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  • 1. A+ Guide to Managing and Maintaining your PC, 6e Chapter 10….. PCs on the Internet
  • 2. Objectives
    • Learn about the TCP/IP suite of protocols
    • Learn how to connect to the Internet using cable modem, DSL, and dial-up connections and how to share those connections
    • Learn how to use a router to enhance and secure a network connection to the Internet
    • Learn about supporting common Internet clients such as Web browsers, e-mail clients, file transfer software, Internet telephone, and Windows XP Remote Desktop
  • 3. Introduction
    • Topics to cover
      • How the TCP/IP suite of protocols is used
      • Creating and troubleshooting broadband connections
      • How to create and troubleshoot dial-up connections
      • How to install and use a router
      • Supporting Internet applications; e.g., Web browsers
  • 4. The TCP/IP Suite of Protocols
    • Client/server application
      • Client application on one PC requests data from server
      • Server application on another PC returns data
    • Example: World Wide Web
      • The client is a Web browser
      • The server is a Web server; e.g., Apache HTTP server
      • Requested data is a Web page
    • Client applications are installed as programs
    • Server applications are installed as services
  • 5. Figure 18-1 A Web browser (client software) requests a Web page from a Web server (server software); the Web server returns the requested file or files to the client
  • 6. Using IP and Port Addresses to Identify Services
    • Port (port address, port number)
      • Number that identifies server application to client
      • Server application listens for request at assigned port
      • Example: port 80 is typically assigned to Web servers
    • Port numbers appear at the end of an IP address
      • Example: 138.60.30.5:80
    • A few other common ports and assigned services
      • Port 20: FTP (File Transfer Protocol)
      • Port 25: E-mail (using SMTP protocol)
      • Port 443: Web server (using HTTPS protocol)
  • 7. Using IP and Port Addresses to Identify Services (continued)
    • Communication protocol
      • Defines rules of communication between client/server
      • Example: POP3 is used by client to receive e-mail
    • Information flow between client and server
      • Application sends request to OS
      • OS passes request to NIC
      • NIC places request on network
      • NIC on receiving end sends request to OS
      • OS passes request to Web server application
      • Web server responds by sending data to OS
  • 8. Common Port Numbers
    • http:// www.iss.net/security_center/advice/Exploits/Ports /
  • 9. TCP/IP Packet
  • 10. Figure 18-3 Applications, operating systems, and the physical network manage communication at all three levels
  • 11. TCP/IP Protocol Layers
    • TCP/IP suite lies between applications and the OS
    • API: application programming interface
    • How application protocols are used
      • Application makes an API call to the OS
      • The API causes OS to generate a request
        • Request follows format specified by application protocol
      • After response is passed back, a session is established
    • Example involving HTTP (Hypertext Transfer Protocol)
      • Web browser makes an API call to the OS
      • OS makes an HTTP request for a browser
  • 12. Figure 18-4 How software, protocols, and technology on a TCP/IP network relate to each other
  • 13. TCP/IP Protocol Layers (continued)
    • Transmission Control Protocol (TCP)
      • A connection-oriented protocol
      • Makes a connection, checks delivery, resends data
    • User Datagram Protocol (UDP)
      • A connectionless or best-effort protocol
      • Does not guarantee delivery
    • Internet Protocol (IP)
      • Breaks up and reassembles data into packets
      • Routes packets to their destination
    • TCP uses IP to establish session and verify delivery
  • 14. Figure 18-5 TCP turns to IP to prepare the data for networking
  • 15. TCP/IP Protocol Layers (continued)
    • ARP (Address Resolution Protocol)
      • Responsible for locating a host on a local network
    • RARP (Reverse Address Resolution Protocol)
      • Discovers Internet address of host on a local network
    • ICMP (Internet Control Message Protocol)
      • Communicates problems with a transmission
      • Example: message deleted due to excessive hops
    • Network protocols used by hardware
      • Ethernet and PPP (Point-to-Point Protocol)
  • 16. TCP/IP Utilities
