computer networking

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*What is computer network? *Types of network *Network topology *Computer components *Network components *Internet security


  • 1. COMPUTER NETWORK Networking & Security

2. CONTENTS What is a computer network? Types of network Network topologies Computer components Network components Internet security 3. A computer network is where two or more networks are connected or linked. so that they can exchange data. Network devices that originate, route and terminate the data are called network nodes. Nodes can include host like servers and personal computers, as well as networking hardware. Two networks are said to networked when a process in onedevice can exchange information with a process in another device. 4. The connection (network links) between networked computing device (network nodes) are established using either cable media or wireless media. The best known computer network is Internet. Computer networks support applications such as world wide web, shared use of application and storage servers, printers, faxmachine, and use of email and instant text messaging application. 5. TYPES OF NETWORK Main Types Of Network:1. 2. 3. 4.PAN (Personal Area Network) LAN (Local Area Network) WAN (Wide Area Network) MAN (Metropolitan Area Network) 6. PAN - This type of network is used for a portable computer and a handheld for sharing photos, music, including email and calendar appointments, short distance connection using USB, Firewire, Bluetooth or Infrared. LAN This type of network is used to connect computers which belong to the same organization, within a building or small area. WAN This type of network is used to connect multiple LANs with each other from far places. MAN - This type of network is used to connect two or more computers in nearby cities using fiber optic cable. 7. NETWORK TOPOLOGY Network topology is the layout or organizational hierarchy of interconnected nodes of a computer network.Common layouts: 1. bus network 2. star network 3. ring network4. tree network 5. mesh network 8. BU S N E T WO R K In bus network each node is connected to a single cable. A signal from the source travels in both directions to all all the machines connected to bus cable until it reaches intended receipt. Advantage Its economical; Disadvantage If Backbone breaks whole network will shutdown. 9. S TA R N E T WO R K In star network each network host is connected to a central hubwith a point-to-point connection. The hub is the server and peripherals are the client. All the data on the star topology passes through the centraldevice before reaching the intended destination. Advantage - Reliable; Disadvantage Expensive to install 10. R I N G N E T WO R K In Ring Topology, all the nodes are connected to each-other in such a way that they make a closed loop. Each workstation is connected to two other components on either side, and it communicates with these two adjacent neighbors. Data travels around the network, in one direction. Sending and receiving of data takes place by the help of TOKEN. Advantage Less wiring; Disadvantage Very slow 11. T R E E N E T WO R K Tree Topology integrates the characteristics of Star and Bus Topology. In Tree Topology, the number of Star networks are connected using Bus. This main cable seems like a main stem of a tree, and other star networks as the branches. It is also called Expanded Star Topology. Advantage Its big; Disadvantage - Not reliable 12. MESH NETWORK In Mesh Network each node, computer and other devices are interconnectedto each other. Every node not only sends its own signals but also relays data from other nodes. This type of topology is very expensive as there are many redundant connections, thus it is not mostly used in computer networks. It is commonly used in wireless networks. Advantage Traffic abundance; Disadvantage Highly expensive 13. COMPUTER COMPONENTS 14. Input Devices:1. Mouse (Pointer Device) 2. Keyboard 3. Joystick4. Scanner 5. Microphone 6. Webcam 15. Central Processing Unit: 1. Processor (CPU) 16. Output Devices:1. Monitor (Screen) 2. Printers3. Speakers 17. Storage Devices:1. ROM (Random Access Memory) 2. ROM (Read Only Memory) 3. Hard Disks (Read/Write)4. CD/DVD Drives 18. NETWORK COMPONENTS Network interference card - is found in the circuit board or mother board. It helps devices to connect to a network. Network software - is software designed to manage a network. Network cable/wire - Used to connect devices together to form a network. Hub- Central device used in Star Networks which is not reliable and is slow. Switch- Central device used in Star Network which is safe Router A device which forwards data packets to the appropriate computer network. 19. INTERNET SECURITY The Need Of Internet Security:1. It is protection against viruses, malware etc. even hackers. 