Other computer protection methods

Other computer protection methods

Beside antivirus software, virus infection prevention can be assisted by other means such as implementing a network firewall, or utilizing system virtualization^{[citation needed]}.

[edit] Antivirus Card

This method was used in the early 1990s by DOS users and involves the installation of an ISA interface card which takes over the DOS interrupt and monitors the WRITE operation.

[edit] Network Firewall

Network firewalls prevent unknown programs and Internet processes from accessing the system protected. However, they are not antivirus systems as such and thus make no attempt to identify or remove anything. They may protect against infection from outside the protected computer or LAN, and limit the activity of any malicious software which is present by blocking incoming or outgoing requests on certain TCP/IP ports. A firewall is designed to deal with broader system threats that come from network connections into the system and is not an alternative to a virus protection system.

[edit] System Virtualization

This method virtualizes the working system, which prevents the actual system from being altered by a virus as it stops any alteration attempts to the whole system under virtualization. Although this may in general be the case, infection may spread to the non-virtual system if the virus is so conceived that after infecting the virtual system, it will break (crack) the virtualization environment by using one of its exploits and then spread to the non-virtual environment.^{[citation needed]}

In general, without any antivirus software the virtual system can still be infected and suffer damage or malicious action, but as soon as the system is shut down and restarted, all the changes and damage previously done to the virtual system will be reset. This way, the system is protected and the virus is removed. However, any damages to unprotected or unvirtualized data will remain, as will the malicious effects it has caused such as data theft.^{[citation needed]}

Since not all virtualization software loads the virtual computer from a standard (unchangeable) boot image, in certain cases it works just as any real computer which has its own (virtual) hard disk, i.e. infection with a virus will have to be cured in order to disinfect the system, or the virtual system will have to be destroyed (deleted) in order to get rid of the damage. This is the case for VMware and VirtualPC, if there is set up a virtual computer with its own virtual hard disk. Virtualization software like Sandboxie may prevent infection from spreading to the main (non-virtual) system and then indeed the only damage made by the virus is data/identity theft, i.e. stealing the data which is made available by the non-virtual system to the virtual browsing/document processing environment. As mentioned before, if Sandboxie has exploits, a virus may use such exploits in order to infect the non-virtual environment.^{[citation needed]}

Effectiveness

Effectiveness

Studies in December 2007 have shown that the effectiveness of Antivirus software is much reduced from what it was a few years ago, particularly against unknown or zero day attacks. The German computer magazine c't found that detection rates for these threats had dropped from 40-50% in 2006 to 20-30% in 2007. At that time, the only exception was the NOD32 antivirus, which managed a detection rate of 68 percent.^[3]

The problem is magnified by the changing intent of virus authors. Some years ago it was obvious when a virus infection was present. The viruses of the day, written by amateurs, exhibited destructive behavior or pop-ups. Modern viruses are often written by professionals, financed by criminal organizations.^[22] It is not in their interests to make their viruses or crimeware evident, because their purpose is to create botnets or steal information for as long as possible without the user realizing. If an infected user has a less-than-effective antivirus product that says the computer is clean, then the virus may go undetected. Nowadays, viruses generally do not attempt to overwhelm the Internet by flooding. Instead, viruses take a more controlled approach, as damaging the vector of infection does not result in financial gain.

Traditional antivirus software solutions run virus scanners on schedule, on demand and some run scans in real time. If a virus or malware is located the suspect file is usually placed into a quarantine to terminate its chances of disrupting the system. Traditional antivirus solutions scan and compare against a publicised and regularly updated dictionary of malware otherwise known as a blacklist. Some antivirus solutions have additional options that employ an heuristic engine which further examines the file to see if it is behaving in a similar manner to previous examples of malware. A new technology utilized by a few antivirus solutions is whitelisting, this technology first checks if the file is trusted and only questioning those that are not.^[23] With the addition of wisdom of crowds, antivirus solutions backup other antivirus techniques by harnessing the intelligence and advice of a community of trusted users to protect each other. By providing these multiple layers of malware protection and combining them with other security software it is possible to have more effective protection from the latest zero day attack and the latest crimeware than previously was the case with just one layer of protection.

