Linux Project Professor: Glen Gray Department of Information Systems is 311 tth 3: 30 4: 45 pm

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Linux Project

Professor: Glen Gray

Department of Information Systems

IS 311 TTh 3:30 - 4:45 PM

Luis E Solis
Charles Chong

Dina Rodriguez

Shreejana Singh

Himanshu Kathuria


The development and growth of the Linux operating system parallels that of the personal computer and the Internet. The growth of the personal computer was made possible by the use of open architecture standards. That is hardware specifications were not proprietary to any specific vendor. Therefore many vendors develop and produce the same components for the PC. As a result of this competition the cost of the PC was greatly reduced due to economies of scale. Linux is yet another operating system. It is significant because its design and development are driven by the needs of those who use it, not a commercial entity driven by its own monetary gain. Linux is rooted in the community of software developers dedicated to producing a quality operating system. The human readable instructions that realize the Linux operating system are freely available. These instructions are collectively called source code. This makes Linux and open source operating system. It is the antithesis of the proprietary model that most mainstream operating systems follow. Linux is licenses under the GNU General Public Licenses (GPL). This ensures that the source code will always be freely available to anyone wants it

TCP/IP and the Internet

The TCP/IP protocol is the communication conventions that the Internet uses to connect or internetwork different hardware technologies. The internet technology hides the details of network hardware, and permits computers to communicate independent of their physical network connections. The internet technology is an example of open system inter-connection. It is called open because, unlike proprietary communication systems available from one specific vendor, the specifications are publicly available. The entire technology has been designed to facilitate communication among machines with diverse hardware architectures, to use almost any network hardware, to accommodate a wide variety of applications, and to accommodate multiple computer operating systems. The TCP/IP protocol allows us to discuss computer communication independent of any particular vendor’s network hardware. Programmers do not need to build a special version of application software for each type of computer or each type of network. Instead, software built to use TCP/IP is general-purpose; the same code can be compiled and run on an arbitrary computer. The University of California’s Berkeley Software Distribution, commonly called Berkeley UNIX was the first to incorporate and implements TCP/IP protocols and utilities for network services that resembled the UNIX services used on a single machine for use with UNIX operating system. The original UNIX was first developed in 1969 when minicomputers and mainframe computers were the norm in the corporate world. UNIX is the basic operating system of which there are different versions from different vendors such as Sun Microsystems or Hewlett-Packard.

Open Source Linux
Because the specifications of the Internet was publicly available, the Internet is one of the most successful open source, open protocol projects. It is the success of the Internet that makes it possible in 1991 for Linus Torvalds a college student to use the Internet in a collaborative fashion to develop and release the kernel of the Linux operating system. At the University of Helsinki Torvalds was running the Unix-like operating system Minix on his 386 computer. Minix was written from scratch by Andrew S. Tanenbaum, a Dutch professor who wanted to teach his students the inner workings of a real operating system. It was designed to run on the Intel 8086 microprocessors that had flooded the world market. Unhappy with some of the limitations of Minix and fueled by the desire to explore low level hardware programming Torvalds began to develop his own operating system. Richard Stallman and the free software foundation also began work on an alternative operating system in the mid-1980s. In 1990 they had develop functional alternatives to every major UNIX component except for the kernel. The combined work of Torvalds and Stallman became the Linux we know today. The Linux is a clone of the UNIX operating system and does not contain any proprietary UNIX code. Since the Internet was mostly created and implemented on UNIX-based computers many of the products and software components available on the UNIX are also used in Linux. Linux models the UNIX operating system in many respects. It strives to be POSIX compliant, the open standard used to maintain compatibility with various versions of UNIX. It was therefore easy to port TCP/IP over to Linux making this operating system very Internet friendly. Trovalds and Stallman made the source code of the operating system freely available over the Internet so other programmers can collaborate, modify and improve the program. Since all the Internet protocols are supported the Internet community quickly embraced and developed Linux into an Internet aware operating system. Linux has an official mascot, the Linux Penguin, which was selected by Linus Torvalds to represent the image he associates with the operating system he created. Please see timeline figure 1.

Linus Torvalds

The Linux operating system

Operating system is a generic term that is used to describe several families of systems. In a single task system only one program may be run at a time, and therefore only one person may work on the machine at one time. However, the process may use the whole of the resources and power of the computer unit. In multi-task systems several processes can be executed in parallel. Operating time is cut into small intervals and each process is executed during these short periods. In order to have efficient execution of these processes complex prioritization and scheduling algorithms are used to ensure optimum sharing between the processes. The system may be multi-user as well as multiprocessor.

