USAHA

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!!