Network operating systems1


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Network operating systems1

  1. 1. Bangladesh University of Business and Technology Course No: CSE 305 Course Title: Operating Systems 1
  2. 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 2
  3. 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) 3
  4. 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 4
  5. 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 5
  6. 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 6
  7. 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 7
  8. 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 8
  9. 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 9
  10. 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 “,“ a computer that is located at Yale University -> user must have a valid account on that machine telnet 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 ““ computer 10
  11. 11.  connection has been established  transparent, bidirectional link that all characters entered by the user are sent to a process ““  all the output from that process is sent back to the user 11
  12. 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: ““ wants to access a file located on another computer ““ 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
  13. 13. Example:  User on ““ -> copy Java program that resides on ““  Invoke FTP program ftp  Login name and password  Correct information has been received, user must connect to the file and after copy the file by executing get 13
  14. 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 ““  FTP provides a way to allow a user to copy files remotely  Remote copying is accomplished through “anonymous FTP“ method 14
  15. 15. Anonymous FTP Method  File to be copied ( 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
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  17. 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 17
  18. 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 18
  19. 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 19
  20. 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 20
  21. 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 21
  22. 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. 22
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  24. 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 24
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  26. 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 26
  27. 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 27
  28. 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 28
  29. 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 29
  30. 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 30
  31. 31. Sources  Book: “Operating System Concepts“  system   png 31
  32. 32. Thank you for attention!! 32