Wikipedia - User contributions [en]

TCP offload engine

2023-07-12T15:51:40Z

Gotar: /* Support in Linux */ updated link

{{short description|Technology used in network interface cards}}

'''TCP offload engine''' ('''TOE''') is a technology used in some [[network interface card]]s (NIC) to offload processing of the entire [[TCP/IP]] stack to the network controller. It is primarily used with high-speed network interfaces, such as [[gigabit Ethernet]] and [[10 Gigabit Ethernet]], where processing overhead of the network stack becomes significant.
TOEs are often used<ref>{{cite conference |date=2003-05-18 |author=Jeffrey C. Mogul|title=TCP Offload Is a Dumb Idea Whose Time Has Come |conference=HotOS |publisher=[[Usenix]] |url=https://www.usenix.org/conference/hotos-ix/tcp-offload-dumb-idea-whose-time-has-come}}</ref> as a way to reduce the overhead associated with [[Internet Protocol]] (IP) storage protocols such as [[iSCSI]] and [[Network File System]] (NFS).

==Purpose==
Originally [[Transmission Control Protocol|TCP]] was designed for unreliable low speed networks (such as early [[dial-up]] [[modem]]s) but with the growth of the Internet in terms of [[Internet backbone|backbone]] transmission speeds (using [[Optical Carrier]], [[Gigabit Ethernet]] and [[10 Gigabit Ethernet]] links) and faster and more reliable access mechanisms (such as [[digital subscriber line|DSL]] and [[cable modem]]s) it is frequently used in [[data center]]s and desktop [[personal computer|PC]] environments at speeds of over 1 Gigabit per second. At these speeds the TCP software implementations on host systems require significant computing power. In the early 2000s, full-duplex gigabit TCP communication could consume more than 80% of a 2.4 GHz [[Pentium 4]] processor,<ref name="Foong"/> resulting in small or no processing resources left for the applications to run on the system.

TCP is a [[connection-oriented protocol]] which adds complexity and processing overhead. These aspects include:
* [[Transmission Control Protocol#Connection establishment|Connection establishment]] using the "3-way handshake" (SYNchronize; SYNchronize-ACKnowledge; ACKnowledge).
* Acknowledgment of packets as they are received by the far end, adding to the message flow between the endpoints and thus the protocol load.
* [[Checksum]] and sequence number calculations - again a burden on a general purpose CPU to perform.
* [[Sliding window]] calculations for packet acknowledgement and [[congestion control]].
* [[Transmission Control Protocol|Connection termination]].

Moving some or all of these functions to dedicated hardware, a TCP offload engine, frees the system's main [[CPU]] for other tasks. As of 2012, very few consumer network interface cards support TOE.

===Freed-up CPU cycles===
A generally accepted rule of thumb is that 1 Hertz of CPU processing is required to send or receive {{val|1|ul=bit/s}} of TCP/IP.<ref name="Foong">{{cite conference |author1=Annie P. Foong |author2=Thomas R. Huff |author3=Herbert H. Hum |author4=Jaidev P. Patwardhan |author5=Greg J. Regnier |date=2003-04-02 |title=TCP performance re-visited |conference=Proceedings of the International Symposium on Performance Analysis of Systems and Software (ISPASS) |location=Austin, Texas |url=http://www.nanogrids.org/jaidev/papers/ispass03.pdf}}</ref> For example, 5 Gbit/s (625 MB/s) of network traffic requires 5 GHz of CPU processing. This implies that 2 entire cores of a 2.5 GHz [[multi-core processor]] will be required to handle the TCP/IP processing associated with 5 Gbit/s of TCP/IP traffic. Since Ethernet (10GE in this example) is bidirectional, it is possible to send and receive 10 Gbit/s (for an aggregate throughput of 20 Gbit/s). Using the 1 Hz/(bit/s) rule this equates to eight 2.5 GHz cores.

Many of the CPU cycles used for TCP/IP processing are ''freed-up'' by TCP/IP offload and may be used by the CPU (usually a [[Server (computing)|server]] CPU) to perform other tasks such as file system processing (in a file server) or indexing (in a backup media server). In other words, a server with TCP/IP offload can do more '''server''' work than a server without TCP/IP offload NICs.

===Reduction of PCI traffic===
In addition to the protocol overhead that TOE can address, it can also address some architectural issues that affect a large percentage of host based (server and PC) endpoints.
Many older end point hosts are [[Peripheral Component Interconnect|PCI]] bus based, which provides a standard interface for the addition of certain [[peripherals]] such as Network Interfaces to [[Server (computing)|Servers]] and PCs.
PCI is inefficient for transferring small bursts of data from main memory, across the PCI bus to the network interface ICs, but its efficiency improves as the data burst size increases. Within the TCP protocol, a large number of small packets are created (e.g. acknowledgements) and as these are typically generated on the host CPU and transmitted across the PCI bus and out the network physical interface, this impacts the host computer IO throughput.

A TOE solution, located on the network interface, is located on the other side of the PCI bus from the CPU host so it can address this I/O efficiency issue, as the data to be sent across the TCP connection can be sent to the TOE from the CPU across the PCI bus using large data burst sizes with none of the smaller TCP packets having to traverse the PCI bus.

==History==
One of the first patents in this technology, for UDP offload, was issued to [[Auspex Systems]] in early 1990.<ref>
[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5355453.PN.&OS=PN/5355453&RS=PN/5355453 United States Patent: 5355453 ''"Parallel I/O network file server architecture category"'']</ref> Auspex founder Larry Boucher and a number of Auspex engineers went on to found [[Alacritech]] in 1997 with the idea of extending the concept of network stack offload to TCP and implementing it in custom silicon. They introduced the first parallel-stack full offload network card in early 1999; the company's SLIC (Session Layer Interface Card) was the predecessor to its current TOE offerings. Alacritech holds a number of patents in the area of TCP/IP offload.<ref>
[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6247060.PN.&OS=PN/6247060&RS=PN/6247060 United States Patent: 6247060 ''"Passing a Communication Block from Host to a Local Device such that a message is processed on the Device"'']</ref>

By 2002, as the emergence of TCP-based storage such as [[iSCSI]] spurred interest, it was said that "At least a dozen newcomers, most founded toward the end of the dot-com bubble, are chasing the opportunity for merchant semiconductor accelerators for storage protocols and applications, vying with half a dozen entrenched vendors and in-house ASIC designs."<ref>[http://www.eetimes.com/electronics-news/4143213/Newcomers-spin-storage-network-silicon "Newcomers spin storage network silicon "], Rick Merritt,
10/21/2002, EE Times</ref>

In 2005 [[Microsoft]] licensed Alacritech's patent base and along with Alacritech created the partial TCP offload architecture that has become known as TCP chimney offload. TCP chimney offload centers on the Alacritech "Communication Block Passing Patent". At the same time, Broadcom also obtained a license to build TCP chimney offload chips.

==Types==

Instead of replacing the TCP stack with a TOE entirely, there are alternative techniques to offload some operations in co-operation with the operating system's TCP stack. [[TCP checksum offload]] and [[large segment offload]] are supported by the majority of today's Ethernet NICs. Newer techniques like [[large receive offload]] and TCP acknowledgment offload are already implemented in some high-end Ethernet hardware, but are effective even when implemented purely in software.<ref name=lwn-lro>{{cite news |author=Jonathan Corbet |date=2007-08-01 |publisher=[[LWN.net]] |title=Large receive offload |url=https://lwn.net/Articles/243949/ |access-date=2007-08-22 }}</ref><ref name=menon>{{cite conference |date=2008-04-28 |author1=Aravind Menon |author2=Willy Zwaenepoel |title=Optimizing TCP Receive Performance |conference=USENIX Annual Technical Conference |publisher=USENIX |url=http://www.usenix.org/event/usenix08/tech/full_papers/menon/menon_html/paper.html }}</ref>

===Parallel-stack full offload===
Parallel-stack full offload gets its name from the concept of two parallel TCP/IP Stacks. The first is the main host stack which is included with the host OS. The second or "parallel stack" is connected between the [[Internet protocol suite#Application layer|Application Layer]] and the [[Internet protocol suite#Transport layer|Transport Layer (TCP)]] using a "vampire tap". The vampire tap intercepts TCP connection requests by applications and is responsible for TCP connection management as well as TCP data transfer. Many of the criticisms in the following section relate to this type of TCP offload.

===HBA full offload===
HBA (Host Bus Adapter) full offload is found in iSCSI [[host adapter]]s which present themselves as disk controllers to the host system while connecting (via TCP/IP) to an [[iSCSI]] storage device. This type of TCP offload not only offloads TCP/IP processing but it also offloads the iSCSI initiator function. Because the HBA appears to the host as a disk controller, it can only be used with iSCSI devices and is not appropriate for general TCP/IP offload.

===TCP chimney partial offload===
TCP chimney offload addresses the major security criticism of parallel-stack full offload. In partial offload, the main system stack controls all connections to the host. After a connection has been established between the local host (usually a server) and a foreign host (usually a client) the connection and its state are passed to the TCP offload engine. The heavy lifting of data transmit and receive is handled by the offload device. Almost all TCP offload engines use some type of TCP/IP hardware implementation to perform the data transfer without host CPU intervention. When the connection is closed, the connection state is returned from the offload engine to the main system stack. Maintaining control of TCP connections allows the main system stack to implement and control connection security.

===Large receive offload===
'''Large receive offload''' ('''LRO''') is a technique for increasing inbound [[throughput]] of high-[[bandwidth (computing)|bandwidth]] network connections by reducing [[central processing unit]] (CPU) overhead. It works by aggregating multiple incoming [[packet (information technology)|packet]]s from a single [[stream (computing)|stream]] into a larger buffer before they are passed higher up the networking stack, thus reducing the number of packets that have to be processed. [[Linux]] implementations generally use LRO in conjunction with the [[New API]] (NAPI) to also reduce the number of [[interrupt]]s.

According to benchmarks, even implementing this technique entirely in software can increase network performance significantly.<ref name=lwn-lro/><ref name=menon /><ref>{{cite mailing list |author= Andrew Gallatin |title= lro: Generic Large Receive Offload for TCP traffic |mailing-list= linux-kernel |date= 2007-07-25 |url= https://lkml.org/lkml/2007/7/25/313 |access-date= 2007-08-22 }}</ref> {{As of | 2007 | April}}, the [[Linux kernel]] supports LRO for [[Transmission Control Protocol|TCP]] in software only. [[FreeBSD]] 8 supports LRO in hardware on adapters that support it.<ref>{{cite web|url=http://www.freebsd.org/cgi/man.cgi?cxgb|title=Cxgb|website=Freebsd.org|access-date=12 July 2018}}</ref><ref>{{cite web|url=http://www.freebsd.org/cgi/man.cgi?mxge|title=Mxge|website=Freebsd.org|access-date=12 July 2018}}</ref><ref>{{cite web|url=http://www.freebsd.org/cgi/man.cgi?nxge|title=Nxge|website=Freebsd.org|access-date=12 July 2018}}</ref>
<ref name=vmxnet-lro>{{cite news | date= 2011-07-04 |publisher= [[VMware]] | title= Poor TCP performance can occur in Linux virtual machines with LRO enabled |url= http://kb.vmware.com/kb/1027511 |access-date= 2011-08-17 }}</ref>

LRO should not operate on machines acting as routers, as it breaks the [[end-to-end principle]] and can significantly impact performance.<ref>{{cite web|url= http://downloadmirror.intel.com/14687/eng/readme.txt|title= Linux* Base Driver for the Intel(R) Ethernet 10 Gigabit PCI Express Family of Adapters|publisher= [[Intel Corporation]]|date= 2013-02-12|access-date= 2013-04-24}}</ref><ref>{{cite web|url= https://bugzilla.redhat.com/show_bug.cgi?id=772317|title= Disable LRO for all NICs that have LRO enabled|publisher= [[Red Hat, Inc.]]|date= 2013-01-10|access-date= 2013-04-24}}</ref>

====Generic receive offload====
'''Generic receive offload''' ('''GRO''') implements a generalised LRO in software that isn't restricted to TCP/[[IPv4]] or have the issues created by LRO.<ref>{{cite web|url=https://lwn.net/Articles/358910/|title=JLS2009: Generic receive offload|website=[[lwn.net]]}}</ref><ref>{{cite conference | last1 = Huang| first1 = Shu| last2 = Baldine| first2 = Ilia| title = Performance Evaluation of 10GE NICs with SR-IOV Support: I/O Virtualization and network Stack Optimizations| editor1-last = Schmitt| editor1-first = Jens B. | conference = Measurement, Modeling, and Evaluation of Computing Systems and Dependability and Fault Tolerance: 16th International GI/ITG Conference, MMB & DFT 2012 |location=Kaiserslautern, Germany |date=March 2012 | url = https://books.google.com/books?id=C3wQBwAAQBAJ| series = Lecture Notes in Computer Science | volume = 7201| publisher = Springer| publication-date = 2012| page = 198| isbn = 9783642285400| access-date = 2016-10-11| quote = Large-Receive-Offload (LRO) reduces the per-packet processing overhead by aggregating smaller packets into larger ones and passing them up to the network stack. Generic-Receive-Offload (GRO) provides a generalized software version of LRO [...].}}
</ref>

===Large send offload===
In [[computer network]]ing, '''large send offload''' ('''LSO''') is a technique for increasing egress [[throughput]] of high-[[Bandwidth (computing)|bandwidth]] network connections by reducing [[central processing unit|CPU]] overhead. It works by passing a multipacket buffer to the [[network interface card]] (NIC). The NIC then splits this buffer into separate packets. The technique is also called '''TCP segmentation offload''' ('''TSO''') or '''generic segmentation offload''' ('''GSO''') when applied to [[Transmission Control Protocol|TCP]]. LSO and LRO are independent and use of one does not require the use of the other.

When a system needs to send large chunks of data out over a computer network, the chunks first need breaking down into smaller segments that can pass through all the network elements like routers and switches between the source and destination computers. This process is referred to as ''[[Packet segmentation|segmentation]]''. Often the TCP protocol in the host computer performs this segmentation. Offloading this work to the NIC is called ''TCP segmentation offload'' (TSO).

For example, a unit of 64 KiB (65,536 bytes) of data is usually segmented to 45 segments of 1460 bytes each before it is sent through the NIC and over the network. With some intelligence in the NIC, the host CPU can hand over the 64 KB of data to the NIC in a single transmit-request, the NIC can break that data down into smaller segments of 1460 bytes, add the TCP, [[Internet Protocol|IP]], and data link layer protocol headers — according to a template provided by the host's TCP/IP stack — to each segment, and send the resulting frames over the network. This significantly reduces the work done by the CPU. {{As of | 2014}} many new NICs on the market support TSO.

Some network cards implement TSO generically enough that it can be used for offloading fragmentation of other [[transport layer]] protocols, or for doing [[IP fragmentation]] for protocols that don't support fragmentation by themselves, such as [[User Datagram Protocol|UDP]].

==Support in Linux==
Unlike other operating systems, such as FreeBSD, the Linux kernel does not include support for TOE (not to be confused with other types of network offload).<ref>[https://lwn.net/Articles/148697/ "Linux and TCP offload engines"], August 22, 2005, LWN.net</ref> While there are patches from the hardware manufacturers such as [[Chelsio]] or [[Qlogic]] that add TOE support, the Linux kernel developers are opposed to this technology for several reasons:<ref>{{citation | url = https://wiki.linuxfoundation.org/networking/toe | title = Networking:TOE | publisher = Linux Foundation}}.</ref>
* ''Security'' – because TOE is implemented in hardware, patches must be applied to the TOE [[firmware]], instead of just software, to address any security vulnerabilities found in a particular TOE implementation. This is further compounded by the newness and vendor-specificity of this hardware, as compared to a well tested TCP/IP stack as is found in an operating system that does not use TOE.
* ''Limitations'' of hardware – because connections are buffered and processed on the TOE chip, resource starvation can more easily occur as compared to the generous CPU and memory available to the operating system.
* ''Complexity'' – TOE breaks the assumption that kernels make about having access to all resources at all times – details such as memory used by open connections are not available with TOE. TOE also requires very large changes to a networking stack in order to be supported properly, and even when that is done, features like [[quality of service]] and [[packet filtering]] might not work.
* ''Proprietary'' – TOE is implemented differently by each hardware vendor. This means more code must be rewritten to deal with the various TOE implementations, at a cost of the aforementioned complexity and, possibly, security. Furthermore, TOE firmware cannot be easily modified since it is closed-source.
* ''Obsolescence'' – Each TOE NIC has a limited lifetime of usefulness, because system hardware rapidly catches up to TOE performance levels, and eventually exceeds TOE performance levels.

==Suppliers==
Much of the current work on TOE technology is by manufacturers of 10 Gigabit Ethernet interface cards, such as [[Broadcom]], [[Chelsio Communications]], [[Emulex]], [[Mellanox Technologies]], [[QLogic]].

==See also==
* [[Scalable Networking Pack]]
* [[I/O Acceleration Technology]] (I/OAT)
* [[Energy Efficient Ethernet]] (EEE)
* [[Autonomous peripheral operation]]

==References==
{{Reflist|30em}}

==External links==
* Article: [https://web.archive.org/web/20041028124133/http://acmqueue.com/modules.php?name=Content&pa=showpage&pid=154 TCP Offload to the Rescue] by Andy Currid at [http://www.acmqueue.com/ ACM Queue]
* [http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220040042487%22.PGNR.&OS=DN/20040042487&RS=DN/20040042487 Patent Application 20040042487 ]
* {{cite conference
|first= Jeffrey C.
|last= Mogul
|title= TCP offload is a dumb idea whose time has come
|book-title= Proceedings of HotOS IX: The 9th Workshop on Hot Topics in Operating Systems
|publisher= USENIX Association
|year=2003
|url= http://www.usenix.org/events/hotos03/tech/full_papers/mogul/mogul.pdf
|access-date= 23 July 2006
}}
* {{cite web
|title= TCP/IP offload Engine (TOE)
|url= http://line-provider.com/whitepapers/tcpip-offload-engine-toe/
|publisher= [[10 Gigabit Ethernet Alliance]]
|date=April 2002
}}
* [https://docs.microsoft.com/en-us/windows-hardware/drivers/network/offloading-the-segmentation-of-large-tcp-packets Windows Network Task Offload]
* [http://www.linuxfoundation.org/collaborate/workgroups/networking/gso GSO in Linux]
* [https://wiki.geant.org/pages/releaseview.action?pageId=121340564 Brief Description of LSO in Linux]
* [https://wiki.geant.org/display/public/EK/Case+Studies Case Studies of Performance issues with LSO and Traffic Shaping (Linux)]
* [http://www.onlamp.com/pub/a/bsd/2008/02/26/whats-new-in-freebsd-70.html?page=1 FreeBSD 7.0 new features, brief discussion on TSO support]

[[Category:Networking hardware]]
[[Category:Network acceleration]]
[[Category:Transmission Control Protocol|Offload Engine]]

Linux adoption

2023-07-01T18:19:35Z

Gotar: /* Routers */ FRRouting

{{Short description|Organizations that have moved to using Linux for their operating system}}
{{Use dmy dates|date=December 2019}}
{{Use American English|date=February 2021}}
'''Linux adoption''' is the [[Adoption (software implementation)|adoption]] of [[Linux]] computer [[operating system]]s (OS) by households, nonprofit organizations, businesses, and governments.

Many factors have resulted in the expanded use of Linux systems by traditional desktop users as well as operators of server systems, including the desire to minimize software costs, increase [[network security]] and support for [[open source|open-source]] philosophical principles.<ref name="Cornet">{{cite web |url=http://www.whylinuxisbetter.net/ |title=Why Linux is Better |access-date=15 March 2009 |last=Cornet |first=Manu |date=n.d. |archive-url=https://web.archive.org/web/20090313031313/http://www.whylinuxisbetter.net/ |archive-date=13 March 2009 |url-status=dead }}</ref>{{Better source needed|date=April 2020}} In recent years several governments, at various levels, have enacted policies shifting state-owned computers to Linux from [[proprietary software]] regimes.

In August 2010, Jeffrey Hammond, principal analyst at [[Forrester Research]], declared, "Linux has crossed the chasm to mainstream adoption," a statement attested by the large number of enterprises that had transitioned to Linux during the [[late-2000s recession]]. In a company survey completed in the third quarter of 2009, 48% of surveyed companies reported using an open-source operating system.<ref name="Kerner12Aug10">{{cite web |url=http://itmanagement.earthweb.com/osrc/article.php/3898206/LinuxCon-Analysts-Linux-Is-Winning.htm |title=LinuxCon Analysts: Linux Is Winning |access-date=12 August 2010 |last=Kerner |first=Sean Michael |date=August 2010 |archive-date=25 January 2021 |archive-url=https://web.archive.org/web/20210125120406/http://itmanagement.earthweb.com/osrc/article.php/3898206/LinuxCon-Analysts-Linux-Is-Winning.htm |url-status=live }}</ref>

The [[Linux Foundation]] regularly releases publications regarding the [[Linux kernel]], Linux OS [[Linux distribution|distributions]], and related themes.<ref>{{cite web |url=http://www.linuxfoundation.org/publications |title=Publications of the Linux Foundation |access-date=3 November 2013 |archive-url=https://web.archive.org/web/20131105104156/http://www.linuxfoundation.org/publications |archive-date=5 November 2013 |url-status=dead }}</ref> One such publication, "Linux Adoption Trends: A Survey of Enterprise End Users," is freely available upon registration.<ref>{{cite web |url=http://www.linuxfoundation.org/publications/linux-foundation/linux-adoption-trends-end-user-survey |title=Linux Adoption Trends: A Survey of Enterprise End Users |access-date=3 November 2013 |archive-url=https://web.archive.org/web/20160508094808/http://www.linuxfoundation.org/publications/linux-foundation/linux-adoption-trends-end-user-survey |archive-date=8 May 2016 |url-status=dead }}</ref>

Traditionally, the term Linux adoption refers to adoption of a Linux OS made for "desktop" computers, the original intended use (or adoption on servers, that is essentially the same form of OS). Adoption of that form on personal computers is still low relatively, while adoption of the [[Android (operating system)|Android]] operating system is very high. The term Linux adoption, often overlooks that operating system or other uses such as in [[ChromeOS]] that also use the [[Linux kernel]] (but have almost nothing else in common, not even the name – Linux – usually applied; while Android is the most popular variant – in fact the most popular operating system in the world).