Linux is a member for large family of UNIX like operating system. The Linux operating system is composed of the operating system kernel and a base set of utilities and scripts. The kernel is the heart of the operating system and is responsible for managing the system hardware. The base set of system programs, utilities, and scripts helps the kernel perform its task and provide basic user functionality. With the standard kernel model the entire kernel and the base set of programs are loaded into memory when the computer boots. However the Linux kernel can dynamically load and unload some portion of the kernel code (for example device drivers) called the modules into memory. This is the reason why Linux is very fast and uses memory very efficiently. Please see figure 2. A module is an object file was code can be linked to (and unlinked from) the kernel at runtime. The object code usually consists of a set of functions that implements a file system, a device driver, or other features at the kernel's upper of layer. Modules are easy to develop and do not depend on a fix hardware platform. For example, a disk drive module that relies on the SCSI standard works as well on an IBM compatible PC as a does on a Compaq's Alpha. UNIX and Linux differ from other operating systems in that it was developed in the C high-level programming language. The use of a high-level language has allowed the porting of the system to several different machine types. Therefore porting Linux to other computers only requires adapting that part of the code which is machine specific. So architecture independent modules may be reused.

Figure 2.

Multitasking operation

Linux is a clone of UNIX therefore most of the features of UNIX are available to the user. Linux is preemptive, multitasking so it is capable of running a large number of simultaneous applications at the same time. Please see figure 3. So programs A, B and C can all the running the same time. On a single CPU system multitasking that creates the appearance of simultaneous activity by switching rapidly between tasks as the demands for those processes dictate. This is in contrast to cooperative multitasking operating systems, such as Windows 3.1. With a cooperative multitasking operating system, each application is responsible to yield processor time. So if an application never yields, of applications will not receive any processor time. Linux also support computers with multiple processors, such as dual Pentium III systems. The systems can in fact perform two actions at exactly the same time. Combination of multitasking with multiple processors greatly increased the number of simultaneous applications of computer can run smoothly.

Multi-user operation

Linux is also a multi-user operating system. Linux allows multiple simultaneous users to be loved on the one machine and to utilize its services. The great advantage of this is that Linux can be deployed as an application server. Desktop users or terminals can log onto a Linux server across a local area network and run applications on the server instead of their desktop PC.

Figure 3.

Virtual memory

Linux supports the concept virtual memory. By using a dedicated portion of a machine’s hard drive, called the swap partition, the operating system swaps pages in and out of the swap space as required. To Linux and any running applications, the machine appears to have more physical memory than what actually exist. This of course, comes at a costs which is the reading and writing to the hard drive.

Linux Today

UNIX and its clones have a history of being very difficult to learn, install and support. However the latest versions overcome these obstacles making it very user-friendly. Linux has all the features found in today's modern operating system. Linux is very stable and seldom crashes or locks up. The architecture of Linux is such that a normal user application cannot corrupt the system. Linux is fast and manages system resources very efficiently. Linux users can measures uninterrupted run time of their computers in months or even years. Linux runs on almost every major computing platform in existence including Intel, Macintosh, PowerPC, Amiga, Atari, Sun Sparc, DEC Alpha, ARM, and others. While Linux is being scaled up to support high-end servers with extended symmetric multiprocessing demand, it is also being scaled down to the embedded system level. There are versions of Linux that runs on PDAs and also supercomputers.

Features of Linux:

  • Multitasking: several programs running at the same time.

  • Multi-user: several users on the same machine at the same time (and no two-user licenses!).

  • Multiplatform: runs on many different CPUs, not just Intel.
  • Multiprocessor: SMP support is available on the Intel and SPARC platforms (with work currently in progress on other platforms), and Linux is used in several loosely-coupled MP applications, including Beowulf systems and the Fujitsu AP1000+ SPARC-based supercomputer.

  • Multithreading: has native kernel support for multiple independent threads of control within a single process memory space.

  • Has memory protection between processes, so that one program can't bring the whole system down.

  • Demand loads executables: Linux only reads from disk those parts of a program that are actually used.

  • Virtual memory using paging (not swapping whole processes) to disk: allowing you to use more memory than is physically available in your computer.

  • A unified memory pool for user programs and disk cache, so that all free memory can be used for caching, and the cache can be reduced when running large programs.

  • Dynamically linked shared libraries (DLL’s) and static libraries too, of course.

  • Mostly compatible with POSIX, System V, and BSD at the source level.

  • Through an iBCS2-compliant emulation module, mostly compatible with SCO, SVR3, and SVR4 at the binary level.

  • All source code is available, including the whole kernel and all drivers, the development tools and all user programs; also, all of it is freely distributable. Plenty of commercial programs are being provided for Linux without source, but everything that has been free, including the entire base operating system, is still free.

  • POSIX job control.

  • Pseudo-terminals (pty's).

  • 387-emulation in the kernel so that programs don't need to do their own math emulation. Every computer running Linux appears to have a math coprocessor. Of course, if your computer already contains an FPU, it will be used instead of the emulation, and you can even compile your own kernel with math emulation removed, for a small memory gain.
  • Support for many national or customized keyboards, and it is fairly easy to add new ones dynamically.

