that they could communicate to the US Government after a nuclear war. The first TCP/IP wide area network was operational in 1984 when the United States' National Science Foundation (NSF) constructed a university network backbone that would later become the NSFNet. It was then followed by the opening of the network to commercial interests in 1995. Important separate networks that offered gateways into, then later merged into the Internet include Usenet, Bitnet and the various commercial and educational X.25 networks such as Compuserve and JANET. The ability of TCP/IP to work over these pre-existing communication networks allowed for a great ease of growth. Use of Internet as a phrase to describe a single global TCP/IP network originated around this time. The collective network gained a public face in the 1990s. In August 1991 CERN in Switzerland publicized the new World Wide Web project, two years after Tim Berners-Lee had begun creating HTML, HTTP and the first few web pages at CERN in Switzerland. In 1993 the Mosaic web browser version 1.0 was released, and by late 1994 there was growing public interest in the previously academic/technical Internet. By 1996 the word "Internet" was common public currency, but it referred almost entirely to the World Wide Web. Meanwhile, over the course of the decade, the Internet successfully accommodated the majority of previously existing public computer networks (although some networks such as FidoNet have remained separate). This growth is often attributed to the lack of central administration, which allows organic growth of the network, as well as the non-proprietary open nature of the Internet protocols, which encourages vendor interoperability and prevents any one company from exerting too much control over the network.

Today's Internet

FidoNets, FTP client, and Telnet client]] Apart from the complex physical connections that make up its infrastructure, the Internet is held together by bi- or multi-lateral commercial contracts (for example peering agreements) and by technical specifications or protocols that describe how to exchange data over the network. Indeed, the Internet is essentially defined by its interconnections and routing policies. In an often-cited, if perhaps gratuitously mathematical definition, Seth Breidbart once described the Internet as "the largest equivalence class in the reflexive, transitive, symmetric closure of the relationship 'can be reached by an IP packet from'". Unlike older communications systems, the Internet protocol suite was deliberately designed to be independent of the underlying physical medium. Any communications network, wired or wireless, that can carry two-way digital data can carry Internet traffic. Thus, Internet packets flow through wired networks like copper wire, coaxial cable, and fiber optic; and through wireless networks like Wi-Fi. Together, all these networks, sharing the same high-level protocols, form the Internet. The Internet protocols originate from discussions within the Internet Engineering Task Force (IETF) and its working groups, which are open to public participation and review. These committees produce documents that are known as Request for Comments documents (RFCs). Some RFCs are raised to the status of Internet Standard by the Internet Architecture Board (IAB). Some of the most used protocols in the Internet protocol suite are IP, TCP, UDP, DNS, PPP, SLIP, ICMP, POP3, IMAP, SMTP, HTTP, HTTPS, SSH, Telnet, FTP, LDAP, SSL, and TLS. Some of the popular services on the Internet that make use of these protocols are e-mail, Usenet newsgroups, file sharing, Instant Messenger, the World Wide Web, Gopher, session access, WAIS, finger, IRC, MUDs, and MUSHs. Of these, e-mail and the World Wide Web are clearly the most used, and many other services are built upon them, such as mailing lists and blogs. The Internet makes it possible to provide real-time services such as Internet radio and webcasts that can be accessed from anywhere in the world. Some other popular services of the Internet were not created this way, but were originally based on proprietary systems. These include IRC, ICQ, AIM, and Gnutella. There have been many analyses of the Internet and its structure. For example, it has been determined that the Internet IP routing structure and hypertext links of the World Wide Web are examples of scale-free networks. Similar to how the commercial Internet providers connect via Internet exchange points, research networks tend to interconnect into large subnetworks such as:
- GEANT
- Internet2
- GLORIAD These in turn are built around relatively smaller networks. See also the list of academic computer network organizations In network schematic diagrams, the Internet is often represented by a cloud symbol, into and out of which network communications can pass.