==Linux adopters==
{{Main|List of Linux adopters}}
Outside of traditional web services, Linux powers many of the biggest Internet properties (e.g., [[Google]],<ref>Jonathan Corbet, [https://lwn.net/Articles/357658/ "KS2009: How Google uses Linux"] {{Webarchive|url=https://web.archive.org/web/20170731071041/https://lwn.net/Articles/357658/ |date=31 July 2017 }}, ''LWN.net'', 21 October 2009</ref> [[Amazon.com|Amazon]],<ref>Stephen Shankland, [https://www.cnet.com/news/how-linux-saved-amazon-millions "How Linux saved Amazon millions"] {{Webarchive|url=https://web.archive.org/web/20190922213006/https://www.cnet.com/news/how-linux-saved-amazon-millions/ |date=22 September 2019 }}, ''CNET'', 7 May 2002</ref> [[Facebook]], [[eBay]], [[Twitter]] or [[Yahoo!]]<ref>Steven J. Vaughan-Nichols, [http://www.zdnet.com/article/yahoo-the-linux-company/ "Yahoo: The Linux Company"] {{Webarchive|url=https://web.archive.org/web/20170309052930/http://www.zdnet.com/article/yahoo-the-linux-company/ |date=9 March 2017 }}, ''ZDNet'', 6 April 2011</ref>).

==Hardware platforms with graphical user interface==
Linux is used on desktop computers, servers and supercomputers, as well as a wide range of devices.

===Desktop and Nettop computers and Laptops===
{{anchor|Desktop Linux adoption}}
{{See also|Desktop Linux}}
[[File:Ubuntu_22.10_Kinetic_Kudu.png|thumb|[[Ubuntu]], a popular distribution of Linux.]]

===={{anchor|DESKTOP}}Measuring desktop adoption====
Because Linux desktop distributions are not usually distributed by retail sale, there are no sales numbers that indicate the number of users. One downloaded file may be used to create many CDs and each CD may be used to install the operating system on multiple computers. On the other hand, the file might be used only for a test and the installation erased soon after. Due to these factors estimates of current Linux desktop often rely on webpage hits by computers identifying themselves as running Linux. The use of these statistics has been criticized as unreliable and as underestimating Linux use.<ref name="Paul2007">{{cite news | first=Ryan | last=Paul | title=Linux market share set to surpass Win 98, OS X still ahead of Vista | date=3 September 2007 | publisher=Ars Technica, LLC | url=https://arstechnica.com/news.ars/post/20070903-linux-marketshare-set-to-surpass-windows-98.html | work=Ars Technica | access-date=19 November 2007 | archive-date=16 November 2007 | archive-url=https://web.archive.org/web/20071116080339/http://arstechnica.com/news.ars/post/20070903-linux-marketshare-set-to-surpass-windows-98.html | url-status=live }}</ref><ref name="LinuxCounter2">{{cite web|url = https://www.linuxcounter.net/|title = The Linux Counter Project|access-date = 7 November 2014|date = March 2005|archive-url = https://web.archive.org/web/20181205060932/https://www.linuxcounter.net/|archive-date = 5 December 2018|url-status = dead}}</ref>

Using webpage hits as a measure, until 2008, Linux accounted for only about 1% of desktop [[market share]], while [[Comparison of Microsoft Windows versions|Microsoft Windows operating systems]] held more than 90%.<ref name="Paul2007" /><ref>{{cite news | first=Peter | last=Galli | title=Vista Aiding Linux Desktop, Strategist Says | date=8 August 2007 | publisher=Ziff Davis Enterprise Inc. | url=http://www.eweek.com/c/a/Linux-and-Open-Source/Vista-Aiding-Linux-Desktop-Strategist-Says/ | work=eWEEK | access-date=19 November 2007 | archive-date=9 July 2009 | archive-url=http://arquivo.pt/wayback/20090709050715/http://www.eweek.com/c/a/Linux-and-Open-Source/Vista-Aiding-Linux-Desktop-Strategist-Says/ | url-status=live }}</ref><ref>{{cite news|first=Stan |last=Beer |title=Vista to play second fiddle to XP until 2009: Gartner |date=23 January 2007 |publisher=iTWire |url=http://www.itwire.com.au/content/view/8842/53/ |work=iTWire |access-date=19 November 2007 |url-status=dead |archive-url=https://web.archive.org/web/20081203204529/http://www.itwire.com.au/content/view/8842/53/ |archive-date=3 December 2008 }}</ref><ref>{{cite web |url=http://marketshare.hitslink.com/report.aspx?qprid=2&qpmr=15&qpdt=1&qpct=3&qptimeframe=Y |title=Operating System Marketshare for Year 2007 |access-date=19 November 2007 |date=19 November 2007 |work=Market Share |publisher=Net Applications |archive-date=24 June 2013 |archive-url=https://web.archive.org/web/20130624203258/http://marketshare.hitslink.com/report.aspx?qprid=2&qpmr=15&qpdt=1&qpct=3&qptimeframe=Y |url-status=live }}</ref><ref>{{cite news|title=Vista slowly continues its growth; Linux more aggressive than Mac OS during the summer |date=24 September 2007 |publisher=AT Internet/XiTi.com |url=http://www.xitimonitor.com/en-us/internet-users-equipment/operating-systems-august-2007/index-1-2-7-107.html |work=XiTiMonitor |access-date=19 November 2007 |url-status=dead |archive-url=https://web.archive.org/web/20071113105328/http://www.xitimonitor.com/en-us/internet-users-equipment/operating-systems-august-2007/index-1-2-7-107.html |archive-date=13 November 2007 }}</ref><ref>{{cite web |url=http://www.w3counter.com/globalstats.php |title=Global Web Stats |access-date=19 November 2007 |date=10 November 2007 |work=W3Counter |publisher=Awio Web Services LLC |archive-date=28 June 2012 |archive-url=https://archive.today/20120628/http://www.w3counter.com/globalstats.php |url-status=live }}</ref><ref>{{cite web |url=https://www.google.com/press/zeitgeist/zeitgeist-jun04.html |title=June 2004 Zeitgeist |access-date=19 November 2007 |date=12 August 2004 |work=Google Press Center |publisher=Google Inc. |archive-date=3 October 2017 |archive-url=https://web.archive.org/web/20171003022458/http://www.google.com/press/zeitgeist/zeitgeist-jun04.html |url-status=live }}</ref> This might have been because Linux was not seen at that time as a direct replacement for Windows.<ref>{{cite web|url=http://www.linux-mag.com/id/4357 |archive-url=https://web.archive.org/web/20080415032312/http://linux-mag.com/id/4357 |url-status=usurped |archive-date=15 April 2008 |title=Is 2008 the Year of the Linux Desktop? |access-date=19 November 2007 |last=Brockmeier |first=Joe |date=15 November 2007 |work=Linux Magazine |publisher=QuarterPower Media }}</ref>

{{As of|2017|2}}, ''W3Counter'' estimated "Linux" web browser market share to be 4.63%, while "Android" versions 6, 5 and 4 combined (which is based on the [[Linux kernel]]) were estimated to be 33.77%.<ref>{{cite web|url = http://www.w3counter.com/globalstats.php?year=2017&month=2|title = Global Web Stats|access-date = 3 March 2015|website = W3Counter|archive-date = 14 March 2017|archive-url = https://web.archive.org/web/20170314152216/https://www.w3counter.com/globalstats.php?year=2017&month=2|url-status = live}}</ref>

In September 2014 [[Pornhub]] released usage statistics of their website and reported 1.7% Linux users.<ref>[https://www.phoronix.com/scan.php?page=news_item&px=MTc3NDk OS Battle: Linux Takes 1.7% Desktop Marketshare] {{Webarchive|url=https://web.archive.org/web/20161229023117/https://www.phoronix.com/scan.php?page=news_item&px=MTc3NDk |date=29 December 2016 }} on [[Phoronix]] by [[Michael Larabel]] (28 August 2014)</ref>

The [[Unity (game engine)|Unity]] [[game engine]] gathers user statistics and showed in March 2016 0.4% Linux users.<ref>[http://hwstats.unity3d.com/pc/os.html Platforms Top on 2016-03] {{Webarchive|url=https://web.archive.org/web/20170627193942/http://hwstats.unity3d.com/pc/os.html |date=27 June 2017 }} ''Windows Player: 97.3%, OS X Player: 2.3%, Others (click to show): 0.4% Linux Player: 0.4%''</ref> Similarly, the [[Steam (service)|Steam]] client tracks usage and reported in May 2015 around 1% Linux users.<ref>[http://www.escapistmagazine.com/news/view/140901-Linux-Steam-Users-Under-1 Linux Users Drop to Under 1% In Latest Steam Survey] {{Webarchive|url=https://web.archive.org/web/20170409073256/http://www.escapistmagazine.com/news/view/140901-Linux-Steam-Users-Under-1 |date=9 April 2017 }} by Steven Bogos on [[The Escapist (magazine)|The Escapist]] (26 May 2015)</ref>

In April 2009, Aaron Seigo of [[KDE]] indicated that most web-page counter methods produce Linux adoption numbers that are far too low given the system's extensive penetration into non-North American markets, especially China. He stated that the North American-based web-measurement methods produce high Windows numbers and ignore the widespread use of Linux in other parts of the world. In estimating true worldwide desktop adoption and accounting for the Windows-distorted environment in the US and Canada he indicated that at least 8% of the world desktops run Linux distributions and possibly as high as 10–12% and that the numbers are rising quickly. Other commentators have echoed this same belief, noting that competitors are expending a lot of effort to discredit Linux, which is incongruent with a tiny market share:<ref name="Byfield04May09">{{cite web|url = http://itmanagement.earthweb.com/osrc/article.php/12068_3818696_2/Linux-Desktop-Market-Share-Greater-Than-One-Percent.htm|title = Linux Desktop Market Share: Greater Than One Percent?|access-date = 6 May 2009|last = Byfield|first = Bruce|date = May 2009|archive-date = 7 May 2009|archive-url = https://web.archive.org/web/20090507183542/http://itmanagement.earthweb.com/osrc/article.php/12068_3818696_2/Linux-Desktop-Market-Share-Greater-Than-One-Percent.htm|url-status = live}}</ref><ref name="Schroder28May09">{{cite web |url = http://blog.linuxtoday.com/blog/2009/05/1-linux-microso.html |title = Tiny 1% Linux = Big Microsoft Terror |access-date = 30 May 2009 |last = Schroder |first = Carla |date = May 2009 |archive-date = 31 May 2009 |archive-url = https://web.archive.org/web/20090531140510/http://blog.linuxtoday.com/blog/2009/05/1-linux-microso.html |url-status = live }}</ref>

{{blockquote|I don't believe that the desktop Linux market share is barely 1%. I think it is a lot higher. I have no good data to share; I base my assessment on experience and knowing the industry. There is something else that is even more persuasive, and that is how Microsoft behaves. If Linux is so insignificant, why do they pay so much attention to it?|Carla Schroder, Linux Today<ref name="Schroder28May09" />}}

In May 2009, Preston Gralla, contributing editor to [[Computerworld]].com, in reacting to the Net Applications web hit numbers showing that Linux use was over 1%, said that "Linux will never become an important desktop or notebook operating system". He reasoned that the upsurge in Linux desktop use recently seen was due to Linux netbooks, a trend he saw as already diminishing and which would be further eroded when [[Windows 7]] became available (and indeed, Linux netbooks did fall by the wayside, though whether they were solely responsible for the upsurge in Linux usage is open to question). He concluded: "As a desktop operating system, Linux isn't important enough to think about. For servers, it's top-notch, but you likely won't use it on your desktop – even though it did finally manage to crack the 1% barrier after 18 years".<ref name="Gralla18May09">{{cite web|url=http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=338839 |title=Opinion: Why you shouldn't care about Linux on the desktop |access-date=20 May 2009 |last=Gralla |first=Preston |date=May 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090521132147/http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=338839 |archive-date=21 May 2009 }}</ref>

In 2009, [[Microsoft]] then-CEO [[Steve Ballmer]] indicated that Linux had a greater desktop market share than Mac, stating that in recent years Linux had "certainly increased its share somewhat". Just under a third of all [[Dell]] netbook sales in 2009 had Linux installed.<ref name="Martin07Sep10">{{cite web|url = http://broadcast.oreilly.com/2010/09/debunking-the-1-myth.html|title = Debunking the 1% Myth|access-date = 14 September 2010|last = Martin|first = Caitlyn|date = September 2010|archive-date = 27 February 2011|archive-url = https://web.archive.org/web/20110227195510/http://broadcast.oreilly.com/2010/09/debunking-the-1-myth.html|url-status = live}}</ref>

Caitlyn Martin, researching retail market numbers in the summer of 2010 also concluded that the traditional numbers mentioned for Linux desktop adoption were far too low:

{{blockquote|It seems like almost every day someone in the tech press or someone commenting in a technical forum will claim that Linux adoption on the desktop (including laptops) is insignificant. The number that is thrown around is 1%. These claims are even repeated by some who advocate for Linux adoption. Both the idea that Linux market share on the desktop is insignificant and the 1% figure are simply false and have been for many years...Where does the 1% number come from? There are two sources: very old data and web counters. The problem with using web counters to try and ascertain market share is that they generally only include websites that have paid to be counted. That pretty much guarantees that Windows will be overcounted.|Caitlyn Martin<ref name="Martin07Sep10" />}}

====Reasons for adoption====
Reasons to change from other operating systems to Linux include better system stability, better [[Linux malware|malware]] protection, low or no cost, that most distributions come complete with application software and hardware drivers, simplified updates for all installed software, free software licensing, availability of application repositories and access to the [[source code]]. Linux desktop distributions also offer multiple desktop workspaces, greater customization, free and unlimited support through forums, and an operating system that doesn't slow down over time. Environmental reasons are also cited, as Linux operating systems usually do not come in boxes and other retail packaging, but are downloaded via the Internet. The lower system specifications also mean that older hardware can be kept in use instead of being recycled or discarded. Linux distributions also get security vulnerabilities patched much more quickly than non-free operating systems and improvements in Linux have been occurring at a faster rate than those in Windows.<ref name="Cornet" /><ref name="Siu28Jul06">{{cite web|url = http://www.psychocats.net/ubuntucat/the-linux-desktop-myth/|title = The Linux Desktop Myth|access-date = 19 March 2009|last = Siu|first = A.Y.|date = July 2006|archive-date = 16 June 2020|archive-url = https://web.archive.org/web/20200616152507/https://www.psychocats.net/ubuntucat/the-linux-desktop-myth/|url-status = live}}</ref>{{unreliable source?|date=December 2016}}<ref name="Wallen17Aug08">{{cite web|url = http://www.techrepublic.com/blog/linux-and-open-source/why-would-anyone-choose-windows-over-linux/|title = Why would anyone choose Windows over Linux?|access-date = 19 March 2009|last = Wallen|first = Jack|date = August 2008|archive-date = 2 March 2015|archive-url = https://web.archive.org/web/20150302135409/http://www.techrepublic.com/blog/linux-and-open-source/why-would-anyone-choose-windows-over-linux/|url-status = live}}</ref>

A report in [[The Economist]] in December 2007 said:

{{cquote|Linux has swiftly become popular in small businesses and the home. That’s largely the doing of Gutsy Gibbon, the code-name for the Ubuntu 7.10 from Canonical. Along with distributions such as Linspire, Mint, Xandros, OpenSUSE and gOS, Ubuntu (and its siblings Kubuntu, Edubuntu and Xubuntu) has smoothed most of Linux’s geeky edges while polishing it for the desktop. No question, Gutsy Gibbon is the sleekest, best integrated and most user-friendly Linux distribution yet. It’s now simpler to set up and configure than Windows.<ref name="Economist">{{cite news|url = http://www.economist.com/science/displaystory.cfm?story_id=10410912|title = Technology in 2008|access-date = 1 April 2008|newspaper = The Economist|date = December 2007|archive-date = 22 March 2008|archive-url = https://web.archive.org/web/20080322045229/http://www.economist.com/science/displaystory.cfm?story_id=10410912|url-status = live}}</ref>}}

Further investments have been made to improve desktop Linux usability since that 2007 report.

Indian bulk computer purchaser the [[Electronics Corporation of Tamil Nadu]] (ELCOT) started recommending only Linux in June 2008. Following testing they stated: "ELCOT has been using [[SUSE Linux]] and [[Ubuntu]] Linux operating systems on desktop and laptop computers numbering over 2,000 during the past two years and found them far superior as compared to other operating systems, notably the Microsoft Windows Operating System."<ref name="KingmanJune2008" />

In many developing nations, such as China, where, due to widespread [[software piracy]], [[Microsoft Windows]] can be easily obtained for free, Linux distributions are gaining a high level of adoption. Hence in these countries where there is essentially no cost barrier to obtaining proprietary operating systems, users are adopting Linux based on its merit, rather than on price.<ref name="Dawson17Jun09" />

In January 2001, [[Microsoft]] then-CEO [[Bill Gates]] explained the attraction of adopting Linux in an internal memo that was released in the ''Comes vs Microsoft'' case. He said:

{{blockquote|Our most potent Operating System competitor is Linux and the phenomena around Open Source and free software. The same phenomena fuels competitors to all of our products. The ease of picking up Linux to learn it or to modify some piece of it is very attractive. The academic community, start up companies, foreign governments and many other constituencies are putting their best work into Linux.<ref name="GroklawComesVsMSExhibit08256">{{cite web|url = http://groklaw.net/pdf/iowa/www.iowaconsumercase.org/011607/8000/PX08256.pdf|title = Comes vs Microsoft E-mail Exhibit|access-date = 29 June 2009|last = Gates|first = Bill|date = January 2001|archive-date = 12 January 2016|archive-url = https://web.archive.org/web/20160112100827/http://groklaw.net/pdf/iowa/www.iowaconsumercase.org/011607/8000/PX08256.pdf|url-status = live}}</ref> }}

====Barriers to adoption====
The greatest barrier to Linux desktop adoption is probably that few desktop PCs come with it from the factory. A.Y. Siu asserted in 2006 that most people use Windows simply because most PCs come with Windows pre-installed; they didn't choose it. Linux has much lower market penetration because in most cases users have to install it themselves, a task that is beyond the capabilities of many PC users: "Most users won’t even use Windows restore CDs, let alone install Windows from scratch. Why would they install an unfamiliar operating system on their computers?"<ref name="Siu28Jul06" />{{unreliable source?|date=December 2016}}

[[TechRepublic]] writer Jack Wallen expands on this barrier, saying in August 2008:<ref name="Wallen17Aug08" />

{{blockquote|Why would anyone choose Windows over Linux?...In my seriously biased opinion, I think this question is answered with a simple conspiracy theory: Microsoft is doing everything it can to keep the public blind to Linux. Think about it? Remember the whole Wintel conspiracy where MS and Intel played off of each other to continue their strangle-hold monopoly in the PC industry? That era played a huge part in the blinding of consumers. Top that with the business practices MS forces upon big box shops to ensure their operating system is sold on nearly every PC sold and you can see that conspiracy is more of a reality than one might think.<ref name="Wallen17Aug08" /> }}

Linus Torvalds stated, in his June 2012 interaction with students at [[Aalto University]],<ref name="aalto">{{cite web |url = https://www.youtube.com/watch?v=KFKxlYNfT_o |title = Q&A session with Linus Torvalds: Why is Linux not competitive on desktop? |website = [[YouTube]] |date = 15 June 2012 |access-date = 27 November 2016 |archive-date = 3 December 2016 |archive-url = https://web.archive.org/web/20161203054123/https://www.youtube.com/watch?v=KFKxlYNfT_o |url-status = live }}</ref> that although Linux was originally conceived as a desktop system, that has been the only market where it has not flourished. He suggested that the key reason that keeps Linux from getting a substantial presence in the desktop market is that the average desktop user does not want to install an operating system, so getting manufacturers to sell computers with Linux pre-installed would be the missing piece to fulfill the vision of Linux in the desktop market.<ref>{{cite web |url = https://www.bbc.co.uk/news/technology-18419231 |title = Linus Torvalds: Linux succeeded thanks to selfishness and trust |author = Leo Kelion |date = 13 June 2012 |publisher = BBC |access-date = 20 June 2018 |archive-date = 5 January 2018 |archive-url = https://web.archive.org/web/20180105081446/http://www.bbc.co.uk/news/technology-18419231 |url-status = live }}</ref> He added that Chromebooks, by shipping with the Linux-based [[ChromeOS]], could provide the key turning point in such a transition, much like [[Android (operating system)|Android]] allowed Linux to spread in the mobile space.<ref name="aalto" />

In September 2012, [[GNOME]] developer [[Michael Meeks (software developer)|Michael Meeks]] also indicated that the main reason for the lack of adoption of Linux desktops is the lack of manufacturers shipping computers with it pre-installed, supporting Siu's arguments from six years earlier. Meeks also indicated that users wouldn't embrace desktop Linux until there is a wider range of applications and developers won't create that wider range of applications until there are more users, a classic [[Catch-22 (logic)|Catch-22]] situation.<ref>McAllister, Neil (11 September 2012), [https://www.theregister.co.uk/2012/09/11/michael_meeks_linux_desktop/ GNOME hacker: Culture isn't holding desktop Linux back] {{Webarchive|url=https://web.archive.org/web/20170129095619/http://www.theregister.co.uk/2012/09/11/michael_meeks_linux_desktop/ |date=29 January 2017 }}, [[The Register]], retrieved 12 August 2013</ref>

In an [[openSUSE]] survey conducted in 2007, 69.5% of respondents said they [[dual boot]]ed a [[Microsoft Windows]] operating system in addition to a Linux operating system.<ref>{{cite web|url=http://files.opensuse.org/opensuse/en/6/6c/Opensuse_survey_102_data_final.pdf |title=openSUSE 10.2 Survey Results |access-date=19 November 2007 |date=4 May 2007 |work=openSUSE |publisher=openSUSE |url-status=dead |archive-url=https://web.archive.org/web/20080516231251/http://files.opensuse.org/opensuse/en/6/6c/Opensuse_survey_102_data_final.pdf |archive-date=16 May 2008 }}</ref> In early 2007 Bill Whyman, an analyst at Precursor Advisors, noted that "there still isn't a compelling alternative to the [[Microsoft]] infrastructure on the desktop."<ref>{{cite news |first = Robert A. |last = Guth |title = Linux Starts to Find Home on Desktops |date = 13 March 2007 |publisher = Dow Jones & Company, Inc. |url = https://www.wsj.com/articles/SB117374336173334742 |work = The Wall Street Journal Online |access-date = 19 November 2007 |archive-date = 22 December 2015 |archive-url = https://web.archive.org/web/20151222223215/http://www.wsj.com/articles/SB117374336173334742 |url-status = live }}</ref>