Privacy

Privacy

Some antivirus programs may be configured to automatically upload infected or suspicious files to the developer for further analysis. Care should be taking when deploying antivirus software to ensure that documents containing confidential or proprietary information are not sent to the product's developer without prompting the user.

[edit] Rogue security applications

Some antivirus programs are actually malware masquerading as antivirus software, such as WinFixer and MS Antivirus.^[18]

[edit] False positives

If an antivirus program is configured to immediately delete or quarantine infected files (or does this by default), false positives in essential files can render the operating system or some applications unusable.^[19]

[edit] System related issues

Running multiple antivirus programs concurrently can degrade performance and create conflicts.^[20] It is sometimes necessary to temporarily disable virus protection when installing major updates such as Windows Service Packs or updating graphics card drivers.^[21] Active antivirus protection may partially or completely prevent the installation of a major update.

Privacy

Privacy

Some antivirus programs may be configured to automatically upload infected or suspicious files to the developer for further analysis. Care should be taking when deploying antivirus software to ensure that documents containing confidential or proprietary information are not sent to the product's developer without prompting the user.

[edit] Rogue security applications

Some antivirus programs are actually malware masquerading as antivirus software, such as WinFixer and MS Antivirus.^[18]

[edit] False positives

If an antivirus program is configured to immediately delete or quarantine infected files (or does this by default), false positives in essential files can render the operating system or some applications unusable.^[19]

[edit] System related issues

Running multiple antivirus programs concurrently can degrade performance and create conflicts.^[20] It is sometimes necessary to temporarily disable virus protection when installing major updates such as Windows Service Packs or updating graphics card drivers.^[21] Active antivirus protection may partially or completely prevent the installation of a major update.

Issues of concern

Issues of concern

[edit] Performance

Some antivirus software can considerably reduce performance. Users may disable the antivirus protection to overcome the performance loss, thus increasing the risk of infection. For maximum protection, the antivirus software needs to be enabled all the time^{[citation needed]} — often at the cost of slower performance (see also software bloat).

[edit] Security

Antivirus programs can in themselves pose a security risk as they often run at the 'System' level of privileges and may hook the kernel — Both of these are necessary for the software to effectively do its job, however exploitation of the antivirus program itself could lead to privilege escalation and create a severe security threat. Arguably, use of antivirus software when compared to the principle of least privilege is largely ineffective when ramifications of the added software are taken into account.

[edit] Unexpected renewal costs

When purchasing antivirus software, the end-user license agreement may include a clause that the subscription will be automatically renewed, and the purchaser's credit card automatically billed, at the renewal time without explicit approval. For example, McAfee requires one to unsubscribe at least 60 days before the expiration of the present subscription.^[16] Norton Antivirus also renews subscriptions automatically by default.^[17]

Virus removal tools

Virus removal tools

A virus removal tool is software for removing specific viruses from infected computers. Unlike complete antivirus scanners, they are usually not intended to detect and remove an extensive list of viruses; rather they are designed to remove specific viruses, usually more effectively than normal antivirus software. Sometimes they are also designed to run in places that regular antivirus software can't. This is useful in the case of a severely infected computer. Examples of these tools include McAfee Stinger and the Microsoft Windows Malicious Software Removal Tool (which is run automatically by Windows update).

Heuristics

Heuristics

Some more sophisticated antivirus software uses heuristic analysis to identify new malware or variants of known malware. Three methods are used: file analysis, file emulation, and generic signatures.^{[citation needed]}

File analysis is the process by which antivirus software will analyze the instructions of a program. Based on the instructions, the software can determine whether or not the program is malicious. For example, if the file contains instructions to delete important system files, the file might be flagged as a virus. While this method is useful for identifying new viruses and variants, it can trigger many false positives.^{[citation needed]}

The second heuristic approach is file emulation, which runs the target file in a virtual system environment, separate from the real system environment. The antivirus software would then log what actions the file takes in the virtual environment. If the actions are found to be damaging or malicious, the file may be marked a virus. But again, this method can trigger false positives.^{[citation needed]}

Another type of heuristics is generic signatures.^{[citation needed]}

Many viruses start as a single infection and through either mutation or refinements by other attackers, can grow into dozens of slightly different strains, called variants. Generic detection refers to the detection and removal of multiple threats using a single virus definition. ^[12]

