1

Course No: CSE 305Course Title: Operating

Systems

Bangladesh University of Business and Technology

NETWORKING OPERATING SYSTEM

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

2

What is a system?• set of interacting or interdependent entities

Multiple meaning: collection of organized thingsway of organizing or planningwhole 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)

 

3

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

4

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

 

5

User 1 User 2 User 3 User n

System and Application Programs

Operating System

Computer Hardware

Compiler Assembler Text editor DatabasesSystem

........

Figure: Abstract view of the components of a computer system 6

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

7

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

8

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

9

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:

10

telnet 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  

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

11

Remote File TransferProvide 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

12

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

13

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

14

Anonymous FTP MethodFile 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“

15

16

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

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

17

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

18

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

19

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

20

Novell NetWare

Is a NOSUsed cooperative multitasking to run several services on a PC

File sharing instead of disk sharingNDS (Novell Directory Services)Server administrationDesktop ManagementSoftware distributionIntegrated cacheEnhanced security

21

Novell NetWare ProtocolsAre 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.

22

23

LinuxFree 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

24

25

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

26

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

27

MS-DOS EnvironmentNo 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

28

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

29

SummaryNOS 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

30

Sources

Book: “Operating System Concepts“

www.answers.com/topic/network-operating-system

www.wikipedia.com

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

31

Thank you for attention!!

32