Internet culture

The Internet is also having a profound impact on work, leisure, knowledge and worldviews. worldviews]]

ICANN

The Internet Corporation for Assigned Names and Numbers (ICANN) is the authority that coordinates the assignment of unique identifiers on the Internet, including domain names, Internet protocol addresses, and protocol port and parameter numbers. A globally unified namespace (i.e., a system of names in which there is one and only one holder of each name) is essential for the Internet to function. ICANN is headquartered in Marina del Rey, California, but is overseen by an international board of directors drawn from across the Internet technical, business, academic, and non-commercial communities. The US government continues to have a privileged role in approving changes to the root zone file that lies at the heart of the domain name system. Because the Internet is a distributed network comprising many voluntarily interconnected networks, the Internet, as such, has no governing body. ICANN's role in coordinating the assignment of unique identifiers distinguishes it as perhaps the only central coordinating body on the global Internet, but the scope of its authority extends only to the Internet's systems of domain names, Internet protocol addresses, and protocol port and parameter numbers.

The World Wide Web

Through keyword-driven Internet research using search engines like Google, millions worldwide have easy, instant access to a vast and diverse amount of online information. Compared to encyclopedias and traditional libraries, the World Wide Web has enabled a sudden and extreme decentralization of information and data. Some companies and individuals have adopted the use of 'weblogs' or blogs, which are largely used as easily-updatable online diaries. Some commercial organizations encourage staff to fill them with advice on their areas of specialization in the hope that visitors will be impressed by the expert knowledge and free information, and be attracted to the corporation as a result. One example of this practice is Microsoft, via whose product developers publish their personal blogs in order to pique the public's interest in their work. For more information on the distinction between the World Wide Web and the Internet itself — as in everyday use the two are sometimes confused — see Dark internet where this is discussed in more detail.

Remote access

The Internet allows computer users to connect to other computers and information stores easily, wherever they may be across the world. They may do this with or without the use of security, authentication and encryption technologies, depending on the requirements. This is encouraging new ways of working from home, collaboration and information sharing in many industries. An accountant sitting at home can audit the books of a company based in another country, on a server situated in a third country that is remotely maintained by IT specialists in a fourth. These accounts could have been created by home-working book-keepers, in other remote locations, based on information e-mailed to them from offices all over the world. Some of these things were possible before the widespread use of the Internet, but the cost of private, leased lines would have made many of them infeasible in practice. An office worker away from his or her desk, perhaps the other side of the world on a business trip or a holiday, can open a remote desktop session into his or her normal office PC using a secure Virtual Private Network (VPN) connection via the Internet. This gives him or her complete access to all their normal files and data, including e-mail and other applications, while they are away.

Collaboration

This low-cost and nearly instantaneous sharing of ideas, knowledge and skills has revolutionized some, and given rise to whole new, areas of human activity. One example of this is the collaborative development and distribution of Free/Libre/Open-Source Software (FLOSS) such as Linux, Mozilla and OpenOffice.org. See Collaborative software.

File-sharing

A computer file can be e-mailed to customers, colleagues and friends as an attachment. It can be uploaded to a website or FTP server for easy download by others. It can be put into a "shared location" or onto a file server for instant use by colleagues. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networking. In any of these cases, access to the file may be controlled by user authentication; the transit of the file over the Internet may be obscured by encryption and money may change hands before or after access to the file is given. The price can be paid by the remote charging of funds from, for example a credit card whose details are also passed - hopefully fully encrypted - across the Internet. The origin and authenticity of the file received may be checked by digital signatures or by MD5 message digests. These simple features of the Internet, over a world-wide basis, are changing the basis for the production, sale and distribution of many types of product, wherever they can be reduced to a computer file for transmission. This includes all manner of office documents, publications, software products, music, photography, video, animations, graphics and the other arts. This in turn is causing seismic shifts in each of the existing industry associations, such as the RIAA and MPAA, that previously controlled the production and distribution of these products.