For example, the Vundo trojan has several family members, depending on the antivirus vendor's classification. Symantec classifies members of the Vundo family into two distinct members, Trojan.Vundo and Trojan.Vundo.B.^[13][14]

While it may be advantageous to identify a specific virus, it can be quicker to detect a virus family through a generic signature or through an inexact match to an existing signature. Virus researchers find common areas that all viruses in a family share uniquely and can thus create a single generic signature. These signatures often contain non-contiguous code, using wildcard characters where differences lie. These wildcards allow the scanner to detect viruses even if they are padded with extra, meaningless code. ^[15] Padded code is used to confuse the scanner so it can't recognize the threat.

A detection that uses this method is said to be "heuristic detection."

Suspicious behavior monitoring

Suspicious behavior monitoring

The suspicious behavior approach does not attempt to identify known viruses, but instead monitors the behavior of all programs. If one program tries to write data to an executable program, for example, the antivirus software can flag this suspicious behavior, alert a user and ask what to do.^{[citation needed]}

The suspicious behavior approach provides protection against zero day viruses that are not yet in the dictionary. However, it can also sound a large number of false positives and users may become desensitized to the warnings. This problem has worsened since 1997, since many more non-malicious program designs came to modify other executablea without regard to this false positive issue. In recent years, however, sophisticated behaviour analysis has emerged, which analyzes processes and calls to the kernel in context before making a decision, which gives it a lower false positive rate than rules-based behavior monitoring.^{[citation needed]}

Signature based detection

Signature based detection

Traditionally, antivirus software heavily relied upon signatures to identify malware. This can be very effective, but cannot defend against malware unless samples have already been obtained and signatures created. Because of this, signature-based approaches are not effective against new, unknown viruses.

When antivirus software scans a file for viruses, it checks the contents of a file against a dictionary of virus signatures. A virus signature is the viral code. If a virus signature is found in a file the antivirus software can resort to some combination of quarantine, repair or deletion. Quarantining a file will make it inaccessible, and is usually the first action antivirus software will take if a malicious file is found. Encrypting the file is a good quarantining technique because it renders the file useless without the encryption key.^{[citation needed]}

Sometimes a user wants to save the content of an infected file because viruses can sometimes embed themselves in files, called code injection, and the file may be essential to normal operation. To do this, antivirus software will attempt to repair the file. To do this, the software will try to remove the viral code from the file. Unfortunately, some viruses might damage the file upon injection.^{[citation needed]}

If a file repair operation fails, usually the best thing to do is to just delete the file. Deleting the file is necessary if the entire file is infected.^{[citation needed]} This may be necessary in the case of infected ZIP files, or similar "packed" files.

Because new viruses are being created each day, the signature-based detection approach requires frequent updates of the virus signature dictionary. To assist the antivirus software companies, the software may allow the user to upload new viruses or variants to the company, allowing the virus to be analyzed and the signature added to the dictionary.^[9]

Signature-based antivirus software typically examines files when the computer's operating system creates, opens, closes, or e-mails them. In this way it can detect a known virus immediately upon receipt. System administrators can schedule antivirus software to scan all files on the computer's hard disk at a set time and date.^{[citation needed]}

Although the signature-based approach can effectively contain virus outbreaks, virus authors have tried to stay a step ahead of such software by writing "oligomorphic", "polymorphic" and, more recently, "metamorphic" viruses, which encrypt parts of themselves or otherwise modify themselves as a method of disguise, so as to not match virus signatures in the dictionary.^[11]

An emerging technique to deal with malware in general is whitelisting. Rather than looking for only known bad software, this technique prevents execution of all computer code except that which has been previously identified as trustworthy by the system administrator. By following this "default deny" approach, the limitations inherent in keeping virus signatures up to date are avoided. Additionally, computer applications that are unwanted by the system administrator are prevented from executing since they are not on the whitelist. Since organisations often have large quantities of trusted applications, the limitations of adopting this technique rests with the system administrators' ability to properly inventory and maintain the whitelist of trusted applications. Viable implementations of this technique include tools for automating the inventory and whitelist maintenance processes.^{[citation needed]}

Identification methods

Identification methods

ClamWin 0.95.1 running on Windows XP

There are several methods which antivirus software can use to identify malware.