    • TCP/IP component includes a group of utilities
      • Location: Windows or Winnt folder
    • Commonly used utilities: Ping, Winipcfg, Ipconfig
    • SNMP (Simple Network Management Protocol)
      • Provides system management tools for networks
    • Microsoft SNMP Agent
      • Utility installed after TCP/IP is installed
      • Used to monitor remote connections
    • Tracert (trace route): shows hops along packet route
  • 17. Figure 18-9 The Tracert command traces a path to a destination computer
  • 18. Connecting to the Internet
    • Broadband: supports multiple transmission types
    • Internet Service Provider (ISP)
      • Connects a PC or network to the Internet
    • Bandwidth technologies used by ISPs:
      • Regular telephone lines
      • Cable modem
      • DSL (Digital Subscriber Line)
      • ISDN (Integrated Services Digital Network)
      • Satellite access
      • Wireless access
  • 19. Cable Modem and DSL Connections
    • Comparing communication media
      • Cable modem: TV cables shared by multiple users
      • DSL: dedicated phone lines
    • Comparing service plans
      • Both: sliding-scale residential and business plans
    • Comparing setup
      • Both: a modem interfaces PC and broadband jack
    • Comparing installation services:
      • Both: will install equipment at additional cost
  • 20. Figure 18-10 Cable modem connecting to a PC through a network card installed in the PC
  • 21. Cable Modem and DSL Connections (continued)
    • Overview of installing cable service or DSL
      • Connect the PC to the cable modem or DSL box
      • Connect cable modem/DSL box to broadband jack
      • Plug up power and turn on the broadband device
      • Configure TCP/IP settings for connection to the ISP
      • Test connection by using a browser to surf the Web
    • Devices and information needed for an installation
      • A computer with an available network or USB port
      • Modem/box and network cable
      • TCP/IP settings
  • 22. Figure 18-18 Sample setup for DSL
  • 23. Dial-Up Connections
    • Based on a modem and regular phone line
    • How dial-up networking works
      • TCP/IP creates data packets for transport
      • PPP adds its own header and trailer to data packets
      • PPP presents packet to modem for delivery on line
      • Process is reversed when data packet is received
    • Overview of setting dial-up in Windows XP
      • Install an internal or external modem
      • Launch New Connection Wizard
      • Follow directions onscreen
  • 24. Figure 18-19 PPP allows a PC to connect to a network using a modem
  • 25. Figure 18-21 The New Connection Wizard asks how to configure the connection
  • 26. Dial-Up Connections (continued)
    • A few troubleshooting tips
      • Plug in a regular phone and check line for a dial tone
      • Try another phone number
      • Reboot your PC and try again
    • Overview of setting dial-up in Windows 9x/Me
      • Dial-Up Networking must first be installed
        • A dial-up adapter will also be installed
      • Install an internal or external modem
      • Create connection with Make New Connection Wizard
      • Configure the connection from Properties dialog box
  • 27. Figure 18-27 Configuring the server type for a connection to the Internet in Windows 9x/Me
  • 28. Dial-Up Connections (continued)
    • High-speed dial-up: reduces download time by half
    • Enhancements needed to support high-speed dialup
      • Abbreviated handshake
      • Data compression
      • Filtering
      • Server-side caching
      • Client-side caching
  • 29. Figure 18-30 Server-side caching and client-side caching improve download times by reducing the number of requests for data
  • 30. Sharing a Personal Internet Connection
    • Networked PCs access Internet through a host
    • Connecting two PCs
      • Single crossover network cable links two PCs
      • Host PC connects to the modem
    • Connecting three or more PCs
      • PCs connect to hub/switch using patch cables
      • Host connects to modem via USB cable
    • Internet Connection Sharing (ICS)
      • Manages shared Internet connections
      • Enables host to use NAT and act as proxy server
  • 31. Figure 18-31 Two or more networked computers can share a single Internet connection
  • 32. Network Address Translation
  • 33. Implementing a Software Firewall
    • Guidelines for protecting your PC
      • Keep Windows updates current
      • Use a software or hardware firewall
      • Run antivirus software and keep it current
    • Services provided by a hardware or software firewall