Streaming media and VoIP

Many existing radio and television broadcasters have provided Internet 'feeds' of their live audio and video streams (for example, the BBC). They have been joined by a range of pure Internet 'broadcasters' who never had on-air licences. This means that an Internet-connected device, such as a computer or something more specific, can be used to access on-line media in much the same way as was previously possible only with a TV or radio receiver. The range of material is much wider, from pornography to highly specialised technical web-casts. The simplest equipment can allow anybody, with little censorship or licencing control, to broadcast on a worldwide basis. Time-shift viewing or listening is not a problem as the BBC have shown with their Preview, Classic Clips and Listen Again features. Web-cams can be seen as an even lower-budget extension of this phenomenon. In this case the picture may update only slowly - perhaps once every few seconds or slower, but Internet users can watch animals around an African waterhole, ships in the Panama Canal or the traffic at a local roundabout live and in real time. Video chat rooms, video conferencing, and remote controllable webcams have become popular. Some people install webcams in their bedrooms that can be accessed by other voyeurs, often with two-way sound. VoIP stands for Voice over IP, where IP refers to the Internet Protocol that underlies all Internet communication. This phenomenon began as an optional two-way voice extension to some of the Instant Messaging systems that took off around the turn of the millennium. In recent years many people and organizations have made VoIP systems as easy to use and as convenient as a normal telephone. The benefit is that, as the actual voice traffic is carried by the Internet, VoIP is free or costs much less than an actual telephone call, especially over long distances and especially for those with always-on ADSL or DSL Internet connections anyway. The disadvantages are that it is still difficult to initiate a call with someone, unless they also have a VoIP phone or are at their computer and that there are still several competing standards that are mitigating against universal acceptance. In all of these cases, existing large organisations, that have grown accustomed to regular incomes for their services, are finding increased competition in their service areas, coming directly from the Internet. While newcomers strive to make these inroads, the traditional industries are having to adapt, adopt, complain or suffer. Meanwhile the consumer in each case most probably benefits from the increased range of services and possible price reductions. Some worry about censorship and control while others see a continuing globalisation of culture and norms.

Language

Main article: English on the Internet The most prevalent language for communication on the Internet is English. This may be due to the Internet's origins or to the growing role of English as an international language. It may also be related to the poor capability of early computers to handle characters other than those in the basic Latin alphabet (see Unicode). After English (32 % of web visitors) the most-requested languages on the world wide web are Chinese 13 %, Japanese 8 %, Spanish 6 %, German 6 % and French 4 %. (From [http://www.internetworldstats.com/stats7.htm Internet World Stats]) By continent, 33 % of the world's Internet users are based in Asia, 29 % in Europe and 23 % in North America.[http://www.internetworldstats.com/stats.htm] The Internet's technologies have developed enough in recent years that good facilities are available for development and communication in most widely used languages. However, some glitches such as mojibake still remain.

Cultural awareness

From a cultural awareness perspective, the Internet has been both an advantage and a liability. For people who are interested in other cultures it provides a significant amount of information and an interactivity that would be unavailable otherwise. However, for people who are not interested in other cultures there is some evidence indicating that the Internet enables them to avoid contact to a greater degree than ever before.

Censorship

Some countries, such as Iran and the People's Republic of China, restrict what people in their countries can see on the Internet, especially unwanted political and religious content. In the Western world, it is Germany that has the highest rate of censorship. Internet Service Providers are required by law to block some sites that contain child pornography or Nazi or Islamist propaganda. Censorship is sometimes done through government sponsored censoring filters, or by means of law or culture, making the propagation of targeted materials extremely hard. At the moment most Internet content is available regardless of where one is in the world, so long as one has the means of connecting to it.

Internet access

Germany Common methods of home access include dial-up, landline broadband (over coaxial cable, fiber optic or copper wires), Wi-Fi, satellite and cell phones. Public places to use the Internet include libraries and Internet cafes, where computers with Internet connections are available. There are also Internet access points in many public places like airport halls, in some cases just for brief use while standing. Various terms are used, such as "public Internet kiosk", "public access terminal", and "Web payphone". Many hotels now also have public terminals, though these are usually fee based. Wi-Fi provides wireless access to computer networks, and therefore can do so to the Internet itself. Hotspots providing such access include Wi-Fi-cafes, where a would-be user needs to bring their own wireless-enabled devices such as a laptop or PDA. These services may be free to all, free to customers only, or fee-based. A hotspot need not be limited to a confined location. The whole campus or park, or even the entire city can be enabled. Grassroots efforts have led to wireless community networks. Apart from Wi-Fi, there have been experiments with proprietary mobile wireless networks like Ricochet, various high-speed data services over cellular or mobile phone networks, and fixed wireless services. These services have not enjoyed widespread success due to their high cost of deployment, which is passed on to users in high usage fees. New wireless technologies such as WiMAX have the potential to alleviate these concerns and enable simple and cost effective deployment of metropolitan area networks covering large, urban areas. There is a growing trend towards wireless mesh networks, which offer a decentralized and redundant infrastructure and are often considered the future of the Internet. Broadband access over power lines was approved in 2004 in the United States in the face of stiff resistance from the amateur radio community. The problem with modulating a carrier signal onto power lines is that an above-ground power line can act as a giant antenna and jam long-distance radio frequencies used by amateurs, seafarers and others. Countries where Internet access is available to a majority of the population include Germany, India, China, Chile, Iceland, Finland, Sweden, Greece, Italy, Australia, Denmark, the United States, Canada, the United Kingdom, The Netherlands, Japan, Singapore, Taiwan, Thailand, South Korea and Norway. The use of the Internet around the world has been growing rapidly over the last decade, although the growth rate seems to have slowed somewhat after 2000. The phase of rapid growth is ending in industrialized countries, as usage becomes ubiquitous there, but the spread continues in Africa, Latin America, the Caribbean and the Middle East. However, there are still problems for many. ADSL and other broadband access are rare or nonexistent in most developing countries. Even in developed countries, high prices, mediocre performance and access restrictions often limit its uptake. Within individual countries, wide differences may exist between larger cities (often having multiple providers of broadband access) and some rural areas, where no broadband access may be available at all. The expansion of the availability of Internet access is a way to bridge the so-called digital divide.

Capitalization conventions

In formal usage, Internet is traditionally written with a capital first letter. The Internet Society, the Internet Engineering Task Force, the Internet Corporation for Assigned Names and Numbers, the World Wide Web Consortium, and several other Internet-related organizations all use this convention in their publications. In English grammar, proper nouns are capitalized. Most newspapers, newswires, periodicals, and technical journals also capitalize the term. Examples include the New York Times, the Associated Press, Time, The Times of India, Hindustan Times and Communications of the ACM. In other cases, the first letter is often written small (internet), and many people are not aware of any convention of using a capital letter. Some argue that internet is the correct form. Since 2000, a significant number of publications have switched to using internet. Among them are The Economist, the Financial Times, the London Times, and the Sydney Morning Herald. As of 2005, most publications using internet appear to be located outside of North America although one American news source, Wired News, has adopted the lowercase spelling.

Leisure

The Internet has been a major source of leisure since before the World Wide Web, with entertaining social experiments such as MOOs being conducted on university servers, and humor-related USENET groups receiving much of the main traffic. Today, many Internet forums have sections devoted to neta; short cartoons in the form of Flash movies are also popular. The pornography and gambling industries have both taken full advantage of the World Wide Web, and often provide a significant source of advertising revenue for other Web sites. Although many governments have attempted to put restrictions on both industries' use of the Internet, this has generally failed to stop their widespread popularity. One main area of leisure on the Internet is multiplayer gaming. This form of leisure creates communities, bringing people of all ages and origins to enjoy the fast-paced world of multiplayer games. These range from MMORPG to first-person shooters, from role-playing games to online gambling. This has revolutionized the way many people interact and spend their free time on the Internet. Online gaming began with services such as GameSpy and MPlayer, which players of games would typically subscribe to. Non-subscribers were limited to certain types of gameplay or certain games. With the release of Diablo by Blizzard Entertainment, gamers were treated to a built in online game service that was free of charge. With Blizzard's next game, StarCraft, the gaming world saw an explosion in the numbers of players using the Internet to play multi-player games. StarCraft may have been the first non-MMO game in which most players utilized the online gameplay as opposed to the single-player gameplay. Online gaming has progressed so much in the last 10 years that gamers earn a living from being a professional at the subject by winning tournaments and prizes as well as signing sponsor deals. Because there is a large support for certain online games, a new community has been born for people modding games, where users edit games to add a whole new element to it. This is how games such as Counter-Strike were born from the Half-Life Gaming Engine. Cyberslacking has become a serious drain on corporate resources; the average UK employee spends 57 minutes a day surfing, according to a study by Peninsula Business Services[http://news.scotsman.com/topics.cfm?tid=914&id=1001802003].

A complex system

Many computer scientists see the Internet as a "prime example of a large-scale, highly engineered, yet highly complex system" (Willinger, et al). The Internet is extremely heterogeneous. (For instance, data transfer rates and physical characteristics of connections vary widely.) The Internet exhibits "emergent phenomena" that depend on its large-scale organization. For example, data transfer rates exhibit temporal self-similarity.

Marketing

The Internet has also become a big market, and the biggest companies today have grown by taking advantage of the efficient low-cost advertising and commerce through the Internet. It is the fastest way to spread information to a vast community of people all at once. The Internet has revolutionized shopping –– a person can order a CD online and receive it in the mail within a couple of days, or download it directly in some cases.

Criticism

Many hyperlinks are outdated as time takes its toll on the existence of URL weblinks. These weblinks are often times defunct and are retained as hyperlinks for extended timeframes as a result of laziness or being busy enough to be sidetracked away from updating webpages. This is a common hoax for people who are fans in the field of what those links provide them with/to.

External links

General

- [http://www.channel101.com/ Internet TV Stations]
- [http://www.isoc.org/ The Internet Society (ISOC)]
- [http://www.techterms.org/internet.php Internet Dictionary] - Definitions of Internet-related terms
- [http://www.experienced-people.co.uk/1099-webmaster-glossary/ The Alternate Internet Glossary] (Humor)
- A [http://www.illusivecreations.com Calgary Web Design] company that has put together over 300 articles about the internet and web development. You can view them by going [http://www.illusivecreations.com/articles/ here].
- [http://www.clickz.com/stats/sectors/geographics/article.php/5911_151151 Internet access stats]
- [http://www.sharpened.net/glossary/ Glossary of Computer and Internet Terms]
- [http://scoreboard.keynote.com/scoreboard/Main.aspx?Login=Y&Username=public&Password=public Internet Health Report] from Keynote
- [http://www.internetworldstats.com/stats.htm Internet World Stats]

Articles

- [http://www.iht.com/articles/2005/09/29/business/net.php "EU and U.S. clash over control of the Net" - International Herald Tribune article by Tom Wright]
- [http://www.wired.com/wired/archive/13.08/intro.html "10 Years that changed the world" - WiReD looks back at the evolution of the Internet over last 10 years]
- [http://www.fourmilab.ch/documents/digital-imprimatur/ John Walker: The Digital Imprimatur]
- [http://www.addressingtheworld.info addressingtheworld.info] - website accompanying a book (ISBN 0742528103) on the history of DNS
- [http://computer.howstuffworks.com/internet-infrastructure.htm How Stuff Works explanation of the Infrastructure of the Internet]
- [http://www.searchandgo.com/articles/internet/net-explained-1.php Internet Explained] Seven part article explaining the origins to the present and a future look at the Internet.
- [http://www.wired.com/news/culture/0,1284,64596,00.html?tw=wn_tophead_7 "It's Just the 'internet' Now" - Wired.com article by Tony Long]

History

- [http://www.isoc.org/internet/history/brief.shtml The Internet Society History Page]
- [http://www.internetvalley.com/archives/mirrors/cerf-how-inet.txt How the Internet Came to Be]
- [http://www.zakon.org/robert/internet/timeline/ Hobbes' Internet Timeline v7.0]
- [http://www.ciolek.com/PAPERS/e-scholarship2000.html Futures and Non-futures for Scholarly Internet. ]
- [http://www.lk.cs.ucla.edu/internet_history.html History of the Internet links]
- [http://www.ietf.org/rfc/rfc801.txt RFC 801, planning the TCP/IP switchover]
- [http://www.archive.org/ Internet Archive] - A searchable database of old cached versions of websites dating back to 1996
- A list of lectures, some of which relate to the Internet, from the Massachusetts Institute of Technology is available [http://ocw.mit.edu/OcwWeb/Comparative-Media-Studies/CMS-930Media--Education--and-the-MarketplaceFall2001/VideoLectures/index.htm here]. Of particular interest is lecture #3 The Next Big Thing: Video Internet which is delivered in Real Player format. The lecture gives a brief history of networking; discusses convergence between the internet/telephone/television networks; the expansion of broadband access; makes predictions about the future of delivery of video over the internet.

References

- Walter Willinger, Ramesh Govindan, Sugih Jamin, Vern Paxson, and Scott Shenker. (2002). Scaling phenomena in the Internet. In Proceedings of the National Academy of Sciences, 99, suppl. 1, 2573 – 2580. Category:Communication Category:Digital media Category:Internet Category:Digital Revolution Category:Technology Category:Computer networks Category:Networks ko:인터넷 ms:Internet ja:インターネット simple:Internet th:อินเทอร์เน็ต fiu-vro:Internet

Digital Subscriber Line

Digital Subscriber Line, or DSL, is a family of technologies that provide digital data transmission over the wires used in the "last mile" of a local telephone network. Typically, the download speed of DSL ranges from 128 kilobits per second (Kb/s) to 6000 Kb/s depending on DSL technology and service level implemented. Upload speed is lower than download speed for ADSL and symetrical for SDSL.

