Download Training Report (LINUX) PDF

TitleTraining Report (LINUX)
Tags Computer File Booting File System
File Size365.3 KB
Total Pages68
Table of Contents
                            Private sector

		Salient Features of LINUX
			Advantages of Linux :-
Virus proof
Advanced OS
Crash proof
User friendly GUI
Powerful networking
Variety of servers
	Who are using Linux :-
Managing a User account
Adding a User
Removing a user & viewing a user
		Network Designing & Implementation (Local Area Network):-
IBM Server   	     Compaq Server	         HCL Squid Proxy
	Operating System : Windows 2000 Server , Running  FTP Server
	Operating System : Redhat Linux 8.0 Professional Server
Document Text Contents
Page 34

These are specified in the /etc/fstab file; see the fstab man page for details on the
format. The details of exactly when the extra filesystems are mounted depend on many
factors, and can be configured by each administrator if need be; see Chapter 6.
When a filesystem no longer needs to be mounted, it can be unmounted with umount. 8
umount takes one argument: either the device file or the mount point. For example, to
unmount the directories of the previous example, one could use the commands
$ umount /dev/hda2
$ umount /usr
See the man page for further instructions on how to use the command. It is imperative
that you always unmount a mounted floppy. Don’t just pop the floppy out of the drive!
Because of disk caching, the data is not necessarily written to the floppy until you
unmount it, so removing the floppy from the drive too early might cause the contents to
become garbled. If you only read from the floppy, this is not very likely, but if you write,
even accidentally, the result may be catastrophic.

Mounting and unmounting requires super user privileges, i.e., only root can do it. The
reason for this is that if any user can mount a floppy on any directory, then it is rather
easy to create a floppy with, say, a Trojan horse disguised as /bin/sh, or any other
often used program. However, it is often necessary to allow users to use floppies, and
there are several ways to do this:
• Give the users the root password. This is obviously bad security, but is the easiest
solution. It works well if there is no need for security anyway, which is the case on many
non-networked, personal systems.
• Use a program such as sudo to allow users to use mount. This is still bad security, but
doesn’t directly give super user privileges to everyone. 9
• Make the users use mtools, a package for manipulating MS-DOS filesystems, without
mounting them.
This works well if MS-DOS floppies are all that is needed, but is rather awkward
• List the floppy devices and their allowable mount points together with the suitable
options in /etc/fstab.
The last alternative can be implemented by adding a line like the following to the
\fn{/etc/fstab} file:
/dev/fd0 /floppy msdos user,noauto 0 0
The columns are: device file to mount, directory to mount on, filesystem type, options,
backup frequency (used by dump), and fsck pass number (to specify the order in which
filesystems should be checked upon boot; 0 means no check).
The noauto option stops this mount to be done automatically when the system is started
(i.e., it stops mount -a from mounting it). The user option allows any user to mount the
filesystem, and, because of security reasons, disallows execution of programs (normal or
setuid) and interpretation of device files from the mounted filesystem. After this, any user
can mount a floppy with an msdos filesystem with the following command:
$ mount /floppy

Page 35

The floppy can (and needs to, of course) be unmounted with the corresponding
\cmd{umount} command.
If you want to provide access to several types of floppies, you need to give several mount
points. The settings can be different for each mount point. For example, to give access to
both MS-DOS and ext2 floppies, you could have the following to lines in /etc/fstab:
/dev/fd0 /dosfloppy msdos user,noauto 0 0
/dev/fd0 /ext2floppy ext2 user,noauto 0 0
For MS-DOS filesystems (not just floppies), you probably want to restrict access to it by
using the uid, gid, and umask filesystem options, described in detail on the mount
manual page. If you aren’t careful, mounting an MS-DOS filesystem gives everyone at
least read access to the files in it, which is not a good idea.

Understanding Shells

After we log on, Linux places us in our home directory & runs a program called a Shell.

A shell is really more than a program designed to accept commands from the user &

execute them. Many kinds of programs can be used as shells, but there are several

standard shells available with almost all versions of Linux.

Linux shells are equivalent to COMMAND.COM used by MS-DOS. Both accept &

execute commands, run batch files & other programs.

One of the shells installed by Linux is BASH (bash) shell (Bourne Again Shell). Linux

also provides a C Shell (csh), T Shell (tsh) and Z Shell (zch).

The shell is a program that starts after we log on & interprets our commands. Because it

serves as a primary interface between the operating system & the user, many users

identify the shell with Linux. Users expect shell to have common properties required by

them & to be programmable. Remember that the shell is not a part of the Kernel of the

operating system.

In the simplest form, the Bourne & Korn shell use the dollar sign ($) as their standard

prompt; the C shell uses the percent sign (%) as the prompt. Fortunately, these prompts

can be changed so that you may or may not see either the dollar or percent sign when you

first log on.

Page 68

As per the need of my project of networking on linux operating system, I required

information regarding various tools used in networking. Therefore I have gone through

several books for above informations. My project co-ordinator has suggested me to go

through some books whose list is as follows :-


1. Red Hat Linux System Administration RH133.

2. Red Hat Linux Essentials RH033.

3. Red Hat Linux Networking and Security Administration RH253.

provided by Red Hat Corporation.

4. Special Edition usingLINUX by Jack Tackett, jr., David Gunter, Lance






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