Application support, the quality of peripheral support, and end user support were at one time seen as the biggest obstacles to desktop Linux adoption. According to a 2006 survey by The [[Linux Foundation]], these factors were seen as a "major obstacle" for 56%, 49%, and 33% of respondents respectively at that time.<ref>{{cite web|url=http://www.computerworld.com.au/index.php/id;1462899608;fp;4194304;fpid;1 |title=Living (and dying) with Linux in the workplace |access-date=19 November 2007 |last=Machlis |first=Sharon |date=22 March 2007 |work=Computerworld |publisher=IDG Communications |archive-url=https://web.archive.org/web/20071221085731/http://www.computerworld.com.au/index.php/id%3B1462899608%3Bfp%3B4194304%3Bfpid%3B1 |archive-date=21 December 2007 |url-status=dead}}</ref><ref>{{cite web |url=http://blogs.zdnet.com/hardware/?p=420 |title=Five crucial things the Linux community doesn't understand about the average computer user |access-date=19 November 2007 |last=Kingsley-Hughes |first=Adrian |date=21 May 2007 |work=ZDNet |publisher=CNET Networks, Inc. |archive-date=20 December 2007 |archive-url=https://web.archive.org/web/20071220214820/http://blogs.zdnet.com/hardware/?p=420 |url-status=live }}</ref><ref>{{cite web |url=http://www.desktoplinux.com/news/NS6087894103.html |title=Why Windows wins and Linux loses |access-date=19 November 2007 |last=Vaughan-Nichols |first=Steven J. |date=3 January 2007 |work=DesktopLinux.com |publisher=Ziff Davis Publishing Holdings Inc. |url-status=dead |archive-date= 4 December 2007 |archive-url=https://web.archive.org/web/20071204050814/http://www.desktoplinux.com/news/NS6087894103.html}}</ref><ref name="ACM">{{cite journal |title=Desktop Linux: Where Art Thou? |journal=ACM Queue |date=May 2004 |first=Bart |last=Decrem |volume=2 |issue=3 |pages=48–56 |doi=10.1145/1005062.1005067 |doi-access=free}}</ref><ref>{{cite web |url=http://www.desktoplinux.com/news/NS9755856281.html |title=Who are the Linux desktop users? |access-date=19 November 2007 |last=Vaughan-Nichols |first=Steven J. |date=6 May 2007 |work=DesktopLinux.com |publisher=Ziff Davis Publishing Holdings Inc. |archive-url=https://web.archive.org/web/20071117181549/http://www.desktoplinux.com/news/NS9755856281.html |archive-date=17 November 2007 |url-status=dead}}</ref><ref>{{cite news |title=Dell to use Ubuntu on Linux PCs |date=1 May 2007 |publisher=BBC |url=http://news.bbc.co.uk/2/hi/business/6610901.stm |work=BBC News |access-date=19 November 2007 |archive-date=15 December 2007 |archive-url=https://web.archive.org/web/20071215045433/http://news.bbc.co.uk/2/hi/business/6610901.stm |url-status=live }}</ref><ref>{{cite news |first=Antone |last=Gonsalves |title=Study: Lack of App Support Stunting Linux |date=1 December 2005 |work=TechWeb |publisher=CMP Media LLC |url=http://www.techweb.com/showArticle.jhtml?articleID=174403447 |access-date=19 November 2007 |archive-date=11 June 2011 |archive-url=https://web.archive.org/web/20110611123304/http://www.techweb.com/showArticle.jhtml?articleID=174403447 |url-status=live }}</ref><ref name="Dell Ubuntu">{{cite web|url=http://www.dell.com/content/topics/segtopic.aspx/ubuntu?c=us&cs=19&l=en&s=dhs&~ck=mn |title=Ubuntu |access-date=19 November 2007 |work=Dell Home & Home Office |publisher=Dell |archive-url=https://web.archive.org/web/20100228203033/http://www.dell.com/content/topics/segtopic.aspx/ubuntu?c=us&cs=19&l=en&s=dhs&~ck=mn |archive-date=28 February 2010 |url-status=dead}}</ref><ref name="OSDL 2006">{{cite web |url=https://mwiki.static.linuxfound.org/images/a/a9/2006survey-analysis.pdf |title=2006 Desktop Linux Client Survey: Analysis |access-date=6 January 2022 |year=2006 |work=OSDL Desktop Linux Working Group |publisher=Linux Foundation |archive-date=6 January 2022 |archive-url=https://web.archive.org/web/20220106112853/https://mwiki.static.linuxfound.org/images/a/a9/2006survey-analysis.pdf |url-status=live }}</ref>

=====Application support=====
{{See also|Virtual machine|Wine (software)}}

The November 2006 ''Desktop Linux Client Survey'' identified the foremost barrier for deploying Linux desktops was that users were accustomed to Windows applications which had not been ported to Linux and which they "just can't live without". These included [[Microsoft Office]], [[Adobe Photoshop]], [[Autodesk]] [[AutoCAD]], [[Microsoft Project]], [[Microsoft Visio|Visio]] and [[Intuit]] [[QuickBooks]].<ref name="OSDL 2006" /><ref>{{cite news|first=Steven J. |last=Vaughan-Nichols |title=Where are the American Linux desktop users? |date=23 October 2007 |publisher=Ziff Davis Enterprise Holdings Inc. |url=http://www.desktoplinux.com/news/NS2619861157.html |work=DesktopLinux.com |access-date=19 November 2007 |url-status=dead |archive-url=https://web.archive.org/web/20071121011218/http://www.desktoplinux.com/news/NS2619861157.html |archive-date=21 November 2007 }}</ref> This creates a [[chicken or the egg]] situation where developers make programs for Windows due to its market share, and consumers use Windows due to availability of said programs.
In a DesktopLinux.com survey conducted in 2007, 72% of respondents said they used ways to run Windows applications on Linux.<ref>{{cite web|url=http://www.desktoplinux.com/cgi-bin/survey/survey.cgi?view=archive&id=0813200712407 |archive-url=https://archive.today/20120524145331/http://www.desktoplinux.com/cgi-bin/survey/survey.cgi?view=archive&id=0813200712407 |url-status=dead |archive-date=24 May 2012 |title=2007 Desktop Linux Market survey |access-date=11 December 2007 |date=21 August 2007 |work=DesktopLinux.com |publisher=Ziff Davis Enterprise Holdings Inc }}</ref>

51% of respondents to the 2006 Linux Foundation survey, believed that cross-distribution Linux desktop standards should be the top priority for the Linux desktop community, highlighting the fact that the fragmented Linux market is preventing application vendors from developing, distributing and supporting the operating system.<ref name="ACM" /><ref name="OSDL 2006" /> In May 2008, [[Gartner]] predicted that "version control and incompatibilities will continue to plague open-source OSs and associated middleware" in the 2013 timeframe.<ref name="ZDNet Gartner">{{cite web|url=http://blogs.zdnet.com/open-source/?p=2216 |title=Gartner report forecasts bad news, good news for open source |access-date=7 April 2008 |last=Rooney |first=Paula |date=1 April 2008 |work=ZDNet |publisher=CNET Networks, Inc. |url-status=dead |archive-url=https://web.archive.org/web/20080405204558/http://blogs.zdnet.com/open-source/?p=2216 |archive-date= 5 April 2008 }}</ref>

By 2008, the design of Linux applications and the porting of Windows and Apple applications had progressed to the point where it was difficult to find an application that did not have an equivalent for Linux, providing adequate or better capabilities.<ref name="Alternatives">{{cite web |url = http://linuxappfinder.com/alternatives |title = Windows and OS X Software Alternatives |access-date = 19 March 2009 |website = Linux App Finder |year = 2008 |archive-date = 18 March 2009 |archive-url = https://web.archive.org/web/20090318063443/http://linuxappfinder.com/alternatives |url-status = live }}</ref><ref name="TuxSoftware">{{cite web |url = http://www.tuxsoftware.com/home/ |title = Linux Software Search |access-date = 19 March 2009 |website = TuxSoftware.com |archive-url = https://web.archive.org/web/20080822001523/http://www.tuxsoftware.com/home/ |archive-date = 22 August 2008 }}</ref>

An example of application progress can be seen comparing the main productivity suite for Linux, [[OpenOffice.org]], to [[Microsoft Office]]. With the release of OpenOffice.org 3.0 in October 2008 [[Ars Technica]] assessed the two:<ref name="Paul13Oct08">{{cite web |url = https://arstechnica.com/open-source/news/2008/10/openoffice-org-3-0-officially-released.ars |title = OpenOffice.org 3.0 officially released |access-date = 19 March 2009 |last = Paul |first = Ryan |date = October 2008 |archive-date = 12 February 2009 |archive-url = https://web.archive.org/web/20090212174809/http://arstechnica.com/open-source/news/2008/10/openoffice-org-3-0-officially-released.ars |url-status = live }}</ref>

{{blockquote|Although OpenOffice.org has not yet reached full parity with Microsoft Office, it is maturing at a rapid pace and is already capable of meeting the basic needs of many average computer users. It is an ideal choice for schools and is an increasingly viable choice for small businesses and home users that don't rely on the more advanced capabilities of Microsoft's office suite.<ref name="Paul13Oct08" /> }}

=====Peripheral support=====
In the past the availability and quality of open source [[device driver]]s were issues for Linux desktops. Particular areas which were lacking drivers included printers as well as wireless and audio cards.<ref name="OSDL 2006" /><ref name="OSDL 2005">{{cite web |url = https://www.linux-foundation.org/images/3/3b/DTL_Survey_Report_Nov2005.pdf |title = 2005 Desktop Linux Client Survey Report |access-date = 19 November 2007 |year = 2005 |work = OSDL Desktop Linux Working Group |publisher = Linux Foundation }}{{dead link|date=December 2017 |bot=Balon Greyjoy |fix-attempted=yes }}</ref> For example, in early 2007, [[Dell]] did not sell specific hardware and software with [[Ubuntu (operating system)|Ubuntu]] 7.04 computers, including printers, projectors, [[Bluetooth]] keyboards and mice, [[TV tuner card|TV tuners]] and [[remote control handset|remote controls]], desktop [[modem]]s and [[Blu-ray]] drives, due to incompatibilities at that time, as well as legal issues.<ref>{{cite web |url = http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?c=us&dl=false&l=en&s=gen&docid=33C0764C597FC6CCE040A68F5B2872A3&doclang=en |title = Hardware and Software Not Sold on Dell Ubuntu 7.04 Computers |access-date = 19 November 2007 |date = 26 July 2007 |work = Dell USA |publisher = Dell |archive-date = 24 February 2023 |archive-url = https://web.archive.org/web/20230224001709/https://www.dell.com/support/home/en-us |url-status = live }}</ref>

By 2008, most Linux hardware support and driver issues had been adequately addressed. In September 2008, Jack Wallen's assessment was:

{{blockquote|Years ago, if you wanted to install Linux on a machine you had to make sure you hand-picked each piece of hardware or your installation would not work 100 percent...This is not so much the case now. You can grab a PC (or laptop) and most likely get one or more Linux distributions to install and work nearly 100 percent. But there are still some exceptions; for instance, hibernate/suspend remains a problem with many laptops, although it has come a long way.<ref name="Wallen03Sep08" /> }}

=====End-user support=====
Some critics have stated that compared to Windows, Linux is lacking in end-user support. Linux has traditionally been seen as requiring much more technical expertise.<ref name="WSJ Mossberg">{{cite news |first = Walter S. |last = Mossberg |title = Linux's Free System Is Now Easier to Use, But Not for Everyone |date = 13 September 2007 |publisher = Dow Jones & Company, Inc. |url = https://www.wsj.com/articles/SB118963540721725614 |work = The Wall Street Journal Online |access-date = 19 November 2007 |archive-date = 11 January 2015 |archive-url = https://web.archive.org/web/20150111114300/http://www.wsj.com/articles/SB118963540721725614 |url-status = live }}</ref><ref>{{cite web|url=http://www.crn.com/software/190900617 |title=A Linux OS For All |access-date=19 November 2007 |last=Ohlhorst |first=Frank J. |date=21 July 2006 |work=CRN |publisher=CMP Media LLC |url-status=dead |archive-url=https://web.archive.org/web/20071203004836/http://www.crn.com/software/190900617 |archive-date=3 December 2007 }}</ref> [[Dell]]'s website described open source software as requiring intermediate or advanced knowledge to use.<ref name="Dell Ubuntu" /> In September 2007, the founder of the Ubuntu project, [[Mark Shuttleworth]], commented that "it would be reasonable to say that this is not ready for the mass market."<ref name="WSJ Mossberg" />

In October 2004, [[Chief technical officer|Chief Technical Officer]] of Adeptiva Linux, Stephan February, noted at that time that Linux was a very technical software product, and few people outside the technical community were able to support consumers. Windows users are able to rely on friends and family for help, but Linux users generally use discussion boards, which can be uncomfortable for consumers.<ref>{{cite news |first = Geoffrey P. |last = Ramos |title = Linux not ready for mass market |date = 29 October 2004 |publisher = IDG |url = http://www.techworld.com/opsys/news/index.cfm?NewsID=2510 |work = Techworld |access-date = 19 November 2007 |archive-date = 23 October 2007 |archive-url = https://web.archive.org/web/20071023185406/http://www.techworld.com/opsys/news/index.cfm?NewsID=2510 |url-status = live }}</ref><ref>{{cite web |url = http://blogs.zdnet.com/hardware/?p=424 |title = Three more things that the Linux community doesn't get |access-date = 19 November 2007 |last = Kingsley-Hughes |first = Adrian |date = 23 May 2007 |work = ZDNet |publisher = CNET Networks, Inc. |archive-date = 21 December 2007 |archive-url = https://web.archive.org/web/20071221020252/http://blogs.zdnet.com/hardware/?p=424 |url-status = live }}</ref>

In 2005, Dominic Humphries summarized the difference in user tech support:<ref name="Humphries">{{cite web |url = http://linux.oneandoneis2.org/LNW.htm |title = Linux is Not Windows |access-date = 19 March 2009 |last = Humphries |first = Dominic |date = December 2005 |archive-date = 3 March 2021 |archive-url = https://web.archive.org/web/20210303001237/http://linux.oneandoneis2.org/LNW.htm |url-status = live }}</ref>

{{blockquote|Windows users are more or less in a customer-supplier relationship: They pay for software, for warranties, for support, and so on. They expect software to have a certain level of usability. They are therefore used to having rights with their software: They have paid for technical support and have every right to demand that they receive it. They are also used to dealing with entities rather than people: Their contracts are with a company, not with a person.

Linux users are in more of a community. They don't have to buy the software, they don't have to pay for technical support. They download software for free & use Instant Messaging and web-based forums to get help. They deal with people, not corporations.<ref name="Humphries" /> }}

More recently critics have found that the Linux user support model, using community-based forum support, has greatly improved. In 2008 Jack Wallen stated:<ref name="Wallen03Sep08">{{cite web|last=Wallen|first=Jack.|date=September 2008|title=Ten key differences between Linux and Windows|url=http://resources.zdnet.co.uk/articles/features/0,1000002000,39483863-1,00.htm|access-date=19 March 2009|archive-date=16 January 2009|archive-url=https://web.archive.org/web/20090116161330/http://resources.zdnet.co.uk/articles/features/0,1000002000,39483863-1,00.htm|url-status=live}}</ref>

{{blockquote|With Linux, you have the support of a huge community via forums, online search, and plenty of dedicated websites. And of course, if you feel the need, you can purchase support contracts from some of the bigger Linux companies (Red Hat and Novell, for instance).

However, when you use the peer support inherent in Linux, you do take a chance with time. You could have an issue with something, send out email to a mailing list or post on a forum, and within 10 minutes be flooded with suggestions. Or these suggestions could take hours or days to come in. It seems all up to chance sometimes.

Yet generally speaking, most problems with Linux have been encountered and documented, so the chances are good you'll find your solution fairly quickly.<ref name="Wallen03Sep08" /> }}

In addressing the question of user support, Manu Cornet said:

{{blockquote|One of the great assets of the Open Source community (and Linux in particular), is that it's a real community. Users and developers really are out there, on web forums, on mailing lists, on IRC channels, helping out new users. They're all happy to see more and more people switch to Linux, and they're happy to help them get a grip on their new system...you'll find literally thousands of places where nice people will answer you and walk you out of your problem most of the time<ref name="Cornet" /> }}

=====Other factors=====
Linux's credibility has also been under attack at times, but as Ron Miller of LinuxPlanet points out:<ref name="LinuxPlanet">{{cite web |url = http://www.linuxplanet.com/linuxplanet/reports/5401/1/ |title = Linux Criticism Revs Up |access-date = 19 November 2007 |last = Miller |first = Ron |date = 20 May 2004 |work = LinuxPlanet |publisher = Jupitermedia Corporation |archive-date = 7 August 2011 |archive-url = https://web.archive.org/web/20110807034808/http://www.linuxplanet.com/linuxplanet/reports/5401/1 |url-status = dead }}</ref>

{{blockquote|...the fact that Linux is being criticized is probably a good thing.

First of all, it shows that Linux is making headway in the enterprise and beginning to have an impact on competitors and they are reacting to that. Secondly, it's healthy to take a long look at any solution and analyze its strengths and weaknesses and the economic ramifications of one choice over another.

Ultimately, consumers and decision makers need to look carefully at the data including the sources of the data and the criticism and decide if Linux is the right decision, but as more people choose Linux and it finds its place in the market, it is bound to wear a target. That's simply the price you pay for success in the marketplace.<ref name="LinuxPlanet" /> }}

There is continuing debate about the [[total cost of ownership]] of Linux,<ref>{{cite news|first=Vincent |last=Ryan |title=Anti-Linux Comments Rile Supporters |date=19 June 2003 |publisher=NewsFactor Network |url=http://www.newsfactor.com/story.xhtml?story_id=21764 |work=NewsFactor.com |access-date=19 November 2007 |url-status=dead |archive-url=https://web.archive.org/web/20071203014025/http://www.newsfactor.com/story.xhtml?story_id=21764 |archive-date=3 December 2007 }}</ref><ref>{{cite news|first=Jennifer |last=Mears |title=Novell boosts its Linux desktop |date=13 March 2006 |publisher=Network World, Inc. |url=http://www.networkworld.com/news/2006/031306-novell-linux.html |work=Network World |access-date=19 November 2007 |url-status=dead |archive-url=https://web.archive.org/web/20071203000603/http://www.networkworld.com/news/2006/031306-novell-linux.html |archive-date= 3 December 2007 }}</ref> with [[Gartner]] warning in 2005 that the costs of migration may exceed the cost benefits of Linux.<ref>{{cite news |first = Andy |last = McCue |title = Gartner sounds desktop Linux warning |date = 9 September 2005 |publisher = CNET Networks, Inc. |url = http://news.zdnet.co.uk/software/0,1000000121,39217113,00.htm |work = silicon.com |access-date = 19 November 2007 |archive-date = 18 October 2012 |archive-url = https://web.archive.org/web/20121018023608/http://www.zdnet.co.uk/news/application-development/2005/09/09/gartner-sounds-desktop-linux-warning-39217113/ |url-status = dead }}</ref> Gartner reiterated the warning in 2008, predicting that "by 2013, a majority of Linux deployments will have no real software total cost of ownership (TCO) advantage over other operating systems."<ref name="ZDNet Gartner" /> However, in the Comes v. Microsoft lawsuit, Plaintiff's exhibit 2817<ref>{{Cite web |url=http://groklaw.net/pdf/Comes-2817.pdf |title=Plaintiff's exhibit 2817 |access-date=15 February 2014 |archive-date=12 January 2016 |archive-url=https://web.archive.org/web/20160112100827/http://groklaw.net/pdf/Comes-2817.pdf |url-status=live }}</ref> revealed that Microsoft successfully lobbied Gartner for changing their TCO model in favour of Microsoft in 1998. Organizations that have moved to Linux have disagreed with these warnings. Sterling Ball, CEO of [[Ernie Ball]], the world's leading maker of premium guitar strings and a 2003 Linux adopter, said of total cost of ownership arguments: "I think that's propaganda...What about the cost of dealing with a virus? We don't have 'em...There's no doubt that what I'm doing is cheaper to operate. The analyst guys can say whatever they want."<ref name="Becker2003">[http://arquivo.pt/wayback/20090707003009/http://news.cnet.com/2008-1082_3-5065859.html?tag=lh Rockin' on without Microsoft | Newsmakers | CNET News.com]</ref>

In the [[SCO-Linux controversies]], the [[SCO Group]] had alleged that [[UNIX]] source code donated by IBM was illegally incorporated into Linux. The threat that SCO might be able to legally assert ownership of Linux initially caused some potential Linux adopters to delay that move. The court cases bankrupted SCO in 2007 after it lost its four-year court battle over the ownership of the UNIX copyrights. SCO's case had hinged on showing that Linux included intellectual property that had been misappropriated from UNIX, but the case failed when the court discovered that [[Novell]] and not SCO was the rightful owner of the copyrights. During the legal process, it was revealed that SCO's claims about Linux were fraudulent and that SCO's internal source code audits had showed no evidence of infringement.<ref name="LinuxPlanet" /><ref name="Becker2003" /><ref name="Paul12Jan09">{{cite web |url = https://arstechnica.com/tech-policy/news/2009/01/sco-aims-to-reorganize-fight-on-with-corporate-garage-sale.ars |title = SCO aims to reorganize, fight on with corporate garage sale |access-date = 19 March 2009 |last = Paul |first = Ryan |date = January 2009 |archive-date = 21 March 2009 |archive-url = https://web.archive.org/web/20090321125014/http://arstechnica.com/tech-policy/news/2009/01/sco-aims-to-reorganize-fight-on-with-corporate-garage-sale.ars |url-status = live }}</ref>

A rival operating system vendor, [[Green Hills Software]], has called the [[open source]] paradigm of Linux "fundamentally insecure".<ref>{{cite news |first = Alexander |last = Wolfe |title = Green Hills calls Linux 'insecure' for defense |date = 4 September 2004 |publisher = CMP Media LLC |url = http://www.eetimes.com/article/showArticle.jhtml?articleId=18900949 |work = EE Times |access-date = 19 November 2007 |archive-url = https://web.archive.org/web/20110809020713/http://www.eetimes.com/electronics-news/4048562/Green-Hills-calls-Linux-insecure-for-defense |archive-date = 9 August 2011 |url-status = dead }}</ref>

The US Army does not agree that Linux is a security problem. Brigadier General Nick Justice, the Deputy Program Officer for the Army's Program Executive Office, Command, Control and Communications Tactical (PEO C3T), said in April 2007:<ref name="DoD" />

{{blockquote|Our job is to provide accurate and timely information to the soldier in the field so they can perform their mission. Open source software is part of the integrated network fabric which connects and enables our command and control system to work effectively, as people's lives depend on it.