  • Multiple virtual consoles: several independent login sessions through the console, you switch by pressing a hot-key combination (not dependent on video hardware). These are dynamically allocated; you can use up to 64.

  • Supports a large number of file-systems including:

    • Minix

    • HFS (Macintosh)

    • ISO 9660 (CDROM) with rockridge and/or Joliet extensions

    • MS-DOS FAT and VFAT

    • UFS (Berkeley Fast File System)

    • Amiga FFS

    • Read-only HPFS (OS/2)

  • TCP/IP networking, including ftp, telnet, NFS, etc.

  • AppleTalk server

  • Netware client and server

  • LAN Manager/Windows Native (SMB) client and server

  • Many networking protocols: the base protocols available in the latest development kernels include TCP, IPv4, IPv6, AX.25, X.25, IPX, DDP (AppleTalk), Netrom, and others. Stable network protocols included in the stable kernels currently include TCP, IPv4, IPX, DDP, and AX.25.

Why use or recommend Linux?
Even though Linux is growing in popularity every day, one question remains in the mind of many people, “why if Linux is more powerful and less expensive than Windows not every company is using it.” Well, the fact is that a lot of companies are using it and a lot more are thinking about switching to Linux in the near future. Nonetheless, questions like the former illustrate a common attitude in the general public towards Linux. This attitude can be traced to a very specific number of factors, all of which involve misinformation. These misconceptions are addressed in the next paragraphs.

Let's begin by mentioning current events related to the adoption of Linux by the major corporations. In January 29, 2002, IBM the world's leading server company and information technology provider, with 80 years of leadership in helping businesses innovate, announced in New York that it had nearly recouped the $1 billion it invested in the Linux OS in 2001. During that year IBM spent money on tasks such as bringing the UNIX clone to its full line of servers, bringing its broad software portfolio to Linux, training its services and consulting personnel, and placing advertisements such as full-page ads in major daily newspapers. Bill Zeitler, head of the server group, said in an interview before his keynote speech Wednesday at the "Linux World Conference and Expo" We think it was money well spent. Almost all of it, we got back." IBM is taking more advantage of Linux and the open-source movement than any of their competitors.
IBM's support of Linux has succeeded in drowning out rival server companies with substantial support with its backing of Linux. IBM has probably placed itself in the first tier. Hewlett-Packard is probably second along with SGI followed closely by. Sun has done a lot for the open-source community, but they somehow always say something in a way that would offend the open-source community. IBM unquestionably has heavy support for Linux, most recently exemplified by its Linux-only mainframe that will go on sale in March after more than two years of effort getting the software working on the high-end, old-guard servers.

IBM has lured some prestigious customers along the way. E*Trade is moving to a Linux-only operation, starting with IBM Intel servers that replace Sun Microsystems systems, Zeitler said. Digital-animation studio Pixar is replacing the SGI machines used to animate "Toy Story 2" and "Monsters, Inc.," with IBM Linux workstations, Zeitler said. HP also has been working to woo similar customers and will announce more than one in the near future, said Terry Brown, HP's manager of entertainment industry solutions. "We've been developing some key technology for this industry for more than two years now," he said. "It's good to see that other manufacturers are entering the market."

Linux forms the basis of a major push at IBM called "grid computing," servers and storage systems linked into a seamless network of computing power. Higher-level software on the grid makes sure the right computing power is allocated to the right computer users. IBM's grid push includes Linux and is built atop software protocols it's developing with the Globus Project, which shares the nonproprietary open-source development philosophy at the heart of Linux.

Open initiatives such as grid computing and Linux will transform business computing by breaking the lock that companies held on customers who weren't able to easily switch to another's hardware or software. That old order includes IBM's mainframes; Zeitler plans to say in the keynote address. IBM has thus far convinced mostly academia and research-heavy businesses to buy into grid computing, but analysts believe grids will spread in use and that Big Blue will benefit accordingly. "Grid computing moves value to higher levels of sophistication where IBM can make money on software, services and more complex hardware," said Merrill Lynch analyst Steve Milunovich in a report Monday. "Grid computing is an example of IBM planning for where the puck is going."

Linux has overcome obstacles, but not all, Zeitler said. "Earlier in the year, the biggest concern I would get when calling a financial institution is, 'Who's going to support this?' We now have a good solid set of people we can point to," he said. "The next thing people would say is, 'Show me a company...that's done this.' (Now) we've got 120 references." But the Linux job isn't done. "I think the real challenge now is one of maturity in the market," he said.

Linux is becoming extremely popular in the retail industry and the government. This is due in big part by the strong support of a growing number of contributors and sponsors, some of which are: Caldera Inc., Compaq, Corel Corporation, The Debian Project, Enhanced Software Technologies, Inc., Hewlett Packard (sponsor), IBM (sponsor), Intel (sponsor), Linuxcare, Linux for PowerPC, MandrakeSoft, netSweng, LLC, MSC, Software, Olliance, The Open Group, Oracle, SGI, Turbolinux Inc., Red Hat Software, Software in the Public Interest, Inc., SuSE GmbH, The USENIX Association, VA Linux, WGS Inc.

