analyze individual data packets as they pass through. In addition to the packet header, Stateful inspection also assesses the packet’s payload and looks at the application protocol. It can then make access decisions based on the source, destination, and service that is requested by the packet. With this level of information, the firewall is able to make a more informed policy decision than can be made by traditional firewalls. Although Stateful inspection offers the highest level of security, none of the current Linux-based firewalls currently support this method.

Determining Linux Roles and Services

Now that I’ve shown you how Linux can support servers with DNS, e-mail, file, firewall, FTP, proxy, Web, and many other server services and clients with word processors, e-mail programs, spreadsheets, database, graphic views and manipulators, Web browsers, file transfer, printing support, presentation, and virtually every other type of program, it’s time to determine the roles and services that a system may require. You can use Linux for all the roles that I have discussed, and in fact, Linux is often used for all of these and many more.

Comparing Linux with other operating systems

1.8 Describe the functions, features, and benefits of a Linux solutions as compared with other operating systems (e.g., Linux players, distributions, available software)

Because Linux can support all of the services that other operating systems can, how do they compare? Because Linux is a true 32-bit OS with real multiuser and multiprocessing capabilities, it compares very well to other operating systems. The proof is in the real world uses of Linux.

Use on the Web

The search engine Google is a prime example of the ability of Linux to compete with other operating systems. Google is one of the premier search engines on the Internet and it runs on a Linux cluster. Over 60 percent of Web servers run Apache Web Server, which is completely supported under Linux and provides all of the efficiency and reliability of a high-end UNIX server. Linux has proven its capability to provide all the services that are needed in a server or desktop environment.

Installation

Installation of Linux is comparable to UNIX, Mac, and Microsoft operating systems. All of these operating systems provide a friendly user interface that allows the installation of the operating system with very little user input. The fact that Microsoft includes an extremely large number of device drivers with the initial installation package makes it attractive to non-technical users and gives it a slight advantage in this area. For the more technical user, Linux can also be installed from the command line, enabling a variety of advanced installation options.

Stability

After it is configured, the reliability of the operating system is clearly an issue to be considered. Because Linux is UNIX-like, it has gained many of the benefits of UNIX. For example, UNIX has always been considered one of the most reliable and stable operating systems available, but Linux is clearly in the same class of service as UNIX. The Microsoft operating systems are usually considered to be less stable; however, they have made great strides with recent releases of their enterprise software and hope to be rid of that reputation. It is clear, however, that UNIX and Linux are considered to be the best choices for services regarding stability.

New technology

Although Linux has improved greatly in many areas over the years, it still trails in the ability to support new technology as well as UNIX or Microsoft. Because Linux relies on private and public developers and volunteers to create device drivers for new and often expensive hardware, it is obvious why Linux can’t support as many new devices as these other commercial operating systems. For example, in the case of support for Fibre Channel drive arrays, Linux clearly supports the technology but has also been shown to trail both UNIX and Microsoft Server 2000 in data throughput under load. This will change as Fiber Channel matures, but at this time, Linux clearly has some issues to resolve. Although Linux has some ground to gain on correcting the issues of new technology support, it excels in the support of older hardware. While other operating systems often abandon the support of older hardware, Linux continues to provide useful applications for old systems.

Cost

Finally, and perhaps most importantly, the cost of all these operating systems is an issue that can’t be overlooked. Linux is freely licensed and can be installed in as many desktops or servers that you desire. Microsoft has traditionally used a single purchase license and client licensing method, but they are moving to a new licensing method that requires renewal of a software license on a regular basis. UNIX, which was once considered to be the most costly to purchase, is now being led by Sun Microsystems, which is currently distributing their Solaris binary code for no charge with media available for a drastically reduced price. Linux is clearly the winner here. Even fully supported distributions that are available for purchase are usually much less expensive than the competition. However, the initial cost of Linux does not mean that the long-term costs are lower than other operating systems. A belief persists that Linux costs more in the long run because it requires a more knowledgeable support staff, and that when users encounter problems, it often takes longer to resolve. Indeed, the ability to support any operating system requires a knowledgeable staff, and all operating systems have issues that can be difficult to resolve, but the long-term cost of any operating system is very comparable and no operating system is clearly less or more expensive than the others. Although Linux has not separated itself as a clear leader in every situation, it has shown that it should be considered and performs well versus its competition.

Hardware compatibility

1.2 Identify all system hardware required and validate that it is supported by Linux (e.g., CPUs, RAM, graphics cards, storage devices, network interface cards, modem)

The hardware compatibility of Linux has always been one of its big advantages. Although Linux doesn’t support the newest technologies on a level comparable to other operating systems, it does provide excellent support for most other hardware. Linux also supports perhaps the largest list of hardware platforms. Because it was built to be UNIX-like, Linux also benefits from the easy portability to other platforms, and has been shown to run on virtually every platform available. This is an enormous benefit for Linux because it has become the standard for installations on embedded devices, and this fact alone may help Linux to gather more support on other platforms as it matures and receives more coverage. The ability of Linux to work on many platforms and on most of the hardware in the marketplace can make determining compatibility of a specific piece of equipment difficult. Thankfully, most Linux distributions support a Hardware Compatibility List (HCL) on their Web sites.

Understand the Hardware Compatibility List (HCL) because it is an important concept and will be covered on the exam.

The HCL shows all the hardware that the vendors tested with their distribution of Linux. By providing the HCL, a system and all of its components can be verified as compatible with Linux before the operating system is installed. This way, a user knows if the CPU, RAM, graphics cards, storage devices, network interface cards, modem, and virtually any other hardware component will be supported.

Linux software packages and package distribution types

1.10 Identify where to obtain software and resources

Not all software services and applications are included in every distribution. If the software package is not available in the distribution, it is usually available for download from the Internet. The software packages that have been discussed in this chapter are typical services that are necessary for a desktop or server system. The following is a list of many of the sites that can provide most of these software packages:

http://www.abiword.org/

http://www.apache.org/

http://www3.corel.com

http://www.htdig.org/

http://www.isc.org/products/INN/

http://koffice.kde.org/

http://www.konqueror.org/

http://www.leafnode.org/

http://www.linux.org

http://www.linuxdoc.org

http://www.lotus.com/home.nsf/welcome/domino

http://netfilter.filewatcher.org

http://www.netscape.com/

http://www.opera.com/

http://www.proftpd.net/

http://www.sendmail.org/

http://www.squid-cache.org/

http://www.sun.com/software/star/staroffice/

http://www.trolltech.com/

Although these Web sites have excellent support for the software packages, sometimes you may have a need for more information. This information is available in the MAN pages and documentation that are included with most software packages.

Determining customer resources

1.11 Determine customer resources for a solution (e.g., staffing, budget, training)

After you have determined a need for a desktop or server system, you also need to determine the ability of the customer to provide the resources necessary to install and support these systems. The hardware is just the beginning. If a desktop installation has been selected, then you must have a PC on which to install the operating system. After Linux is installed, you may need to purchase some specific software to integrate the PC into the existing network. You will also need ongoing maintenance to keep the distribution up-to-date and you will need to repair any hardware failures in the PC. For a server installation, not only is there a requirement verifying hardware compatibility and all the desktop installation requirements, there is also the requirement for expansion and scalability of the server to be able to support an increased userbase in the future. Because servers often expand beyond the initial hardware, the expansion of the server should be verified before the installation begins. The customer’s ability to upgrade the server should also be taken into account. Finally, you face the ongoing cost for staff to support the systems. Budgets must be allocated not only for staff but also for equipment maintenance, replacement, and continued training to properly keep the systems up-to-date and running.