When we rolled into Baghdad, we did it using open source. It may come as a surprise to many of you, but the U.S. Army is "the" single largest install base for Red Hat Linux. I'm their largest customer.<ref name="DoD">{{cite web|url=http://www.linux.com/feed/61302 |title=Open Technology within DoD, Intel Systems |access-date=18 October 2008 |website=Linux.com |date=April 2007 |url-status=dead |archive-url=https://web.archive.org/web/20080706083117/http://www.linux.com/feed/61302 |archive-date=6 July 2008 }}</ref> }}

===Netbooks===
{{Main|Netbook#Linux|l1 = Netbook (Linux)}}
In 2008, [[Gartner]] analysts predicted that mobile devices like Netbooks with Linux could potentially break the dominance of [[Microsoft]]'s Windows as operating system provider, as the netbook concept focuses on OS-agnostic applications built as Web applications and browsing.<ref>{{cite web |url=http://www.computerworld.com/s/article/9076698/Windows_is_collapsing_Gartner_analysts_warn |title=Windows is 'collapsing,' Gartner analysts warn – The researchers damn Windows in current form, urge radical changes |first=Gregg |last=Keizer |date=10 April 2008 |access-date=3 October 2013 |publisher=[[Computer World]] |quote=''And increasingly, users work with "OS-agnostic applications," the two analysts said in their presentation. [...] Microsoft [...]it's going to have trouble competing with Web applications and small, specialized devices.'' |archive-date=14 July 2014 |archive-url=https://web.archive.org/web/20140714134327/http://www.computerworld.com/s/article/9076698/Windows_is_collapsing_Gartner_analysts_warn |url-status=live }}</ref> Until 2008 the netbook market was dominated by Linux-powered devices; this changed in 2009 after [[Microsoft Windows XP|Windows XP]] became available as option.<ref name=itwire>{{cite web |url=http://www.itwire.com/it-industry-news/market/22362-windows-crushing-linux-in-netbook-market-acer |title=Windows crushing Linux in netbook market: Acer |first=Stan |last=Beer |publisher=itwire.com |date=17 December 2008 |access-date=3 October 2013 |quote=[…] Acer and other leading vendors have confirmed that Microsoft Windows XP now dominates the emerging sub-notebook market with more than 90% of new sales. Meanwhile, Linux, which had the netbooks market to itself until April this year, has seen its share of the space eroded to less than 10% in a breath-taking decline. |archive-date=27 January 2021 |archive-url=https://web.archive.org/web/20210127125334/https://www.itwire.com/it-industry-news/market/22362-windows-crushing-linux-in-netbook-market-acer |url-status=live }}</ref> One of the reasons given was that many customers returned Linux-based netbooks as they were still expecting a Windows-like environment, despite the netbook vision: a web-surfing and web-application device.<ref>{{cite web |url=http://www.informationweek.com/windows/operating-systems/microsoft-96-of-netbooks-run-windows/216402927 |quote=''[…] United Kingdom's Car phone Warehouse dropped Linux-based netbooks after seeing return rates as high as 20%.'' |title=Microsoft: 96% Of Netbooks Run Windows – Gains in PC market's hottest category come at the expense of Linux, Redmond says. |first=Paul |last=McDougall |publisher=InformationWeek |date=6 April 2009 |access-date=3 October 2013 |archive-date=12 October 2013 |archive-url=https://web.archive.org/web/20131012064500/http://www.informationweek.com/windows/operating-systems/microsoft-96-of-netbooks-run-windows/216402927 |url-status=live }}</ref><ref>[http://blog.laptopmag.com/ubuntu-confirms-linux-netbook-returns-higher-than-anticpated Ubuntu Confirms Linux Netbook Returns Higher than Anticipated] {{Webarchive|url=https://web.archive.org/web/20150712193841/http://blog.laptopmag.com/ubuntu-confirms-linux-netbook-returns-higher-than-anticpated |date=12 July 2015 }} on Laptopmag.com (Joanna Stern, 6 October 2008)</ref>

===Thin clients===
{{Main|Thin client|l1 = Web thin client}}
{{Expand section|date = September 2013}}
In 2011, [[Google]] introduced the [[Chromebook]], a [[thin client]] running the Linux-based [[ChromeOS]], with the ability to use [[web applications]] and [[remote desktop]] in to other computers running Windows, Mac OS X, a traditional Linux distribution or ChromeOS, using [[Chrome Remote Desktop]]. In 2012 Google and Samsung introduced the first version of the Chromebox, a small-form-factor desktop equivalent to the Chromebook.

By 2013, Chromebooks had captured 20–25% of the sub-$300 US laptop market.<ref>{{cite web|url = https://www.telegraph.co.uk/technology/google/10173494/Google-Chromebook-sales-soar-in-face-of-PC-decline.html|title = Google Chromebook sales soar in face of PC decline|date = 11 July 2013|access-date = 3 September 2013|website = [[Daily Telegraph]]|last = Williams|first = Rhiannon|archive-date = 25 September 2013|archive-url = https://web.archive.org/web/20130925104825/http://www.telegraph.co.uk/technology/google/10173494/Google-Chromebook-sales-soar-in-face-of-PC-decline.html|url-status = live}}</ref>

===Mobile devices===
[[File:Samsung Galaxy Note series 2.jpg|thumb|Android smartphones]]

''Note: The term "mobile devices" in the computing context refers to cellphones and tablets; ''{{asof|2013|lc = y}}'', the term does not include regular laptops, despite the fact that they have always been designed to be mobile.''

[[Android (operating system)|Android]], which is based on Linux and is open source, is the most popular mobile platform. During the second quarter of 2013, 79.3% of smartphones sold worldwide were running Android.<ref>{{cite web| url = https://techcrunch.com/2013/08/07/android-nears-80-market-share-in-global-smartphone-shipments-as-ios-and-blackberry-share-slides-per-idc/| title = Android Nears 80% Market Share in Global Smartphone Shipments, As iOS And BlackBerry Share Slides, Per IDC| date = 7 August 2013| access-date = 25 June 2017| archive-date = 5 July 2017| archive-url = https://web.archive.org/web/20170705111948/https://techcrunch.com/2013/08/07/android-nears-80-market-share-in-global-smartphone-shipments-as-ios-and-blackberry-share-slides-per-idc/| url-status = live}}</ref> Android [[Tablet computer|tablets]] are also available.

==== Discontinued Linux-based mobile operating systems ====
[[Firefox OS]] was another open source Linux-based mobile operating system, which has now been discontinued.

Nokia previously produced some phones running a variant of Linux (e.g. the [[Nokia N900]]), but in 2013, Nokia's handset division was bought by [[Microsoft]].

===Other embedded systems with graphical user interface===
[[Smartphone]]s are gradually replacing these kinds of embedded devices, but they still exist. An example are the [[Portable media player]]s. Some of the OEM firmware is Linux based. A community-driven fully free and open-source project is [[Rockbox]].{{Citation needed|date=September 2013}}

[[In-vehicle infotainment]] hardware usually involves some kind of display, either built into the [[Dashboard]] or additional displays. The [[GENIVI Alliance]], now called COVESA (Connected Vehicle Systems Alliance), works on a Linux-based open platform to run the IVI. It may have an interface to some values delivered by the [[Engine control unit]] but is albeit completely separate system. There will be a special variant of [[Tizen]] for IVI, different for the Tizen for smartphones in several regards.{{Citation needed|date=September 2013}}

==Hardware platforms without graphical user interface==

===Embedded systems without graphical user interface===
{{See also|Linux-powered device}}
Linux is often used in various single- or multi-purpose [[computer appliance]]s and [[embedded systems]].<ref>{{cite web|url=http://linuxdevices.com/articles/AT4936596231.html|title=The Linux Devices Showcase|archive-url=https://web.archive.org/web/20090312084819/http://linuxdevices.com/articles/AT4936596231.html|archive-date=12 March 2009 }}</ref>

[[Customer-premises equipment]] are a group of devices that are embedded and have no graphical user interface in the common sense. Some are remotely operated via [[Secure Shell]] or via some Web-based user interface running on some [[Comparison of web server software|lightweight web server software]]. Most of the OEM firmware is based on the Linux kernel and other free and open-source software, e.g. [[Das U-Boot]] and [[Busybox]]. There are also a couple of community driven projects, e.g. [[OpenWrt]].{{Citation needed|date=September 2013}}

Smaller scale embedded [[network-attached storage]]-devices are also mostly Linux-driven.{{Citation needed|date=September 2013}}

===Servers===
{{further|Linux#Servers, mainframes and supercomputers}}

Linux became popular in the Internet [[Server (computing)|server]] market particularly due to the [[LAMP (software bundle)|LAMP]] software bundle. In September 2008 [[Steve Ballmer]] (Microsoft CEO) claimed 60% of servers run Linux and 40% run [[Windows Server]].<ref name="PC World September 2008">{{cite web|url = https://www.pcworld.com/article/151568/ballmer_still_searching_for_an_answer_to_google.html|title = Ballmer Still Searching for an Answer to Google|access-date = 4 June 2009|last = Niccolai|first = James|date = September 2008}}{{Dead link|date=February 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> According to IDC's report covering Q2 2013, Linux was up to 23.2% of worldwide server revenue<ref>{{cite web | url=https://arstechnica.com/information-technology/2013/10/linux-is-king-nix-of-the-data-center-but-unix-may-live-on-forever/ | title=Linux is king *nix of the data center—but Unix may live on forever | access-date=1 November 2013 | last=Brodkin | first=Jon | date=22 October 2013 | archive-date=2 December 2017 | archive-url=https://web.archive.org/web/20171202215826/https://arstechnica.com/information-technology/2013/10/linux-is-king-nix-of-the-data-center-but-unix-may-live-on-forever/ | url-status=live }}</ref> although this does compensate for the potential price disparity between Linux and non-Linux servers. In May 2014, W3Techs estimated that 67.5% of the top 10 million (according to Alexa) websites run some form of Unix, and Linux is used by at least 57.2% of all those websites which use Unix.<ref>{{cite web | url=http://w3techs.com/technologies/details/os-unix/all/all | title=Usage Statistics and Market Share of Unix for Websites, May 2014 | work=W3Techs | date=May 2014 | access-date=14 May 2014 | archive-date=24 February 2023 | archive-url=https://web.archive.org/web/20230224001711/https://w3techs.com/technologies/details/os-unix | url-status=live }}</ref>

====Web servers====
Linux-based [[solution stack]]s come with all the [[Free and open-source software#Advantages and benefits of free and open-source software|general advantages and benefits of free and open-source software]]. Some more commonly known examples are:
* [[LAMP (software bundle)|LAMP]]
* [[MEAN (solution stack)|MEAN stack]]

According to the [[Netcraft]], {{asof|2019|lc=1}}, [[nginx]] had the highest market share.<ref>Netcraft, [http://news.netcraft.com/archives/category/web-server-survey Survey] {{Webarchive|url=https://web.archive.org/web/20170909224237/https://news.netcraft.com/archives/category/web-server-survey/ |date=9 September 2017 }} July 2021</ref>

====LDAP servers====
{{Main|Lightweight Directory Access Protocol}}
There are various freely available implementations of [[List of LDAP software#SERVER|LDAP servers]]. Additionally, [[Univention Corporate Server]], as an integrated management system based on Debian, supports the functions provided by Microsoft [[Active Directory]] for the administration of computers running Microsoft Windows.

====Routers====
Free routing software available for Linux includes [[Bird Internet routing daemon|BIRD]], [[B.A.T.M.A.N.]], [[FRRouting]], [[Quagga (software)|Quagga]] and [[XORP]]. Whether on [[Customer-premises equipment]], on [[Personal computer hardware]] or on [[Server (computing)|server]]-hardware, the mainline Linux kernel or an adapted highly optimized Linux kernel is capable of doing [[routing]] at rates that are limited by the hardware bus throughput.

===Supercomputers===
{{Main|Supercomputer operating system}}
Linux is the most popular operating system among [[supercomputer]]s due to the [[free and open-source software#Advantages and benefits of free and open-source software|general advantages and benefits of free and open-source software]], like superior performance, flexibility, speed and lower costs. In November 2008 Linux held an 87.8 percent share of the world's top 500 supercomputers.<ref>[http://www.top500.org/stats/list/34/osfam Operating system Family share for 11/2009 | TOP500 Supercomputing Sites] {{webarchive |url=https://web.archive.org/web/20091119022533/http://www.top500.org/stats/list/34/osfam |date=19 November 2009 }}</ref><ref>[[:Image:Top500 OS.png]]</ref><ref name="CW23Nov09">{{cite web|url= http://blogs.computerworld.com/linux_it_doesnt_get_any_faster |title=Linux: It doesn't get any faster| access-date=24 June 2009| last=Vaughn-Nichols| first=Steven J.| date=June 2009| archive-url=https://web.archive.org/web/20090626043246/http://blogs.computerworld.com/linux_it_doesnt_get_any_faster| archive-date=26 June 2009| url-status=dead}}</ref><ref name="PT13Jun08">{{cite web |url=http://practical-tech.com/infrastructure/linux-computer-smashes-petaflop-supercomputer-barrier/ |title=Linux Computer Smashes Petaflop Supercomputer Barrier |access-date=15 October 2009 |website=Practical Technology |date=June 2009 |archive-date=21 November 2009 |archive-url=https://web.archive.org/web/20091121035112/http://practical-tech.com/infrastructure/linux-computer-smashes-petaflop-supercomputer-barrier/ |url-status=live }}</ref><ref name="InTech01Sep03">{{cite web|last=Strothman |first=Jim |title=Linux elbows into super-computer turf |url=http://www.isa.org/InTechTemplate.cfm?Section=InTech&template=/ContentManagement/ContentDisplay.cfm&ContentID=29241 |access-date=15 October 2009 |date=September 2003 |url-status=dead |archive-date=5 August 2005 |archive-url=https://web.archive.org/web/20050805073753/http://www.isa.org/InTechTemplate.cfm?Section=InTech&template=%2FContentManagement%2FContentDisplay.cfm&ContentID=29241}}</ref>

Since June 2018, every computer on the [[TOP500]] list ran some version of Linux.<ref name=top500stats>{{cite web |title=List Statistics |website=TOP500 |url=http://www.top500.org/statistics/list/ |access-date=18 October 2022 |archive-date=18 July 2018 |archive-url=https://web.archive.org/web/20180718013118/https://www.top500.org/statistics/list/ |url-status=live }}</ref>

In January 2010, Weiwu Hu, chief architect of the [[Loongson]] family of CPUs at the Institute of Computing Technology, which is part of the [[Chinese Academy of Sciences]], confirmed that the new Dawning 6000 supercomputer will use Chinese-made [[Loongson|Loongson processors]] and will run Linux as its operating system. The most recent supercomputer the organization built, the Dawning 5000a, which was first run in 2008, used AMD chips and ran [[Windows HPC Server 2008]].<ref name="Mims19Jan10">{{cite web |url=http://www.technologyreview.com/computing/24374/?a=f |title=China Details Homemade Supercomputer Plans |access-date=20 January 2010 |last=Mims |first=Christopher |date=January 2010 |archive-date=21 January 2010 |archive-url=https://web.archive.org/web/20100121035857/http://www.technologyreview.com/computing/24374/?a=f |url-status=live }}</ref>

==Advocacy==
Many organizations advocate for Linux adoption. The foremost of these is the [[Linux Foundation]] which hosts and sponsors the key kernel developers, manages the Linux trademark, manages the Open Source Developer Travel Fund, provides legal aid to open source developers and companies through the Linux Legal Defense Fund, sponsors kernel.org and also hosts the Patent Commons Project.

The [[International Free and Open Source Software Foundation]] (iFOSSF) is a nonprofit organization based in [[Michigan]], USA dedicated to accelerating and promoting the adoption of FOSS worldwide through research and civil society partnership networks.

The [[Open Invention Network]] was formed to protect vendors and customers from patent royalty fees while using [[Open-source software|OSS]].

Other advocates for Linux include:
* [[IBM]] through its Linux Marketing Strategy
* [[Linux User Group]]s
* [[Asian Open Source Centre]] (AsiaOSC)
* [[Brazil|The Brazilian government]], under president [[Luiz Inácio Lula da Silva]]<ref>{{cite web|title=A lei é digitalizar|url=http://www.softwarelivre.gov.br|publisher=softwarelivre.gov.br|access-date=23 March 2008|archive-url=https://web.archive.org/web/20080512082208/http://www.softwarelivre.gov.br/|archive-date=12 May 2008|url-status=dead}} {{in lang|pt}}</ref>
* [[Software Livre Brasil]], a Brazilian organization promoting Linux adoption in schools, public departments, commerce, industry and personal desktops.<ref>{{cite web|title=Portal do Projeto Software Livre Brasil|url=http://www.softwarelivre.org/|access-date=14 April 2012|archive-date=13 April 2012|archive-url=https://web.archive.org/web/20120413111859/http://softwarelivre.org/|url-status=live}} {{in lang|pt}}</ref>
* FOSS: Free and Open Source Software Foundations of India and China.{{Citation needed|date=May 2011}}

==History==
{{Main|History of Linux}}
[[Gartner]] claimed that Linux-powered personal computers accounted for 4% of unit sales in 2008.<ref name="YahooFinance">
{{cite web|url = http://www.investors.com/NewsAndAnalysis/Article/455992/200808081544/Netbooks-A-Linux-Stronghold-.aspx|title = Netbooks A Linux Stronghold?|access-date = 12 August 2008|last = Womack|first = Brian|date = August 2008|url-status = dead|archive-url = https://archive.today/20130126093338/http://www.investors.com/NewsAndAnalysis/Article/455992/200808081544/Netbooks-A-Linux-Stronghold-.aspx|archive-date = 26 January 2013|df = dmy-all}}</ref> However, it is common for users to install Linux in addition to (as a [[dual boot]] arrangement) or in place of a factory-installed [[Microsoft Windows]] operating system.<ref name="Siu28Jul06" />{{unreliable source?|date=December 2016}}

===Timeline===

* 1983 (September): [[GNU Project]] announced publicly
* 1991 (September): First version of the [[Linux kernel]] released to the Internet
* mid-1990s: Linux runs on cluster computers at NASA and elsewhere<ref name="security">{{cite book |title=Practical UNIX and Internet Security |first1=Simson |last1=Garfinkel |first2=Gene |last2=Spafford |first3=Alan |last3=Schwartz |publisher=O'Reilly |year=2003 |pages=21}}</ref>
* late 1990s: [[Dell]], [[IBM]] and [[Hewlett-Packard]] offer commercial support for Linux on their hardware; [[Red Hat]] and [[VA Linux]] have [[initial public offerings]]{{r|security}}
* 1999: [[EmperorLinux]] started shipping specially configured laptops running modified [[Linux distribution]]s to ensure usability<ref name="Why">{{cite web|url = http://www.emperorlinux.com/why/|title = Why?|access-date = 27 May 2009|website = EmperorLinux|year = 2009|archive-date = 24 May 2009|archive-url = https://web.archive.org/web/20090524153637/http://www.emperorlinux.com/why/|url-status = live}}</ref>
* 2001 (second quarter): Linux server unit shipments recorded a 15% annual growth rate<ref name="www.idc.com">{{cite web|url=http://www.idc.com/getdoc.jsp?containerId=fr2004_11_02_093312 |access-date=8 August 2005 }}{{dead link|date=February 2017|bot=medic}}{{cbignore|bot=medic}}</ref>
* 2004: Linux shipped on approximately 50% of the worldwide [[server blade]] units, and 20% of all [[Rack mount|rack-optimized]] servers<ref name="www.idc.com" />
* 2005: [[System76]], a Linux-only computer OEM, starts selling Ubuntu pre-installed on laptops and desktops.<ref>{{cite web|url=https://www.facebook.com/system76?sk=info|title=System76|work=Facebook|access-date=19 February 2015|archive-date=12 January 2016|archive-url=https://web.archive.org/web/20160112100827/https://www.facebook.com/system76?sk=info|url-status=live}}</ref>

====2007====
* [[Dell]] announced it would ship select models with [[Ubuntu (operating system)|Ubuntu]] Linux pre-installed<ref>{{cite news | url=http://news.bbc.co.uk/2/hi/business/6610901.stm | work=BBC News | title=Dell to use Ubuntu on Linux PCs | date=1 May 2007 | access-date=7 May 2010 | archive-date=27 August 2009 | archive-url=https://web.archive.org/web/20090827191257/http://news.bbc.co.uk/2/hi/business/6610901.stm | url-status=live }}</ref>
* [[ZaReason]] is founded as a Linux only hardware OEM.<ref name="ZR12Sep10">{{cite web|url = http://zareason.com/shop/Our-Story.html|title = Our Story|access-date =14 October 2011|website= ZaReason|date=October 2011|archive-url = https://web.archive.org/web/20100912185324/http://zareason.com/shop/Our-Story.html |archive-date = 12 September 2010}}</ref>
* [[Lenovo]] announced it would ship select models with [[SUSE Linux Enterprise Desktop]] pre-installed<ref>[http://news.lenovo.co.uk/news.nsf/0/DABDA91E954025DD802573360052D0CB?open Lenovo – News – Lenovo, bilgisayarlarını Linux ile donatacak – DEFAULT] {{webarchive|url=https://web.archive.org/web/20070928172129/http://news.lenovo.co.uk/news.nsf/0/DABDA91E954025DD802573360052D0CB?open |date=28 September 2007 }}</ref>
* [[Hewlett-Packard|HP]] announced that it would begin shipping computers preinstalled with [[Red Hat Enterprise Linux]] in Australia<ref>{{cite web |url=http://apcmag.com/7034/hp_launches_red_hat_linux_pc |title=HP launches RedHat Linux desktop PC |website=APC Magazine |date=30 August 2007 |first=Dan |last=Warne |archive-url=https://web.archive.org/web/20070902190853/http://apcmag.com/7034/hp_launches_red_hat_linux_pc |archive-date=2 September 2007}}</ref>
* [[ASUS]] launched the Linux-based [[ASUS Eee PC]]<ref>[http://www.itwire.com/content/view/15922/1141/ iTWire – The top Linux/FOSS events of 2007] {{webarchive|url=https://web.archive.org/web/20080117033936/http://www.itwire.com/content/view/15922/1141/ |date=17 January 2008 }}</ref>