Signature based detection is the most common method. To identify viruses and other malware, antivirus software compares the contents of a file to a dictionary of virus signatures. Because viruses can embed themselves in existing files, the entire file is searched, not just as a whole, but also in pieces.^[9]

Malicious activity detection is another approach used to identify malware. In this approach, antivirus software monitors the system for suspicious program behavior. If suspicious behavior is detected, the suspect program may be further investigated, using signature based detection or another method listed in this section. This type of detection can be used to identify unknown viruses or variants on existing viruses.^{[citation needed]}

Heuristic-based detection, like malicious activity detection, can be used to identify unknown viruses. This can be accomplished in one of two ways: file analysis and file emulation.^{[citation needed]}

File analysis is the process of searching a suspect file for virus-like instructions. For example, if a program has instructions to reformat the C drive, the antivirus software might further investigate the file. One downside of this feature is the large amount of computer resources needed to analyse every file, resulting in slow operation.^{[citation needed]}

File emulation is another heuristic approach. File emulation involves executing a program in a virtual environment and logging what actions the program performs. Depending on the actions logged, the antivirus software can determine if the program is malicious or not and then carry out the appropriate disinfection actions.^[10]

Identification methods

Identification methods

ClamWin 0.95.1 running on Windows XP

There are several methods which antivirus software can use to identify malware.

Signature based detection is the most common method. To identify viruses and other malware, antivirus software compares the contents of a file to a dictionary of virus signatures. Because viruses can embed themselves in existing files, the entire file is searched, not just as a whole, but also in pieces.^[9]

Malicious activity detection is another approach used to identify malware. In this approach, antivirus software monitors the system for suspicious program behavior. If suspicious behavior is detected, the suspect program may be further investigated, using signature based detection or another method listed in this section. This type of detection can be used to identify unknown viruses or variants on existing viruses.^{[citation needed]}

Heuristic-based detection, like malicious activity detection, can be used to identify unknown viruses. This can be accomplished in one of two ways: file analysis and file emulation.^{[citation needed]}

File analysis is the process of searching a suspect file for virus-like instructions. For example, if a program has instructions to reformat the C drive, the antivirus software might further investigate the file. One downside of this feature is the large amount of computer resources needed to analyse every file, resulting in slow operation.^{[citation needed]}

File emulation is another heuristic approach. File emulation involves executing a program in a virtual environment and logging what actions the program performs. Depending on the actions logged, the antivirus software can determine if the program is malicious or not and then carry out the appropriate disinfection actions.^[10]

History of Antivirus

History

See also: Timeline of notable computer viruses and worms

There are competing claims for the innovator of the first antivirus product. Possibly the first publicly documented removal of a computer virus in the wild was performed by Bernt Fix in 1987.^[4][5]

ClamTk 4.08 virus scanner running on Ubuntu 9.04

An antivirus program to counter the Polish MKS vir was released in 1987. Dr. Solomon's Anti-Virus Toolkit, AIDSTEST and AntiVir were released by in 1988. Dr. Ahn Chul Soo (Charles Ahn, founder of AhnLab Inc) in South Korea also released the Anti-Virus software called 'Vaccine Ⅰ' in June 10, 1988^{[citation needed]}. By late 1990, nineteen separate antivirus products were available including Norton AntiVirus and McAfee VirusScan.^{[citation needed]} Early contributors to work on computer viruses and countermeasures included Fred Cohen, Peter Tippett, John McAfee and Ahn Chul Soo.

Before Internet connectivity was widespread, viruses were typically spread by infected floppy disks. Antivirus software came into use, but was updated relatively infrequently. During this time, virus checkers essentially had to check executable files and the boot sectors of floppy and hard disks. However, as internet usage became common, initially through the use of modems, viruses spread throughout the Internet.^[6]

Powerful macros used in word processor applications, such as Microsoft Word, presented a further risk. Virus writers started using the macros to write viruses embedded within documents. This meant that computers could now also be at risk from infection by documents with hidden attached macros as programs.^[7]

Later email programs, in particular Microsoft Outlook Express and Outlook, were vulnerable to viruses embedded in the email body itself. Now, a user's computer could be infected by just opening or previewing a message. This meant that virus checkers had to check many more types of files. As always-on broadband connections became the norm and more and more viruses were released, it became essential to update virus checkers more and more frequently. Even then, a new zero-day virus could become widespread before antivirus companies released an update to protect against it.^[8]

Antivirus software

ClamTk 3.08 free antivirus software running on Ubuntu 8.04 Hardy Heron

Antivirus (or anti-virus) software is used to prevent, detect, and remove malware, including computer viruses, worms, and trojan horses. Such programs may also prevent and remove adware, spyware, and other forms of malware.