The following is a list of ten new customers in the Travel, Telecommunications, Government, and Retail Industries that have moved to Linux with the strong support of IBM, and it’s Business Partners. These leaders in their industries are the latest of more than 4,600 IBM customer engagements around Linux.
Linux's new customers

  • Air New Zealand

  • Deutsche Telekom

  • 7-Eleven

  • Wolfermans

  • Westport River Winery

  • Satellite Records

  • The Jet Propulsion Laboratory (JPL)

  • Centrelink

  • Mississippi State University

The university has also performed detailed physics simulations for NASA of the vortex ring with tiltrotor aircraft flight and maneuvering. The work done on the IBM Linux cluster contributes to the aircraft safety including subjecting the rotating blades to microburst wind gusts and winter icing conditions.

  • Triaton

  • Furthermore on September 16, 2002, in Raleigh, NC, and Armonk, NY, IBM and Red Hat announced a multiyear global alliance to deliver enterprise Linux solutions including services and expanded support for software and servers that will enable the two companies to provide broad Linux® support to enterprise customers worldwide.
    As part of today's agreement Red Hat will deliver Red Hat Linux Advanced Server for IBM's eServer, zSeries, iSeries, and pSeries. IBM Global Services will provide support for Red Hat Linux Advanced Server on IBM's entire eServer product line.

Skepticism about Linux

Many arguments have been made against Linux that cannot be neatly classified, and the most common of them are addressed in this section. These are serious questions that need to be answered equally seriously.

What is FUD?

FUD stands for Fear, Uncertainty, and Doubt. It is a marketing technique used when a competitor launches a product that is both better than yours and costs less, i.e. your product is no longer competitive. Unable to respond with hard facts, scare mongering is used via 'gossip channels' to cast a shadow of doubt over the competitors offerings and make people think twice before using it.
In general it is used by companies with a large market share, and the overall message is 'Hey, it could be risky going down that road, stick with us and you are with the crowd. Our next soon-to-be-released version will be better than that anyway. In the computer world, IBM first practiced FUD on a large scale in the 1970's. Many people cite Amdahl as coining the phrase when he left IBM to start his own company thus making himself a FUD target.
When IBM moved into the desktop market with the launch of the IBM PC, it took FUD tactics along with it. IBM themselves only reckoned on selling around 100 to 200 thousand units of the PC, which were to be sold as an alternative to the APPLE II in 'all IBM' companies. It should be remembered that in many respects the IBM PC was an overpriced and retrograde step for the desktop market which had already reached the level of 16 bit multi-user, multi-tasking machines with a good deal of flexibility and inter-operability of hardware. The IBM PC had none of these characteristics and cost more, but by marketing on the strength of the IBM label (stick with us, we are big), the PC exceeded all expectations and killed off the existing market.

Of course the PC story is perhaps more a tale of big name marketing rather than deliberate FUD mongering, but the PC also brought Microsoft to the forefront as the supplier of the basic-in-ROM cum disk operating system. Microsoft soon picked up the art of FUD from IBM, and throughout the 80's used FUD as a primary marketing tool, much as IBM had in the previous decade. They ended up out FUD-ding IBM themselves during the OS2 vs. Win3.1 years.

A good example of MS FUD, and its potential, was demonstrated when Digital Research launched their DR DOS against MS-DOS5. DR-DOS offered more features and cost less, and was widely acclaimed by all. Then the new MS windows 3.1 releases flashed up a trivial error message when run under DR DOS, and all of a sudden everybody was saying DR DOS is great but you can have problems running Windows on it. At the same time Microsoft announced the 'imminent' release of MS DOS6 which would be far more feature packed than DR DOS. In reality they had nothing, they had only just started looking at a 'DOS 6' in response to the DR launch, and it is also questionable whether the MS product was better. This classic FUD pack occurred together with a dealer package designed to make it financially advantageous to offer MS DOS with windows, and the result is history. Many believe this was the making of the MS monopoly.

The Linux FUD factor FAQ

Linux is growing in popularity and, as a consequence, is finding its way into everyday conversation and media articles. Unfortunately, much of this conversation is ill informed. This document presents some of the more frequently cited 'myths' about Linux and open source software in general.