      • Firewalls can filter data packets
      • Firewalls can filter ports
      • Firewalls can block certain activity within the network
      • Firewalls can filter inappropriate information
    • Example of a software firewall: Windows Firewall
  • 34. Figure 18-34 Windows Firewall is set for maximum protection
  • 35. Using a Router on Your Network
    • Disadvantages of using a host to share a connection
      • Host computer must always be turned on
      • Only low-level security for your network
      • Bottlenecks at host can slow traffic within network
    • Solution: use a router to interface with the Internet
    • Router provides two functions
      • Takes place of host as gateway to the Internet
      • Serves a hardware firewall to protect your network
  • 36. Figure 18-36 A router stands between the Internet and a local network
  • 37. Advantages of Using a Router
    • Host PC will not be a performance bottleneck
    • Internet access is not dependent on running host
    • Router can also serve as a hardware firewall
    • The router can provide additional features
      • DHCP server, switch, or wireless access point
    • Example: Wireless-G Broadband Router by Linksys
  • 38. Figure 18-37 This Linksys router allows computers on a LAN to share a broadband Internet connection and is an access point for computers with wireless adapters
  • 39. Installing and Configuring a Router
    • Run the setup program on any network PC
    • Connect the cable or DSL modem to the router
      • Follow the instructions on the setup screen
    • Connect PCs on your network to your router
      • PC can connect directly to a network port
      • You can also connect a switch or hub to the router
    • Plug in the router and turn it on
    • Sign in with default password and then reset it
  • 40. Installing and Configuring a Router (continued)
    • Configuring a router (using Linksys as an example)
      • Access configuration program on router firmware
        • Enter the IP address of the router (192.168.1)
      • View and/or change default settings in Setup window
    • Configure a hardware firewall
      • Settings in Security tab and Access Restrictions tab
    • Port filtering: open or close certain ports for use
    • Port forwarding
      • Request to certain ports forwarded to certain PCs
      • Local PC must have static address for this service
  • 41. Figure 18-39 Basic Setup screen used to configure the router
  • 42. Figure 18-42 With port forwarding, a router allows requests initiated outside the network
  • 43. Virtual Private Network
    • How VPN security works
      • Remote user sends id to authentication server
      • Authentication server encrypts data
        • Various encryption protocols are used; e.g., CHAP
      • Tunnel is created so all data transferred is encrypted
        • Various tunneling protocols are used; e.g., PPP
    • How to configure a router to support VPN
      • Select encryption and tunneling protocols
      • Configure each tunnel the VPN will support
    • Configure client for VPN from Network Connections
  • 44. Figure 18-45 With a VPN, tunneling is used to send encrypted data over wired and wireless networks and the Internet
  • 45. Figure 18-48 Properties window of a VPN connection
  • 46. Supporting Internet Clients
    • Section task: support Internet clients
    • Common Internet clients
      • Web browsers
      • E-mail
      • FTP
      • VoIP
      • Windows XP Remote Desktop
  • 47. Supporting Web Browsers
    • Web page: text file with an .htm or .html extension
      • Coded in HTML (Hypertext Markup Language)
    • Web browser: requests pages from a Web server
    • Uniform Resource Locator (URL): Web page address
    • Components of a URL
      • Protocol, host name, network name, folder, file name
      • Domain name = host name + network name
      • Example: http://www.course.com/myfolder/myfile.html
    • Name resolution service relates name to IP address
  • 48. Figure 18-49 A URL contains the protocol used, the host name of the Web server, the network name, and the path and filename of the requested file
  • 49. Table 18-3 Suffixes used to identify top-level domain names
  • 50. Supporting Web Browsers (continued)
    • Examples of Web browser software
      • Firefox by Mozilla, Internet Explorer (IE) by Microsoft
    • Some configuration tasks you can perform in IE
      • Configure the pop-up blocker
      • Manage IE add-ons
      • Set Internet Explorer security levels
      • Control how and if scripts are executed
