Computer Network Concepts PDF

3.1.1 - Computer network – comprised of two or more computer systems that are connected and able to communicate and exchange data - Connected by cable or wireless media SERVER – can either be a computer system or a so=ware applica>o...

3.1.1 - Computer network – comprised of two or more computer systems that are connected and able to communicate and exchange data - Connected by cable or wireless media SERVER – can either be a computer system or a so=ware applica>on that provides services to S the other computer systems connected to the same network computer system - can provide the ability to the rest of the computer on the network to store and share software application files, taking the role of a file server - is a host running server so=ware applica>on sharing its resources with clients that make & CLIENT requests – can either be a computer system or a so=ware applica>on that requests a service from a server connected to the same network - does not share any of its resources but requests content from a server the most commonly used network components that play an essen>al part in the crea>on of a network are: Hub, Switch, Router HUB - the connec>on point for devices on a single network - other devices connect to hub using Ethernet cables that aIach to a port - consists of mul>ple ports SWITCH - the connec>on point for mul>ple devices on a single network - can iden>fy which device is connected to which port à this allows the switch to transmit data to the exact port and network device for which it is intended ROUTER - a more sophis>cated device than both hub and switch - used to join mul>ple networks and serve as an intermediary between these networks so that data can be exchanged effec>vely and efficiently between network devices of those networks TYPES OF NETWORKS LAN > - wined > - limited geographical area - computer network that connects computer systems that are within a limited geographical area such as a room, a home, an office building - computer systems interconnected with a LAN usually have high data transfer rates between them - allows the sharing of peripheral devices between the connected computer networks - peripheral devices can be used by any computer system in the LAN that is desired à eliminates the need to buy certain peripheral devices for every computer system used - data can also be shared à allows sharing of data between clients, thus elimina>ng the need to physically send data using other means (USB s>cks, DVD,…) - used technology to build wired LAN à hub or a switch using Ethernet cabling  - A CLIENT-SERVER MODE – allows for a single computer system to act as the server and be responsible for supplying various services to the clients in the network WLAN - Links 2 or more computer systems within a limited geographical area, similar to LAN - WLAN devices are connected by wireless connec>on method à allows users to have mobile devices and laptops connected to the network and be able to move around - Can be less secure than wired LANs - The most common technology to build wireless LANs is Wi-Fi àallows the exchange of data between computer systems using radio waves VLAN - Instead of having to set up switches and cabling in order to create separate LANs for every department, a VLAN can be used to par>>on the ini>al LAN, where every department is connected, into logic separate networks - Safer than LAN WAN - Computer network that connects computer systems that are within a large geographical area - - Example of WAN: Internet - Allows individuals, businesses, and governments to carry out their daily business regardless of loca>on SAN - Network that is created so that large storage devices can be accessible from servers in a convenient and easy way - There can be various servers connected to a network such as a company’s LAN - 135 str. INTRANET eduroam - The broad team for a collec>on of private computer networks within a company, a - school, or an organiza>on that u>lizes standard network protocols - MAIN PURPOSE: to facilitate communica>on between individuals or work groups and to improve data sharing INTERNET - A global WAN connec>ng millions of computer systems - - Provides extensive number of services to users such as World Wide Web (WWW), which consists of websites and webpages, as well as support for email, file transfer - Is decentralized by design INTERNET OF THINGS (IoT) - The network of individual things that are able to connect to the Internet, communicate, and exchange data - All “things” carry the necessary hardware and so=ware and are assigned an IP-address EXTRANET - Computer network that u>lizes the Internet to allow controlled access by specific users raise to a specific LAN or WLAN VPN - A computer network that connects 2 or more computer systems, similar to a LAN or a - WLAN, but also allows clients from remote loca>ons to connect to the network and appear to be inside the LAN as if they were physically present - Has all the benefits of LAN, allowing users to share data and resources without compromising security PAN - Network that interconnects devices that are centered around an individual person’s workspace - Using a wireless group of devices using Bluetooth technology in order to interconnect is also known as a piconet PEER-TO-PEER (P2P) - A network that does not u>lize the client/server model where clients request resources and servers provide them à instead PSP network uses a distributed network architecture where all the computer systems in the network are decentralized and are both clients and servers at the same >me, consuming and supplying resources from and to the other computer systems connected to the network 3.1.13 WIRELESS NETWORKING - All wireless devices communicate and exchange data through radio transmissions, without any physical connec>on or cabling - Wireless systems and devices include cell phones, cordless computer keyboards, local area networks, mouse devices, remote controls, etc. ADVANTAGES AND DISADVANTAGES HEALTH CONCERNS - Extensive use of mobile devices and wireless networks cause many health issues - Radiofrequency fields can cause >ssue hea>ng - Electromagne>c hypersensi>vity - Increased risk of brain tumor Social acMviMes - Increased risk of crashes during tex>ng or using mobile phones - Social isola>on - Easier ways to learn using plaeorms Environmental issues - Devices are o=en improperly disposed which leads to pollu>on since they contain hazardous