  • We can't trust production data to a freeware program! Well, if yours is one of the hundreds of thousands of organizations worldwide that process production data using Perl scripts, you already do! Perl is free software, just like Linux. If there is a bug in Perl that subtly alters your production data, it could cost you money and even expose you to litigation! And no, you can't take the main author, Larry Wall, to court for damages. The free "Artistic License" under which Perl is distributed, expressly disclaims responsibility for any damage caused by the program, and you "agreed" when you installed the software. Does this send a chill down your spine? But wait! Before you storm in there and forbid the use of those trusty Perl scripts, ask around. As your or any IT department could tell you after years of experience with the software, Perl is extremely powerful, thoroughly reliable and of very high quality. It is more than value for money, because it doesn't even cost money! Just think about this. If you're comfortable letting "freeware" Perl scripts loose on your production data, what's wrong with compiling your production systems' C and C++ programs using the freeware GNU C/C++ compiler? That's a tried and tested piece of software, too. And if that's OK, what's wrong with hosting your corporate website on a freeware web server like Apache that's used by over half the Internet sites in the world (including, amazingly, Microsoft's Hotmail with its 30 million subscribers)? Well, if you can stomach all that, what makes you hesitate to use a freeware operating system that's growing faster than any other OS, and has even been used in experiments on the Space Shuttle? The "F" word still has some strange stigma attached to it, even though there are plenty of examples of extremely high-quality free software that deliver excellent value. The pragmatic manager evaluates software based on its merits and the experiences of other users. A prejudiced attitude, on the other hand, can keep you and your organization from enjoying the significant benefits that many good free software programs can give you. Just make reasonable arrangements for support, either in-house or third party.

  • Free Software. This phrase always makes people think of software that is given away at no cost, has no owner, and thus no support or warranty of continuation. In reality the 'free' in free software means that the source code has been liberated and anybody may copy and compile it, but that does not exclude payment. As the Free Software Foundation (FSF, originators of the GNU license) puts it: think free speech not free beer.  Most people using Linux for real applications are using commercial distributions that they have paid for and they expect (and get) the same level of quality and support as any other commercial product. As so much confusion has been caused by use of the term free, many developers now prefer to use the term 'Open Source'.

  • Linux is a UNIX clone cut down to run on a PC. Linux is not cut down. It is fully fledged and continues to evolve with the latest developments in the software industry. Nor is it just for the PC. Stable, commercially used versions exist for x86, Sparc, DEC Alpha, power Macintosh and Strong ARM platforms. Beta versions exist, or are in various stages of development for 68xxx (old MAC, Amiga, Atari), PowerPC (IBM/Motorola type platforms), MIPS, HP, SGI,  APX100, The PalmPilot, Merced, and probably more!

  • Why compromise just to save a few bucks? Ask Linux users why they use Linux, words like flexibility, openness, reliability and efficient use of hardware are commonly cited. Few people use it to save money, although most acknowledge a lot of money can be saved. At the outset many Linux users were people who wanted to play with UNIX at home but could not afford the 'Workstation' costs. But Linux soon grew beyond that. SCO now make their UNIX version freely available for home/private use, but few take up the offer, preferring the advantages of Linux.

But money issues are mostly about corporate use. If corporate staffs are familiar with one OS and not Linux, setting up a server with Linux will probably cost more as savings on the OS price get eaten up by time on the learning curve. But once installed and setup, Linux systems require low maintenance, and subsequent systems will require less time and thus save money. But beyond saving a few bucks, the license issue goes further. Many system administrators prefer the thin server approach, were services are spread across multiple low cost machines rather than centered on big central boxes, with the load being split by service rather than users. This approach is more easily scalable and limits downtime. It also makes it easier to upgrade and maintain individual system elements. But if you need per user licenses on each box, it can become an economic non-starter. Linux not only makes the thin server model financially viable, the high efficiency of the OS means that desktop machines no longer considered good enough for the latest desktop OS may be recycled as non critical servers and routers.

  • Linux is neither warranted nor supported. Who does warranty software products? Most software (including major OS's) are sold on an 'as is' agreement, and it is up to the user to check that the software is suitable for the application. That said, as we noted in the first point, commercial distributions of Linux are widely available, and include support options. They offer the same kind of deal as other commercial packages and there is no reason to 'differentiate' these products just because they have an open source base. On the other hand, users of open source software do have the source, so they may (and often do) put in that little bug fix or enhancement that they need to do their work. If they think their enhancement may be useful to others, they release it to be folded back into the main Linux release. No software may be 'all things to all men', and many people who swear by open source software do so because in the past they have found themselves locked into a system that is not quite doing all they want, but the necessary 'fix' has not been forthcoming, or, as is more often they case, it finally arrives bundled into a pay for upgrade which includes many other new but undesired elements with a new set of bugs. Open source software allows users to tie the system down to do what they want it to.
  • Linux is Insecure. This is a FUD manglers dream phrase, as there is no direct means of refuting it (as system administrators are reluctant to admit break-ins, hard statistics of one OS Vs another are unavailable). Linux is, strictly speaking, a kernel, and an OS kernel is inherently secure, as it has no means on its own of communicating with the outside world. Break-ins occur via support programs, which offer specific network services, and it is in these programs that weaknesses normally occur. That may sound like a pedantic comment but it is important as virtually all the network support code (ftp, web servers, email etc.) used in Linux is not Linux specific but generally available UNIX software, and in this sense Linux security may be considered no different to UNIX security in general. There is a caveat to this, Linux is available in many distributions including types that are aimed at home users and hackers which put ease of use and flexibility before vulnerability. As such they may be without shadow passwords, and may enable by default esoteric protocols, which are known to be risky. But, as one quip put it, you do not cancel your vacation in Florida because of hurricane warnings in Japan. Mainstream Linux distributions are more careful, and offer orthodox levels of security by default. By contrast, some distributions are specifically designed for robustness, such as the Linux Router project that specialize in dedicated routing/fire-walling systems, or Red-Hats secure server which is designed for e-commerce with encrypted credit card authorization etc. As always, common sense is required in setting up a secure system, but fundamental weaknesses on the part of Linux are unknown.

