~ CHAPTER 1: INTRODUCTION TO LINUX ~

The advantage of Free Software

If the GLP seems a bad idea from the standpoint of commercialism, consider the recent surge of

successful freeware packages – they are indicative of a system that does indeed work.

Here’s another reason for the success of generally licensed software: Any project manager who

has worked on commercial software knows that the real cost of development software isn’t in the

development phase. It’s really in the cost of selling, marketing, supporting, documenting, packaging,

and shipping that software.

Since anyone can take the Linux kernel (and other supporting programs), repackage them,

and resell them, some people have made money with Linux. As long as these individuals release

the kernel’s full source code along with their individual packages, and as long as the packages

are protected under the GPL, everything is legal.

Why commercial Software Doesn’t Mean Liability

You cannot sue someone who has released their code under the GPL because the code was

unfit for your needs and caused you financial harm. So if no one is taking the heat for when

things go wrong, why should the IT managers?

Single Users VS Multi-user vs. Network Users

Today the most common implementation of a multi-user setup is to support servers – systems

dedicated running large programs for use by many clients. Each member of a department can

have a smaller workstation on the desktop, with enough power for day-to-day work.

Separation of the GUI and the Kernel

• Taking a cue from the Macintosh design concept, Windows 2000 developers integrated the

graphical user interface (GUI) with the core operating system. One simply does not exist

without the other.

• On the other hand, Linux (and UNIX in general) has kept the two elements, user interface and

operating system, separate.

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• The X Windows system interface is run as a user-level application,

which makes it more stable.

• The most significant feature of X Windows is its ability to display windows across

a network and onto another workstation’s screen. This allows a user sitting on Host A

to log in to Host B, run an application on Host B, and have all of the output routed back

to Host A.

• Linux distributions come with several windows managers and include support for

GNOME and KDE, both of which are available on other variants of UNIX as well.

• When set as default, both GNOME and KDE offer an environment that is friendly

even to the casual Windows user.

The Network Neighborhood

The native mechanism for Windows folk to share disks on servers or with each other is through

the Network Neighborhood. In a typical scenario, users attach to a share and have the system

assign it a drive letter.

With Windows 2000, a new feature borrowed from UNIX has also appeared: mounting.

A common example of mounting partitions under Linux is with mounted home directories:

The user’s home directories reside on a server, and the client mounts the directories at boot time

(automatically). So /home exists on the client, but /home/username exists on the server.

Under Linux NFS, the user never has to know server names or directory paths, and their

ignorance, is your bliss!

NOTE: If you intend to use Linux to serve Windows 2000/NT/via the Samba package,

you’ll have to deal with notifying users about server shares and printer assignments.

The Registry vs. Text Files

Linux does not have a registry. This is both a blessing and a curse. With most tools that come

with Linux, configuration files exist in the /etc directory or one of its subdirectories.

Each application or server can have its own format.

In reality, having text files to hold configuration information usually turns out to be an efficient

method.

NOTE: A very interesting side effect of having configuration files exist as a series of text files is

that configuration of these files can be automated. This is very useful in situations where a large

number of workstations needs to be deployed or new workstations are added frequently.

Even with tools like Norton Ghost, Windows installer simply cannot be automated or scripted.

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Domains

For a group of Windows NT systems to work well together, they should exist in a domain.

This requires a dedicated NT Server system configured as a PDC. The basis of Linux’s network

security model is NIS, Network Information Service. NIS is a simple database (based on

text files!).

Any client workstation wanting to join this domain is allowed to do, as long as it can set its

domain name. To set the domain name, you must use the root user – Linux’s equivalent to

an Administrative user.

Instead, each host looks up the login and password information from the server and

compares it to the user’s entered information.

The only limitation is that each NIS map can only have one key, and the database mechanism

doesn’t scale well beyond about 20,000 entries. A final note about NT domains and NIS:

Neither is required for the base operating system to work. Nevertheless, they are key if you

need to maintain a multi-user site with a reasonable level of security.

Active Directory

So how does NIS stack up to Active Directory? Good question. The answer is “it doesn’t”.

Active Directory was designed to be much more than what NIS was designed for.

AD is also an opportunity for Microsoft to fix many of its broken naming schemes and move

toward an Internet-centric scheme based on DNS Linux uses LDAP. The radius authentication

protocol is also becoming more common.

Summary:

• Linux distributions, the GNU license (GPL), and the major design differences between

Windows 2000 and Linux. You should now have a sharp picture of what lies ahead.