A variety of strategies are typically employed. Signature-based detection involves searching for known malicious patterns in executable code. However, it is possible for a user to be infected with new malware in which no signature exists yet. To counter such so called zero-day threats, heuristics can be used. One type of heuristic approach, generic signatures, can identify new viruses or variants of existing viruses for looking for known malicious code (or slight variations of such code) in files. Some antivirus software can also predict what a file will do if opened/run by emulating it in a sandbox and analyzing what it does to see if it performs any malicious actions. If it does, this could mean the file is malicious.

However, no matter how useful antivirus software is, it can sometimes have drawbacks. Antivirus software can degrade computer performance if it is not designed efficiently. Inexperienced users may have trouble understanding the prompts and decisions that antivirus software presents them with. An incorrect decision may lead to a security breach. If the antivirus software employs heuristic detection (of any kind), the success of it is going to depend on whether it achieves the right balance between false positives and false negatives. False positives can be as destructive as false negatives. In one case, a faulty virus signature issued by Symantec mistakenly removed essential operating system files, leaving thousands of PCs unable to boot.^[1] Finally, antivirus software generally runs at the highly trusted kernel level of the operating system, creating a potential avenue of attack^[2]

In addition to the drawbacks mentioned above, the effectiveness of antivirus software has also been researched and debated. One study found that the detection success of major antivirus software dropped over a one-year period.^[3]

