Network Fundamentals Chapter 7: Networking and Security CS10001 Computer Literacy Network Two or more computers connected by hardware or software so that they can communicate with each other Nodes Devices connected to a network Computers Peripherals Modems Chapter 7: Networking and Security 1 Chapter 7: Networking and Security 2 Network Fundamentals Network Benefits Sharing peripherals via external storage Sharing files between or among computers via shared directories Sharing a broadband Internet connection via a router Network Architecture Two methods of design 1. The way in which they are controlled Locally Centrally 2. The distance between the network nodes Chapter 7: Networking and Security 3 Chapter 7: Networking and Security 4 1
Network Designs Way in which they are controlled Locally Controlled Peer-to-peer or P2P Nodes are considered to be peers Easy to set up Popular for home applications Network Designs Way in which they are controlled Centrally Controlled Communication between client and server Control dictated by the server Contains >= 10 nodes Beneficial in business applications Chapter 7: Networking and Security 5 Chapter 7: Networking and Security 6 Network Designs Network Components The distance between nodes LANs Local area networks Nodes located in a small geographic area (labs) WANs Wide area networks LANs connected over long distances (separate campuses) Networks need the following to function 1. A means of connecting nodes via a transmission media (cable or wireless) 2. Special devices to allow node communication 3. Software to run the network Chapter 7: Networking and Security 7 Chapter 7: Networking and Security 8 2
Network Functions Network Functions A means of connecting nodes via a transmission media Types or forms available 1. Existing wiring (telephone lines) 2. Cables (twisted pair, coaxial, fiberoptic) 3. Wireless (radio waves) A means of connecting nodes via a transmission media cont d. Speeds 1. Bandwidth is the maximum speed of transmission between nodes (Mbps) 2. Throughput is the actual speed of transmission and is often less than bandwidth (Mbps) Chapter 7: Networking and Security 9 Chapter 7: Networking and Security 10 Network Functions Network Functions Special devices to allow node Special devices to allow node communication communication Network adapters Network navigation devices Installed internally on the motherboard in the nodes Assist in the transmission of data packets between nodes Connected externally via USB ports on the Available via network adapters (simple nodes networks) Installed internally as expansion cards Handled via special navigation devices (network interface cards) (complex networks) Chapter 7: Networking and Security 11 Chapter 7: Networking and Security 12 3
Network Functions Network Functions Special devices to allow node communication Handled via special navigation devices (complex networks) Routers transfer data between networks (home and Internet) Switches transfer data inside a network to the intended node Software to run the network Home networks need operating systems to support P2P Vista Home, XP Home, 2000, 98 Client/server networks require that the server have a network operating system installed Vista Enterprise, XP Professional, Server 2003, Novell Chapter 7: Networking and Security 13 Chapter 7: Networking and Security 14 1. Wired Ethernet networks 2. Wireless Ethernet networks 3. Power-line networks 4. Phoneline networks Wired Ethernet networks Use the IEEE standard that determines node communication (802.3) Extremely efficient because of complex algorithms Require special navigation devices (routers and switches) Data transmission rate = 100Mbps or 1,000Mpbs Chapter 7: Networking and Security 15 Chapter 7: Networking and Security 16 4
Wired Ethernet networks cont d. Wired Ethernet networks cont d. Network adapters or network interface Switches transfer the data packets to cards are required the destination node Nodes connected by UTP Cable Hubs may be used as another special (unshielded twisted pair cable) and navigation device to broadcast to all Ethernet connectors (RJ-45) intended nodes UTP cable runs are <= 328 feet Router required to transfer data packets Requires repeaters to amplify the signal between networks (home to Internet) if UTP cable run > 328 feet Chapter 7: Networking and Security 17 Chapter 7: Networking and Security 18 Wireless Ethernet networks Wireless Ethernet networks cont d. Use radio waves as the transmission Wireless network adapters are required media between nodes Internally on the motherboard Use the IEEE standard determining node communication (802.11 for Wireless Fidelity or Wi-Fi) 802.11a, 802.11b, 802.11g, 802.11n Differences are the data transfer rate and types of security support Internally as expansion slots Externally as USB devices Transceivers translate the electronic data from the nodes into radio waves, broadcasting the radio waves to all other nodes (also receives signals) Chapter 7: Networking and Security 19 Chapter 7: Networking and Security 20 5