materials like mercury and lead HARDWARE DEVICES NEEDED Modem - Allows you to connect to the internet Wireless - O=en serves as WAP and allows data transfer between a devices and a network Wireless network adapter - Known as NIC, is required for each device on a wireless network Node - Devices that connects to the Internet (PC, laptop, tablet,…) Wireless antennas - Used to increase the effec>ve communica>on area of wireless network - Fixed, op>onal, or removable Wireless reapeter - Connected to a router or access point - Receiving an exis>ng signal and rebroadcast it Ethernet to wireless access point O - Uses Ethernet cables to carry the signal to WAP or reapeater C Ethernet over power line to wireless repeater - Uses Ethernet cables to carry the signal to the wireless repeater or WAP SOFTWARE NEEDED DHPH - Dynamic Host Configuration Protocol - Allows server to automatically assign an IP adress to a client device SOFTWARE FIREWALL - Network security system used determine what data goes in and comes out of a network or PC Name/SSID - Service set of identification of 32 alphanumeric characters - Used to differentiate one WLAN from another NIC DRIVERS - Operates or controls hardware of the card - Acts like a translator between the wireless card and the applications or operating system of the device OS - Operating System - Handles resources and is responible for managing all the protocols, hardware and applications that have to cooperate SECURITY SOFTWARE - Includes all software that prevents unauthorized access - Access control, firewall, anti-spyware, antivirus software, IDS, IPS, sandbox, anti- - m tamper software… WAP - Wireless Application Protocol - Specifies a set of protocols for accessing information over a mobile wireless network WEB BROWSER - software used to find, retrieve , and display content on WWW. 3.1.15. CHARACTERISTICS OF WIRELESS NETWORK Wi-Fi (Wireless Fidelity) - Also called Wireless LAN (WLAN) - Used in laptops/ mobile devices in order to connect to home network wirelessly - Most preferred network type to implement a home network - Allows relatively slow to fast data transmissions (depending on the version) - Backwards compatible with most older Wi-Fi standards (a/b/g/n) - Small transmitting radius makes it suited for homes, usually less then 20m Generations 1G, 2G - -The first generation of mobile tehnology that used analog transsmision 3G - - Third generation of mobile networking and telecommunication tehnology - Widely used in wireless telephony, GPS, video calls and mobile TV - Can provide a data transfer rate of 200 kbit/s - - More secure than 2G 4G E - Fourth generation of mobile telecommunication technology - Speed requirement at 100 Mbit/s for high mobility communication ( use from trains, - cars, buses…) and 1 Gbit/s for low mobility communication - Doesn’t support traditional circuit telephony service only IP-based communication 5G - Fifth generation of mobile telecommunication - Also known as Tactile Internet LTE - Long Term Evolution - 4G network - - Standard for wireless communication of high-speed data m e m - Highest download rate at 300 Mbit/s and upload rates 75 Mbit/s - - 4G LTE evolved into LTE Advances that provides even more data capacity WiMax - WiMAX = Worldwide Interoperability for Microwave Access Designed for large distance high-speed internet access - 4G network - Relatively cheap method of providing internet over a large area - suited for poorer countries - Allows connectivity even in remote and isolated areas (where no Wi-Fi) - Rivalled by Long Term Evolution (LTE) standard - Can be used as a form of wireless variant of DSL phone transmission lines Security Networks - Used to measure data and parameters for physical (temperature, sound, pressure) or environmental reason (health-care monitoring, environmental sampling…) - Placed in fixed locations and linked by wireless network to perform sensing tasks - Wireless sensor network requires nodes to communicate and ensure appropriate coordination and cooperation 3.1.16 Different methods of network security - As smart tehnology omproves, innovative devices are being developed to provide advanced functionality, portability, ease to use and complex function - Wireless networks, devices and services are more vulnerable than convential wired networks - Intruder, hackers and unathorised users can: disable operation, disturb the privacy of legitimate users, steal identities, steal devices, gain unauthorized access ENCRYTION - Necessary to protect data from unauthorized during Internet use - Uses complex mathematical algorithms and encryption keys to alter a message info a form that is not understandable to an unauthorized person - There are two types of encryption: 1. Symmetric-key encryption - Same key is used for encryption and decryption 2. Public-key encryption - Uses a public key for encryption and a private one for decryption FREE ACCESS - Wireless data transmission extends beyond walls and window screens - When you buy a wireless router or an access point, its security features are not enabled - - When you set up a wireless network you may not want to provide open and free Internet access to your neighbours - So you have to enable security features METHODS OF NETWORK SECURITY - Use a password to access your device - - Install an antivirus program on your device - - Use a software firewall installed on each device - - Use a password to access the web interference that is used to setup your wireless - router on many access points - Turn On/Off Wireless Connectivity - - Enable/Disable SSID Broadcast - Block access to wireless devices by MAC address - WEP Wireless security - WPA,WPA2, Wireless Security - WPS (Wireless Protected Setup) WEB METHODS - Pin- personal identification number should be entered in the device that we wish to connect to network - Push button- the user pushes a WPS button on both devices ( wireless router or access point and client device) - Near field communication ( NFC) - new device should be close to the access point/router - Use transfer method- to transfer data between wireless rounter or access point and the client device OTHER METHODS - Prevent physical access - its possible for a building to be shielded from electromagnetic interference - Use router hardware firewall - protects your connection and is able to block incoming traffic - Use encryption software for sensitive information set over the Internet ( attached files sent with email)