Some argue that UNIX itself is vulnerable, but the basis for this argument is the high number of security alerts issued for UNIX network service software. But at the same time it should be remembered that 70% of Internet traffic is destined for UNIX like servers, with the rest being spread over a variety of proprietary systems. UNIX is also the predominant system for academic servers (where highly skilled would be attackers abound). Most other systems sit behind firewalls or on closed networks, or are just not important to warrant any attack. It is impossible to compare UNIX systems with other systems in terms of vulnerability because no other system comes near it in terms of exposure or the range of services offered.

Certificates such as C2 certification are an aid in setting up a secure system, but they do not state a system is secure, nor does the lack of a certificate (and Linux does not have one) make a system insecure. A C2 certificate is issued when a company submits a system for testing, and states not "This system is secure" but "In order to reach a C2 security level with this system, the following configuration was used" (The interpretation is the authors, not the actual certificate wording). The fact is you cannot globally state an OS as being secure, because security is so dependent on what protocols are being offered and how the system is configured. By the same logic, you cannot say a particular OS is insecure.

Security is taken seriously by the Linux community.

It must be, many Linux systems are in the front line and would not last two minutes if problems where not properly tackled. When security alerts are issued, fixes arrive very quickly (if not at the same time). Linux distributors, consultants and large sites were Linux is deployed have people dedicated to security, and as ever in the Linux world, these people collaborate. At the same time the basic motto of Linux is flexibility and user choice. You can make (or buy) a secure system with Linux. But as security is inversely proportional to flexibility and ease of use, you may decide to forgo security and enable lots of network 'gadgetry'. On a closed network or behind a firewall were the users are known (actually the case of most servers) there is a lot to be said in favor of using less trusted protocols. The choice is in the hands of the users, secure or flexible, and Linux offers what is probably the largest range of options to the end user than any other system.

How do I convince my boss that Linux is an excellent operating system for business use?

It's a question that Linux users around the world have been asking. People who have used Linux know it is technically superior -- and let's face it, you can't beat the price.

Why use Linux?

Here are 10 reasons why Linux could be the best operating system for you:

  • A Linux Distribution has thousands of dollars worth of software for no cost (or a couple of dollars if purchased on CD/DVD)

  • Linux is a complete operating system that is:

  • stable - the crash of an application is much less likely to bring down the operating system under Linux

  • reliable - Linux servers are often up for hundreds of days compared with the regular reboots required with a Windows system

  • extremely powerful

  • Comes with a complete development environment, including C, C++, Fortran compilers, toolkits such as Qt and scripting languages such as Perl, Awk and sed. A C compiler for Windows alone would set you back hundreds of dollars.

  • Excellent networking facilities: allowing you to share CPUs, share modems etc; all of which are not included or available with Windows 95.

  • The ideal environment to run servers such as a web server (e.g. Apache), or an FTP server.

  • A wide variety of commercial software is available if your needs aren't satisfied by the free software.

  • An operating system that is easily upgradeable. After any length of time a typical installation of Windows and software gets into a complete mess. Often the only way to clear out all the debris is to reformat the hard disk and start again. Linux, however, is much better for maintaining the system.

  • Supports multiple processors as standard.

  • True multi-tasking; the ability to run more than one program at the same time.

  • An excellent window system called X; the equivalent of Windows but much more flexible.

Red Hat Linux

Hardware Requirements
Before installing Linux, the user needs to be aware of the hardware requirements and limitations that Linux has. Because Linux was developed by its users, the hardware that it supports is only the hardware which the users and developers actually have access to. Most of the popular hardware and peripherals for 80386/80486 systems are supported by Linux, and as time goes on, a wider range of hardware is supported.

One drawback for hardware support under Linux is that many companies have decided to keep the hardware interface proprietary. This means that volunteer Linux developers can’t write drivers for those devices (Welsh 28).

  • Motherboard and CPU Requirements: Linux does not support the Intel 286 and earlier processors. However, the system fully supports the Intel 80386, 80486, Pentium, Pentium Pro, Pentium II, and Pentium III processors. Some users feel that their 80386 Linux systems respond very slow, especially when running X. So, to achieve maximum performance, the system should be installed on a PC having an 80486 processor or better.

Linux also supports non-Intel processors such as the Cyrix 6x86 and the AMD K5 and K6. Most Linux users have systems that use Intel chips, so using a system that uses a non-Intel chip will make it harder to resolve possible problems (O’Reilly 18).

The system motherboard must use ISA or EISA bus architecture. These define how the system interfaces with peripherals and other components on the main bus. Systems that use local bus architecture (for faster video and disk access) are supported as well.

  • Memory Requirements: Linux requires very little memory to run compared to other operating systems. You should have at the very least two megabytes of RAM. The more memory you have, the faster the system will run. Linux can support the full 32-bit address range of the 386/486, and will utilize your entire RAM automatically. Linux will run well with only four megabytes of RAM, however, having more memory is almost as important as having a faster processor. Eight megabytes is more than enough for personal use; sixteen megabytes or more may be needed if you are expecting a heavy user load on the system.

  • Hard Drive Controller Requirements: You do not need to have a hard drive to run Linux. You can run a minimal system completely form floppy. However, this would be very slow and limited. You must have an AT-Standard (16-bit) controller. Linux should support all MFM, RLL, and IDE controllers. Most, but not all, ESDI controllers are supported. The general rule for non-SCSI hard drive and floppy controllers is that if you can access the drive from another operating system, you should be able to access if from Linux.

  • Hard Drive Space Requirements: The amount of hard drive space required depends greatly on the needs of the user and on the amount of software that will be installed. You can run a complete system in ten to twenty megabytes of space on your drive. However, if you want room for expansion, and for larger packages such as X windows, you will need more space. Also, if multiple users will be using the machine, then storage space will need to be allocated for their files. Although you can run a minimal system with less than 20 megabytes, a larger system with room for many users and space for future expansion will require a range of 100-150 megabytes (Welsh 30). Installing Linux on a system with so little disk space will force you to omit many useful applications and will not allow a lot of room to work. More realistically, if you want to use Linux as a workstation, you should have at least 600 megabytes of free disk space. If you are planning to use the Linux system as a server, then you should have at least 1.6 GB (1,600MB) of free disk space.

  • Monitor and Video Adaptor Requirements: Linux supports all standard Hercules, CGA, EGA, VGA, IBM monochrome, and super VGA video cards and monitors for the default text-based interface. In general, if the video card and monitor coupling works under another operating system, it should work well with Linux.

The above section describes the hardware that is required to run a Linux system. However, there are other “optional” devices such as CD-ROM storage, soundboards, and others that are supported by Linux.

For the most part, a mouse will be used only under a graphical environment such as the X windows system. However, several Linux applications not associated with a graphics environment do make use of the mouse. Linux supports all standard serial mice. All other pointing devices, such as trackballs, should work as well.
Almost all CD-ROM drives use the SCSI interface. As long as you have a SCSI adaptor supported by Linux, then the CD-ROM drive should work. Linux supports the standard ISO-9660 file system for CD-ROMS.
Linux supports the complete range of parallel printers and the full range of serial modems, both internal and external. If the printer and modem are accessible form another operating system, then they can be accessed form Linux as well with no difficulty.

Linux Performance

Key factors that users consider when choosing an operating system is features and performance. One of the great things about Linux is that it offers great performance. This table compares certain features and performance characteristics of Linux with those of Microsoft Windows NT 4.0 and Sun Microsystems Solaris 2.6. All of these operating systems can be run on an Intel-architecture PC. When compared to these operating systems, Linux turns out to be the best. It runs on a wider range of hardware platforms and runs on less expensive and powerful systems. Also, the typical downtime of a Linux system is less that of a Windows NT system and its performance is better than that of a Solaris system. Linux also exceeds the other operating systems in its multi-processing capabilities and its support of advanced TCP/IP networking facilities. As a whole, Linux users are more satisfied than Windows NT users and Solaris users.





Windows NT



Range of compatible hardware


Very Wide





Minimal hardware


386 PC


486 PC



Representative Cost of hardware







Average downtime


Very low


As low as 30 min./week


Very low





Comparable to Linux


Half of Linux to same as Linux

Multi-processing capabilities







IP Security (IPSec)











Privately demonstrated



Overall user satisfaction







Source code readily available







Installed base






Hundreds of thousands

Many desktop systems are sometimes employed as servers. Because Linux was designed for use as a server operating system, its features and performance are better than most desktop operating systems used as servers. For example, Microsoft’s software license for Windows NT Workstation restricts the number of clients connected at the same time to ten. If a Windows NT Workstation accepts more than ten client connections, then it is operating in breach of the license. However, Linux does not restrict the number of clients connected at the same time. The Linux desktop is free to accept as many client connections as it can handle.

Linux also provides more reliable data storage than other desktop operating systems. Most Linux users store their disk data using the EXT2 file system, which is superior in performance and reliability to file systems provided by Microsoft operating systems. Linux also provides advanced disk management (RAID), which makes it possible to automatically duplicate stored data on several hard drives. This improves the reliability of data storage and is important because if one hard drive fails, the data can be read from another one. Other desktop operating systems such as Microsoft Windows 95/98 do not support this capability unless a driver is added (O’Reilly 10-14).
Linux Software


From household appliance control to World Wide Web tools, Linux has a lot to offer. One accomplishment, which the free software community is particularly fond of, is the GIMP, the GNU Image Manipulation Program, similar to Photoshop but highly extensible, completely free and guaranteed to stay that way. Linux has audio applications galore from players and recorders to mod trackers, drum machines, synthesizers, and synthesis languages. Linux can also be used for ham radio and video applications.

Development Software:

Nearly all development software for LINUX is free and covered under the GNU public License, which guarantees that it will always remain free. Linux systems come standard with C and C++ compilers and an assembler, APL, BASIC, Dylan, Eiffel, Euler, Forth, FORTRAN, GOMscript, INTERCAL, Logo, LISP, Mercury, Modula, Oberon, Objective C, Pascal, Prolog, Perl, Python, Rexx, Sather, SIMULA, and Tcl/Tk. Moreover, the source code available for nearly any Linux program is freely available. This phenomenon is called Open source, in which not only the bugs are discovered and corrected almost immediately, but also development of software proceeds at a much faster pace than one finds even at extremely successful commercial software houses. Programmers also have a choice between using gcc and egcs, the GNU C Compiler and the Experiment GNU Compiler System, the latter of which has become quite popular due to its features, flexibility and functionality. Linux is a platform for programmers.
Linux has tons of games-the Linux Game Tome lists over 400 entries. Linux games have a charm all their own, though developers have recently turned their attention to producing slick, commercial 3-D games. Free Linux games, however, are often of very high quality and most entertaining. As many Linux programmers come from other platforms, there are many ports and recreations of classic computer games. Fans of traditional board game such as CHESS and GO will find excellent interfaces for playing on-line, and even strong computer opponents. Emulation, combined with the speed of modern hardware, makes available literally thousands of computer games, from early games on home computers like the COMMODORE 64 and AMIGA to coin-operated arcades.
Scientific Software:

UNIX was originally used by scientists and is often their preferred OS, so there is a wealth of scientific software available for Linux, including TeX and LaTeX scientific typesetting packages. There are scientific applications for astronomy, biology, cartography, chemistry, laboratory work, mathematics, graphics, and visualization, among others. In conjunction with the numerous scientific and mathematical languages available, Linux is quite at home in scientific applications and is often used to laboratories.

System Software:

Since Linux is based on UNIX and very much compatible with it, there is also an abundance of system software for Linux. System software includes things from daemons (programs that run in the background) to networking to file systems, hardware support, emulation, benchmark testing and generic file utilities. Linux supports parallel processing (which is why it is often used to make supercomputers) and RAID (Redundant Array of Independent Disks), and has resources for managing all sorts of hardware issues which would not usually come up for mainframe and supercomputers, including power management, multi-user/multi-group systems administration, backup, and system diagnostics. Linux also have software RAID implemented in operating system, this however means more overhead for the CPU.
Utilities are used for things such as disk and file manipulation, terminal customization, compression, archiving, scripting and other small but important things that keep a home computer running at its best. Linux has command-line and even graphic interfaces for all sorts of disk and file operations, from converting sound and audio formats to compressing, archiving, and encrypting files.

Linux has a very bright future; many companies are choosing Linux to power their workstations and servers. Many companies are also replacing currently install UNIX and Windows machines with Linux boxes. Linux is a very stable multitasking multi-user operating system. Linux is constantly in the news, whether that is computer-related or business related. Many companies are using Linux as file servers, print servers, Web and application servers, and workstations. Linux is a scalable operating system; it can serve up an office with two personal computers or accommodate a Fortune 100 company with thousands of personal computers. You can now purchase new computer systems preinstalled with Linux, you can also purchased technical support as part of the package. Linux continues to evolve, with new kernel releases coming out regularly.


Stallings, W. Computer Organization and Architecture, 6th edition.

Upper Saddle River, NJ: Prentice-Hall, 2002.

Bovet, D. Understanding the Linux Kernel, 1st edition.

Beijing, Cambridge [Mass.]: O’Riley, 2001.

Purdell, John, Robinson, Amanda, eds.  The Linux Bible.  San Jose: Yggdrasil Computing, Inc, 1996

The Linux Documentation Project:
The Linux System Administrators' Guide:
The Linux Network Administrators' Guide:
The Linux Programmer's Guide:
The Linux HOWTOs:
The Linux "man" (manual) pages for download:
Linux FAQs (Frequently Asked Questions):
O'Reilly computer books home page:

What is Linux?

Linux Distributions Compared

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Review Questions

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