1 Technology in Action Chapter 12 Behind the Scenes: Networking and Security Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

2 Networking Advantages Networks – –Increase productivity – –Enable the sharing of hardware resources – –Facilitate knowledge sharing – –Enable the sharing of software – –Facilitate Internet connectivity – –Enable enhanced communication Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

3 Client/Server Networks Server-based network – –Clients and servers Data flows efficiently Servers respond to requests from clients Servers perform specific tasks Scalable Centralized Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

4 Classifications of Client/Server Networks LAN – –Local area network – –Computers linked over a small geographic region Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

5 Classifications of Client/Server Networks WAN – –Wide area network – –Computers linked over large geographic locations MAN – –Metropolitan area network – –Computers linked within a city or county Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

6 Classifications of Client/Server Networks PAN – –Personal area network – –Wireless devices connected in close proximity to each other Intranet – –Private corporate network – –Protected by a firewall Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

Classifications of Client/Server Networks Extranets – –Only certain corporations or individuals can access – –Useful for enabling electronic data interchange – –Use virtual private networks (VPN) for security added security measures 7 Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

8 Constructing Client/Server Networks Servers Network topologies Transmission media Network operating system (NOS) software Network adapters Network navigation devices (routers) Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

9 Servers Number and types of servers depend on network size and workload Dedicated servers: (described below) – –Perform one specific function Authentication servers – –Keep track of network logins and services available File servers – –Store and manage files Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

10Servers Print servers – –Manage client-requested printing jobs – –Create print queue (prioritize print jobs) Application servers – –Act as a storage area for application software Database servers – –Provide clients with access to database information servers – –Process and deliver incoming and outgoing (anti-virus, anti-spam, anti-spyware, firewall) Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

11 Servers Communications servers – –Handle communications between networks, including the Internet (firewall, anti-hacking) – –Often the only device on the network directly connected to the Internet Web servers – –Host a Web site available through the Internet – –Markup pages, interaction with user Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

12 Network Topologies The physical or logical layout of computers, transmission media, and other components Types of network topologies – –Bus topology – –Ring topology – –Star topology – –Hybrid topology Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

13 Bus Topology All nodes are connected in sequence on a single cable Used most often in peer-to-peer networks Networked computers communicate with each other One computer transmits data at a time – –Access methods avoid data collisions – –Data is transmitted in packets – – bytes Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

14 Ring Topology Nodes are laid out in a ring. A token (data packet) flows in one direction from device to device. Recent versions have data transfer rates of up to 100 Mbps. Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

15 Star Topology Nodes connect to a central communications device (switch or hub). A node sends a signal to the switch, which retransmits it to the destination node only. Hub-sends to all nodes A node accepts only signals addressed to it (?). Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

16 Avoiding Data Collisions on an Ethernet Network Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

17 Transmission Media The routes data takes to flow between devices on a network Wired – –Twisted pair – –Coaxial – –Fiber-optic Wireless -usually microwave, could be RF Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

18 Choosing a Cable Maximum run length Bandwidth Bend radius Cable cost Cable and installation costs Susceptibility to interference Signal transmission methods Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

19 Twisted Pair Cable Pairs of copper wire twisted around each other Twists make the wires less susceptible to interference Shielded twisted pair (STP) – –Layer of foil shielding Unshielded twisted pair (UTP) – –Cat 5E: Bandwidth 200 Mbps – –Cat 6: Bandwidth 1 Gbps – –No foil layer Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

20 Coaxial Cable Four components – –Copper core – –Nonconductive insulating material – –Braided metal – –Plastic cover Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

21 Fiber-Optic Cable Components include – –Glass or plastic fibers – –Cladding – –Outer jacket Uses light impulses to transmit data Immune to interference Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

22 Wireless Media Standard Wi-Fi (short for Wireless Fidelity) – –802.11b – –802.11a – –802.11g – –Super G – –802.11n Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

23 Network Operating Systems (NOS) Provide the protocol that controls the communication among devices on the network Many modern OSs include NOS client software Major network operating systems – –Windows Server 2008 – –UNIX – –Novell Open Enterprise Server Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

24 Network Adapters Devices that enable computers to communicate on a network Network interface cards (NICs) Three functions – –Generate network transmission signals – –Create data packets – –Act as information gatekeepers Ethernet compliant Wireless NICs Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

25 Network Navigation Devices Media Access Control (MAC) address – –Six two-digit numbers (such as 01:40:87:44:79:A5) – –Physical address of network adapter – –Internal network identification Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

26 Network Navigation Devices Switches and bridges – –Send data on a specific route through the network – –Bridges send data between collision domains Routers – –Send information between two networks Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

27 Network Navigation Devices Repeaters – –Amplify a signal and retransmit it – –Extend cable runs Hubs – –Transmit signals; have multiple ports Receive a signal from a device Reconstruct the signal Transmit the signal to all ports on the hub (amplifies also) Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

28 Network Security Threats Human errors and mistakes Malicious human activity – –Current and former employees hacking or planting viruses Natural events and disasters – –Hurricanes, floods, fire – –Disaster Recovery Plan Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

29 Network Security Firewalls – –Prevent access to the network by unauthorized users – –Composed of software and/or hardware – –Screen and validate data packets – –Bastion host/proxy server Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall

30 Network Firewall Layout Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall