LQWiki - User contributions [en]

Cramfs

2006-02-01T20:47:49Z

Glennji: Initial contribution.

The '''compressed RAM filesystem''' is a compressed [[filesystem]] that is often used for a [[initrd|initial ramdisk]] because it can be used by the [[kernel]] without uncompressing.

It is also used for [[embedded]] Linux devices and when Linux is installed on hand held [[PDA]] devices such as the IPAQ.

Cramfs uses the [[zlib]] library.

Future Tech

2005-10-24T16:29:37Z

Glennji: Added link to Beagle search

Future Tech

* [[New Hardware]]
* [[PDA | PDAs]]
* [[Tablet PC | Tablet PCs]]
* [[Non-Stable Kernels]]

Upcoming Desktop Software

* [http://galago.sf.net Galago] - this is a unified desktop "presence" framework, which allows instant messengers and other chat programs to broadcast information on who is online and what their status is. Other parts of the desktop like email programs, web browsers etc can watch this information and use it to present a better interface. It's in the early stages of development but shows great potential for the future.

* [http://autopackage.org/ autopackage] - a software installation framework for Linux that hopes to make installing programs far easier in future

* [http://www.nat.org/dashboard/ Dashboard] - the Dashboard watches what you are doing on the desktop and ties information from many different sources together into a coherant whole. This is sort of a dynamic, constantly updating search engine. Still in the early stages.

* [http://beaglewiki.org/Main_Page Beagle] - a search tool for your ''personal information space'': documents, web bookmarks, instant messages, emails, music, source code, etc.

http://wiki.linuxquestions.org/wiki/Hardware

LQWiki:FAQ

2005-10-18T22:04:15Z

Glennji:

As we get questions we will build a [[FAQ]] here.
----
Q: What is the best way to reach administrators? Where can I make suggestions/complaints? Where is general policy decided?

A: The [http://lists.linuxquestions.org/mailman/listinfo/lqwiki-list Mailing-list].

----
Q: I need a help link that explains the editing syntax of this wiki. Where is it?

A: [[Wiki markup]]

----
Q: How do you delete a redundant page? I accidentally created a page that was already covered. I now want to remove it. Nothing links to the page anymore, but it still exists. I could not find it in the Wiki documentation anywhere.

A: Looks like it's an [http://meta.wikipedia.org/wiki/Meta:Deletion_policy admin-only option]. Presumably there's some way to request a deletion. Meantime, I guess you could [http://wiki.linuxquestions.org/wiki/LQWiki:How_to_use_a_redirect redirect] your accidental page to the existing one. See also http://meta.wikipedia.org/wiki/Redirect redirect for more information.

----
Q: What about #REDIRECTS(s) to pages that don't exist send you to that page in edit mode rather than displaying the soon to be redirected away from page with a list of the form:

1. REDIRECT Page To Redirect To?

A: Not sure I understand your question, but hopefully this will help:
You can create a redirect page to a page that doesn't exist yet. However, it will take you straight to the edit section of the nonexistent page. Until someone either changes the redirect or writes some content in the new page, it'll stay like that.

Note that you can't have a list of options on a redirect page, only one redirect is allowed, otherwise the redirect page is invalid.

See also [[LQWiki:How_to_use_a_redirect]]

----
Q: What software is being used for this Wiki?

A: http://sourceforge.net/projects/wikipedia/

----
Q: Why are all the articles in the root directory instead of being categorized like http://kb.mozillazine.org does it?

A: Mainly because we haven't set up a guideline for categorizing stuff. mozillazine uses the same software, just a different theme, so it all depends on how the users lay out stuff. If you wanted to categorize your stuff just stick a colon in the title like I did with [[IpodLinux]]'s documentation and screenshots. --[[User:Flonejek|Flonejek]] 16:38, May 3, 2004 (EDT)

----
Q: How would I highlight code, is there any standard mechanism for highlighting code? (I already checked help pages) --[[User:Flonejek|Flonejek]] 09:25, May 3, 2004 (EDT)

----
Q: How do I sign my messages?

A: With 4 tildes <nowiki>~~~~</nowiki> goes to [[User:Flonejek|Flonejek]] 16:38, May 3, 2004 (EDT). I always stick two dashes in front of mine, I dunno why. --[[User:Flonejek|Flonejek]] 16:38, May 3, 2004 (EDT)
----
Q: Which Wiki Version are you (wiki.linuxquestions.org) using?

A: MediaWiki 1.4.4 - see [[Special:Version|here]] for further information.

----

Q: Can images (screenshots, etc) be included?

Source distributions

2005-10-18T19:47:55Z

Glennji: This isn't really a stub -- what else is there to say?

'''Source based [[distribution]]s''' enable the more experienced user to have a considerable degree of control over their system. Compiling and optimizing software for your particular hardware can bring noticeable performance improvements - however, compiling software can be a lengthy process. Another benefit of [[Compilation_From_Source | compiling]] a package instead of installing a pre-built binary is that some packages have optional parts in them with optional dependencies on other packages, which can be only selected at compile time. If you rely on pre-built packages, you can't make those selections any more. Usually the package maintainer chooses to switch all these options on, something which leads to the so called "dependency hell".

For more information on the various Source based distributions, click on the links below.

*[[Core Linux]]
*[[Gentoo]]
*[[Linux From Scratch]]
*[[Lunar Linux]]
*[[ROCK Linux]]
*[[Source Mage]]
*[[Vida Linux]]
*[[Garnome]] (GNOME distribution)

*NIX

2005-10-18T19:46:28Z

Glennji: This isn't really a stub -- what else is there to say?

'''*NIX''' is a general term for operating systems which resemble [[UNIX]].

It is also sometimes written *n?x, a [[regular expression]] that matches both "Unix" and "Linux".

Such systems include:

* GNU/Linux
* Free/Open/Net/DesktopBSD (etc)
* Various types of Unix

.NET

2005-10-18T19:32:56Z

Glennji: redirect

#REDIRECT [[.Net]]

Tgz

2005-10-18T18:52:07Z

Glennji: Redirect

#REDIRECT [[Tar]]

D-BUS

2005-10-18T18:48:49Z

Glennji: Initial contrib

'''D-BUS''' is a generalised messaging system for applications to communicate with each other. It provides a message bus with which applications can provide and use asynchronous information. D-BUS was developed by Freedesktop.org for use on a variety of desktop environments.

==See also==
* http://www.freedesktop.org/wiki/Software_2fdbus

GFDL

2005-10-18T18:24:36Z

Glennji: Initial contrib

The '''GNU Free Documentation License''' is a licensing document in the spirit of the [[GPL]] but designed for documentation -- manuals, user guides, programming tutorials, etc.

==See Also==
* http://www.gnu.org/copyleft/fdl.html

Kpart

2005-10-18T14:55:16Z

Glennji: Fix a link

A '''kpart''' is a [[KDE]] concept that allows file viewing capability to be plugged into [[Konqueror]] and other programs.

Konqueror uses kparts to display everything from [[directories]] to movies. The list of file types that can be displayed in Konqueror is not finite, and new kparts are being written all the time.

Some people find this a very elegent way to work, because using the same browser for all their files provides a consistant interface. A good example is clicking a link to a pdf on the web. Since the web browser and pdf viewer are the same program the file is opened as smoothly as if were another page of html.

Some file types can be viewed with a choice of kparts. Html, for example, may be viewed as a graphical page or as markup code. In the Konqueror menu go to View->View Mode to switch the view. You can change the default view from the KDE [[file associations]].

Besides content display kparts may also specify [[widgets]], which Konqueror augments with the standard toolbar.

==List of kparts==
:Kparts have been written for many different file types. Here is a list of some of them, with the formats they support:

* khtml - [[W3C]] complient html display engine
::[[html]]
* kplayer - plays films, using [[MPlayer]]
::[[Quicktime]], [[AVI]], [[Mpeg]]
* QtVisionApplet (installed with qtvision)
::Catured TV, via [[V4L]]
* kGhostview
::[[pdf]], [[postscript]]
* kpdf
::[[pdf]]
* Cuckooo - uses [[OOo]] to display many formats
::All OOo formats, MS Office formats, Corel Office etc
* Embeded advanced text editor
::Any text, with syntax highlighting for most computer languages
* Embeded VIM component
::Text, [[VIM]] style
* Cervista
::[[CVS]]
* FS View Part - view of the filesystem in which files take up space (on screen) proportional to their size (in the filesystem)
:: Files and directories
* Embedable image viewer - simple image viewer
::[[jpeg]], [[png]], [[TIFF]], [[gif]], [[bitmap]], [[svg]] and others
* Image viewer part - fuller featured image viewer, with zooming etc
::[[jpeg]], [[png]], [[TIFF]], [[gif]], [[bitmap]] and others
* Netscape kpart (official name?)
:: Any format for which there is a netscape plugin. Includes flash and [[Java]] applets.

If you use a format not listed here and understand object oriented programming, kparts are relatively simple to write. In most cases the real rendering work is done by another application and the interface side is mostly specified using [[XML]].

===External links===
[http://developer.kde.org/documentation/tutorials/kparts/] - A good page on creating new kparts.

[http://artax.karlin.mff.cuni.cz/~kendy/cuckooo/] - Cuckooo Home page

User:Glennji

2005-10-18T14:03:45Z

Glennji:

A [[maker]] and [[hacker]]-wannabe, '''Glennji''' spends his days avoiding real work and contributing to [[open source]] projects whenever possible -- which is considerably less often than he would like!

Born and raised in Australia, Glennji has moved to Edinburgh in Scotland with his beloved and cannot wait to start exploring. Kilts, Celts and whiskey ahoy!

JIT

2005-10-18T12:01:44Z

Glennji: Initial contrib

'''Just In Time''' (JIT) is a type of late compilation whereby code is [[compile]]d from an intermediate format ([[source]] or [[bytecode]]) into [[machine code]] at runtime, just before or during execution. It is common with the [[Java]] language, but is also available in other systems including [[Python]] and [[.NET]].

Half-Life

2005-10-18T11:01:00Z

Glennji: Fix a link

'''Half-life''' is a [[First Person Shooter]] game from [[Valve Corporation]] featuring [[ultra-violent]] [[realtime]] [[gaming]] action with a massive [[gaming community]]. Half life, Counter Strike and a number of other high profile games can be run under Linux using [[Cedega]].

==See also==
*[[Cedega]]
*[[Counter Strike]]
*[[gaming]]

IPod

2005-09-15T15:02:27Z

Glennji: initial edit (stub)

A popular [[MP3]] player designed manufactured by [[Apple]] Computing, the iPod was first released as an Apple [[Macintosh]] peripheral in 2001.

==Using with Linux==

The iPod connects to the PC via USB or Firewire. Under Linux it will be detected as an external hard-drive, formatted with a HFS+ or FAT32 filesystem. There are also a number of utilities available specifically for using the iPod, such as GtkPod[http://www.gtkpod.org/about.html].

==Linux on the iPod==

A version of Linux can be installed on some of the iPods

==External Links==
* [http://www.gtkpod.org/about.html GtkPod]

{{stub}}

Mkinitrd

2005-09-15T14:00:25Z

Glennji: initial edit

'''mkinitrd''' is a script used to create an [[initrd]] filesystem.

For example, to create an initrd that contains the modules required for booting from a strange device one might use:

<code>mkinitrd -o myinitrd</code>

The file ''myinitrd'' could then be placed in the /boot filesystem and loaded by the kernel at start time.

== Synopsis ==

<code>mkinitrd [-k] [-d confdir] [-m command] -o outfile [-r root] [version]</code>

;-k:Do not delete the temporary working directory.
;-d confdir:The configuration directory is usually <code>/etc/mkinitrd</code -- use this to override.
;-m command:Override the command that creates the initrd filesystem.
;-o outfile:The file to create the initrd filesystem inside.
;-r root:Override the root options.
;version:The kernel version to use (the currently running kernel by default).

== See also ==

man mkinitrd

JDBC

2005-09-15T12:41:10Z

Glennji:

The '''Java Database Connectivity''' (JDBC) [[API]] is a standard abstraction layer and library for using databases in Java.

''This article is a [[LQWiki:stub_articles|stub]] and needs to be finished. [[LQWiki:plunging_forward|Plunge forward]] and [[LQWiki:How_to_edit_a_page|help it grow]] !''

JDBC

2005-09-15T12:40:44Z

Glennji: initial edit (stub)

The '''Java Database Connectivity''' [[API]] is a standard abstraction layer and library for using databases in Java.

''This article is a [[LQWiki:stub_articles|stub]] and needs to be finished. [[LQWiki:plunging_forward|Plunge forward]] and [[LQWiki:How_to_edit_a_page|help it grow]] !''

Lex

2005-09-15T11:56:05Z

Glennji:

'''lex''' is a program which generates a lexical analyser. It takes a input file which consists of a table of [[regular expression]]s and corresponding [[code]] fragments, and generates an application which can read an input [[stream]] and execute the code fragments on an matches.

lex is often used with [[yacc]] (or the open source [[bison]]).

[[flex]] is an open source implementation of lex.

''This article is a [[LQWiki:stub_articles|stub]] and needs to be finished. [[LQWiki:plunging_forward|Plunge forward]] and [[LQWiki:How_to_edit_a_page|help it grow]] !''

Lex

2005-09-15T11:53:49Z

Glennji:

'''lex''' is a program which generates a lexical analyser. It takes a input file which consists of a table of [[regular expression]]s and corresponding [[code]] fragments, and generates an application which can read an input [[stream]] and execute the code fragments on an matches.

lex is often used with [[yacc]] (or the open source [[bison]]).

''[[flex]]'' is an open source implementation of lex.

''This article is a [[LQWiki:stub_articles|stub]] and needs to be finished. [[LQWiki:plunging_forward|Plunge forward]] and [[LQWiki:How_to_edit_a_page|help it grow]] !''

Lex

2005-09-15T11:52:52Z

Glennji: initial edit (stub)

'''lex''' is a program which generates a lexical analyser. It takes a input file which consists of a table of [[regular expression]]s and corresponding [[code]] fragments, and generates an application which can read an [[input stream]] and execute the code fragments on an matches.

lex is often used with [[yacc]] (or the open source [[bison]]).

''[[flex]]'' is an open source implementation of lex.

''This article is a [[LQWiki:stub_articles|stub]] and needs to be finished. [[LQWiki:plunging_forward|Plunge forward]] and [[LQWiki:How_to_edit_a_page|help it grow]] !''

Beagle

2005-09-15T11:20:16Z

Glennji:

'''Beagle''' is a [[desktop]] search tool. It can index various sources to allow fast searching for information. It currently supports searching the [[filesystem]], [[email]] messages, [[instant messaging]] history, web browser history, [[RSS]] feeds and many other sources are being created and added. Since Beagle is aimed at the [[Gnome]] desktop, it can currently only read the email from [[Evolution]], the browser history from [[Epiphany]] and the [[IM]] messages from [[GAIM]], etc.

For searching the filesystem, Beagle supports getting extra info from certain filetypes like [[openoffice.org]] or [[Microsoft]] Word documents, [[HTML]] files, [[JPG]] images, music files (like [[mp3]] and [[ogg]]) and many other types.

Beagle consists out of a [[daemon]] ''beagled'' which does the indexing of the files and other information and a [[GUI]] called [[best]] for searching. For storing information about when the a file was last indexed Beagled uses [[extended attributes]] (and falls back to a slower [[sqlite]] database backend when that's not available). It can also use [[inotify]] when that's available on the system to receive notification of when to index changed or new files.

==External links==
*[http://beaglewiki.org Main Beagle website]

Beagle

2005-09-15T11:18:38Z

Glennji: Internal link

'''Beagle''' is a [[desktop]] search tool. It can index various sources to allow fast searching for information. It currently supports searching the [[filesystem]], [[email]] messages, [[instant messaging]] history, web browser history, [[RSS]] feeds and many other sources are being created and added. Since Beagle is aimed at the [[Gnome]] desktop, it can currently only read the email from [[Evolution]], the browser history from [[Epiphany]] and the [[IM]] messages from [[GAIM]], etc.

For searching the filesystem, Beagle supports getting extra info from certain filetypes like [[openoffice.org]] or [[Microsoft]] Word documents, [[HTML]] files, [[JPG]] images, music files (like [[mp3]] and [[ogg]]) and many other types.

Beagle consists out of a [[daemon]] ''beagled'' which does the indexing of the files and other information and a [[GUI]] called [[best]] for searching. For storing information about when the a file was last indexed Beagled uses [[extended attributes]] (and falls back to a slower [[sqlite]] database backend when that's not available. It can also use [[inotify]] when that's available on the system to receive notification of when to index changed or new files.

==External links==
*[http://beaglewiki.org Main Beagle website]

RSS

2005-09-15T10:58:08Z

Glennji: initial edit (stub)

'''Really Simple Syndication''' (RSS) is an XML format for sharing news headlines and other web content.

An RSS document is called a "feed", and can be "syndicated" when other websites include the feed content with its own web content, which can then be viewed with a regular web browser. RSS feeds can also be viewed with an RSS news reader or "aggregator" which collects feeds from a number of sources.

''This article is a [[LQWiki:stub_articles|stub]] and needs to be finished. [[LQWiki:plunging_forward|Plunge forward]] and [[LQWiki:How_to_edit_a_page|help it grow]] !''

Centericq

2005-09-15T09:23:17Z

Glennji: Spelling and internal links

'''Centericq''' is a text mode menu- and window-driven [[IM]] interface that supports the ICQ2000, Yahoo!, [[AIM]], [[IRC]] and [[Jabber]] protocols. It's highly customizable and scriptable. It's perfect if you wan't to add functionatily (eg. message forwarding, autoreply etc.) to your account/server.

'''Program functionality:'''

'''Text mode user interface'''

* Based on the [[ncurses]] library
* Provides windows, menus and dialogs
* Configurable color schemes
* Ability to use the program remotely via [[telnet]] or [[ssh]]
* Configuration is done with dialogs
* Support for displaying Hebrew and Arabic texts
* UI messages translated into 15 languages

'''General instant messaging features'''

* [[ICQ]], [[YIM|Yahoo!]], [[AIM]], [[IRC]] and [[Jabber]] are supported
* Sending, receiving and forwarding events
* Command line parameters for sending events through an already running instance
* Mass-sending events
* Contact list groups support
* Configurable sounds for specific events and users
* External programs to process incoming events
* Viewing users' personal data
* Updating self user info
* List of ignored users
* Configurable servers' hostnames and port numbers

'''ICQ support'''

* Sending and receiving messages, [[URL]]s, contacts and [[SMS]]es
* Receiving [[email]] express and web pager messages
* Delivery of SMSes through email [[gateway]]s supported by Mirabilis
* Sending SMSes to any phone numbers, feature to send from the command line
* Searching for users by their UINs, through White Pages and by keywords
* Random chat: searching for availble persons and setting own chat group
* Registering of new UINs
* Setting own and reading others' away messages
* Server-based contact lists
* Controllable visibility and invisibility for specific users
* Peer-to-peer port range specification

'''Yahoo! support'''

* File transfers
* Conferencing
* Fetching of custom status messages
* Typing notifications
* Searching for users through directory

'''Jabber support'''

* Users directory search
* [[SSL]] secured connections
* [[vCard]] information: both fetching and updating
* Registration on services supported by server
* Invisible mode
* Groupchat

'''IRC support'''

* Support for private and channel-wide chat
* Showing IRC contacts on the list as well as detecting their being online
* Advanced user listing modes
* NickServ authentification support
* File transfers
* The [[PING]] command
* Password protected channels

'''Integrated client for LiveJournal'''

* Posting of entries into a [[LiveJournal]]
* Friend list management tools
* Notifications about new entries in friends' journals
* Notifications when someone adds or removes your account from their friend list
* Notifications about birthdays of LJ friends

'''Other'''

* Integrated [[RSS|RSS-feeds]] reader
* Integrated LiveJournal client
* Builds and works under [[Linux]], [[FreeBSD]], [[NetBSD]], [[OpenBSD]], [[Solaris]], [[Windows]] and [[MacOS]] X/Darwin
* Script for migrating contact list and history from [[licq]], [[kxicq2]], [[gnomeicu]] and [[micq]]
* Extensive application logging
* Re-reading the configuration on-the-fly if changed
* Extensive and interesting documentation
* The friendly and active users community at the centericq.de fan-club site

==External links==
*[http://thekonst.net/centericq/ Centericq website]

Bonobo

2005-09-15T09:00:18Z

Glennji: initial edit

'''Bonobo''' is an architecture for creating reusable software [[component]]s and constructing [[compound document]]s. It is an [[API]] defined by a set of [[CORBA]] interfaces, and used extensively in the [[GNOME]] Desktop and Developer Platform.

Using Bonobo, developers can utilise shared components written in any language that supports CORBA.

It allows for compound documents: embedded data-specific renderers and controls similar to those in the [[OLE]] system. A [[word processor]], for example, can easily embed a spreadsheet by using the Bonobo-compliant [[spreadsheet]] component.

Bonobo components also allow for application scripting and automation. A [[Perl]] script, for example, could be used to control [[Gnumeric]], a Bonobo-enabled spreadsheet.

Finally, Bonobo allows for various [[UI]] controls or [[widget]]s to be written in any Bonobo-supported language. It is this language-agnostism that is fundamental to the GNOME project.

User:Glennji

2005-05-16T06:08:17Z

Glennji: About me.

A [[maker]] and [[hacker]]-wannabe, '''Glennji''' spends his days avoiding real work and contributing to [[open source]] projects whenever possible.

Born and raised in Australia, Glennji is soon relocating to Scotland with his beloved. Kilts, Celts and whiskey ahoy!

Route

2005-05-16T06:02:50Z

Glennji: Disambiguation.

'''route''' is the command to view and edit the [[routing table]]. With <tt>route</tt> you can see what is the routing for IP-[[packet]]s coming from a [[network interface]] for a specified destination is. A [[default gateway]] may be listed for non-routable packets.

<pre>
# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
10.0.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 10.0.0.138 0.0.0.0 UG 0 0 0 eth1
</pre>

==Options==
-n show numerical addresses instead of hostnames

Interface

2005-05-16T06:01:58Z

Glennji: Disambiguation page

* [[Command line interface]]
* [[Graphical user interface]]
* [[Network interface]]

{{msg:disambig}}

Zombie

2005-05-16T05:14:17Z

Glennji: Clarification of signals

A '''zombie''' computer is one that has been taken over (by a [[cracker]], using a [[trojan]] or [[virus]]) and is being used by the [[cracker]] to spread [[spam]], [[trojan]]s or virii.

A '''zombie''' process is one that will not respond to user commands; it has often become orphaned when it's parent process was killed, and may not even respond to the lower-powered [[signal]]s (such as SIGHUP and SIGKILL).

A '''zombie''' is a dead human who has been reanimated (by dark forces or high technology) and set upon an unsuspecting world. Zombie humans often require live brain tissue to survive, and may require destruction with a shotgun or chainsaw to stop their bloody rampage.

Zombie

2005-05-16T05:11:30Z

Glennji: Initial content added.

A '''zombie''' computer is one that has been taken over (by a [[cracker]], using a [[trojan]] or [[virus]]) and is being used by the [[cracker]] to spread [[spam]], [[trojan]]s or virii.

A '''zombie''' process is one that will not respond to user commands; it has often become orphaned when it's parent process was killed, and may not even respond to the lower-powered signals.

A '''zombie''' is a dead human who has been reanimated (by dark forces or high technology) and set upon an unsuspecting world. Zombie humans often require live brain tissue to survive, and may require destruction with a shotgun or chainsaw to stop their bloody rampage.

History of Hacking

2005-05-16T04:44:12Z

Glennji: Typo/spelling error

This '''History of Hacking''' is intended to trace the history of the [[hacker]] culture. In order to be a member of a hacker culture, a person must have access to a computer, not just to use it, but to also ''play'' with it. Also, to be a member of a hacker culture, and not just a lone hacker, a hacker must be in contact with other hackers, preferably through the medium of the computer.

==Prehistory==
===The Babbage Analytical Engine===
The first computer honored in hacker lore was the Babbage Analytical Engine. This steam-driven mechanical computer was first described by [[Charles Babbage]] in 1837, but was never built. Although Babbage continued work on it until his death in 1871, Victorian Era machining technology was not able to create parts to the precision required by this computer. Modern day analysis says that the computer would have worked, and that it was capable of the same functions as modern day computers. This was not the first computer, abacuses had been around for centuries. But it was the first computer that was something more than a simple adding machine. Its legacy inspired some of the electro-mechanical computers of the 1930s.

Ada King, Countess of Lovelace, became the worlds first computer [[programmer]] in 1843, when she described a program that could be run on the Analytical Engine. The [[Ada]] programming [[language]] is named in her honor.

===The Birth of Science Fiction===
Although science fiction is not directly related to computing, the hacker culture as a whole enjoys SF, and there is a massive overlap between hackerdom and science fiction fandom. Science fiction also had its start in the Victorian Era. Jules Verne's ''Journey to the Center of the Earth'' was written in 1864, and H.G. Wells wrote ''The Time Machine'' in 1896. While not himself a Science Fiction author, Rudyard Kipling influenced later SF authors in the Golden Age of Science Fiction and beyond. His writing career began in 1886, with the publication of ''Departmental Ditties''.

===IBM===
The company that became [[IBM]] started operations in 1888, and was incorporated June 15, 1911. Before the development of computers, it specialized in [[punch card]] machines. Punch cards became a primary means of interacting with computers in the early days.

===Ham Radio===
[[Ham radio|Ham]], or amateur, radio developed at least as early as 1910, when the Wireless Institute of Australia. Many hams, with their background in electronics, became involved in computers later on. Ham radio takes advantage of a phenomenon known as ionosphere bounce, which allows radio waves to travel around the world. However, this only works at night, when solar radation is not disturbing the upper reaches of the atmosphere. This is an early precedent of the quasi-nocturnal nature of the hacker. This community, communicating with friends that they might never see face-to-face over low-[[bandwidth]] medium, also served as a precedent for later hacker communications mediums, such as [[Usenet]], [[IRC]], [[MUD]]s, and even this wiki.

===Pre-Electronic Computers===
Work continued on non-electronic computers, inspired in part by the Babbage Engine. An example is the Differential Analyzer, a mechanical analog computer designed by [[Vannevar Bush]] in 1927.

===The Golden Age of Science Fiction===
In 1937, John W Cambell took over editorship of the pulp science fiction magazine ''Astounding'' (which is still printed to this day under the name ''Analog''). This event marked the beginning of the Golden Age of Science Fiction, as notable authors, such as Robert Heinlein, Issac Asimov, Arthur C Clarke, as well as Cambell himself, combined good solid story telling with solid (or at least plausible) science under his leadership. Somewhat before this, First Fandom arose out of the readership of the pulp magazines. According to some chronologies, the Golden Age came to an end during WWII, when the pulp magazines shut down due to paper shortages.

==Stone Age==
1943 - approx. 1955

The beginning of the [[Stone Age]], and modern computing in general, is usually marked from the commissioning of [[ENIAC]] ('''E'''lectronic '''N'''umerical '''I'''ntergrator '''A'''nd '''C'''omputer) on May 17, 1943. It was the first all-electronic, Turing-complete computer, and was finished February 14, 1946.

===Alan Turing===
But the story of modern computing begins with [[Alan Turing]]. As one [[fortune]] file quote puts it, "[[Computer Science]] is merely the post-Turing decline of in formal systems theory." He authored "On Computable Numbers, with an Application to the Entscheidungsproblem", which was published May 28, 1936. In it, he described the [[Turing Machine]], a theoritical computer. (Not to be confused with a computer which can pass the [[Turing Test]]. All modern day computers are Turing Machines, except that they have merely large, not infinite, amounts of [[memory]].

When WWII broke out in 1939, Turing joined the code breaking team at Bletchley Park in Great Britain, cracking Nazi Germany's Enigma code. To help in this effort, the Colossus, the first programmable digital electronic computer was commisioned in 1943, and Janurary of 1944, the Mark I was finished. The story of Bletchley Park has a role in the fictional historical novel Cryptnomicon, written by Neil Stephenson, who also wrote [[In the beginning was the command line]].

Turing's work remained secret until the 1970s, since many Third World nations and coporations continued to use the Enigma cypher, and the Allied governments did not want them to know how easily they could decypher it. In 1952, Turing was convicted of being a homosexual (still a crime then!) and was given a hormone treatment with the goal of supressing his libido. In 1954, Turing committed suicide.

*[http://en.wikipedia.org/wiki/Alan_Turing Wikipedia article on Turing]

===John von Neumann===
Another Great Name from the Stone Age is [[John von Neumann]]. Turing was a student of his following the publication of the Entsheidungsproblem paper. (1936-1938) During the war, von Neumann was involved in the Manhattan Project. After the war, he began the study of game theory, and concieved the MAD (Mutual Assured Destruction) doctrine. He also created the study of cellular automata, which in turned lead to the idea of the von Neumann replicator - the "nanites" of Star Trek.

He also invented the [[von Neumann machine]] (like the Turing Machine, all modern day computers are von Neumann machines).

von Neumann once spoke out against [[assembler]]s since it was the misuse of valuable scientific equipment (computers) for a clerical task that could be done by grad students. (Unfortunately [[User:Crazyeddie|I've]] been unable to relocate that quote.)

*[http://en.wikipedia.org/wiki/Von_Neumann Wikipedia article on von Neumann]

===Vannevar Bush===
A influential event that happend in the Stone Age was the publication of "As We May Think" by Vannevar Bush. This article descibed the memex system, and influenced the creation of the [[GUI]] at [[PARC]] as well as the system of [[hyperlink]]s that allows the [[World Wide Web]] to function.

*[http://en.wikipedia.org/wiki/Vannevar_Bush Wikipedia article on Vannevar Bush]

===The Model Railroad Club===
In 1946, The Model Railroad Club ([[TMRC]]) of [[MIT]] was formed. Many of the members of TMRC later joined the MIT AI Lab and many of the earliest terms of the [[Jargon File]] come from there. (The most important being [[foo]].)

===The Technology of the Stone Age===
The Stone Age of computing is called that partially because the technology of the time was based on glass vacuum tubes for processing and mecury-delay lines for memory. Computers were room-filling monstrosities that doubled as building heating plants. Entire teams of technicians were required to replace blown vacuum tubes. Input was mainly through [[punch card]]s and [[paper tape]]. Interaction with computers was generally through [[batch]] operations.

==Bronze Age==
mid 1950s - 1961

The [[Bronze Age]] is a transitional period in the history of computing. It began with the mainstream use of [[transistor]]s and [[drum memory]] and ended with the mainstream introduction of [[core memory]]. Many chronologies consider the Bronze Age to be just the latter part of the Stone Age.

The [[transistor]] had been invented in 1947, but was not practical until transistors began to be made from silicon instead of germanium in the early 1950s. The integrated circuit had been conceived in 1952, and was independently developed in both 1958 and 1961.

During the Bronze Age, computers became cheap enough to be used by entites other than major governments. Now major universities and businesses could use them too. To cater to this market, the [[Datamation]] magazine began publication in 1957.

[[High level language]]s were developed at this time, as a quick-and-dirty way of making specific programs. They were used much the same way [[Interpreter|interpreted]] languages were used about 2000, and "serious" programs were still written using [[assembler]] or [[machine code]]. The first high level language was [[Fortran]], which was designed 1954-57, and was used for mathematical calculations.

The computing field began to diverge culturally into business computing (this field is what [[data processing]] usually refers to) and university-based scientific computing (see [[Computer Science]]). The present-day [[hacker]] culture is mainly descended from the scientific computing community. [[MIT]]'s AI Lab, one of the earliest centers of hacker culture, was founded in 1959.

In addition to its technical flaws, some of the ritualistic hatred and loathing of [[COBOL]] (released in 1959) comes from the fact that it was used by the [[code grinder]]s of business computing, not the hackers of the scientific computing community.

The Bronze Age came to an end with the mainsteam introduction of [[core memory]]. Core memory was expensive to produce, since it required that conductive wire been handwoven around the doughnut-like cores. Core memory became pratical when its production was moved to Third World countries in Asia, where the cost of labor was cheap. The [[Story of Mel]] takes place during the switchover to core memory.

==Iron Age==
1961-1971

The [[Iron Age]] is often bracketed by the release of the [[PDP-1]] in 1960 and the release of the Intel 4004 in 1971. It was a formative period where the first [[hacker]] cultures were finally allowed to develop.

These cultures developed at major universities, and were brought together by the advent of [[timesharing]] [[operating system]]s. By this point, computers had become powerful enough that they could no longer be kept busy with [[batch]] programs. But at the same time, computers were expensive enough that hundreds of users were needed to justify the expense. The first timesharing OS was [[CTSS]], which was developed in 1961. [[Email]] was introduced in 1965, as a means of users on the same computer to communicate with each other.

The first center of hacking, the [[MIT]] AI Lab, had already been founded in 1959. It spun-off [[Project MAC]] in 1963. Other major hacking cultures of this era include Stanford's AI Lab ([[SAIL]]) and Carnegie Mellon University's ([[CMU]]) computing program, both started in 1965.

Also in 1965, [[Moore's Law]] was formulated for the first time.

The end of the Iron Age came with the introduction of the first [[minicomputer]]s (aka [[mainframe]]s) in 1971. The name "mainframe computer" comes from the fact that one can fit in the [[CPU]] rack - or main frame - of an Iron Age era computer.

In 1969, the first [[ARPAnet]] link was created. Also in that year, the [[ITS]] operating system was written by programmers who disagreed with the direction that [[CTSS]] was heading, and [[Unix]] was first written. (See [[History of Unix]].)

==Elder Days==
1969-1980

===Mainframes===
According to some, the [[elder days]] refer to the entire period before 1980. Other's say that the elder days began with the introduction of the first [[mainframe]]s in 1971. But it might be more useful to date it to 1969, when several very important events happened.

* the first [[ARPAnet]] link was created.
* the [[ITS]] operating system was written by programmers who disagreed with the direction that [[CTSS]] was heading
* [[Unix]], the most influential [[operating system]] in history, was first written. (See [[History of Unix]].)

Other events in the [[mainframe]] world during the elder days:

*In 1970, [[PARC]] opened.
*In 1972, the [[email]] address convention of ''user''@''host'' was created for use on the ARPAnet.
*In 1975, the [[Jargon File]] was begun at [[SAIL]].

===Microcomputers===
In 1975, an entirely new class of computer was introduced in the form of the [[Altair]] - the [[microcomputer]]. The Altair wasn't much, but it was the first computer that was cheap enough to owned by a single person. With its introduction, an entire culture of [[hacker]]s sprung into being, which had little to do with the older, [[timesharing]]-based hacker cultures.

[[CP/M]] (which had been developed a few years before) was the first (disk) operating system for the Altair.

Events of 1975:

* [[Homebrew Computer Club]] founded
* [[Microsoft]] founded by [[Bill Gates]] and [[Paul Allen]]. Its first product was a [[BASIC]] [[interpreter]] for the [[Altair]].
* [[BYTE]] magazine launched.

As a foreshadowing of things to come, [[Bill Gates]] criticized the [[Homebrew Computer Club]] for [[gratis|freely distributing]] [[BASIC]] [[compiler]]s and [[interpreter]]s.

In 1976, the [[Apple]] computer company was founded by [[Steve Jobs]] and [[Steve Wozniak|Steve "Woz" Wozniak]], both members of the [[Homebrew Computer Club]]. In 1977, the [[Apple II]] was released.

Also in 1977, the [[Commodore]] [[Commodore PET|PET]] and the [[Tandy TRS-80]] were launched.

Microcomputers were derided by old school [[mainframe]] hackers - see the [[Jargon File]] entry for [[bitty box]]. Strangely enough, the purpose of the [[PARC]] project was to build the computer of ten years in the future - when [[Moore's Law]] would make [[timesharing]] computers obsolete. Many of the features of the PARC's [[PARC Alto|Alto]] eventually made their way into personal computers. But the PARC hackers mainly came from the scientific computing community, and their prejudice towards microcomputers almost caused them to miss the boat. Or, according to some, PARC did miss the boat - but that had more to do with the [[suit]]s of their parent company.

In December of 1979, at the very close of the elder days, an event happened that looms so large in legend that the legend obscures the true history. [[Steve Jobs]] came to [[PARC]]. PARC had been working on many concepts that would eventually make it into personal computing, including the [[GUI]]. [[Apple]] had already been working on a GUI-capable computer of their own - Project Lisa. It is not sure how much PARC influenced the development of the [[Macintosh]]. The main effect of the tour was that it let Apple's engineers know that certain things were even possible, such as [[bitblt]], which enabled overlapping windows.

===Other Events During the Elder Days===
In the early 70s, modern-style Dynamic [[RAM]], or DRAM, was introduced. It differed from the earlier [[core memory]] in that each bit had to be refreshed constantly - if power was cut, the stored information would be lost. One of the first projects to use DRAM was the MAXC, [[PARC]]'s clone of the [[PDP-10]]. At that time, DRAM was difficult to produce, and quality control workers sorting for working chips out of batches of duds referred to the task as "polishing a turd". The MAXC frequently developed bad DRAM chips, which had to be replaced. The cost of DRAM alone was about a third of the total cost of the MAXC.

The ''Principa Discordia'', the foundational text of the parody religion [[Discordianism]], was released in 1968 - a little before the end of the Iron Age. The book became popular in the early 70s, and was quickly adopted by main in the hacker community or communities. In 1975, the Illuminatus! trilogy, which can be considered a novelization of the idea of the Principa Discordia, was published by Robert Shea and Robert Anton Wilson. This trilogy consists of five books in three volumes. This arrangement of five books in a trilogy is oddly similar to another series loved by hackers - the Hitchhiker's Guide to the Galaxy Trilogy. This trilogy consists of the original three books, but when two additional books were written, the fans kept the name. This also oddly fits in with a Discordian belief/joke - the Law of Five, which states that everything somehow relates to the number five. For example, "Two is even. Three is odd. Two and Three make Five. Therefore, Five is both even and odd."

In 1972, the first video game, Pong, was released by Atari. Atari also released the first cartridge-based game console in 1977.

Sometime before 1971, the art of phone [[phreaking]], or the hacking of phones, was developed. In 1971, it became popular with the counterculture yippies, and many of the early microcomputer hackers played with it. At this stage in its development, phone phreaking was done for reasons of curiosity and entertainment, not (or at least "not just") for profit, and abided by the [[hacker ethic]].

===Networking===
In addition to the already existing [[ARPAnet]], several networks began to spring up by the end of the elder days. In the microcomputer world, the first [[BBS]] went online in 1978, and in the mainframe world, the [[Usenet]] started in 1979. Usenet relied on [[UUCP]] or Unix-to-Unix Copying Protocol.

===References===
The paragraphs concerning [[PARC]], including mainframe hackers' contempt for the microcomputers, the Steve Jobs tour, and the MAXC's DRAM problems, used ''Dealers of Lightning: XEROX PARC and the Dawn of the Computer Age'' by Michael Hiltzik (ISBN 0-88730-891-0) as a reference.

==The Microcomputer Era==
===The Great Microcomputer Crash of 1983===
At the beginning of the 80s, the [[microcomputer]] world was getting crowded. In addition to [[Apple]]'s offerings and the [[Tandy TRS-80]], [[Commodore]] had released the [[Commodore 64]], and Atari, seeing microcomputers as competition for their game console business, offered its own line of microcomputers.

[[IBM]] also entered the fray with the original IBM [[PC]]. IBM originally wanted [[CP/M]] as the [[operating system]], but wound up going with [[Microsoft]] instead. (For the details, see the [[CP/M]] article.) Microsoft, at the time, was mainly known for its [[BASIC]] [[compiler]]s and [[interpreter]]s, and had no operating system of its own. So it bought one, [[QDOS]] or Quick-and-Dirty Operating System. It was later renamed [[DOS]] or Disk Operating System.

The overcrowding caused the microcomputer market to crash in 1983. Due to Atari's involvement, it also caused a crash in the game console market. Ironically enough, given later events, the IBM PC bombed in the home market, but found a niche market in businesses.

===The Commercialization of Unix===
Up until the early 80s, AT&T was not allowed to sell [[UNIX]] because of anti-trust regulations. So UNIX was fairly freely redistributed and modified. In the early 80s, AT&T was broken up into smaller companies and deregulated, removing this roadblock to the commercialization of UNIX. In protest of the closing of Unix, the [[GNU]] project was launched by [[RMS]] to [[clone]] a [[free]] version of Unix. Unix devolved into a maze of Unix-alikes, with varying degrees of inter-compatibility. Standards, such as [[Posix]] were created to address this problem, but to little avail. One factor in this failure was the existence of multiple standards. (Hence the hacker saying, "The great thing about standards is that there are so many to choose from!")

See [[History of Unix]].

===The BBS scene and the Rise of the Crackers===
With the spread of microcomputers, and the birth of the [[BBS]]s, large amounts of teenagers were allowed access to computers for the first time. Some BBSs developed "elite" sections, where trusted members exchanged [[warez]] - pirated software. This is where the term "leet" comes from. [[Leet]] is a written-only dialect which first developed on the BBSs, probably to defeat obscenity-censoring filter programs. Phone [[phreaking]] became popular among BBS users, since it allowed phreakers to connect to BBSs in other area codes without paying huge telephone bills.

In 1984, [[2600]], the "hacker's" quarterly, launched. Its name comes from the 2600 Hz tone used in certain [[phreaking]] exploits.

Although the BBS "hackers" had little actual contact with the older [[hacker]] cultures, they did know of it, and used the name hackers themselves in their criminal (or at least youthfully irresponsible antics). To protect themselves from the negative publicity, old-school hackers tried to apply the term [[cracker]]s to computer criminals, but with no great success.

Another event that sealed the hacker-as-criminal idea in the minds of the [[mundane]]s was the Morris [[sendmail]] worm or [[Great Worm]] of 1988.

===The Rise of the GUI===
Following the [[microcomputer]] crash of 1983, [[GUI]]s began to arrive on the computer scene. In 1984, [[Apple]] released the [[Macintosh]]. [[Commodore]] released the [[Amiga]] in 1985. Also in 1985, [[Microsoft]] released [[Windows]] 1.0.

[[IBM]]'s [[PC]] had been bombed in the home market during the crash, but had found refuge in the business market. The existence of PC [[clone]]s, from manufacturers such as [[Compaq]], caused IBM to lower prices, which in turn encouraged sales.

===The Great Renaming===
In 1987, the [[Backbone Cabal]] brought the [[Usenet]] through the [[Great Renaming]].

==The Nineties==

==Current Day==

IPv6 deployment:addressing

2005-05-16T03:55:38Z

Glennji: Some internal links added.

===IPv6 and IPv4 addressing compared===

For the networking professional, the most obvious change from [[IPv4]] to [[IPv6]] is the vast increase in [[IP address]] space. [[IPv6]] addresses have a 128 bit address space, which yields approximately 2128 addresses (3.4 * 1038) Compare this with [[IPv4]], where the address space is 32 bits, which yields approximately 232 addresses (4.3 billion or 4.3 * 109). This represents a significantly larger number of addresses! This helps because many studies conducted have estimated that we will run out of address space in the [[IPv4]] Internet within the next few years [RFC 1744].

In [[IPv6]], the expression of an address as a "dotted-quad," or [[dotted decimal]] has been replaced by a different representation. As you may recall, [[IPv4]] addresses are typically represented as a sequence of four 8-bit values (bytes), each byte separated by a period. Thus, the following [[IPv4]] address (in [[binary]]):

10111101001000001100111101100001

would be divided into four bytes:

10111101.00100000.11001111.01100001

which in turn would be translated into decimal equivalents as:

189.32.207.97

With [[IPv6]] addresses, the notation is slightly different. Each address is broken into eight 2-byte pieces which are delimited by a colon. Thus, the following [[IPv6]] address (in binary):

:<tt>11111110 11000000 00000000 00000000 00000000 00000000 00000000 00000000 00000010 00100000 11101101 11111111 11111110 01101010 00001111 01110110</tt>

would be divided into eight 2-byte pieces (note that we insert extra spaces for readability, but they are not required in the notation):

:<tt>1111111011000000: 0000000000000000: 0000000000000000: 0000000000000000: 0000001000100000: 1110110111111111: 1111111001101010: 0000111101110110</tt>

which in turn would be translated into hexadecimal equivalents as:

:<tt>fec0:0000:0000:0000: 0220:edff:fe6a:0f76</tt>

With IPv6 addresses, some shorthand can be taken. For instance, leading "0"s within each 2-byte piece can be dropped:

fec0:0:0:0:220:edff:fe6a:f76

Also, a single series of "0"s can be dropped and replaced with two adjacent colons to signify that "0"s can be added to make the address fit into 128 bits:

fec0::220:edff:fe6a:f76

However, this reduction can only be used once in any address in order to not violate uniqueness. Imagine the trouble we would get into trying to represent the following addresses with more than one double colon:
<tt>
:8d:0:0:2d69:0:0:0:1234 can safely be represented as 8d:0:0:2d69::1234
:8d:0:2d69:0:0:0:0:1234 can safely be represented as 8d:0:2d69::1234
:8d:0:0:0:2d69:0:0:1234 can safely be represented as 8d::2d69:0:0:1234
</tt>
This reduction can be used for the localhost interface in IPv6 (the equivalent of IPv4's 127.0.0.1). This localhost address is 0:0:0:0:0:0:0:1 or ::1. The reduction can also be applied to the default network (the equivalent of IPv4's 0.0.0.0) as simply ::.

[[Subnet]]ting in [[IPv6]] follows similar rules as in [[IPv4]]. The general idea is that a [[subnet mask]] can be applied to any address. Using this [[subnet mask]], a router can determine which bits represent the network membership of an address and which bits represent the host's address. In the [[IPv4]] world, the network address 192.168.1.4/24 (or alternative notation of subnet mask 255.255.255.0) means that the network address is represented by the first 24 bits of the address and that the host address is represented by the remaining 8 bits (32 bit address space minus 24 bit network address = 8 bits for host address). The notation 192.168.1.4/24 is usually referred to as a CIDR (Classless Interdomain Routing) address. We give an example of subnet masking in binary, which is easier to visualize:

:The IPv4 address 192.168.1.4 would be represented in binary as:
11000000.10101000.00000001.00000100
:The subnet mask 255.255.255.0 would be represented in binary as:
11111111.11111111.11111111.00000000
:which shows that the first 24 bits of the subnet mask are "1". Then "bitwise AND" the 2 values together to get the network address:
11000000.10101000.00000001.000000000
:which indicates that the network portion of the address is 192.168.1.0 (24 bits of network address, plus a trailing zero byte). Then subtract the network address from the original address to get the host's address:
00000000.00000000.00000000.00000100
:which indicates that the host is 0.0.0.4, or, more simply, just 4.

In [[IPv6]], the idea of subnet masks is similar, but the network addresses are much larger (explained later in this section). We illustrate with our previous [[IPv6]] address example, assuming a network of /64 (meaning that the network address is the left-hand 64 bits of the total 128 bits). We will use hexadecimal arithmetic rather than [[binary]] arithmetic, because binary is just too cumbersome for [[IPv6]] addresses.
:The IPv6 address fec0::220:edff:fe6a:f76 would be expanded to:
fec0:0000:0000:0000:0220:edff:fe6a:0f76
:The subnet mask for a /64 network would be:
ffff:ffff:ffff:ffff:0000:0000:0000:0000
:Then "bitwise AND" the 2 values together to get the network address:
fec0:0000:0000:0000:0000:0000:0000:0000
:(64 bits of network address, plus a 64 trailing zero bits). Then subtract the network address from the original address to get the host's address:
0000:0000:0000:0000: 0220:edff:fe6a:0f76

In [[IPv4]], there is a traditional classification of network, based on the first octet (leftmost byte) of the address. However, this classification is no longer formally part of the IP addressing architecture, and has been replaced by CIDR (Classless Interdomain Routing). In summary:

{| border=1
|
<tt>
Allocation 1st Octet
----------- --------
Class "A" 0 - 126
Reserved 127

Class "B" 128 - 191
Class "C" 192 - 223

Class "D" 224 - 239
Class "E" 240 - 254
Reserved 255

Or, by using the "First Octet" Rule:

Bit Pattern Class of Address
------------ ----------------
0 A
10 B
110 C
1110 D
1111 E</tt>
|}
<center>Figure 1.2 IPv4 Network Allocations
</center>

However, in [[IPv6]] we have 2 octets of information with which to divide our networks (also see RFC 3513).

{| border=1
|
<tt>

Allocation Prefix Fraction of
(binary) Address Space
------------------------------ -------- -------------
Reserved 0000 0000 1/256
Unassigned 0000 0001 1/256

Reserved for NSAP Allocation 0000 001 1/128
Reserved for IPX Allocation 0000 010 1/128

Unassigned 0000 011 1/128
Unassigned 0000 1 1/32
Unassigned 0001 1/16
Unassigned 001 1/8

Provider-Based Unicast Address 010 1/8

Unassigned 011 1/8

Reserved for Geographic-
Based Unicast Addresses 100 1/8

Unassigned 101 1/8
Unassigned 110 1/8
Unassigned 1110 1/16
Unassigned 1111 0 1/32
Unassigned 1111 10 1/64
Unassigned 1111 110 1/128

Unassigned 1111 1110 0 1/512

Link-Local Use Addresses 1111 1110 10 1/1024
Site-Local Use Addresses 1111 1110 11 1/1024

Multicast Addresses 1111 1111 1/256
</tt>
|}
<center>Figure 1-3 IPv6 Network Allocations</center>

For the scope of our paper, we are interested in four types of addresses. These are link-local addresses, site-local addresses, global unicast addresses (basically anything marked "unassigned" above) and multicast addresses. The term "global unicast address" supersedes the [[IPv4]] term "IP address." We will not discuss anycast addresses which are used by routers specifically for failover, redundancy, and broadcast in [[IPv6]]. In [[IPv6]], link-local and site-local addresses represent private address space just as reserved addresses represent them in [[IPv4]], (RFC 1918):
10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

In [[IPv6]], any network address fe80::/10 is a "link-local" address. The concept of link-local means that machines are physically located in the same data link layer broadcast domain. This would include machines attached via hubs, bridges, and layer 2 switches as well as any machines directly connected. The addresses in network address fec0::/10 are "site-local" addresses and should not be routed outside of your locally-controlled infrastructure (because of the possibility of address collisions with addresses defined at other sites). All other legal addresses are considered to be "global unicast addresses" and are validly used on any node whether connected to the Internet or not. Global unicast addresses must be globally unique, of course.

As with [[IPv4]], [[IPv6]] addresses can be either statically or dynamically assigned. However, the definition of dynamically assigned has changed somewhat with [[IPv6]]. There are two dynamic address mechanisms in [[IPv6]]. The first (and primary) mechanism for dynamic IP address assignment is called "stateless autoconfiguration"; and uses the hardware address of the machine's interface to negotiate the IP address. For stateless autoconfiguration on a link-local network, an example is:

1. If the node (host or router) has a 48-bit MAC interface identifier of:
00:01:03:31:AA:DD
then the resulting 64-bit IPv6 interface ID will be:
0201:03ff:fe31:aadd
or, in shorthand notation:
201:3ff:fe31:aadd*
:<nowiki>*</nowiki> Note: A 48-bit MAC address must be expanded to a 64-bit address for stateless autoconfiguration. To do so, the value fffe is inserted between the third and fourth bytes of the MAC address. Next, the second low-order bit of the first byte of the MAC address is complemented. In binary, our original MAC address looks like this, after expansion:
<tt>
:''000000'''0'''0'': 00000001: 00000011: <fffe goes here>: 00110001: 10101010: 11011101
</tt>
:The binary string in italics represents the first byte. The "0" in boldface represents the second low order bit. More colloquially, we could call this the "next to last bit in the first byte". [Stateless Autoconfiguration: RFC 2462]

2. The node prepends this 64-bit interface identifier with the 64-bit link-local interface identifier fe80::0. This address becomes the "tentative address."

3. The node joins the "all-nodes" multicast group (ff02::1) and the solicited node multicast group (ff02:0:0:0:0:1:ffxx:xxxx, where xx:xxxx is the low-order 24 bits of the MAC address of the node's interface). (Multicast groups are explained later in this section.)

4. The node broadcasts a "neighbor solicitation" message to the "all-nodes" multicast group asking if the selected address is taken. If the address is taken, the node stops and manual configuration is required. Otherwise, the state of the address is set to "preferred."

5. The node then sends a "router solicitation request" to the "all routers" multicast group (ff02::2) to determine default routes.
The drawback with stateless autoconfiguration is that wherever this mechanism is employed, the size of the host portion of the IP address must be no smaller than 64 bits. This causes quite a few wasted unicast addresses in a typical network address architecture.

The second form of autoconfiguration occurs through the use of the dynamic host configuration protocol (DHCP) and is called "stateful autoconfiguration". DHCP can also be used in conjunction with stateful autoconfiguration to broadcast information other than IP addresses, such as DNS servers, network names, and proxy-servers. This mechanism can subnet a network into much smaller segments than stateless autoconfiguration (creating less wasted network address space) but requires additional management of the DHCP server and the addition of a DHCP client on all machines that require stateful autoconfiguration. Both stateless and stateful autoconfiguration protocols can be used for networks other than site-local through various control protocol mechanisms.

Finally, in [[IPv6]], multicast addresses are used quite frequently for control of network hosts and services. There are two types of multicast addresses; well known and temporary. A diagram for multicast address bits looks like this:

http://dons.usfca.edu/buckwalt/ipv6/image004.gif

<center>Figure 1-4 [[IPv6]] Multicast Address Diagram</center>

The second field, 000x, represents the flags field. The first 3 bits are reserved and must be set to "0". The last bit, x, represents the permanence of the address. 1 represents a temporary multicast address, while 0 represents a permanent (or termed "well-known") address.

The third field, yyyy, represents the "scope" field. The scope of the multicast address can be determined by looking at this table:

{| border=1
|
<tt>

Value Description
----- -----------
0 Reserved
1 Interface-local (network interface card)
2 Link-local scope (same as link-local addr)
3,4 Unassigned
5 Site-Local scope (same as site-local addr)
6,7 Unassigned
8 Organizational scope
9,a,b,c,d Unassigned
e Global scope
f Reserved
</tt>
|}
<center>Figure 1-5 IPv6 Multicast Scope Diagram</center>

And finally, the group identifier is used to determine the subscriber (or function) of the multicast listening nodes. For instance, a multicast address of ff01::1 represents the "all nodes" multicast address of scope "interface local," while ff02::1 and ff05::1 represent the "all nodes" multicast address of link-local and site-local scope, respectively. The group identifier of the addresses is the same, only the scope address is different.

Some well-known group identifiers are:
{| border=1
|
<tt>
Group Identifier Description
---------------- -----------
::1 All nodes
::2 All routers
::9 RIP routers
::1:3 DHCP servers</tt>
|}
<center>Figure 1-6 [[IPv6]] Well-Known Multicast Group Identifiers</center>

For more information on multicast addresses, please see RFC 2375.

==Internal links==
Next section: [[IPv6 deployment:maintenance protocols|Maintenance protocols]]

Main article: [[IPv6 deployment]]

Dotted decimal

2005-05-16T03:45:39Z

Glennji: Initial content added

'''Dotted decimal''' is a representation of a [[binary]] number, most commonly used for [[IPv4]] [[IP address]]es.

An [[IP address]] is a 32 bit number such as:

<pre>
11010001100110001010001100010000
</pre>

To represent this is dotted decimal, we group the number into blocks of 8 bits:

<pre>
11010001 10011000 10100011 00010000
</pre>

then convert each block into the decimal representation of an 8 bit number:

<pre>
11010001 10011000 10100011 00010000
209 152 163 16
</pre>

Finally, these numbers are written down with a decimal point or period as a separator:

209.152.163.16

Subnet

2005-05-16T03:39:06Z

Glennji: Initial content added

A '''subnet''' is the set of all [[network interface]]s which have the same network address.

=Determining the network address=

To determine the network address we use a subnet mask, or "netmask". This is a [[binary]] number that is used to "mask" an IP address into network and host address portions.

For example, an [[IPv4]] [[IP address]] and subnet mask are both 32 bits long. Take an address such as:

209.152.163.16

In binary this is:

11010001 10011000 10100011 00010000

The subnet mask is given as either a [[dotted decimal]] or a bit count. For example, the Class B subnet mask is:

255.255.0.0

In binary this is

11111111 11111111 00000000 00000000

i.e. a string of 16 1's, followed by 0's. The bit count representation is given as a forward-slash followed by the number of 1's:

/16

It is often appended to the end of the IP address.

209.152.163.16/16

The subnet mask is used to determine the network and host portions of an [[IP address]] in the following ways:

To determine the network address, apply a [[binary]] AND operation to the IP address and the subnet mask:

<pre>
11010001 10011000 10100011 00010000
11111111 11111111 00000000 00000000
-----------------------------------
11011001 10011000 00000000 00000000
</pre>

Converting this back to [[dotted decimal]] gives us a network address of:

209.152.0.0

All [[network interface]]s and computers that have this network address can be said to share the same subnet.

==More complex subnets==

Whilst this is a fairly trivial example, more complex subnets can be created by using a subnet mask that does not end on a margin between [[dotted decimal]] numbers.

A subnet mask of:

11111111 11111111 11100000 00000000

is

255.255.224.0

in [[dotted decimal]], or

/19

as a bit count. This type of subnetting is usually done by network administrators to create a number of subnetworks within a single class.