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1. Bangladesh University of Business and Technology
Course No: CSE 305
Course Title: Operating
Systems
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2. Table of content:
 System
 Network
 Network and Operating System
Security
 Operating System
 Novell NetWare and protocols
 Network Operating System
 Linux
 Features
 Windows XP
 Remote Login with an example
 MS-DOS environment
 Remote file transfer
(Example)
 Difference between OS and
NOS
 Anonymous FTP method
 Summary
 Sources
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3. What is a system?
• set of interacting or interdependent entities
Multiple meaning:
 collection of organized things
 way of organizing or planning
 whole composed relationship among the members
Characteristics:
 have a structure that is defined by its parts
and
processes
 tend to function in the same way
(involves inputs and outputs of material)
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4. What is a Network?
 is a communication path between two or more
systems
 vary by the protocols used, the distances
between nodes, and the transport media
 TCP/IP is the most common
network protocol
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5. Operating System
program that manages the computer hardware
 provides a basis for application programs and acts
as an
intermediary between the user and the hardware
 offers a reasonable way to solve the problem of
creating a usable computing system

Types of Operating Systems:
Windows Vista
Linux and Unix
Microsoft Windows
Mac OS X
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6. User 1
Compiler
User 2
Assembler
User 3
........
Text editor
User n
Databases
System
System and Application Programs
Operating System
Computer Hardware
Figure: Abstract view of the components of a computer system
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7. Network Operating System
 provides an environment in which users, who are aware
of multiplicity of machines, can access remote
resources either:
-> logging in to the remote machine* or
-> transferring data from the remote
machine to their own machines
 mostly used with local area networks and widearea
networks
*Remote machine: refers to a computer connected to the
network which a user is using
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8. Features
 Provides basic operating system features;
support for
processors, protocols, automatic hardware
detection, support multi-processing of
applications
 Security features;
authentication, authorization, access
control
 Provides names and directory services
 Provides files, print, web services, back-
up and replication services
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9.  Supports Internetworking such as routing
and WAN ports
 User management and support for login and
logoff, remote access, system management
 Clustering capabilities, fault tolerant and
and high availability systems
Cluster: = group of linked computers working together
closely, connected to LAN
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10. Remote Login with an example
 important function of a NOS is to allow users to log
in remotely
 internet provides the telnet facility for this purpose
 Example: a user at Westminster College wishes to
compute
on “cs.yale.edu,“ a computer that is
located at Yale
University
-> user must have a valid account
on that machine
telnet cs.yale.edu
to log in remotely the user issues
the command:
Command results in the formation of a socket connection between
the local machine at
Westminster College and the “cs.yale.edu“ computer
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11.  connection has been established
 transparent, bidirectional link that
all characters entered by the user
are sent to a process “cs.yale.edu“
 all the output from that process is
sent back to the user
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12. Remote File Transfer
 Provide a mechanism
for remote file
transfer from one machine to another
 Each computer maintains its own local file
system
 User: “cs.uvm.edu“ wants to access a file
located on another computer “cs.yale.edu“
file must be copied from the computer at
Yale to the PC at Uni of Vermont
 Internet provides the transfer with file
transfer protocol (FTP) program
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13. Example:
 User on “cs.uvm.edu“ -> copy Java program
Server.java that resides on “cs.yale.edu“
 Invoke FTP program ftp cs.yale.edu
 Login name and password
 Correct information has been received, user
must connect to the file Server.java and
after copy the file by executing get
Server.java
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14.  File location is not transparent to the
user
 No real file sharing
 Remember: User at the Uni of Vermont must
have login permission on “cs.yale.edu“
 FTP provides a way to allow a user to copy
files remotely
 Remote copying is accomplished through
“anonymous FTP“ method
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15. Anonymous FTP Method
 File to be copied (Server.java) must be
placed in a subdirectory (ftp) with the
protection set to allow the public to read
the file
 User uses ftp command
 Login name – “anonymous“ and password
 Anonymous login is accomplished
 User is allowed to access only those files
that are in the directory tree of user
“anonymous“
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16. www.trainsignaltraining.com/.../ftp_iis7_10.png
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17.  FTP mechanism is implemented (similar to
telnet implementation)
 Daemon on remote site -> watches for
connection requests to system‘s FTP port
 Login authentication is accomplished ->user
can execute commands remotely
 telnet daemon executes any command for user
 FTP daemon responds to a predefined set of
file-related commands
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18.  Get: transfer a file from the remote
machine to the local machine
 Put: transfer from the local machine to the
remote machine
 Ls or dir: list files in the current
directory on the remote machine
 Cd: change the current directory on the
remote machine
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19. Network and Operating System Security
 OS: system must protect itself
 Runway process could constitute an
accidental denial-of-service attack
 Query to service could reveal passwords
 Stack overflow could allow the launching of
an unauthorized process
 List of possible breaches is almost endless
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20.  Travels over private leased lines, shared
lines like the internet, wireless
connections, or dial-up lines
 Intercepting these data could be harmful as
breaking into a computer
 Interruption of communications could
constitute a remote denial-of-service
attack,
diminishing user‘s use of
and trust in the system
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21. Novell NetWare
 Is a NOS
 Used cooperative multitasking to run