      • Configure ActiveX controls
      • Control proxy settings
  • 51. Figure 18-53 Set the security level of Internet Explorer using the Internet Options window
  • 52. Supporting Web Browsers (continued)
    • Solving Internet Explorer problems
      • First perform routine maintenance; e.g., run ScanDisk
      • Clean out cache that IE uses to hold temporary files
      • Suppress downloading images
      • Repair a corrupted Internet Explorer cache
      • Run antivirus software
      • Update Internet Explorer
      • Verify Windows system files using System File Checker
      • Remove and reinstall Internet Explorer 6
  • 53. Figure 18-56 Use the Internet Options window to control the Internet Explorer environment
  • 54. Supporting Web Browsers (continued)
    • Digital certificate: identification plus public key
    • SSL (Secure Sockets Layer)
      • Encryption system using a digital certificate
      • Data is encrypted with public key
      • Data is decrypted with a private key
    • TLS (Transport Layer Security)
      • An improved version of SSL
    • HTTPS (HTTP secure)
      • Can mean HTTP over SSL or HTTP over TLS
      • Indicates secure protocol being used is SSL or TLS
  • 55. Figure 18-61 Using secure HTTP, a Web server and browser encrypt data using a public key before the data is transmitted
  • 56. Supporting E-mail
    • SMTP: Simple Mail Transfer Protocol
    • SMTP AUTH (SMTP Authentication): improved SMTP
    • POP: Post Office Protocol
    • IMAP4: Internet Message Access Protocol, version 4
    • Route traveled by e-mail
      • Client sends e-mail to client e-mail server using SMTP
      • Client e-mail server sends e-mail to recipient with SMTP
      • Recipient’s e-mail server forwards e-mail to recipient
        • Recipient’s e-mail server uses POP or IMAP4
        • Recipient must first login and request e-mail from server
  • 57. Figure 18-63 The SMTP protocol is used to send e-mail to a recipient’s mail server, and the POP3 or IMAP4 protocol is used to download e-mail to the client
  • 58. Supporting FTP
    • File Transfer Protocol (FTP)
      • Used to transfer files between two computers
    • FTP server (or FTP site)
      • Application running on another server; e.g., Unix server
    • FTP from a command prompt
      • Connection to a network must first be established
      • Some commands: FTP, get yourFile.dat
    • File transfer using FTP software
      • FTP utility software: can be downloaded from Internet
      • Web browser: change protocol used in address bar
  • 59. Figure 18-68 Using Internet Explorer as an FTP client
  • 60. Supporting VoIP
    • VoIP (Voice-over-IP)
      • Provides voice communication over a network
    • Two types of phones used in VoIP service
      • Digital telephone: plugs into a network port
      • Analog phone: needs Analog Telephone Adapter (ATA)
    • Special requirements of VoIP
      • Phones must be assigned number by VoIP provider
      • Phones are programmed to use dynamic IP addressing
      • Each network cable to phone needs a ferrite clamp
  • 61. Figure 18-70 Use this ATA to turn an analog telephone into an Internet phone
  • 62. Supporting Remote Desktop
    • Windows XP Professional Remote Desktop
      • Gives user access to desktop from remote locations
      • Server must be running Windows XP Professional
      • Client can run Windows XP Home Ed. or Professional
    • Accessing a Remote Desktop
      • Open the Remote Desktop Connection window
      • Enter address of PC, identification, resources needed
    • Preparing a Remote Desktop for first use
      • Configure the computer for static IP addressing
      • Configure Remote Desktop for service
  • 63. Figure 18-75 The desktop of the remote computer is available on your local computer
  • 64. Summary
    • Internet communication is based on the client/server model
    • TCP/IP: suite of protocols facilitating transfer of data between client and server
    • Bandwidth technologies: telephone lines, DSL, cable modem, ISDN, satellite access, wireless access
    • Internet Connection Sharing (ICS): manages shared Internet connections
    • Firewall: blocks and filters incoming network traffic
  • 65. Summary (continued)
    • Router: manages traffic between two networks
    • Web browser: loads and displays Web pages
    • E-mail client: used to send and receive e-mail
    • FTP client: used to transfer files over the Internet
    • VoIP service: provides voice communications over the Internet

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