This document discusses network operating systems. It begins by defining key concepts like systems, networks, and operating systems. It then introduces network operating systems, which allow users to access remote resources by logging into other machines or transferring files between computers. Example features of network operating systems are described like security, directory services, and file/print sharing. Specific network operating systems are also outlined, such as Novell NetWare, Linux, and Windows XP. The document concludes by summarizing the differences between a regular operating system and a network operating system.

1. Network Operating System
By Elena Otte
Distributed Data Processing

2. Table of content:
 System
 Network
 Operating System
 Network Operating System
 Features
 Remote Login with an example
 Remote file transfer (Example)
 Anonymous FTP method
 Network and Operating System
Security
 Novell NetWare and protocols
 Linux
 Windows XP
 MS-DOS environment
 Difference between OS and
NOS
 Summary
 Sources

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)

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

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

6. User 1 User 2 User 3 User n
Compiler Assembler Text editor Databases
System and Application Programs
Operating System
Computer Hardware
System
........
Figure: Abstract view of the components of a computer system

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

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

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

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
to log in remotely the user issues the command:
t e lnet cs.yale.edu
Command results in the formation of a socket connection between
the local machine at
Westminster College and the “cs.yale.edu“ computer

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

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

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

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

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“

16. www.trainsignaltraining.com/.../ftp_iis7_10.png

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

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

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

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

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

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.

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

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

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

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

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

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

31. Sources
 Book: “Operating System Concepts“
 www.answers.com/topic/network-operating-system
 www.wikipedia.com
 www.trainsignaltraining.com/.../ftp_iis7_10.png

32. Thank you for attention!!