Notes on Computer

Notes

1. ^ In 1946, ENIAC required an estimated 174 kW. By comparison, a modern laptop computer may use around 30 W; nearly six thousand times less. "Approximate Desktop & Notebook Power Usage". University of Pennsylvania. http://www.upenn.edu/computing/provider/docs/hardware/powerusage.html. Retrieved on 2009-06-20.
2. ^ Early computers such as Colossus and ENIAC were able to process between 5 and 100 operations per second. A modern "commodity" microprocessor (as of 2007) can process billions of operations per second, and many of these operations are more complicated and useful than early computer operations. {{cite web |url=http://www.intel.com/cd/channel/reseller/asmo-na/eng/products/mobile/processors/core2duo_m/feature/index.htm |title=Intel® Core™2 Duo Mobile Processor: Features |publisher=Intel Corporation |accessdate=2009-06-20
3. ^ computer, n., Oxford English Dictionary (2 ed.), Oxford University Press, 1989, http://dictionary.oed.com/, retrieved on 2009-04-10
4. ^ "Heron of Alexandria". http://www.mlahanas.de/Greeks/HeronAlexandria2.htm. Retrieved on 2008-01-15.
5. ^ ^{a b} Ancient Discoveries, Episode 11: Ancient Robots, History Channel, http://www.youtube.com/watch?v=rxjbaQl0ad8, retrieved on 2008-09-06
6. ^ Howard R. Turner (1997), Science in Medieval Islam: An Illustrated Introduction, p. 184, University of Texas Press, ISBN 0-292-78149-0
7. ^ Donald Routledge Hill, "Mechanical Engineering in the Medieval Near East", Scientific American, May 1991, pp. 64-9 (cf. Donald Routledge Hill, Mechanical Engineering)
8. ^ The analytical engine should not be confused with Babbage's difference engine which was a non-programmable mechanical calculator.
9. ^ Columbia University Computing History: Herman Hollerith
10. ^ http://www.time.com/time/time100/scientist/profile/turing.html
11. ^ "Inventor Profile: George R. Stibitz". National Inventors Hall of Fame Foundation, Inc.. http://www.invent.org/hall_of_fame/140.html.
12. ^ B. Jack Copeland, ed., Colossus: The Secrets of Bletchley Park's Codebreaking Computers, Oxford University Press, 2006
13. ^ Lavington 1998, p. 37
14. ^ This program was written similarly to those for the PDP-11 minicomputer and shows some typical things a computer can do. All the text after the semicolons are comments for the benefit of human readers. These have no significance to the computer and are ignored. (Digital Equipment Corporation 1972)
15. ^ Attempts are often made to create programs that can overcome this fundamental limitation of computers. Software that mimics learning and adaptation is part of artificial intelligence.
16. ^ It is not universally true that bugs are solely due to programmer oversight. Computer hardware may fail or may itself have a fundamental problem that produces unexpected results in certain situations. For instance, the Pentium FDIV bug caused some Intel microprocessors in the early 1990s to produce inaccurate results for certain floating point division operations. This was caused by a flaw in the microprocessor design and resulted in a partial recall of the affected devices.
17. ^ Even some later computers were commonly programmed directly in machine code. Some minicomputers like the DEC PDP-8 could be programmed directly from a panel of switches. However, this method was usually used only as part of the booting process. Most modern computers boot entirely automatically by reading a boot program from some non-volatile memory.
18. ^ However, there is sometimes some form of machine language compatibility between different computers. An x86-64 compatible microprocessor like the AMD Athlon 64 is able to run most of the same programs that an Intel Core 2 microprocessor can, as well as programs designed for earlier microprocessors like the Intel Pentiums and Intel 80486. This contrasts with very early commercial computers, which were often one-of-a-kind and totally incompatible with other computers.
19. ^ High level languages are also often interpreted rather than compiled. Interpreted languages are translated into machine code on the fly by another program called an interpreter.
20. ^ The control unit's role in interpreting instructions has varied somewhat in the past. Although the control unit is solely responsible for instruction interpretation in most modern computers, this is not always the case. Many computers include some instructions that may only be partially interpreted by the control system and partially interpreted by another device. This is especially the case with specialized computing hardware that may be partially self-contained. For example, EDVAC, one of the earliest stored-program computers, used a central control unit that only interpreted four instructions. All of the arithmetic-related instructions were passed on to its arithmetic unit and further decoded there.
21. ^ Instructions often occupy more than one memory address, so the program counters usually increases by the number of memory locations required to store one instruction.
22. ^ David J. Eck (2000). The Most Complex Machine: A Survey of Computers and Computing. A K Peters, Ltd.. p. 54. ISBN 9781568811284.
23. ^ Erricos John Kontoghiorghes (2006). Handbook of Parallel Computing and Statistics. CRC Press. p. 45. ISBN 9780824740672.
24. ^ Flash memory also may only be rewritten a limited number of times before wearing out, making it less useful for heavy random access usage. (Verma 1988)
25. ^ Donald Eadie (1968). Introduction to the Basic Computer. Prentice-Hall. p. 12.
26. ^ Arpad Barna; Dan I. Porat (1976). Introduction to Microcomputers and the Microprocessors. Wiley. p. 85. ISBN 9780471050513.
27. ^ Jerry Peek; Grace Todino, John Strang (2002). Learning the UNIX Operating System: A Concise Guide for the New User. O'Reilly. p. 130. ISBN 9780596002619.
28. ^ Gillian M. Davis (2002). Noise Reduction in Speech Applications. CRC Press. p. 111. ISBN 9780849309496.
29. ^ However, it is also very common to construct supercomputers out of many pieces of cheap commodity hardware; usually individual computers connected by networks. These so-called computer clusters can often provide supercomputer performance at a much lower cost than customized designs. While custom architectures are still used for most of the most powerful supercomputers, there has been a proliferation of cluster computers in recent years. (TOP500 2006)
30. ^ Agatha C. Hughes (2000). Systems, Experts, and Computers. MIT Press. p. 161. ISBN 9780262082853. "The experience of SAGE helped make possible the first truly large-scale commercial real-time network: the SABRE computerized airline reservations system..."
31. ^ "A Brief History of the Internet". Internet Society. http://www.isoc.org/internet/history/brief.shtml. Retrieved on 2008-09-20.
32. ^ Most major 64-bit instruction set architectures are extensions of earlier designs. All of the architectures listed in this table, except for Alpha, existed in 32-bit forms before their 64-bit incarnations were introduced.

Networking and the Internet

Networking and the Internet

Main articles: Computer networking and Internet

Visualization of a portion of the routes on the Internet.