History

The origin of Digital Subscriber Line technology dates back to 1988, when engineers at Bell Labs devised a way to carry a digital signal over the unused frequency spectrum available on the twisted pair cables running between the telephone company's telephone exchange and the customer premises. Implementation of DSL could permit an ordinary telephone line to provide digital communication without interfering with voice services. However, the management of incumbent local exchange carriers (ILEC) were not enthusiastic about it, since DSL was not as profitable as installing a second phone line for consumers who preferred simultaneous dial-up internet and voice connections, and the broadband data connection would cannibalize existing ISDN customers. This changed in the late 1990s when cable television companies began marketing broadband Internet access. Realizing that most consumers would prefer broadband Internet to dial-up Internet, ILECs rushed out the DSL technology, which they had delayed implementing, as an attempt to win market share from the broadband Internet access offered by cable television operators. As of 2005, DSL is the principal competition of cable modems for providing high speed Internet access to home consumers in Europe and North America. Older ADSL standards can deliver 8 Mbit/s over about 2 km (1.24 miles) of unshielded twisted pair copper wire. The latest standard ADSL2+ can deliver more than 20 Mbit/s over similar distances. Many customers, however, are located farther than 2 km (1.24 miles) from the telephone exchange, which reduces the amount of bandwidth available (thereby reducing the data rate) on the wires. On average, cable is faster than DSL in most commercial situations. Modern cable systems can provide 30 Mbit/s downstream, but this bandwidth is shared between all the users on the cable segment (which could be from 100 to 200 households).

Operation

The local loop of the Public Switched Telephone Network was initially designed to carry POTS voice communication and signaling, since the concept of data communications as we know it today did not exist. For reasons of economy, the phone system nominally passes audio between 300 and 3,400 Hz, which is regarded as the range required for human speech to be clearly intelligible. This is known as commercial bandwidth. Dial-up services using modems are constrained by the Shannon capacity of the POTS channel. At the local telephone exchange (UK terminology) or central office (US terminology) the speech is generally digitized into a 64 kbit/s data stream in the form of an 8 bit signal using a sampling rate of 8,000 Hz, therefore – according to the Nyquist theorem – any signal above 4,000 Hz is not passed by the phone network (and has to be blocked by a filter to prevent aliasing effects). The local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit of POTS. Depending on the length and quality of the loop, the upper limit can be tens of megahertz. DSL takes advantage of this unused bandwidth of the local loop by creating 4312.5 Hz wide channels starting between 10 and 100 kHz, depending on how the system is configured. Allocation of channels continues at higher and higher frequencies (up to 1.1 MHz for ADSL) until new channels are deemed unusable. Each channel is evaluated for usability in much the same way an analog modem would on a POTS connection. More usable channels equates to more available bandwidth, which is why distance and line quality are a factor. The pool of usable channels is then split into two groups for upstream and downstream traffic based on a preconfigured ratio. Once the channel groups have been established, the individual channels are bonded into a pair of virtual circuits, one in each direction. Like analog modems, DSL transceivers constantly monitor the quality of each channel and will add or remove them from service depending on whether or not they are usable. The commercial success of DSL and similar technologies largely reflects the fact that in recent decades, while electronics have been getting faster and cheaper, the cost of digging trenches in the ground for new wires remains expensive. All flavors of DSL employ highly complex digital signal processing algorithms to overcome the inherent limitations of the existing twisted pair wires. Not long ago, the cost of such signal processing would have been prohibitive but because of VLSI technology, the cost of installing DSL on an existing local loop, with a DSLAM at one end and a DSL modem at the other end is orders of magnitude less than would be the cost of installing a new, high-bandwidth fiber-optic cable over the same route and distance. Most residential and small-office DSL implementations reserve low frequencies for POTS service, so that with suitable filters and/or splitters the existing voice service continues to operate independent of the DSL service. Thus POTS-based communications, including fax machines and analog modems, can share the wires with DSL. Only one DSL modem can use the subscriber line at a time. The standard way to let multiple computers share a DSL connection is to use a