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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
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)
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
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
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
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
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
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
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:
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
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
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
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
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“
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
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
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
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
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
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.
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
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
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
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
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
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
Sources
Book: “Operating System Concepts“
www.answers.com/topic/network-operating-system
www.wikipedia.com
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