====2008====
* Dell announced it would begin shipping Ubuntu-based computers to Canada and Latin America.<ref>{{Cite web |url=http://news.softpedia.com/news/Dell-Will-Ship-Ubuntu-in-Canada-and-Latin-America-79296.shtml |title=Dell Will Ship Ubuntu in Canada and Latin America – Inspiron 1525n will ship with Ubuntu 7.10 – Softpedia |access-date=22 February 2008 |archive-date=28 May 2016 |archive-url=https://web.archive.org/web/20160528201135/http://news.softpedia.com/news/Dell-Will-Ship-Ubuntu-in-Canada-and-Latin-America-79296.shtml |url-status=live }}</ref>
* Dell began shipping systems with [[Ubuntu]] pre-installed in China.<ref>{{Cite web |url=http://news.softpedia.com/news/Dell-Is-Shipping-Systems-With-Ubuntu-Pre-installed-In-China-80141.shtml |title=Dell Is Shipping Systems with Ubuntu Pre-installed, in China – ... due to the high number of requests from the customers – Softpedia |access-date=7 March 2008 |archive-date=28 May 2016 |archive-url=https://web.archive.org/web/20160528203751/http://news.softpedia.com/news/Dell-Is-Shipping-Systems-With-Ubuntu-Pre-installed-In-China-80141.shtml |url-status=live }}</ref><ref>[http://direct2dell.com/one2one/archive/2008/03/03/48393.aspx Ubuntu 7.10 Now Available to Customers in China on the Inspiron 530 Desktop] {{webarchive |url=https://web.archive.org/web/20081013073534/http://direct2dell.com/one2one/archive/2008/03/03/48393.aspx |date=13 October 2008 }}</ref>
* [[Acer Inc.|Acer]] launched the Linux-based [[Acer Aspire One]].<ref>[https://web.archive.org/web/20080605121333/http://www.vnunet.com/vnunet/news/2218172/acer-pushes-linux-hard – Acer bets big on Linux]</ref>
* In June 2008, the Electronics Corporation of Tamil Nadu (ELCOT), a bulk computer buyer for students in the [[India]]n state of [[Tamil Nadu]], decided to switch entirely to supplying Linux after Microsoft attempted to use its monopoly position to sell the organization Windows bundled with [[Microsoft Office]]. ELCOT declined the offer stating "Any such bundling could result in serious exploitation of the consumer."<ref name="KingmanJune2008">{{cite web|url=http://www.linux-watch.com/news/NS6504473525.html |title=Microsoft tactics push India toward Linux |access-date=4 July 2008 |last=Kingman |first=Henry |date=June 2008 }}{{dead link|date=April 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
* In August 2008, [[IBM]] cited market disillusionment with [[Microsoft Vista]] in announcing a new partnership arrangement with [[Red Hat]], [[Novell]] and [[Canonical Ltd.|Canonical]] to offer "Microsoft-free" personal computers with IBM application software, including [[Lotus Notes]] and [[IBM Lotus Symphony|Lotus Symphony]].<ref name="ArsTechnicaAug2008">{{cite web|url = https://arstechnica.com/open-source/news/2008/08/ibm-targets-microsoft-with-desktop-linux-initiative.ars|title = IBM targets Microsoft with desktop Linux initiative|access-date = 18 March 2009|last = Paul|first = Ryan|date = August 2008|archive-date = 31 March 2009|archive-url = https://web.archive.org/web/20090331213416/http://arstechnica.com/open-source/news/2008/08/ibm-targets-microsoft-with-desktop-linux-initiative.ars|url-status = live}}</ref>

====2009====
* In January 2009, the [[New York Times]] stated: "More than 10 million people are estimated to run Ubuntu today".<ref name="NYT10Jan09">{{cite news|url = https://www.nytimes.com/2009/01/11/business/11ubuntu.html?_r=2&th&emc=th|title = A Software Populist Who Doesn't Do Windows|access-date = 22 February 2009|last = Vance|first = Ashlee|date = January 2009|work = The New York Times|archive-date = 12 May 2013|archive-url = https://web.archive.org/web/20130512232859/http://www.nytimes.com/2009/01/11/business/11ubuntu.html?_r=2&th&emc=th|url-status = live}}</ref>
* In mid-2009, [[Asus]], as part of its ''It's better with Windows'' campaign, stopped offering Linux, for which they received strong criticism. The company claimed that competition from other netbook makers drove them to offer only [[Windows XP]]. Writing in May 2010 [[Computerworld]] columnist Steven J. Vaughan-Nichols said "I'm sure that the real reason is Microsoft has pressured Asus into abandoning Linux. On ASUS' site, you'll now see the slogan 'ASUS recommends Windows 7' proudly shown. Never mind that, while Windows 7 is a good operating system, Windows 7 is awful on netbooks."<ref name="ASUSFAIRWEATHER">{{cite web |url = http://popey.com/Asus_The_Fair_Weather_Friend |title = Asus, a fair weather friend |access-date = 15 May 2009 |last = Pope |first = Alan |date = May 2009 |url-status = dead |archive-url = https://web.archive.org/web/20090518153752/http://popey.com/Asus_The_Fair_Weather_Friend |archive-date = 18 May 2009 }}</ref><ref name="IBWW">{{cite web|url = http://itsbetterwithwindows.com/|title = It's Better With Windows – Here's Why|access-date = 18 May 2009|date = May 2009|archive-date = 20 February 2009|archive-url = https://web.archive.org/web/20090220033129/http://itsbetterwithwindows.com/|url-status = live}}</ref><ref name="Gedda27May09">{{cite web|url = http://www.computerworld.com.au/article/304693/has_asus_all_given_up_linux?fp=16&fpid=1|title = Has ASUS all but given up on Linux?|access-date = 30 May 2009|last = Gedda|first = Rodney|date = May 2009|archive-date = 30 May 2009|archive-url = https://web.archive.org/web/20090530050944/http://www.computerworld.com.au/article/304693/has_asus_all_given_up_linux?fp=16&fpid=1|url-status = live}}</ref><ref name="eweekeurope01Jul09">{{cite web|url = http://www.eweekeurope.co.uk/news/asus-dumps-linux-from-the-eee-1270|title = Asus Dumps Linux From The Eee|access-date = 2 July 2009|last = Judge|first = Peter|date = July 2009|url-status = dead|archive-url = https://web.archive.org/web/20090705114425/http://www.eweekeurope.co.uk/news/asus-dumps-linux-from-the-eee-1270|archive-date = 5 July 2009|df = dmy-all}}</ref><ref name="VaughanNichols21May10">{{cite web|url = http://blogs.computerworld.com/16161/has_asus_abandoned_netbook_linux|title = Has ASUS abandoned netbook Linux?|access-date = 14 May 2010|last = Vaughan-Nichols|first = Steven J.|date = May 2010|url-status = dead|archive-url = https://web.archive.org/web/20100523054007/http://blogs.computerworld.com/16161/has_asus_abandoned_netbook_linux|archive-date = 23 May 2010|df = dmy-all}}</ref>
* In May 2009, [[Fedora Linux|Fedora]] developer Jef Spaleta estimated on the basis of IP addresses of update downloads and statistics from the voluntary user hardware registration service Smolt that there are 16 million Fedora systems in use.<ref name="Spaleta19May09">{{cite web|url=http://jspaleta.livejournal.com/42464.html |title=Giving accurate Fedora client counting the 115% effort it deserves. |access-date=8 June 2010 |last=Spaleta |first=Jef |date=May 2009 |url-status=dead |archive-url=https://web.archive.org/web/20110819035957/http://jspaleta.livejournal.com/42464.html |archive-date=19 August 2011 }}</ref> No effort was made to estimate how much the Fedora installed base overlaps with other Linux distributions (enthusiasts installing many distributions on the same system).
* In June 2009, [[ZDNet]] reported "Worldwide, there are 13 million active Ubuntu users with use growing faster than any other distribution."<ref name="Dawson17Jun09">{{cite web|url = http://education.zdnet.com/?p=2709|title = Ubuntu a minor player? Not outside the States|access-date = 18 June 2009|last = Dawson|first = Christopher|date = June 2009|archive-date = 24 December 2018|archive-url = https://web.archive.org/web/20181224235831/https://www.zdnet.com/blog/education/?p=2709%20|url-status = live}}</ref>

====2010====
* In April 2010, Chris Kenyon, vice president for OEM at [[Canonical Ltd.]], estimated that there were 12 million Ubuntu users.<ref name="Kerner07Apr10">{{cite web|url = http://www.linuxplanet.com/linuxplanet/reports/7032/1/|title = Ubuntu Claims 12 Million Users as Lucid Linux Desktop Nears|access-date = 7 April 2010|last = Kerner|first = Michael|date = April 2010|archive-date = 10 April 2010|archive-url = https://web.archive.org/web/20100410164921/http://www.linuxplanet.com/linuxplanet/reports/7032/1|url-status = dead}}</ref>
* In June 2010, a [[Quebec Superior Court]] Judge Denis Jacques ruled that the provincial government broke the law when it spent [[Canadian dollar|Cdn$]]720,000, starting in the fall of 2006 to migrate 800 government workstations to Microsoft Windows Vista and Office 2007 without carrying out a "serious and documented search" for alternatives. The search for alternatives was legally required for any expenditures over Cdn$25,000. The court case was brought by ''Savoir Faire Linux'', a small [[Montreal]]-based company that had hoped to bid Linux software to replace the government's aging Windows XP. The judge dismissed the government's contention that Microsoft software was chosen because employees were already familiar with Windows and that switching to a different operating system would have cost more.<ref name="CBC03Jun10">{{cite news|url = http://www.cbc.ca/technology/story/2010/06/03/quebec-microsoft-lawsuit.html|title = Quebec broke law in buying Microsoft software|access-date = 3 June 2010|last = Nowak|first = Peter|date = June 2010|work = CBC News|archive-date = 5 June 2010|archive-url = https://web.archive.org/web/20100605034513/http://www.cbc.ca/technology/story/2010/06/03/quebec-microsoft-lawsuit.html|url-status = live}}</ref>
* In October 2010, a statistics company stated that [[Android (operating system)|Android]], Google's version of Linux for smartphones (and tablets), had become the most popular operating system among new buyers.<ref>{{cite web |last=Hachman |first=Mark |url=https://www.pcmag.com/article2/0,2817,2370259,00.asp |title=Nielsen: Android Is Most Popular Smartphone OS | News & Opinion |publisher=PCMag.com |date=5 October 2010 |access-date=12 August 2013 |archive-date=20 September 2013 |archive-url=https://web.archive.org/web/20130920020641/http://www.pcmag.com/article2/0,2817,2370259,00.asp |url-status=live }}</ref>

====2012====
* In November 2012, Top500.org's November 2012 list has all Top 10 Supercomputers as running a distribution of Linux as their Operating System.<ref>{{cite web|url=http://top500.org/lists/2012/11/|title=November 2012|access-date=19 February 2015|archive-date=24 December 2013|archive-url=https://web.archive.org/web/20131224213924/http://www.top500.org/lists/2012/11/|url-status=live}}</ref>

====2013====
* In February 2013, Dice and the Linux Foundation released a survey that showed Linux skills in high demand among employers.<ref>{{cite web|url=https://www.theregister.co.uk/2013/02/20/dice_linux_jobs_survey/|title=Survey: Bosses are DESPERATE and GAGGING for Linux skills|website=[[The Register]]|access-date=19 February 2015|archive-date=20 February 2015|archive-url=https://web.archive.org/web/20150220010253/http://www.theregister.co.uk/2013/02/20/dice_linux_jobs_survey/|url-status=live}}</ref>
* [[Valve Corporation|Valve]] announces its Linux-based [[SteamOS]] for [[video game console]]s.
* Supercomputers, Japan's bullet trains, traffic control, Toyota [[In car entertainment|IVI]], [[NYSE]], CERN, FAA air traffic control, nuclear submarines and top websites all use Linux.<ref name=powerful>{{cite news|url=http://efytimes.com/e1/fullnews.asp?edid=120870|title=9 Powerful Things Powered By Linux!|access-date=1 May 2014|date=8 November 2013|archive-url=https://web.archive.org/web/20140705031621/http://www.efytimes.com/e1/fullnews.asp?edid=120870|archive-date=5 July 2014|url-status=dead}}</ref>
* In December 2013, the city of [[Munich]] announced that it successfully migrated 12,000 of its 15,000 computers to [[LiMux]] Linux and that the savings in 2013 alone were about 10 million euros.<ref name=Standard-Munich>{{cite news|title=Projekt "Limux" in München: Umstieg auf Linux abgeschlossen|url=http://derstandard.at/1385171067350/Projekt-Limux-in-Muenchen-Umstieg-auf-Linux-abgeschlossen|access-date=12 February 2014|newspaper=Der Standard|date=14 December 2013|archive-date=19 February 2014|archive-url=https://web.archive.org/web/20140219020935/http://derstandard.at/1385171067350/Projekt-Limux-in-Muenchen-Umstieg-auf-Linux-abgeschlossen|url-status=live}}</ref>

====2014====
* In September 2014, the Italian city of [[Turin]], the capital of [[Piedmont]], decided to switch to Linux.<ref name=Guerrini>{{cite web|last1=Guerrini|first1=Federico|title=City of Turin decides to ditch Windows XP for Ubuntu and €6m saving|website=[[ZDNet]]|url=http://www.zdnet.com/city-of-turin-decides-to-ditch-windows-xp-for-ubuntu-and-6m-saving-7000033482/|access-date=21 September 2014|archive-date=20 September 2014|archive-url=https://web.archive.org/web/20140920185422/http://www.zdnet.com/city-of-turin-decides-to-ditch-windows-xp-for-ubuntu-and-6m-saving-7000033482/|url-status=live}}</ref>
* In October 2014, the city of [[Gummersbach]] announced that their IT infrastructure now is based on 300 [[thin client]]s and 6 servers that run SuSe Linux.<ref name=standard-gummersbach>{{cite web|title=Gummersbach: Deutsche Stadt stellt auf Linux um|url=http://derstandard.at/2000006672327/Gummersbach-Deutsche-Stadt-stellt-Verwaltung-auf-Linux-um|access-date=11 October 2014|archive-date=11 October 2014|archive-url=https://web.archive.org/web/20141011000850/http://derstandard.at/2000006672327/Gummersbach-Deutsche-Stadt-stellt-Verwaltung-auf-Linux-um|url-status=live}}</ref>
* June 2014, France's [[National Gendarmerie]] has completed the migration of 65,000 to Linux "[[GendBuntu]]".<ref>{{cite web
| url=https://joinup.ec.europa.eu/community/osor/news/open-standards-and-itil-lead-open-source-frances-gendarmerie-tells-korean-ict-mi
| title='Open standards and ITIL lead to open source', France's Gendarmerie tells Korean ICT ministry
| author=Gijs Hillenius
| date=16 June 2014
| quote=The police force now has 65,000 PC workstations running Ubuntu Linux (version 12.04).
| access-date=1 September 2015
| archive-date=22 December 2015
| archive-url=https://web.archive.org/web/20151222085611/https://joinup.ec.europa.eu/community/osor/news/open-standards-and-itil-lead-open-source-frances-gendarmerie-tells-korean-ict-mi
| url-status=live
}}</ref>
* In November 2014 [[Purism (Company)|Purism]] was founded as an OEM Linux manufacturer.<ref name=":0">{{cite web |url=https://www.sos.wa.gov/corps/search_detail.aspx?ubi=603453485 |title=Registration Detail |author= |date= |website=Washington Secretary of State |access-date=2019-02-26 |archive-date=2 February 2017 |archive-url=https://web.archive.org/web/20170202082352/https://www.sos.wa.gov/corps/search_detail.aspx?ubi=603453485 |url-status=live }}</ref>

====2017====

* In November 2017, all 500 of the world's top supercomputers ran Linux.<ref>{{Cite news|url=https://www.zdnet.com/article/linux-totally-dominates-supercomputers/|title=Linux totally dominates supercomputers|last=Vaughan-Nichols|first=Steven J.|work=ZDNet|access-date=18 August 2018|language=en|archive-date=14 November 2017|archive-url=https://web.archive.org/web/20171114211600/http://www.zdnet.com/article/linux-totally-dominates-supercomputers/|url-status=live}}</ref>

====2018====

* In April 2018, Microsoft announced [[Azure Sphere]], a Linux-based operating system for [[Internet of things|Internet of Things]] applications.<ref>{{Cite news|title=Azure Sphere – Microsoft's Ambitious Plan To Own The Next-Generation IoT Devices|last=MSV|first=Janakiram|work=Forbes|url=https://www.forbes.com/sites/janakirammsv/2018/04/23/azure-sphere-microsofts-ambitious-plan-to-own-the-next-generation-iot-devices/#2f50708e5e64|access-date=18 August 2018|language=en|archive-date=5 July 2018|archive-url=https://web.archive.org/web/20180705121439/https://www.forbes.com/sites/janakirammsv/2018/04/23/azure-sphere-microsofts-ambitious-plan-to-own-the-next-generation-iot-devices/#2f50708e5e64|url-status=live}}</ref>
* In May 2018, pre-orders began for [[Atari VCS (2020 console)|Atari VCS]], a gaming console that is powered by the Linux kernel.<ref>{{Cite news|url=https://mashable.com/2018/05/30/atari-vcs-indiegogo-presales/#ps2R3v3zPPqg|title=You can pre-order the Atari VCS now, but it won't ship till 2019|last=Krol|first=Jake|work=Mashable|access-date=18 August 2018|language=en|archive-date=18 August 2018|archive-url=https://web.archive.org/web/20180818214637/https://mashable.com/2018/05/30/atari-vcs-indiegogo-presales/#ps2R3v3zPPqg|url-status=live}}</ref>

==== 2019 ====

* In May 2019, Microsoft announced Windows Subsystem for Linux 2, which will rely on a pre-installed Linux kernel built by Microsoft. This marks the first time that the Linux kernel has shipped with a Microsoft operating system.<ref>{{Cite web|url=https://www.zdnet.com/article/windows-10-is-getting-a-microsoft-built-linux-kernel/|title=Windows 10 is getting a Microsoft-built Linux kernel|last=Foley|first=Mary Jo|website=ZDNet|language=en|access-date=8 May 2019|archive-date=8 May 2019|archive-url=https://web.archive.org/web/20190508015242/https://www.zdnet.com/article/windows-10-is-getting-a-microsoft-built-linux-kernel/|url-status=live}}</ref>
*In May 2019, [[South Korea]] announced that it was looking to migrate its major government systems to Linux, due to the pending end of support for [[Windows 7]].<ref>{{Cite web |url=https://www.theinquirer.net/inquirer/news/3076048/south-korea-is-switching-to-linux-ahead-of-the-windows-7-shutdown|archive-url=https://web.archive.org/web/20190520132346/https://www.theinquirer.net/inquirer/news/3076048/south-korea-is-switching-to-linux-ahead-of-the-windows-7-shutdown|url-status=dead|archive-date=20 May 2019 |title=South Korea is switching to Linux ahead of the Windows 7 shutdown|last=Merriman|first=Chris |date=20 May 2019|website=[[The Inquirer]]|access-date=28 May 2019}}</ref>

==== 2020 ====
* In June 2020, [[Lenovo]] announced Linux certification for [[ThinkPad]] and [[ThinkStation]] portfolio products.<ref>{{cite web |title=Lenovo Brings Linux® Certification to ThinkPad and ThinkStation Workstation Portfolio, Easing Deployment for Developers & Data Scientists |url=https://news.lenovo.com/pressroom/press-releases/lenovo-brings-linux-certification-to-thinkpad-and-thinkstation-workstation-portfolio-easing-deployment-for-developers-data-scientists/ |website=Lenovo News Portal |access-date=16 November 2022 |archive-date=20 October 2022 |archive-url=https://web.archive.org/web/20221020025634/https://news.lenovo.com/pressroom/press-releases/lenovo-brings-linux-certification-to-thinkpad-and-thinkstation-workstation-portfolio-easing-deployment-for-developers-data-scientists/ |url-status=live }}</ref>

==== 2021 ====

* In January 2021, the government of the Argentinian province of [[Misiones]] announced that it had developed {{interlanguage link|GobMis GNU/Linux|es}}, a distribution based on the [[Devuan]] operating system, specially designed for government offices.<ref>{{Cite web|date=2021-01-26|title=Desarrollaron un sistema operativo seguro y gratuito especialmente para las computadoras del Gobierno de Misiones|website=Ministerio de Coordinación de Gabinete|language=es-ar|url=https://mcgg.misiones.gob.ar/desarrollaron-un-sistema-operativo-seguro-y-gratuito-especialmente-para-las-computadoras-del-gobierno-de-misiones/|access-date=2021-01-27|archive-date=9 September 2021|archive-url=https://web.archive.org/web/20210909202628/https://mcgg.misiones.gob.ar/desarrollaron-un-sistema-operativo-seguro-y-gratuito-especialmente-para-las-computadoras-del-gobierno-de-misiones/|url-status=live}}</ref>
* In February 2021 Linux was first used on [[Mars]] when NASA's [[Perseverance (rover)|Perseverance]] rover landed on 18 February.<ref>{{Cite web|first=Michael|last=Kan|date=2021-02-19|title=Linux Is Now on Mars, Thanks to NASA's Perseverance Rover|url=https://uk.pcmag.com/drones/131849/linux-is-now-on-mars-thanks-to-nasas-perseverance-rover|access-date=2021-02-20|website=PCMag UK|language=en-gb|archive-date=21 February 2021|archive-url=https://web.archive.org/web/20210221034129/https://uk.pcmag.com/drones/131849/linux-is-now-on-mars-thanks-to-nasas-perseverance-rover|url-status=live}}</ref>

==See also==
{{Portal|Linux|Free and open-source software}}

{{columns-list|colwidth=22em|
* [[Diffusion (business)]]
* [[Disruptive innovation]]
* [[History of free and open-source software]]
* [[Comparison of open-source and closed-source software]]
* [[OpenDocument adoption]]
* [[Technology acceptance model]]
* [[Technology life cycle]]
* [[Timeline of free and open-source software]]
}}

==References==
{{Reflist|30em}}

==External links==
* [http://marketshare.hitslink.com/report.aspx?qprid=2 O/S market share monthly estimations, based on internet traffic]
* [https://gs.statcounter.com/os-market-share Operating System Market Share Worldwide | StatCounter Global Stats]
* [https://web.archive.org/web/20060828024309/http://www.linuxworld.com.au/index.php/id;1855967602;fp;2;fpid;3 LinuxWorld: What's Driving Global Linux Adoption?]
* [https://web.archive.org/web/20070204235901/http://old.linux-foundation.org/dtl/DTL_Survey_Report_Nov2005.pdf OSDL Desktop Linux Client Survey]
* [https://web.archive.org/web/20071203022056/http://linuxmednews.org/linuxmednews/1090943082/index_html Canadian Provincial Medical Association To Use Open Source Platform For EMR Project]
* [https://web.archive.org/web/20091008103206/http://www.idc.com/getdoc.jsp?containerId=IDC_P7073 IDC: Latin America Linux Migration Trends 2005]
* [https://web.archive.org/web/20080508232933/http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=%2Fwww%2Fstory%2F08-04-2005%2F0004082258&EDATE= OSDL Claims Linux Making Major Gains in Global Retail Sector]
* [https://web.archive.org/web/20070703023503/http://www.datasync.com/~rogerspl/Advocacy-HOWTO.html Linux Advocacy mini-HOWTO]
* [https://lwn.net/2002/0509/ Measuring total cost of ownership]
* [http://news.zdnet.co.uk/software/0,1000000121,39379900,00.htm Gartner: Open source will quietly take over] {{Webarchive|url=https://web.archive.org/web/20090530045451/http://news.zdnet.co.uk/software/0,1000000121,39379900,00.htm |date=30 May 2009 }}
* [http://www.internetnews.com/software/article.php/3739491 IDC: Linux-Related Spending Could Top $49B by 2011]
* [https://web.archive.org/web/20120108125541/http://www.redhat.com/about/where-is-open-source/activity/ Red Hat – Open Source Activity Map]

{{Linux}}

{{DEFAULTSORT:Linux Adoption}}
[[Category:Linux]]
[[Category:Linux-based devices]]
[[Category:Operating system advocacy]]
[[Category:Technological change]]

Virtual routing and forwarding

2018-12-11T18:25:13Z

Gotar: /* Full implementation */ fixed spacing

{{ref improve|date=January 2014}}

In [[Internet Protocol|IP-based]] [[computer network|computer networks]], '''virtual routing and forwarding''' ('''VRF''') is a technology that allows multiple instances of a [[routing table]] to co-exist within the same router at the same time. Because the routing instances are independent, the same or overlapping [[IP address|IP addresses]] can be used without conflicting with each other. Network functionality is improved because network paths can be segmented without requiring multiple routers.

VRF may be implemented in a network device by distinct routing tables known as [[forwarding information base]]s (FIBs){{fact|date=July 2009}}, one per routing instance. Alternatively, a network device may have the ability to configure different virtual routers, where each one has its own FIB that is not accessible to any other virtual router instance on the same device.

== Simple implementation ==

The simplest form of VRF implementation is '''VRF Lite''' {{Citation needed|date=April 2016}}. In this implementation, each router within the network participates in the virtual routing environment in a peer-based fashion. While simple to deploy and appropriate for small to medium enterprises and shared data centers, VRF Lite does not scale to the size required by global enterprises or large carriers, as there is the need to implement each VRF instance on every router, including intermediate routers. VRFs were initially introduced in combination with [[Multiprotocol Label Switching]] (MPLS), but VRF proved to be so useful that it eventually evolved to live independent of MPLS. This is the historical explanation of the term VRF Lite: usage of VRFs without MPLS.

== Full implementation ==
The scaling limitations of VRF Lite are resolved by the implementation of [[Internet Protocol|IP]] [[Virtual Private Network|VPN]]s. In this implementation, a core backbone network is responsible for the transmission of data across the wide area between VRF instances at each edge location. IP VPNs have been traditionally deployed by carriers to provide a shared wide-area backbone network for multiple customers. They are also appropriate in the large enterprise, multi-tenant and shared data center environments.

In a typical deployment, [[customer edge]] (CE) routers handle local routing in a traditional fashion and disseminate routing information into [[Provider Edge]] (PE) where the routing tables are virtualized. The PE router then encapsulates the traffic, marks it to identify the VRF instance, and transmits it across the provider backbone network to the destination PE router. The destination PE router then decapsulates the traffic and forwards it to the CE router at the destination. The backbone network is completely transparent to the customer equipment, allowing multiple customers or user communities to utilize the common backbone network while maintaining end-to-end traffic separation.

Routes across the provider backbone network are maintained using an [[interior gateway protocol]] – typically [[BGP|iBGP]]. IBGP uses ''extended community'' attributes in a common routing table to differentiate the customers' routes with overlapping IP addresses.

IP VPN is most commonly deployed across an MPLS backbone as the inherent labeling of packets in MPLS lends itself to the identification of the customer VRF. Some IP  VPN implementations (notably Nortel's [[IP-VPN Lite]]) utilize a simpler [[IP in IP|IP-in-IP]] encapsulation over a pure IP backbone, eliminating the need to maintain and support an MPLS environment.

==Cisco implementation==
'''{{visible anchor|VPN routing and forwarding}}''', the key element in the [[Cisco]] [[Multiprotocol Label Switching|MPLS]] VPN technology.<ref>[http://www.cisco.com/en/US/docs/net_mgmt/vpn_solutions_center/1.1/user/guide/VPN_UG1.html Cisco document on MPLS & VRF]</ref>{{clarify|date=July 2009}}

==See also==
* [[Layer 2 Forwarding Protocol]]
* [[Shortest Path Bridging]]

== References ==
{{reflist}}

==External links==
*[https://web.archive.org/web/20110628060758/http://www.multicorepacketprocessing.com/implementing-virtual-routing-on-multicore-cpus-part-12/ VRFs with multicore packet processors]
*[http://blog.ipexpert.com/vrf-route-leaking/ VRF Route Leaking]
*[http://www.juniper.net/techpubs/software/junos/junos85/swconfig85-vpns/frameset.html Juniper documentation on configuring VPNs and VRFs]
*[https://web.archive.org/web/20110714194630/http://support.nortel.com/go/main.jsp?cscat=DOCDETAIL&id=731634&poid=9015 Nortel IPVPN and IPVPN Lite Configuration documentation]

[[Category:MPLS networking]]
[[de:VRF-Instanz]]

EIT

2018-06-24T13:02:03Z

Gotar: link EIT to EPG as the closest match available

'''EIT''' may refer to:
* [[European Institute of Innovation and Technology]], research and development organization of the European Union
* [[Eastern Institute of Technology]], a public Tertiary Education Institution in the Hawke's Bay region of New Zealand
* [[Eritrea Institute of Technology]], university located in the town of Abardae near the town Himbrti, Mai Nefhi, Eritrea
* [[Economies in transition]], used to describe countries of the former Soviet bloc which are transitioning to a market economy
* [[Electrical impedance tomography]], a medical imaging technology
* [[Electromagnetically induced transparency]], an optical phenomenon
* Electronic [[Information Technology]], a broad subject concerned with aspects of managing, editing and processing information
* [[Engineer in Training]], professional certification level
* [[Enhanced interrogation techniques]], U.S. government's program of systematic torture
* [[Extreme ultraviolet Imaging Telescope]], an instrument on the Solar and Heliospheric Observatory spacecraft
* [[Electronic program guide|Event Information Table]], an information table for broadcast events used in [[Digital Video Broadcasting]] and ATSC standards
* ''[[Everything in Transit]]'', an album by Jack's Mannequin
* [[Everything is Terrible!]], a video blog

{{Disambig}}

DNF (software)

2018-03-14T14:29:18Z

Gotar: updated URLs

{{Infobox software
| name = Dandified Yum
| logo =
| logo caption =
| logo_size =
| logo_alt =
| screenshot = Dnf updates fedora22.png
| caption = DNF, installing updates on [[Fedora (operating system)|Fedora]] 22
| screenshot_size =
| screenshot_alt =
| collapsible =
| author =
| developer =
| released = 
| discontinued =
| latest release version = 2.7.5
| latest release date = {{Start date and age|2017|10|18}}<ref name="DNF-release">{{cite web|url=https://github.com/rpm-software-management/dnf/releases|title=Releases · rpm-software-management/dnf · GitHub|website=GitHub DNF Repository|date=2017-10-18|accessdate=2017-10-28}}</ref>
| latest preview version =
| latest preview date = 
| frequently updated = 
| status =
| programming language = [[C (programming language)|C]], [[Python (programming language)|Python]]
| operating system = [[Linux]]
| platform =
| size =
| language = English
| language count = 
| language footnote =
| genre = [[Package management system]]
| license = [[GNU General Public License#Version 2|GPL v2]]
| alexa =
| website = {{URL|https://rpm-software-management.github.io/}}
| standard =
| AsOf =
}}
'''dnf''' or '''Dandified Packaging Tool''' is the next-generation version of the [[Yellowdog Updater, Modified]] (yum), a [[package manager]] for [[.rpm]]-based distributions. DNF was introduced in [[Fedora (operating system)|Fedora]] 18,<ref name="DNF-Fedora">{{cite web|url=http://www.linux-magazine.com/Online/Features/Will-DNF-Replace-Yum|title=Will DNF Replace Yum?|last=Byfield|first=Bruce|website=[[Linux Magazine]]|accessdate=2015-05-28}}</ref> and it has been the default package manager for Fedora since version 22.<ref name="F22_released">{{cite web|url=http://www.webupd8.org/2015/05/fedora-22-released-see-whats-new.html|title=Fedora 22 Released, See What`s New [Workstation]|author=Andrew|publisher=WebUpd8|date=2015-05-26|accessdate=2015-05-28}}</ref>

Perceived deficiencies of yum which DNF is intended to address include poor performance, high memory usage, and the slowness of its iterative [[dependency resolution]].<ref name="lwn580223">{{cite web|url=https://lwn.net/Articles/580223/|title=DNF and Yum in Fedora|last=Edge|first=Jake|publisher=[[LWN.net]]|date=2014-01-15|accessdate=2015-03-29}}</ref> DNF uses libsolv, an external dependency resolver.<ref name="lwn580223"/>

DNF performs package management tasks on top of [[RPM Package Manager|RPM]], and supporting libraries.

DNF was originally written in [[Python (programming language)|Python]], but efforts are under way to port it to C and move most functionality from Python code into the new libdnf library.<ref name="libdnfinitiative">{{cite web|url=http://dnf.baseurl.org/2016/02/24/dnf-into-c-initiative-started/|title=DNF into C initiative started|last=Šilhan|first=Jan|website=DNF blog|date=2016-02-24|accessdate=2017-07-05}}</ref> libdnf is already used by [[PackageKit]], a [[Linux distribution]]-agnostic package system abstraction library, even though the library does not have most of DNF's features.<ref name="packagekitlibdnf">{{cite web|url=https://ctrl.blog/entry/packagekit-dnf|title=Use DNF rather than PackageKit on Fedora|last=Aleksandersen|first=Daniel|website=Ctrl blog|date=2017-07-05|accessdate=2017-08-07}}</ref>

== Adoption ==
DNF has been the default package manager for Fedora since version 22 which was released in May 2015.<ref name="F22_released"/> The libdnf library is used as a package backend in [[PackageKit]].<ref name="packagekitlibdnf"/>
DNF is also available as an alternate package manager for [[Mageia]] Linux since version 6. It may become the default sometime in the future.<ref name="PhoronixMageia">{{cite web|url=https://www.phoronix.com/scan.php?page=news_item&px=Megia-6-To-Have-DNF-Yum|title=Mageia To Offer DNF, But Will Keep Using URPMI By Default|last=Larabel|first=Michael|author-link=Michael Larabel|publisher=[[Phoronix]]|date=2016-09-05|accessdate=2017-12-04}}</ref>

== Dependencies ==

=== libdnf ===
* High-level API for DNF and underlying libraries
* [[C (programming language)|C]], license is LGPLv2+

=== libsolv ===
* A free package dependency solver using a satisfiability algorithm
* For solving packages and reading repositories
* [[C (programming language)|C]], [[New BSD License]]

=== librepo ===
* A library providing C and Python (libcURL like) API for downloading Linux repository metadata and packages
* [[C (programming language)|C]], license is LGPLv2+

=== libcomps ===
* Libcomps is alternative for yum.comps library. It is written in pure C as library and there are bindings for python2 and python3.
* [[C (programming language)|C]], license is GPLv2+

== References ==
{{Reflist}}

== External links ==
* {{Official website|https://rpm-software-management.github.io/}}
[[Category:Fedora Project]]
[[Category:Linux package management-related software]]

{{Free-software-stub}}

Dm-crypt

2018-01-30T20:22:02Z

Gotar: /* Features */ anchor fixed

{{lowercase}}

'''dm-crypt''' is a transparent [[disk encryption]] subsystem in [[Linux kernel]] versions 2.6 and later and in [[DragonFly BSD]]. It is part of the [[device mapper]] infrastructure, and uses cryptographic routines from the kernel's [[Crypto API (Linux)|Crypto API]]. Unlike its predecessor [[cryptoloop]], dm-crypt was designed to support advanced modes of operation, such as XTS, LRW and ESSIV (see [[disk encryption theory]]), in order to avoid [[watermarking attack]]s.<ref name=new-methods>{{cite journal |author=Clemens Fruhwirth |date=2005-07-18 |title=New Methods in Hard Disk Encryption |publisher=[[Vienna University of Technology]] |url=http://clemens.endorphin.org/nmihde/nmihde-A4-ds.pdf |format=PDF |accessdate=2007-04-20}}</ref> In addition to that, dm-crypt also addresses some reliability problems of cryptoloop.<ref>{{cite journal |author=Mike Peters |date=2004-06-08 |title=Encrypting partitions using dm-crypt and the 2.6 series kernel |url=http://archive09.linux.com/feature/36596 |accessdate=2012-02-20}}</ref>

dm-crypt is implemented as a device mapper target and may be stacked on top of other device mapper transformations. It can thus encrypt whole disks (including [[removable media]]), [[disk partitioning|partition]]s, [[software RAID]] volumes, [[logical volume]]s, as well as [[computer file|file]]s. It appears as a block device, which can be used to back [[file systems]], [[swap partition|swap]] or as an [[Logical Volume Manager (Linux)|LVM]] [[physical volume]].

Some [[Linux distribution]]s support the use of dm-crypt on the root file system. These distributions use [[initrd]] to prompt the user to enter a passphrase at the console, or insert a [[smart card]] prior to the normal boot process.<ref name=crypt-fedora/>

==Frontends==
The dm-crypt device mapper target resides entirely in kernel space, and is only concerned with encryption of the [[block device]]{{snd}} it does not interpret any data itself. It relies on [[user space]] [[front and back ends|front-ends]] to create and activate encrypted volumes, and manage authentication. At least two frontends are currently available: <code>[[cryptsetup]]</code> and <code>[[cryptmount]]</code>.

===cryptsetup===
The <code>cryptsetup</code> command-line interface, by default, does not write any headers to the encrypted volume, and hence only provides the bare essentials: encryption settings have to be provided every time the disk is mounted (although usually employed with automated scripts), and only one [[key (cryptography)|key]] can be used per volume; the [[Symmetric-key algorithm|symmetric encryption]] key is directly derived from the supplied [[passphrase]].

Because it lacks a "[[Salt (cryptography)|salt]]", using cryptsetup is less secure in this mode than is the case with [[Linux Unified Key Setup]] (LUKS).<ref>{{cite web |title=cryptsetup FAQ |url=https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions}}</ref> However, the simplicity of cryptsetup makes it useful when combined with third-party software, for example, with [[smart card]] authentication.

<code>cryptsetup</code> also provides commands to deal with the LUKS on-disk format. This format provides additional features such as [[key management]] and [[key stretching]] (using [[PBKDF2]]), and remembers encrypted volume configuration across reboots.<ref name=crypt-fedora/><ref name=tks1>{{cite journal |author=Clemens Fruhwirth |title=TKS1 – An anti-forensic, two level, and iterated key setup scheme |work=draft |url=http://clemens.endorphin.org/TKS1-draft.pdf |format=PDF |date=2004-07-15 |accessdate=2006-12-12 }}</ref>

===cryptmount===
The <code>cryptmount</code> interface is an alternative to the "cryptsetup" tool that allows any user to [[mount (computing)|mount]] and unmount a dm-crypt file system when needed, without needing [[superuser]] privileges after the device has been configured by a superuser.

==Features==
The fact that disk encryption (volume encryption) software like dm-crypt only deals with transparent encryption of abstract [[block device]]s gives it a lot of flexibility. This means that it can be used for encrypting any disk-backed [[file system]]s supported by the [[operating system]], as well as [[swap space]]; [[write barrier]]s implemented by file systems are preserved.<ref>{{cite web
| url = http://www.saout.de/pipermail/dm-crypt/2012-April/002441.html
| title = [dm-crypt] Does dm-crypt support journaling filesystem transactional guarantees?
| date = 2012-04-24 | accessdate = 2014-07-08
| author = Milan Broz | publisher = saout.de
}}</ref><ref>{{cite web
| url = https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=647c7db14ef9cacc4ccb3683e206b61f0de6dc2b
| title = kernel/git/torvalds/linux.git | work = Linux kernel source tree
| date = 2009-06-22 | accessdate = 2014-07-08
| author = Mikulas Patocka | publisher = kernel.org
}}</ref> Encrypted volumes can be stored on [[disk partition]]s, [[logical volume]]s, whole disks as well as [[computer file|file]]-backed [[disk image]]s (through the use of [[loop device]]s with the losetup utility). dm-crypt can also be configured to encrypt [[RAID]] volumes and [[Logical volume management|LVM]] physical volumes.

dm-crypt can also be configured to provide [[booting|pre-boot]] authentication through an [[initrd]], thus encrypting all the data on a computer{{snd}} except the bootloader, the kernel and the initrd image itself.<ref name=crypt-fedora>{{cite web |author=W. Michael Petullo |date=2007-01-18 |title=Disk encryption in Fedora: Past, present and future |publisher=Red Hat Magazine |url=http://www.redhatmagazine.com/2007/01/18/disk-encryption-in-fedora-past-present-and-future/ |accessdate=2007-04-20 }}</ref>

When using the [[block cipher modes of operation#Cipher Block Chaining (CBC)|cipher block chaining]] mode of operation with predictable [[initialization vector]]s as other disk encryption software, the disk is vulnerable to [[watermarking attack]]s. This means that an attacker is able to detect the presence of specially crafted data on the disk. To address this problem in its predecessors, dm-crypt included provisions for more elaborate, disk encryption-specific modes of operation.<ref name=new-methods/> Support for [[ESSIV]] (encrypted salt-sector initialization vector) was introduced in Linux kernel version 2.6.10, [[disk encryption theory#Liskov,_Rivest,_and_Wagner_(LRW)|LRW]] in 2.6.20 and [[disk encryption theory#XTS|XTS]] in 2.6.24.

The Linux Crypto API includes support for most popular [[block cipher]]s and [[hash function]]s, which are all usable with dm-crypt.

Crypted FS support include LUKS volumes, [[loop-AES]] and since Linux kernel 3.13, the [[TrueCrypt]] target called "tcw".<ref>{{cite web|url=https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt#iv-generators|title=dm-crypt: Linux kernel device-mapper crypto target – IV generators|publisher=cryptsetup|date=2014-01-11|accessdate=2015-04-05}}</ref><ref>{{cite web|url=https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt|title=dm-crypt: Linux kernel device-mapper crypto target| accessdate=2015-04-05}}</ref><ref>{{cite web|url=http://www.redhat.com/archives/dm-devel/2013-October/msg00081.html|title=[dm-devel] [PATCH 2/2] dm-crypt: Add TCW IV mode for old CBC TCRYPT containers.|publisher=redhat.com|accessdate=2014-06-17}}</ref>

==Compatibility==
dm-crypt and LUKS encrypted disks can be accessed and used under MS Windows using [[LibreCrypt]] (formerly DoxBox), provided that the filesystem used is supported by Windows (e.g. [[File Allocation Table|FAT]]/FAT32/[[NTFS]]). Encrypted [[ext2]] and [[ext3]] filesystems are supported by using [[Ext2Fsd]] or so-called "Ext2 Installable File System for Windows";<ref>{{cite web|url=http://www.fs-driver.org/|title=Ext2 IFS For Windows|work=fs-driver.org|accessdate=15 February 2015}}</ref> LibreCrypt also supports them.

Cryptsetup/LUKS and the required infrastructure have also been implemented on the DragonFly BSD operating system.<ref>{{cite web |author=Alex Hornung
|date=2010-07-23 |title=HEADS UP: dm, lvm, cryptsetup and initrd on master|url=http://leaf.dragonflybsd.org/mailarchive/users/2010-07/msg00036.html }}</ref>

== See also ==
{{Portal|Linux}}

* [[Comparison of disk encryption software]]

== References ==
{{Reflist|30em}}

==External links==
* Official {{Official website|https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt|dm-crypt}}, {{Official website|https://gitlab.com/cryptsetup/cryptsetup/|cryptsetup-luks}} and {{Official website|http://cryptmount.sourceforge.net|cryptmount}} websites
* [https://web.archive.org/web/20150917051251/http://www.markus-gattol.name/ws/dm-crypt_luks.html All about dm-crypt and LUKS on one page (on archive.org)]{{snd}} a page covering dm-crypt/LUKS, starting with theory and ending with many practical examples about its usage.