Wireless Ethernet networks cont d. Wireless Ethernet networks cont d. Requires a gateway (wireless router) for Problems commonly associated include Internet connection Decreased throughtput because distances May require wireless access points (WAP) to assist with connection problems caused by interference or distance constraints are shorter (about 250 feet) between nodes IEEE standards with 2.4GHz bandwidth may interfere with other devices (cell phones) Interference from objects (walls, large objects) Chapter 7: Networking and Security 21 Chapter 7: Networking and Security 22 Power-line networks Power-line networks Use existing electrical wiring to connect Less popular than Ethernet networks network nodes (any electrical outlet) Bandwidth limitations Data transfer rate of 14Mbps-200Mbps Cost considerations set by the Home Plug Power Line Recent standard upgrades have Alliance resulted in greater throughput, so See www.homeplug.org for details. popularity could increase Chapter 7: Networking and Security 23 Chapter 7: Networking and Security 24 6
Home Network Safety Phoneline networks Uses conventional phone lines for data transmission Requires each node have a home phoneline network adapter installed on each node and then plug into a phone jack Very unpopular, but sometimes suitable Cybercrime Criminal activity perpetrated through computer usage by cybercriminals Internet Networks Personal computers Chapter 7: Networking and Security 25 Chapter 7: Networking and Security 26 Home Network Safety A hacker is anyone breaking into an individual computer or network by unlawful means White-hat hacker breaks into systems for a challenge or to expose network security breaches Black-hat hacker breaks into systems for illegal gain or to destroy information Home Network Safety Script kiddies are amateur hackers that use tools developed by sophisticated hackers Malicious Relatively easy to find through electronic tracks Chapter 7: Networking and Security 27 Chapter 7: Networking and Security 28 7
Hacker Threats Use of packet sniffers Looks at all data packets traveling the Internet Looks for personal information Potential for identity theft Hacker Threats Use of Trojan horses Harmless programs with malicious background activity Uses backdoor programs Infected computers become zombies Chapter 7: Networking and Security 29 Chapter 7: Networking and Security 30 Hacker Threats Denial of Service Attacks (DoS) Hackers request repeated instructions from zombie computers they created Zombies shut down or are bogged down from the flood of requests Hacker Threats Distributed Denial of Service (DDoS) Less traceable than DoS attacks Many zombies coordinate request attacks to the same computer simultaneously Chapter 7: Networking and Security 31 Chapter 7: Networking and Security 32 8
Hacker Threats - Viruses Boot-sector viruses Replicates itself in the Master Boot Record before virus protection is loaded Occurs from leaving infected storage devices in drives during startup Hacker Threats - Viruses Logic bombs and time bombs Logic bombs are viruses triggered by satisfied logical conditions Time bombs are viruses triggered by dates or time passages Chapter 7: Networking and Security 33 Chapter 7: Networking and Security 34 Hacker Threats - Viruses Worms Spreads through computer systems via network connections Attaches to a commonly executed host file Spreads rapidly Hacker Threats - Viruses Script and macro viruses Mini-programs executed without knowledge Via Internet activity (watching clips) Via e-mail attachments Chapter 7: Networking and Security 35 Chapter 7: Networking and Security 36 9
Hacker Threats - Viruses Encryption viruses Performs electronic blackmail Important system or application files kidnapped by hacker, then encrypted Hacker Threats - Viruses Trojan horses Performs maliciously in the background Pretends to offer a useful utility Infected user pays for return of files Chapter 7: Networking and Security 37 Chapter 7: Networking and Security 38 Virus Classifications Polymorphic Usually infects one file and recodes itself periodically Multipartite Infects multiple file types in an effort to fool the antivirus software Stealth Combating Hackers and Viruses Firewall Used to close off logical (internal) ports to hackers May be in the form of software programs or hardware devices Attempts to hide from antivirus software through temporary erasure Chapter 7: Networking and Security 39 Chapter 7: Networking and Security 40 10