2. Commercial & Government Enterprises are reluctant to use the Internet because of security concerns. Since Internet ultimately connects to a public network, the security concerns are very much valid.3. The need for security is being alarmingly realized with the emergence of E-Commerce. Presently, E-Commerce operations are always threatened by fear of loss of money and privacy. 20. 3.Governments, military, corporations, financial institutions, hospitals, and private businesses amass a great deal of confidential information about their employees, customers, products, research and financial status. Most of this information is now collected, processed and stored on electronic computers and transmitted across networks to other computers. 4. Even E-mail is also under threat. When sent across the Internet, the E-mail can be intercepted and read by anybody who can lay his hands on it. 21. If you are planning to connect your organization to Internet and your computers are accessed from remote places, you must have a Firewall to protect your Intranet. Firewall is defined as a group of systems that enforce an access control policy between two networks. In other words it is a mechanism used to protect trusted network from an untrusted network. Firewall acts as a Gatekeeper between a companys internal network and the outside world. It acts as an electronic barrier to stop unauthorized entry. 22. A Firewall Performs Two Basic Functions: 1. Gatekeeping - It examines the location from which the data enters your system and then decides based on your instructions whether or not to allow the information. 2. Monitoring - It includes login of all system activities and generation of reports for system administration. Monitoring can be active or passive. In active monitoring a firewall notifies a manager whenever an incidence occurs, generally by E-mail or Pager. In passive monitoring the manager has to go through the logs to determine and analyze the system activities. 23. Draw Backs Of Firewall:1. An Internet Firewall cannot protect against attacks that do not go through the Firewall. For example, if an unrestricted dial-out connection is permitted from inside the protected network the users can make a direct connection to the Internet. Users who become irritated with the additional authentication required by the Firewall may temp to bypass the security system by purchasing a direct connection to an ISP. 2. The Internet Firewall cannot protect against threats posed by traitors who may copy sensitive data into floppies and other media. A hacker may also persuade someone to reveal a password and grant him a temporary network access. Hence, there is a need to periodically change the passwords. 3. The Firewall Cannot Protect Against The Transfer Of Virus Infected Files Or Software. Hence, Anti-Viral Software Should Be Deployed At Each Desktop. 4. Lastly the Internet Firewall cannot protect against data driven attacks. A data driven attacks occur when seemingly harmless data is mailed or copied to a computer and executed to launch a hidden attack. 24. MALWARES Malware, short for malicious software, is software used to disrupt computer operation, gather sensitive information, or gain access to private computer systems. Malware includes computer viruses, ransomware, worms, trojan horses, rootkits, keyloggers, dialers, spyware, adware, malicious BHOs, rogue security software and other malicious programs. 25. MAIN TYPES OF MALWARES 1. Virus 2. Trojan Horse 3. Spyware 4. Worm 5. Adware 26. VIRUS Viruses are programs that can replicate their structures of effects by inflecting other structures on a computer. The common use of virus is to take over a computer to steal data. 27. TROJAN HORSE A destructive program that masquerades as a being application. Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive. One of the most insidious types of Trojanhorse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer. 28. SPYWARE Spyware is a type of malware that is installed on a computer without the knowledge of the owner in order to collect the owners private information. Spyware is often hidden from the user in order togather information about internet interaction, keystrokes (also known as key logging), passwords, and other valuable data. 29. WORM A program that makes copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism. The worm may do damage and compromise the securityof the computer. It may arrive in the form of a joke program or software of some sort. 30. ADWARE Adware, or advertising-supported software, is any software package which automatically renders advertisements in order to generate revenue for its author. The advertisements may be in the user interface of the software or on a screen presented to the user during the installation process. The functions may be designed to analyze which Internet sites the user visits and to present advertising pertinent to the types of goods or services featured there. The term is sometimes used to r