several services on a PC
File sharing instead of disk sharing
NDS (Novell Directory Services)
Server administration
Desktop Management
Software distribution
Integrated cache
Enhanced security
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22. Novell NetWare Protocols
 Are widely used for PC LANs
 Windows XP Nwlink protocol connects the
NetBIOs to NetWare networks
 In combination with a redirector this
protocol enables a Windows XP client to
connect to a NetWare server
 Some NOSs for DOS and Windows system
include Novell NetWare: Windows NT and 2000
OS/2 etc.
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23. 23

24. Linux
 Free OS based on Unix standards
 Provides a programming interface and user interface
 Core Linux OS kernel is original, but allows much
existing free Unix software to run
 Multiuser system, providing protection between
processes and running multiple processes according
to a time-sharing (or multitasking) scheduler
 Multiple networking protocols can be accessed
simultaneously through socket interface
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25. 25

26.  Uses an abstraction layer to manage
multiple file systems
 Device-oriented, networked, and virtual
file systems are supported
 Network devices are dealt with differently
from block and character devices
 Users cannot directly transfer data to
network devices-instead- must communicate
indirectly by opening a connection to the
kernel‘s networking subsystem
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27. Windows XP
 Was designed to be an extensible, portable OS
 Supports multiple operating environments and





symmetric multiprocessing
32-bit and 64-bit processors
Use of kernel objects to provide basic services
Network device interface specification (NDIS)
and transport driver interface (TDI)
NDIS interface seperates network adapters from
transport protocols
TDI supports both connection-based and
connectionless transport, function to send any
type of data
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28. MS-DOS Environment
 No complexity of other Windows XP subsystems
 Provided by Win32 API application (VDM)
 Windows XP command shell is a program that
creates a window-looks like MS-DOS
 Can run 16-bit and 32-bit executables
 Some MS-DOS access the disk hardware directly -
> fail to operate under Windows XP
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29. Difference between Operating System and
Network Operating System
 OS runs the computer
itself
Example: Windows
 Network OS run on a
server and can be
accessed through client
machines connected on the
network
Example: Novell Netware
and Linux run on a server
and can be used as
NOS, even there are
Windows server OS‘s which
can be used by clients
connected on the network
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30. Summary
 NOS provides features such as file sharing across
the network
 Includes communication scheme
 Allows different processes on different computers to
exchange messages
 Computer running a NOS acts autonomously from all
other computers on the network
 It is aware of the network – able to communicate
with other networked computers
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31. Sources
 Book: “Operating System Concepts“
 www.answers.com/topic/network-operating-
system
 www.wikipedia.com
 www.trainsignaltraining.com/.../ftp_iis7_10.
png
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32. Thank you for attention!!
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