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.^[30]

In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET.^[31] The technologies that made the Arpanet possible spread and evolved.

In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

Software

Software

Main article: Computer software

Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called "firmware" to indicate that it falls into an uncertain area somewhere between hardware and software.

Computer software

Operating system	Unix and BSD	UNIX System V, AIX, HP-UX, Solaris (SunOS), IRIX, List of BSD operating systems
	GNU/Linux	List of Linux distributions, Comparison of Linux distributions
	Microsoft Windows	Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Vista, Windows CE
	DOS	86-DOS (QDOS), PC-DOS, MS-DOS, FreeDOS
	Mac OS	Mac OS classic, Mac OS X
	Embedded and real-time	List of embedded operating systems
	Experimental	Amoeba, Oberon/Bluebottle, Plan 9 from Bell Labs
Library	Multimedia	DirectX, OpenGL, OpenAL
	Programming library	C standard library, Standard template library
Data	Protocol	TCP/IP, Kermit, FTP, HTTP, SMTP
	File format	HTML, XML, JPEG, MPEG, PNG
User interface	Graphical user interface (WIMP)	Microsoft Windows, GNOME, KDE, QNX Photon, CDE, GEM
	Text-based user interface	Command-line interface, Text user interface
Application	Office suite	Word processing, Desktop publishing, Presentation program, Database management system, Scheduling & Time management, Spreadsheet, Accounting software
	Internet Access	Browser, E-mail client, Web server, Mail transfer agent, Instant messaging
	Design and manufacturing	Computer-aided design, Computer-aided manufacturing, Plant management, Robotic manufacturing, Supply chain management
	Graphics	Raster graphics editor, Vector graphics editor, 3D modeler, Animation editor, 3D computer graphics, Video editing, Image processing
	Audio	Digital audio editor, Audio playback, Mixing, Audio synthesis, Computer music
	Software Engineering	Compiler, Assembler, Interpreter, Debugger, Text Editor, Integrated development environment, Performance analysis, Revision control, Software configuration management
	Educational	Edutainment, Educational game, Serious game, Flight simulator
	Games	Strategy, Arcade, Puzzle, Simulation, First-person shooter, Platform, Massively multiplayer, Interactive fiction
	Misc	Artificial intelligence, Antivirus software, Malware scanner, Installer/Package management systems, File manager

Free Software Movement

Free Software Movement

Main article: Free software movement

This section may contain original research or unverified claims. Please improve the article by adding references. See the talk page for details. (July 2008)

There is more than one approach to creating, licensing, and distributing software. For instance, the free software (or open source) community produces software under licensing that makes it free for inspection of its code, modification of its code, and distribution. While the software released under an open source license (such as General Public License, or GPL for short) can be sold for money,^[9] the distribution cannot be restricted in the same way as software with copyright and patent restrictions (used by corporations to require licensing fees).

While some advocates of free software use slogans such as "information wants to be free," hinting that it is easy to copy digital data and that the licenses (enforced through laws) are unnatural restrictions, other creators and users of open source software recognize it to be one model among many for software creation, licensing, and distribution. And the laws themselves are put into place for the ostensible purpose of increasing creative output, by allowing the creators to control and profit most effectively from their intellectual property.

Industry and organizations

Industry and organizations

Main article: Software industry

Software has its own niche industry that is called the software industry made up of different entities and peoples that produce software, and as a result there are many software companies and programmers in the world. Because software is increasingly used in many different areas like in finance, searching, mathematics, space exploration, gaming and mining and such, software companies and people usually specialize in certain areas. For instance, Electronic Arts primarily creates video games.

Also selling software can be quite a profitable industry. For instance, Bill Gates, the founder of Microsoft is the second richest man in the world in 2008 largely by selling the Microsoft Windows and Microsoft Office software programs. The same goes for Larry Ellison, largely through his Oracle database software.

There are also many non-profit software organizations like the Free Software Foundation, GNU Project, Mozilla Foundation. Also there are many software standard organizations like the W3C, IETF and others that try to come up with a software standard so that many software can work and interoperate with each other like through standards such as XML, HTML, HTTP or FTP.

Some of the well known software companies include Microsoft, Apple, IBM, Oracle, Novell, SAP and HP.