{{Clear}}

{{Linux kernel}}
{{Linux}}
{{Operating system}}

{{DEFAULTSORT:Dm-Crypt}}
[[Category:Device mapper]]
[[Category:Disk encryption]]
[[Category:Cryptographic software]]

Rybnik Coal Area

2017-03-24T16:58:09Z

Gotar: extra space removed

'''Rybnik Coal Area''' ({{lang-pl|Rybnicki Okręg Węglowy}}, ''ROW'') is an industrial region in southern [[Poland]].<ref name=PWN>{{pl icon}} [http://encyklopedia.pwn.pl/haslo.php?id=3970320 "''Rybnicki Okręg Węglowy''"] - [[Polish Scientific Publishers PWN|PWN]] Encyclopedia</ref> It is located in the [[Silesian Voivodeship]],<ref name="PWN"/> in a basin between the [[Vistula]] and [[Oder River|Oder]] rivers, sited on the [[Rybnik Plateau]] ({{lang-pl|Płaskowyż Rybnicki}}) between [[Katowice]] ([[Metropolitan Association of Upper Silesia|Upper-Silesian Metropolis]]) to the north and [[Ostrava]] on the south-west. Part a [[Silesian metropolitan area]] populated by 5,294,000 people<ref name=EPSON>[[European Spatial Planning Observation Network]] (ESPON)[http://www.espon.eu/mmp/online/website/content/projects/261/420/index_EN.html]</ref> and [[Silesian metropolitan region]] populated by about 7 million. According to scientific description by Paweł Swianiewicz and Urszula Klimska this area have 507,000 people,<ref>[http://www.wgsr.uw.edu.pl/pub/uploads/pis05/Swianiewicz_1a.pdf "''Społeczne i polityczne zróżnicowanie aglomeracji w Polsce''"] - Paweł Swianiewicz, Urszula Klimska; [[University of Warsaw]] 2005</ref> according to [[European Spatial Planning Observation Network]] - 634,000 people (525,000<ref name=EPSON /> + 109,000<ref name=EPSON /> by Racibórz). Area: about 1,300 km².<ref name=PWN />

==Main cities==
Adjacent main cities and statistics (30.06.2009):<ref name=GUS>[http://www.stat.gov.pl/cps/rde/xbcr/gus/PUBL_L_ludnosc_stan_struktura_30_06_2009.pdf "''Population. Size and structure by territorial division''"] - Central Statistical Office of Poland, 2009, ISSN 1734-6118</ref>
{| class="wikitable sortable"
|- align=center
!City / Town||Population||Area (km2)||Density (km−2)
|-
|[[Rybnik]]||{{Nts|141387}}||{{Nts|148.36}}||{{Nts|952.9}}
|-
|[[Jastrzębie-Zdrój]]||{{Nts|93455}}||{{Nts|88.62}}||{{Nts|1054.5}}
|-
|[[Żory]]||{{Nts|61982}}||{{Nts|64.59}}||{{Nts|959.6}}
|-
|[[Racibórz]]||{{Nts|56675}}||{{Nts|74.96}}||{{Nts|756.0}}
|-
|[[Wodzisław Śląski]]||{{Nts|49386}}||{{Nts|49.62}}||{{Nts|995.2}}
|-
|[[Rydułtowy]]||{{Nts|21833}}||{{Nts|14.95}}||{{Nts|1460.4}}
|-
|[[Radlin, Silesian Voivodeship|Radlin]]||{{Nts|17673}}||{{Nts|12.53}}||{{Nts|1410.4}}
|-
|[[Pszów]]||{{Nts|13753}}||{{Nts|20.42}}||{{Nts|673.5}}
|-
|'''Total'''||{{Nts|456,144}}||{{Nts|474.05}}||{{Nts|962.2}}
|}

== Area ==
[[File:Wodzisław Widok Osiedla.JPG|thumb|250 px|[[Wodzisław Śląski]]]]
Adjacent county ([[powiat]]) and statistics (30.06.2009):<ref name=GUS />
{| class="wikitable sortable"
|- align=center
!County||Population||Area (km2)||Density (km2)
|-
|[[Wodzisław County]]||{{Nts|155,733}}||{{Nts|286.92}}||{{Nts|541.0}}
|-
|[[Rybnik]] city-county||{{Nts|141,387}}||{{Nts|148.36}}||{{Nts|952.9}}
|-
|[[Racibórz County]]||{{Nts|110,557}}||{{Nts|543.98}}||{{Nts|204.9}}
|-
|[[Jastrzębie-Zdrój]] city-county||{{Nts|93,455}}||{{Nts|88.62}}||{{Nts|1054.5}}
|-
|[[Rybnik County]]<ref>[[Gmina Czerwionka-Leszczyny]] in ''Rybnik County'' membership in the Rybnik Coal Area is controversial because it lies on the border Rybnik area and [[Upper Silesian Industrial Region]] and can be considered as part of Upper Silesian Industrial Region.</ref>||{{Nts|74,331}}||{{Nts|224.63}}||{{Nts|327.3}}
|-
|[[Żory]] city-county||{{Nts|61,982}}||{{Nts|64.59}}||{{Nts|959.6}}
|-
|'''Total'''||{{Nts|637,445}}||{{Nts|1357.1}}||{{Nts|469.4}}
|}

==See also==
*[[Upper Silesian Industrial Region]]

==External links==
*[https://maps.google.com/maps?f=q&source=s_q&hl=pl&geocode=&q=Rybnik&ie=UTF8&hq=&hnear=Rybnik,+%C5%9Al%C4%85skie,+Polska&ll=50.039061,18.411713&spn=0.225796,0.441513&z=11 Rybnik Area on ''maps.google.com'']

==References==
{{reflist}}

{{coord missing|Poland}}
{{Silesia topics}}

[[Category:Geography of Silesia]]
[[Category:Metropolitan areas of Poland]]
[[Category:Mining in Poland]]

Figure of speech

2016-07-21T05:41:30Z

Gotar: /* Tropes */ fixed reference (proper disambiguate version)

{{Redirect|Figures of speech|the hip hop group|Figures of Speech}}
[[File:Whitehall MOD 45155526.jpg|thumb|Whitehall is a road in the [[City of Westminster]], [[London]] and used as a figure of speech for central government due to the number of departments located in the area.]]

A '''figure of speech''' or '''rhetorical figure'''<ref>[https://books.google.com/books?id=YWBgAAAAcAAJ&pg=PA113]</ref> is [[figurative language]] in the form of a single [[word]] or [[phrase]]. It can be a special repetition, arrangement or omission of words with literal meaning, or a phrase with a specialized meaning not based on the literal meaning of the words. There are five main figures of speech: [[simile]], [[metaphor]], [[hyperbole]], [[personification]] and [[synecdoche]].{{dubious|date=July 2016}} Figures of speech often provide emphasis, freshness of expression, or clarity. However, clarity may also suffer from their use, as any figure of speech introduces an ambiguity between literal and figurative interpretation.{{dubious|date=July 2016}}

== The four fundamental operations ==
{{Main|Rhetorical operations}}

[[Classical rhetoric]]ians classified figures of speech into [[rhetorical operations|four categories]] or ''quadripartita ratio'':<ref name="Jansen">Jansen, Jeroen (2008) ''[http://www.verloren.nl/boeken/2086/263/2126/renaissance/imitatio Imitatio]'' ISBN 978-90-8704-027-7 [http://home.medewerker.uva.nl/j.jansen/page1.html Summary] translated to English by Kristine Steenbergh. Quote from the summary: <blockquote>Using these formulas, a pupil could render the same subject or theme in a myriad of ways. For the mature author, this principle offered a set of tools to rework source texts into a new creation. In short, the quadripartita ratio offered the student or author a ready-made framework, whether for changing words or the transformation of entire texts. Since it concerned relatively mechanical procedures of adaptation that for the most part could be learned, the techniques concerned could be taught at school at a relatively early age, for example in the improvement of pupils’ own writing.</blockquote></ref>

* addition (''adiectio''), also called repetition/expansion/superabundance
* omission (''detractio''), also called subtraction/abridgement/lack
* transposition (''transmutatio''), also called transferring
* permutation (''immutatio''), also called switching/interchange/substitution/transmutation

These categories are often still used. The earliest known text listing them, though not explicitly as a system, is the ''[[Rhetorica ad Herennium]]'', of unknown authorship, where they are called πλεονασμός (addition), ἔνδεια (omission), μετάθεσις (transposition) and ἐναλλαγή (permutation).<ref>Book V, 21.29, pp.303–5</ref> Quintillian then mentioned them in ''[[Institutio Oratoria]]''.<ref>Institutio Oratoria, Vol. I, Book I, [http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Quintilian/Institutio_Oratoria/1B*.html Chapter 5], paragraphs 6 and 38–41. And also in Book VI [http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Quintilian/Institutio_Oratoria/6C*.html Chapter 3]</ref> [[Philo of Alexandria]] also listed them as addition (πρόσθεσις), subtraction (ἀφαίρεσις), transposition (μετάθεσις), and transmutation (ἀλλοίωσις).<ref>[http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Rhetorica_ad_Herennium/4B*.html Rhetorica ad Herennium]</ref>

== Examples ==
Figures of speech come in many varieties. The aim is to use the language inventively to accentuate the effect of what is being said. A few examples follow:

* "Around the rugged rocks the ragged rascal ran" is an example of [[alliteration]], where the consonant ''r'' is used repeatedly.
:Whereas, "Sister Suzy sewing socks for soldiers" is a particular form of alliteration called [[sibilance]], because it repeats the letter ''s''.
:Both are commonly used in poetry.
* "She would run up the stairs and then a new set of curtains" is a variety of [[zeugma]] called a [[syllepsis]]. ''Run up'' refers to ascending and also to manufacturing. The effect is enhanced by the momentary suggestion, through a [[pun]], that she might be climbing up the curtains. The [[ellipsis (linguistics)|ellipsis]] or omission of the second use of the verb makes the reader think harder about what is being said.
* "Military Intelligence is an [[oxymoron]]" is the use of direct [[sarcasm]] to suggest that the military would have no intelligence. This might be considered to be a [[satire]] and an [[aphorism]].
*"An Einstein" is an example of [[synecdoche]], as it uses a particular name to represent a class of people: geniuses.
* "I had butterflies in my stomach" is a [[metaphor]], referring to my nervousness feeling as if there were flying insects in my stomach.
:To say "it was like having some butterflies in my stomach" would be a [[simile]], because it uses the word ''like'' which is missing in the metaphor.
:To say "It was like having a butterfly farm in my stomach," "It felt like a butterfly farm in my stomach," or "I was so nervous that I had a butterfly farm in my stomach" could be a [[hyperbole]], because it is exaggerated.
*"That filthy place was really dirty" is an example of tautology as there are the two words 'filthy' and 'dirty' having almost the same meaning and are repeated so as to make the text more emphatic.


Scholars of classical Western rhetoric have divided figures of speech into two main categories: schemes and tropes. '''Schemes''' (from the Greek ''schēma'', form or shape) are figures of speech that change the ordinary or expected pattern of words. For example, the phrase, "John, my best friend" uses the scheme known as [[apposition]]. '''Tropes''' (from the Greek ''trepein'', to turn) change the general meaning of words. An example of a trope is irony, which is the use of words to convey the opposite of their usual meaning ("For Brutus is an honorable man; / So are they all, all honorable men").

During the [[Renaissance]], scholars meticulously enumerated and classified figures of speech. [[Henry Peacham (born 1546)|Henry Peacham]], for example, in his ''The Garden of Eloquence'' (1577), enumerated 184 different figures of speech. Professor Robert DiYanni, in his book "Literature – Reading Fiction, Poetry, Drama and the Essay" <ref>Second Edition, McGraw-Hill, ISBN 0-07-557112-9, pp.451</ref> wrote: "Rhetoricians have catalogued more than 250 different ''figures of speech'', expressions or ways of using words in a nonliteral sense.".

For simplicity, this article divides the figures between schemes and [[Trope (linguistics)|tropes]], but does not further sub-classify them (e.g., "Figures of Disorder"). Within each category, words are listed alphabetically. Most entries link to a page that provides greater detail and relevant examples, but a short definition is placed here for convenience. Some of those listed may be considered [[rhetorical device]]s, which are similar in many ways.

=== Schemes ===
{{refimprove section|date=June 2013}}
{{Main|Scheme (linguistics)}}

* [[Accumulation (figure of speech)|accumulation]]: Accumulating arguments in a concise forceful manner.
* [[adnomination]]: Repetition of words with the same [[root word]].
* [[alliteration]]: It is a term that describes a literacy stylistic device. Alliteration occurs when a series of words in a row have the same first consonant sound.
(Eg: She sells sea shells by the sea shore).
* [[adynaton]]: [[hyperbole]] It is an extreme exaggeration used to make a point. It is like the opposite of "understatement".
(Eg: I've told you a million times).
* [[anacoluthon]]: Transposition of clauses to achieve an unnatural order in a sentence.
* [[anadiplosis]]: Repetition of a word at the end of a clause and then at the beginning of its succeeding clause.
* [[Anaphora (rhetoric)|anaphora]]: Repetition of the same word or set of words in a paragraph.
* [[anastrophe]]: Changing the [[object (grammar)|object]], [[subject (grammar)|subject]] and verb order in a clause.
* [[Anti-climax (figure of speech)|Anti-climax]]: It is when a specific point, expectations are raised, everything is built-up and then suddenly something boring or disappointing happens.
(Eg: Men, dogs and houses, all are dead).
* [[antanaclasis]]: Repetition of a single word, but with different meanings.
* [[anthimeria]]: Transformation of a word of a certain word class to another word class.
* [[antimetabole]]: A sentence consisting of the repetition of words in successive clauses, but in reverse order.
* [[:wiktionary:antirrhesis|antirrhesis]]: Disproving an opponent's argument.
* [[epistrophe|antistrophe]]: Repetition of the same word or group of words in a paragraph in the end of sentences.
* [[antithesis]]: Juxtaposition of opposing or contrasting ideas.
* [[aphorismus]]: Statement that calls into question the definition of a word.
* [[aposiopesis]]: Breaking off or pausing speech for dramatic or emotional effect.
* [[apposition]]: Placing of two statements side by side, in which the second defines the first.
* [[assonance]]: Repetition of vowel sounds.
* [[asteismus]]: Mocking answer or humorous answer that plays on a word.
* [[:wiktionary:asterismos|asterismos]]: Beginning a segment of speech with an exclamation of a word.
* [[asyndeton]]: Omission of conjunctions between related clauses.
* [[cacophony]]: Words producing a harsh sound.
* [[cataphora]]: Co-reference of one expression with another expression which follows it, in which the latter defines the first. (example: If you need one, there's a towel in the top drawer.)
* [[classification (literature & grammar)|classification]]: Linking a proper noun and a common noun with an article
* [[chiasmus]]: Two or more clauses are related to each other through a reversal of structures in order to make a larger point
* [[climax (figure of speech)|climax]]: Arrangement of words in order of ascending to descending order.
* commoratio: Repetition of an idea, re-worded
* conduplicatio: Repetition of a key word
* [[conversion (word formation)]]: An unaltered transformation of a word of one word class into another word class
* [[Literary consonance|consonance]]: Repetition of consonant sounds, most commonly within a short passage of verse
* [[:wiktionary:asterismos|dubitatio]]: Expressing doubt and uncertainty about oneself
* [[:wiktionary:tmesis|dystmesis]]: A synonym for [[tmesis]]
* [[Ellipsis (linguistics)|ellipsis]]: Omission of words
* [[elision]]: Omission of one or more letters in speech, making it colloquial
* [[enallage]]: Wording ignoring grammatical rules or conventions
* [[enjambment]]: Incomplete sentences at the end of lines in poetry
* [[enthymeme]]: An informal [[syllogism]]
* [[epanalepsis]]: Ending sentences with their beginning.
* [[epanodos]]: Word repetition.<ref>{{cite book|url=http://books.google.se/books?id=mWw3sbiCWtAC&pg=PT239&dq=epanodos+%22figure+of+speech%22&hl=en&sa=X&ei=ft2QUYmaMces4ATRz4GIDw&redir_esc=y |title=The scientific and literary treasury – Samuel Maunder – Google Books |publisher=Books.google.se |accessdate=2013-05-23}}</ref><ref>{{cite book|url=http://books.google.se/books?id=jlZBAAAAcAAJ&pg=PT616&dq=epanodos+%22figure+of+speech%22&hl=en&sa=X&ei=ft2QUYmaMces4ATRz4GIDw&redir_esc=y |title=Universal Technological Dictionary Or Familiar Explanation of the Terms Used … – George Crabb – Google Books |publisher=Books.google.se |accessdate=2013-05-23}}</ref><ref>{{cite book|url=http://books.google.se/books?id=Ztu2AAAAIAAJ&q=epanodos+%22figure+of+speech%22&dq=epanodos+%22figure+of+speech%22&hl=en&sa=X&ei=od6QUd-NJeKC4ATTmYHwAw&redir_esc=y |title=Naming-day in Eden: The Creation and Recreation of Language – Noah Jonathan Jacobs – Google Books |publisher=Books.google.se |accessdate=2013-05-23}}</ref>
* [[epistrophe]]: (also known as antistrophe) Repetition of the same word or group of words at the end of successive clauses. The counterpart of [[anaphora (rhetoric)|anaphora]]
* [[epizeuxis]]: Repetition of a single word, with no other words in between
* [[euphony]]: Opposite of [[cacophony]] – i.e. pleasant sounding
* [[half rhyme]]: Partially rhyming words
* [[hendiadys]]: Use of two nouns to express an idea when it normally would consist of an adjective and a noun
* [[hendiatris]]: Use of three nouns to express one idea
* [[homeoptoton]]: ending the last parts of words with the same syllable or letter.<ref>{{cite web|title=Henry Peachum., The Garden of Eloquence (1593): Schemas|url=http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.03.0096%3Apart%3DSchemates+Rhetorical%3Asubpart%3DThe+first+order%3Asection%3DFigures+of+Conjunction%3Asubsection%3DHomeoptoton|accessdate=22 April 2013}}</ref>
* [[homographs]]: Words we write identically but which have a differing meaning
* [[homoioteleuton]]: Multiple words with the same ending
* [[homonyms]]: Words that are identical with each other in pronunciation and spelling, but different in meaning
* [[homophones]]: Words that are identical with each other in pronunciation, but different in meaning
* [[homeoteleuton]]: Words with the same ending
* [[hypallage]]: A transferred epithet from a conventional choice of wording.<ref>{{cite book|author=Bernard Marie Dupriez|title=A Dictionary of Literary Devices: Gradius, A-Z|url=http://books.google.com/books?id=uff2N62Jx9wC&pg=PA213|accessdate=31 May 2013|year=1991|publisher=University of Toronto Press|isbn=978-0-8020-6803-3|page=213}}{{cite book|last=Dupriez|first=Bernard Marie|title=A Dictionary of Literary Devices: Gradus, A-Z|url=http://books.google.com/books?id=uff2N62Jx9wC&pg=PA213|year=1991|publisher=University of Toronto Press|isbn=978-0-8020-6803-3|page=213}}</ref>
* [[hyperbaton]]: Two ordinary associated words are detached.<ref name="WilsonWauson2010">{{cite book|author1=Kevin Wilson|author2=Jennifer Wauson|title=The AMA Handbook of Business Writing: The Ultimate Guide to Style, Grammar, Usage, Punctuation, Construction, and Formatting|url=http://books.google.com/books?id=g0cnr5SaMm8C&pg=PA224|year=2010|publisher=AMACOM Div American Mgmt Assn|isbn=978-0-8144-1589-4|page=224}}</ref><ref name="CushmanCavanagh2012">{{cite book|author1=Stephen Cushman|author2=Clare Cavanagh|author3=Jahan Ramazani|author4=Paul Rouzer|title=The Princeton Encyclopedia of Poetry and Poetics: Fourth Edition|url=http://books.google.com/books?id=uKiC6IeFR2UC&pg=PA648|date=26 August 2012|publisher=Princeton University Press|isbn=978-1-4008-4142-4|page=647}}</ref> The term may also be used more generally for all different figures of speech which transpose natural word order in sentences.<ref name="CushmanCavanagh2012" />
* [[hyperbole]]: Exaggeration of a statement
* [[hypozeuxis]]: Every clause having its own independent subject and predicate
* [[hysteron proteron]]: The inversion of the usual temporal or causal order between two elements
* [[isocolon]]: Use of parallel structures of the same length in successive clauses
* [[internal rhyme]]: Using two or more rhyming words in the same sentence
* [[kenning]]: Using a compound word neologism to form a [[metonym]]
*[[litotes]] derived from a Greek word meaning “simple”, is a figure of speech which employs an understatement by using double negatives or, in other words, positive statement is expressed by negating its opposite expressions.
*:Examples: “not too bad” for “very good” is an understatement as well as a double negative statement that confirms a positive idea by negating the opposite. Similarly, saying “She is not a beauty queen,” means “She is ugly” or saying “I am not as young as I used to be” in order to avoid saying “I am old”. Litotes, therefore, is an intentional use of understatement that renders an ironical effect.
* [[merism]]: Referring to a whole by enumerating some of its parts
* [[mimesis]]: Imitation of a person's speech or writing
* [[onomatopoeia]]: Word that imitates a real sound (e.g. tick-tock or boom)
* [[paradiastole]]: Repetition of the disjunctive pair "neither" and "nor"
* [[parallelism (rhetoric)|parallelism]]: The use of similar structures in two or more clauses
* [[paraprosdokian]]: Unexpected ending or truncation of a clause
* [[parenthesis (rhetoric)|parenthesis]]: A parenthetical entry
* [[paroemion]]: Alliteration in which every word in a sentence or phrase begins with the same letter
* [[parrhesia]]: Speaking openly or boldly, in a situation where it is unexpected (e.g. politics)
* [[pleonasm]]: The use of more words than are needed to express meaning
* [[polyptoton]]: Repetition of words derived from the same root
* [[polysyndeton]]: Close repetition of conjunctions
* [[pun]]: When a word or phrase is used in two(or more) different senses
* [[rhythm]]: A synonym for [[parallelism (rhetoric)|parallelism]]<ref>{{cite web|url=http://grammar.about.com/od/rs/g/rhythmterm.htm |title=rhythm – definition and examples of rhythm in phonetics and poetics |publisher=Grammar.about.com |accessdate=2013-05-23}}</ref>
* [[sibilance]]: Repetition of letter 's', it is a form of [[alliteration]]
* [[sine dicendo]]: An inherently superfluous statement, the truth value of which can easily be taken for granted. When held under scrutiny, it becomes readily apparent that the statement has not in fact added any new or useful information to the conversation (e.g. 'It's always in the last place you look.')
* [[solecism]]: Trespassing grammatical and syntactical rules
* [[spoonerism]]: Switching place of syllables within two words in a sentence yielding amusement
* [[superlative]]: Declaring something the best within its class i.e. the ugliest, the most precious
* [[:wiktionary:synathroesmus|synathroesmus]]: Agglomeration of adjectives to describe something or someone
* [[syncope (phonology)|syncope]]: Omission of parts of a word or phrase
* [[symploce]]: Simultaneous use of anaphora and epistrophe: the repetition of the same word or group of words at the beginning and the end of successive clauses
* [[synchysis]]: Words that are intentionally scattered to create perplexment
* [[synesis]]: Agreement of words according to the sense, and not the grammatical form
* [[synecdoche]]: Referring to a part by its whole or vice versa
* [[synonymia]]: Use of two or more synonyms in the same clause or sentence
* [[tautology (rhetoric)|tautology]]: Redundancy due to superfluous qualification; saying the same thing twice
* [[tmesis]]: Insertions of content within a compound word
* [[zeugma]]: The using of one verb for two or more actions

