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“
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.
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
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
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