A Guide to Managing and Maintaining your PC, 6e

1
A Guide to Managing and Maintaining your PC, 6e

• Chapter 18
• PCs on the Internet

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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

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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

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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

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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
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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 138.60.30.580
• 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)

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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

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Figure 18-3 Applications, operating systems, and
the physical network manage communication at all
three levels
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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

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Figure 18-4 How software, protocols, and
technology on a TCP/IP network relate to each
other
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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

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Figure 18-5 TCP turns to IP to prepare the data
for networking
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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)

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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

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Figure 18-9 The Tracert command traces a path to
a destination computer
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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

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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

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Figure 18-10 Cable modem connecting to a PC
through a network card installed in the PC
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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

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Figure 18-18 Sample setup for DSL
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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

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Figure 18-19 PPP allows a PC to connect to a
network using a modem
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Figure 18-21 The New Connection Wizard asks how
to configure the connection
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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

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Figure 18-27 Configuring the server type for a
connection to the Internet in Windows 9x/Me
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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

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Figure 18-30 Server-side caching and client-side
caching improve download times by reducing the
number of requests for data
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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

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Figure 18-31 Two or more networked computers can
share a single Internet connection
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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

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Figure 18-34 Windows Firewall is set for maximum
protection
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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

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Figure 18-36 A router stands between the Internet
and a local network
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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

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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
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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

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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

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Figure 18-39 Basic Setup screen used to configure
the router
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Figure 18-42 With port forwarding, a router
allows requests initiated outside the network
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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

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Figure 18-45 With a VPN, tunneling is used to
send encrypted data over wired and wireless
networks and the Internet
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Figure 18-48 Properties window of a VPN connection
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Supporting Internet Clients

• Section task support Internet clients
• Common Internet clients
• Web browsers
• E-mail
• FTP
• VoIP
• Windows XP Remote Desktop

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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.htm
  l
• Name resolution service relates name to IP address

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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
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Table 18-3 Suffixes used to identify top-level
domain names
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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

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Figure 18-53 Set the security level of Internet
Explorer using the Internet Options window
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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

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Figure 18-56 Use the Internet Options window to
control the Internet Explorer environment
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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

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Figure 18-61 Using secure HTTP, a Web server and
browser encrypt data using a public key before
the data is transmitted
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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
• Recipients e-mail server forwards e-mail to
  recipient
• Recipients e-mail server uses POP or IMAP4
• Recipient must first login and request e-mail
  from server

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Figure 18-63 The SMTP protocol is used to send
e-mail to a recipients mail server, and the POP3
or IMAP4 protocol is used to download e-mail to
the client
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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

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Figure 18-68 Using Internet Explorer as an FTP
client
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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

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Figure 18-70 Use this ATA to turn an analog
telephone into an Internet phone
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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

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Figure 18-75 The desktop of the remote computer
is available on your local computer
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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

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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