=== Tropes ===
{{Main|Trope (linguistics)}}
* [[accismus]]: expressing the want of something by denying it<ref>{{cite book | last1 = Shipley | first = Joseph T. | year = 1943 | title = Dictionary of World Literature: Criticism, Forms, Technique | url = http://www.questia.com/read/37059251/dictionary-of-world-literature-criticism-forms | publisher = Philosophical Library | page = 595 | chapter= Trope}}</ref>
* [[allegory]]: Extended [[metaphor]] in which a symbolic story is told
* [[allusion]]: Covert reference to another work of literature or art
* [[Circumlocution|ambiguity]]: Phrasing which can have two meanings
* [[anacoenosis]]: Posing a question to an audience, often with the implication that it shares a common interest with the speaker
* [[analogy]]: A comparison
* [[anapodoton]]: Leaving a common known saying unfinished
* [[antanaclasis]]: A form of [[pun]] in which a word is repeated in two different senses
* [[anthimeria]]: Transforming a word's word class
* [[anthropomorphism]]: Ascribing human characteristics to something that is not human, such as an animal or a god (see [[zoomorphism]])
* [[antimetabole]]: Repetition of words in successive clauses, but in switched order
* [[antiphrasis]]: A name or a phrase used ironically.
* [[:wiktionary:antistasis|antistasis]]: Repetition of a word in a different sense.
* [[antonomasia]]: Substitution of a proper name for a phrase or vice versa
* [[aphorism]]: Briefly phrased, easily memorable statement of a truth or opinion, an adage
* [[apologia]]: Justifying one's actions
* [[aporia]]: Faked or sincere puzzled questioning
* [[apophasis]]: (Invoking) an idea by denying its (invocation)
* [[appositive]]: Insertion of a parenthetical entry
* [[apostrophe (rhetoric)|apostrophe]]: Directing the attention away from the audience to an absent third party, often in the form of a personified abstraction or inanimate object.
* [[archaism]]: Use of an obsolete, archaic word (a word used in olden language, e.g. Shakespeare's language)
* [[auxesis (figure of speech)|auxesis]]: Form of [[hyperbole]], in which a more important sounding word is used in place of a more descriptive term
* [[bathos]]: Pompous speech with a ludicrously mundane worded [[anti-climax (figure of speech)|anti-climax]]
* [[burlesque metaphor]]: An amusing, overstated or grotesque comparison or example.
* [[catachresis]]: Blatant misuse of words or phrases.
* [[:wiktionary:categoria|categoria]]: Candidly revealing an opponent's weakness
* [[cliché]]: Overused phrase or theme
* [[circumlocution]]: Talking around a topic by substituting or adding words, as in [[euphemism]] or [[periphrasis (rhetoric)|periphrasis]]
* [[commiseration]]: Evoking pity in the audience
* [[congeries]]: Accumulation of synonymous or different words or phrases together forming a single message
* [[correctio]]: Linguistic device used for correcting one's mistakes, a form of which is [[epanorthosis]]
* [[:wiktionary:dehortatio|dehortatio]]: discouraging advice given with seeming sagacity
* [[denominatio]]: Another word for [[metonymy]]
* [[diathesis]]: Articulating silence or mood <ref name="journalofadvancedrhetorics.wordpress.com">Cosmo, Lepota. 2015. [https://journalofadvancedrhetorics.wordpress.com/ Superspeech and its rhetorical figures. 4. Superspeech and its lingual values, rhetorical figures.] ''The journal of advanced rhetorics''.</ref>
* [[:wiktionary:diatyposis|diatyposis]]: The act of giving counsel
* [[double negative]]: Grammar construction that can be used as an expression and it is the repetition of negative words
* [[:wiktionary:dirimens copulatio|dirimens copulatio]]: Juxtaposition of two ideas with a similar message
* [[:wiktionary:distinctio|distinctio]]: Defining or specifying the meaning of a word or phrase you use
* [[dysphemism]]: Substitution of a harsher, more offensive, or more disagreeable term for another. Opposite of [[euphemism]]
* [[:wiktionary:dubitatio|dubitatio]]: Expressing doubt over one's ability to hold speeches, or doubt over other ability
* [[:wiktionary:ekphrasis|ekphrasis]]: Lively describing something you see, often a painting
* [[epanorthosis]]: Immediate and emphatic self-correction, often following a [[Freudian slip|slip of the tongue]]
* [[:wiktionary:encomium|encomium]]: A speech consisting of praise; a eulogy
* [[:wiktionary:enumeratio|enumeratio]]: A sort of amplification and accumulation in which specific aspects are added up to make a point
* [[:wiktionary:epicrisis|epicrisis]]: Mentioning a saying and then commenting on it
* [[:wiktionary:epiplexis|epiplexis]]: Rhetorical question displaying disapproval or debunks
* [[Parable|epithymonexphrasos]]: Speak in such a way making others wish to speak, not to oppose than to join the conversation, exhortation, exoptamus.<ref name="journalofadvancedrhetorics.wordpress.com"/>
* [[:wiktionary:epitrope|epitrope]]: Initially pretending to agree with an opposing debater or invite one to do something
* [[erotema]]: Synonym for [[rhetorical question]]
* [[:wiktionary:erotesis|erotesis]]: [[Rhetorical question]] asked in confident expectation of a negative answer
* [[euphemism]]: Substitution of a less offensive or more agreeable term for another
* [[grandiloquence]]: Pompous speech
* [[:wiktionary:exclamation|exclamation]]: A loud calling or crying out
* [[humour]]: Provoking laughter and providing amusement
* [[hyperbaton]]: Words that naturally belong together separated from each other for emphasis or effect
* [[hyperbole]]: Use of exaggerated terms for emphasis
* [[hypocatastasis]]: An implication or declaration of resemblance that does not directly name both terms
* [[hypophora]]: Answering one's own [[rhetorical question]] at length
* [[hysteron proteron]]: Reversal of anticipated order of events; a form of hyperbaton
* [[innuendo]]: Having a hidden meaning in a sentence that makes sense whether it is detected or not
* [[invective]]: The act of insulting
* [[:wiktionary:inversion|inversion]]: A reversal of normal word order, especially the placement of a verb ahead of the subject (subject-verb inversion).
* imperative sentence: The urging to do something
* [[irony]]: Use of word in a way that conveys a meaning opposite to its usual meaning
* [[kataphora]]: Repetition of a cohesive device at the end
* [[litotes]]: Emphasizing the magnitude of a statement by denying its opposite
* [[malapropism]]: Using a word through confusion with a word that sounds similar
* [[meiosis (figure of speech)|meiosis]]: Use of understatement, usually to diminish the importance of something
* [[merism]]: Referring to a whole by enumerating some of its parts
* [[metalepsis]]: Figurative speech is used in a new context
* [[metaphor]]: Figurative language
* [[metonymy]]: A thing or concept is called not by its own name but rather by the name of something associated in meaning with that thing or concept
* [[neologism]]: The use of a word or term that has recently been created, or has been in use for a short time. Opposite of [[archaism]]
* [[non sequitur (literary device)|non sequitur]]: Statement that bears no relationship to the context preceding
* [[occupatio]]: Mentioning something by reportedly not mentioning it
* [[onomatopoeia]]: Words that sound like their meaning
* [[oxymoron]]: Using two terms together, that normally contradict each other
* [[par'hyponoian]]: Replacing in a phrase or text a second part, that would have been logically expected.
* [[parable]]: Extended [[metaphor]] told as an anecdote to illustrate or teach a moral lesson
* [[:wiktionary:paradiastole|paradiastole]]: Making a euphemism out of what usually is considered adversive
* [[Paradox (literature)|paradox]]: Use of apparently contradictory ideas to point out some underlying truth
* [[paradiastole]]: Extenuating a vice in order to flatter or soothe
* [[paraprosdokian]]: Phrase in which the latter part causes a rethinking or reframing of the beginning
* [[paralipsis]]: Drawing attention to something while pretending to pass it over
* [[parody]]: Humouristic imitation
* [[paronomasia]]: [[Pun]], in which similar sounding words but words having a different meaning are used
* [[pathetic fallacy]]: Ascribing human conduct and feelings to nature
* [[:wiktionary:periphrasis|periphrasis]]: A synonym for [[circumlocution]]
* [[personification]]/prosopopoeia/anthropomorphism: Attributing or applying human qualities to inanimate objects, animals, or natural phenomena
* [[pleonasm]]: The use of more words than is necessary for clear expression
* [[praeteritio]]: Another word for [[paralipsis]]
* [[procatalepsis]]: Refuting anticipated objections as part of the main argument
* [[proslepsis]]: Extreme form of [[paralipsis]] in which the speaker provides great detail while feigning to pass over a topic
* [[:wiktionary:prothesis|prothesis]]: Adding a syllable to the beginning of a word
* [[proverb]]: Succinct or pithy, often metaphorical, expression of wisdom commonly believed to be true
* [[pun]]: Play on words that will have two meanings
* [[rhetorical question]]: Asking a question as a way of asserting something. Asking a question which already has the answer hidden in it. Or asking a question not for the sake of getting an answer but for asserting something (or as in a poem for creating a poetic effect)
* [[satire]]: Humoristic criticism of society
* sensory detail imagery: sight, sound, taste, touch, smell
* [[sesquipedalianism]]: use of long and obscure words
* [[simile]]: Comparison between two things using ''like'' or ''as''
* [[snowclone]]: Alteration of [[cliché]] or [[phrasal template]]
* [[:wiktionary:style|style]]: how information is presented
* [[superlative]]: Saying that something is the best of something or has the most of some quality, e.g. the ugliest, the most precious etc.
* [[syllepsis]]: The use of a word in its figurative and literal sense at the same time ''or'' a single word used in relation to two other parts of a sentence although the word grammatically or logically applies to only one
* [[syncatabasis]] (condescension, accommodation): adaptation of style to the level of the audience
* [[:wiktionary:synchoresis|synchoresis]]: A concession made for the purpose of retorting with greater force.
* [[synecdoche]]: Form of [[metonymy]], referring to a part by its whole, or a whole by its part
* [[synesthesia]]: Description of one kind of sense impression by using words that normally describe another.
* [[tautology (rhetoric)|tautology]]: Superfluous repetition of the same sense in different words Example: The children gathered in a round circle
* [[transferred epithet]]: A synonym for [[hypallage]].
* [[truism]]: a self-evident statement
* [[tricolon|tricolon diminuens]]: Combination of three elements, each decreasing in size
* [[tricolon|tricolon crescens]]: Combination of three elements, each increasing in size
* verbal paradox: Paradox specified to language
* [[verba ex ore]]: Taking the words out of someone’s mouth, speaking of what the interlocutor wanted to say.
* [[verba volitans]]: A word that floats in the air, on which everyone is thinking and is just about to be imposed.<ref name="journalofadvancedrhetorics.wordpress.com"/>
* [[zeugma]]: Use of a single verb to describe two or more actions
* [[zoomorphism]]: Applying animal characteristics to humans or gods

== See also ==
{{Portal|Linguistics}}

* [[Figure of through]]
* [[Idiom]]
* [[List of forms of word play]]
* [[Repetition (rhetorical device)]]
* [[Rhetorical device]]
* [[Stylistic device]]

== References ==
{{wiktionary}}
{{Reflist}}

[[Category:Figures of speech| ]]
[[Category:Rhetoric]]

Captive portal

2016-05-11T12:46:34Z

Gotar: /* See also */ WiFiDog

{{Refimprove|date=February 2011}}
A '''captive portal''' is a special web page that is shown before using the [[Internet]] normally. The portal is often used to present a [[Logging (computer security)|login page]].<ref name=portal>[http://wiki.personaltelco.net/index.cgi/CaptivePortal CaptivePortal]</ref> This is done by intercepting most [[Packet (information technology)|packet]]s, regardless of address or port, until the user opens a browser and tries to access the web. At that time the browser is redirected to a web page which may require authentication and/or [[Payment gateway|payment]], or simply display an [[acceptable use policy]] and require the user to agree. Captive portals are used at many [[Hotspot (Wi-Fi)|Wi-Fi hotspots]], and can be used to control wired access (e.g. apartment houses, hotel rooms, business centers, "open" [[Ethernet]] jacks) as well.

Since the [[Logging (computer security)|login page]] itself must be presented to the client, either that login page is locally stored in the [[Gateway (computer networking)|gateway]], or the [[web server]] hosting that page must be "[[whitelist]]ed" via a [[closed platform]] to bypass the authentication process. Depending on the feature set of the gateway, multiple web servers can be whitelisted (say for [[iframe]]s or [[HTML element#Links and anchors|links]] within the login page). In addition to whitelisting the [[Uniform Resource Locator|URL]]s of web hosts, some gateways can whitelist [[TCP ports]]. The [[MAC address]] of attached clients can also be set to bypass the login process.

This technique has occasionally been referred to as UAM (Universal Access Method) in implementations and standards forums.

==Uses==

Captive portals are mainly used in wireless open networks, where the users are shown a welcome message informing them of the conditions of access (allowed ports, liability, etc.). Administrators tend to do this so that the own users take responsibility for their actions and to avoid any major problems. It is discussed whether this delegation of responsibility is legally valid.

Usually captive portals are used for marketing and commercial communication purposes. In order to do this, access to Internet is done via WIFI as an incentive to exchange personal data that the own user provides by filling out a registration form. This online form opens directly in a navigator configured from factory in the devices Internet access (smartphone, tablet, computer) or it appears when the user opens the navigator and tries to visit any webpage. In other words, the user is captive unable to navigate freely until he accepts the terms, legal conditions or sees the displayed advertisements that are shown in the registry form or welcome page.
This allows the provider of this service to display or send advertisements to the users who connect to the WIFI access point, this type of service is also known as social WIFI, as it usually asks for a social network account to login (Facebook), in order to disseminate the visit to a particular physical space in the digital world of social networks.

The user can find all types of content in the captive portal, and it's frequent to allow access to the Internet in exchange for viewing content or performing a previous action (data collection for commercial contact). In short, the marketing use of the captive portal is a tool for the lead generation (business contacts or potential clients).

Usually the users contact information (email/phone number) collected by the captive portal is used to send newsletters (emailing) or massive advertising campaigns (for example via SMS), generally these are poorly received by the users. There are advanced captive portals for marketing, like Seeketing,<ref>{{cite web|title=Seeketing|url=http://www.seeketing.com}}</ref> that automates and makes better use of the commercial data obtained through the captive portal in order to avoid spamming the user with constant e-mails and messages, even though these have been previously authorized when they filled out the online form. The reason these massive email and advertising campaigns are so poorly received by the users is because the communications they receive are done in an unsuitable time and place, with information that has little to no relevance to them.

The use of Seeketing advanced captive portal provides information on the visitors behavior located around the access point (or node), where you get to know if the visitor is recurrent or not, their average presence time in a specific area or what other areas they tend to go to (where other nodes exist) even if they have not yet been connected to the access point, at the same time it allows you to know if the users that have connected to the access point and the captive portal had browsed the website of any brand or company, in other words, provide information of the online behavior of those people that have previously registered. The nodes can send adverting messages (typically through SMS/whatsapp/email) to the registered visitors smartphone or tablets any time they get close to the access point, by proximity, that is to say at the appropriate time and place. Therefore, this isn't a newsletter or mass mailing, but a personalized message to each and everyone of your visitors, taking into consideration their tastes and observed behavior on the web or online store, and the observed behavior of that same device in the physical store (proximity).

Hence, the captive portal becomes a unique tool to generate high quality business contacts and automatically manage non-intrusive advertising messages. A basic captive portal only allows authorized Internet access to devices that connect to the access point, an advanced captive portal also provides offline behavior information (without being connected, only by being present in the close physical space) and online (when the user visits the website or online store even though they're no longer connected to the WIFI access point that they initially registered at). Furthermore, these advanced captive portals allow messages to be sent by proximity using information provided by the user at the moment of registration in the captive portal and taking into consideration their tastes and the users observed behavior.

==Implementation==

There is more than one way to implement a captive portal.

===ICMP redirect===

Client traffic can also be redirected using [[ICMP Redirect Message|ICMP redirect]] on the layer 3 level.

===Redirection by DNS===

When a client requests a website, [[Domain name system|DNS]] is queried by the browser. The firewall will make sure that only the DNS server(s) provided by DHCP can be used by unauthenticated clients (or, alternatively, it will forward all DNS requests by unauthenticated clients to that DNS server). This DNS server will return the IP address of the Captive Portal page as a result of all DNS lookups.

In order to perform redirection by DNS the captive portal is using [[DNS hijacking]] to perform a [[man-in-the-middle attack]]. To limit the impact of DNS poisoning typically a [[Time to live|TTL]] of 0 is used.

===Circumvention of captive portals===

Captive portals have been known to have incomplete firewall rule sets. In some deployments the rule set will route DNS requests from clients to the Internet, or the provided DNS server will fulfill arbitrary DNS requests from the client. This allows a client to bypass the captive portal and access the open Internet by [[Tunneling protocol|tunneling]] arbitrary traffic within DNS packets.

Some captive portals may be configured to allow appropriately equipped user agents to detect the captive portal and automatically authenticate. User agents and supplemental applications such as Apple's Captive Portal Assistant can sometimes transparently bypass the display of captive portal content against the wishes of the service operator as long as they have access to correct credentials, or they may attempt to authenticate with incorrect or obsolete credentials, resulting in unintentional consequences such as accidental account locking.

A captive portal that uses MAC addresses to track connected devices can sometimes be circumvented by connecting via hard-wire a router that allows setting of the router MAC address. Many router firmwares call this MAC cloning. Once a computer or tablet has been authenticated to the captive portal using a valid username and valid password, the MAC address of that computer or tablet can be entered into the router which will often continue to be connected through the captive portal as it shows to have the same MAC address as the computer or tablet that was previously connected.

==Limitations==
Some of these implementations merely require users to pass an [[Secure Sockets Layer|SSL]] encrypted login page, after which their [[Internet Protocol|IP]] and [[MAC address]] are allowed to pass through the [[Gateway (telecommunications)|gateway]]. This has been shown to be exploitable with a simple [[packet sniffer]]. Once the IP and MAC addresses of other connecting computers are found to be authenticated, any machine can spoof the MAC address and IP of the authenticated target, and be allowed a route through the gateway. For this reason some captive portal solutions created extended authentication mechanisms to limit the risk for usurpation.

Captive portals require the use of a browser; this is usually the first application that users start, but users who first use an email client or other will find the connection not working without explanation, and will need to open a browser to validate. A similar problem can occur if the client uses [[AJAX]] or joins the network with pages already loaded into its browser, causing undefined behavior when such a page tries HTTP requests to its origin server.

Platforms that have [[Wi-Fi]] and a [[TCP/IP stack]] but do not have a web browser that supports [[HTTPS]] cannot use many captive portals. Such platforms include the [[Nintendo DS]] running a game that uses [[Nintendo Wi-Fi Connection]]. Non-browser authentication is possible using [[WISPr]], an [[XML]]-based authentication protocol for this purpose, or MAC-based authentication or authentications based on other protocols.

It is also possible for a platform vendor to enter into a service contract with the operator of a large number of captive portal hotspots to allow free or discounted access to the platform vendor's servers via the hotspot's [[Walled garden (media)|walled garden]]. One such example is the 2005 deal between Nintendo and [[Wayport, Inc.|Wayport]] to provide free WiFi access to Nintendo DS users at certain [[McDonald's]] restaurants.<ref>{{cite web|title=Nintendo And Wayport Join Forces To Bring Free U.S. Wi-Fi Access To Nintendo DS Users|url=http://www.gamesindustry.biz/articles/nintendo-and-wayport-join-forces-to-bring-free-us-wi-fi-access-to-nintendo-ds-users|website=gamesindustry.biz|accessdate=24 November 2015}}</ref> Also, [[Voice over IP|VoIP]] [[Session Initiation Protocol|SIP]] ports could be allowed to bypass the gateway to allow phones to work.

== Captive Portal by Hardware ==

Following devices implements basic Captive Portal functionality:

* Cisco [http://web.archive.org/web/http://www.cisco.com/en/US/products/sw/netmgtsw/ps533/products_user_guide_book09186a0080126bfe.html BBSM-Hotspot]
* Cisco [http://www.cisco.com/en/US/tech/tk888/tk890/tsd_technology_support_protocol_home.html Site Selection Gateway (SSG)] / [http://www.cisco.com/en/US/products/hw/routers/ps314/products_data_sheet09186a0080091f30.html Subscriber Edge Services (SESM)]
* Nomadix [http://www.nomadix.com/products Gateway]
* Antamedia [http://web.archive.org/web/http://www.antamedia.com/es/hardware2/ Hotspot Gateway]
* Aptilo [http://web.archive.org/web/http://www.aptilo.com/solutions_public_access.htm Access Gateway]
* 4ipnet [http://web.archive.org/web/http://www.4ipnet.com/products_hotspot_gateway.htm Hotspot Gateway]
* Mikrotik [http://www.mikrotik.com/ RouterOS]

Following devices implements advanced Captive Portal capabilities:

* Seeketing Nodes [http://seeketing.com/]

==See also==
* [[HTTP proxy]]
* [http://developer.android.com/reference/android/net/CaptivePortal.html Android Captive Portal Setup]
* [[WiFiDog Captive Portal]]

==References==
<references/>

[[Category:Computer network security]]
[[Category:Web technology]]
[[Category:Wireless access points]]

Al Herpin

2010-10-24T13:37:03Z

Gotar: fairy tales removed from pl

{{Cleanup|date=June 2007}}
'''Al Herpin''' was known as the "Man Who Never Slept."<ref>{{cite book | url=http://books.google.ca/books?id=bL_1R7eYGJIC | title=Writing letters for the blind | author=Gary Fincke | authorlink=Gary Fincke | publisher=[[Ohio State University Press]] | year=2003 | page=11 | ISBN=0814209505 | accessdate=2009-08-19}}</ref>

Born in 1853 in, [[Trenton, New Jersey]],{{Contradiction-inline|date=August 2009}} Al Herpin claimed to have developed a rare case of [[insomnia]], whereby he could not [[sleep]]. The supposed cause is unknown, although it may be linked to his mother suffering a major injury a few days prior to his birth.

In the late 1940s, Al Herpin's claim attracted the attention of several medical professionals, who marched to his door one day. They found no bed, or other sleep-related furniture, but only a rocking chair. Herpin claimed that after a long day's work, he would rest in his rocking chair reading the newspaper until dawn, then return to work. He was in good health, and had a constant level of high awareness, defying all scientific understanding of the necessity for sleep.

A piece in the ''[[New York Times]]'' on February 29, 1904 reported that:
<blockquote>
Albert Herpin, born in France in 1862 and for fifteen years a hostler in the employ of Freeholder Walter Phares of this city, declares that he has not slept a wink during the past ten years. Notwithstanding this, he is in perfect health, and does not seem to suffer any discomfort from his remarkable condition.
</blockquote>

Al Herpin died on January 3, 1947 at the age of 94. His death saw another ''New York Times'' story more skeptical of his claim:

<blockquote>
Death came today for Alfred E. Herpin, a recluse who lived on the outskirts of the city and insisted that he never slept. He was 94 years old and, when questioned concerning his claim of "sleeplessness", maintained that he never actually dozed but merely "rested".

No other person with total insomnia has lived for such a long period of time. It was likely that he died for other reasons, not sleep deprivation, as his insomnia did not seem to have any effect on his health.
</blockquote>

==See also==
*[[Thai Ngoc]], Vietnamese insomniac, claimed to be awake for 34 years
*[[Sleep state misperception]]

==Notes==
{{reflist}}

==References==
* "Hasn't Slept in Ten Years; So Trenton Hostler Avers and Physicians Corroborate Him", ''[[New York Times]],'' February 29, 1904
* "Man Who Said He Never Slept Dies at 94; New Jersey Doctors Are Skeptical of Claim", ''New York Times,'' January 4, 1947.

{{DEFAULTSORT:Herpin, Al}}
[[Category:Sleep disorders]]
[[Category:People from Trenton, New Jersey]]
[[Category:1853 births]]
[[Category:1947 deaths]]