1. An Introduction to
Linux operating System
By Biplaba Samantaray
MCA, University of Hyderabad

2. Content
• What is Linux
• Why Linux
• The Linux system
• Security
• OS Comparison

3. What is Linux
• LINUX is a family of open source Unix like operating
system.
• Linux was created by Linus Torvalds in 1991
• Now it has evolved into a very functional, powerful and
usable clone of Unix which has at least 10 million users
worldwide.
• Now it runs on a variety of platforms including PowerPC,
Macintosh, Amiga, DEC Alpha, Sun Sparc, ARM, and
many others

4. Why Linux
• Free and Open source
• Distributions
• Security
• Virus treatment
• Multi processor
• Multi Tasking
• Stable
• Reliable
• Networking

5. The Linux System
• The Linux system excel in many area, ranging
from end user concerns such as stability, speed,
ease of use, to serious concerns such as
development and networking.
a) Linux kernel
b) Linux networking
c) Linux file system

6. Linux Kernel
• Central nervous system/main
component of Linux
• Coded in C language
• It provide resources to all the
other program that sits over it.
• Linux is a modular designed.
• Control major functions

7. Linux networking
• Networking comes naturally to Linux.
In a real sense, Linux is a product of the
Internet or World Wide Web (www).
• Linux is made for networking. Probably
all networking protocols in use on the
Internet are native to Unix and/or Linux.
A large part of the Web is running on
Linux boxes, e.g. : AOL
Linux Network Admin
Server Network
FTP
TELNET
SSH
DHCP
TFTP
Connfigu-
ration
protocols

8. Networking protocols
• The Linux kernel supports several
networking protocols:
– TCP/IP - Transport Control
Protocol/Internet Protocol
• IP is the primary network protocol
supported by Linux
– IPX - Internetwork Packet Exchange
– AppleTalk DDP
– Amateur Radio AX.25 Level 2

9. Linux File System
• Linux has an hierarchical,
unified file system
• Supports 256-character
filenames.
• All command line entries are
case sensitive.
• Use the slash(/) rather than the
backslash() you have been using
in DOS.

10. Security
• Encryption
• Secure shell(ssh)
• Principles of security

11. Encryption
• Encryption commonly used to secure data. It is the
ancient technique of hiding information in plain sight.
Include:
– strong encryption - is stronger than the 40-bit
encryption maximum that can be exported from the
United States under U.S. law.
– Public-key Encryption - is a type of asymmetric
encryption, which is a system that you encrypt your
message with one key, and the recipient decrypts it
with a mathematically related, but different key.

12. Secure shell(ssh)
ssh user_name@host(IP/Domain_name)
• The ssh and its tools use strong encryption to allow
remotely located systems to exchange data securely.
• By using strong encryption, ssh significantly enhances
the security of both the authentication process and
the session itself.

13. Principles of security
Unauthorized access
Active
Passive
Inside
Outside

14. Daniel of Service :
Defense against the attacks:
• enforce the use of password
• use TCP wrappers to limit which resources are made available
to which categories of users.
• monitor internal users, protect your organization against
unauthorized or inappropriate use of the computer facilities
to harass personnel.

15. UNIX vs LINUX
Unix
 It is an operating system which can
be only used by its copyrighters.
 It was developed mainly for
servers, workstations and
mainframes.
 Unix copyright vendors decide
different costs for their respective
Unix Operating systems.
Linux
 It is an open-source operating system which
is freely available to everyone.
 Nowadays, Linux is in great demand.
Anyone can use Linux whether a home
user, developer or a student.
 Linux is freely distributed, downloaded,
and distributed through magazines also.
And priced distros of Linux are also
cheaper than Windows.

16. Linux vs Windows
Linux
 Linux is a open source operating system.
 Linux is free of cost.
 It's file name case-sensitive.
 In Linux, monolithic kernel is used.
 Linux is more efficient in comparison of
windows.
 There is forward slash is used for
Separating the directories.
 Linux provides more security than
windows.
Windows
 While windows are the not the open
source operating system.
 While it is costly.
 While it's file name is case-insensitive.
 While in this, micro kernel is used.
 While windows are less efficient.
 While there is back slash is used for
Separating the directories.
 While it provides less security than Linux.

17. References :
• http://www.Linux.org
• http://www.croftj.net/~jam
• http://metalab.unc.edu/LDP/HOWTO/
NET-3-HOWTO-4.html#ss4.1