1. Chapter 9 Windows on the Internet
A+ Guide to Software, 4e
Chapter 9
Windows on the Internet

2. 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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3. 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: :80
A few other common ports and assigned services
Port 20: FTP (File Transfer Protocol)
Port 25: (using SMTP protocol)
Port 443: Web server (using HTTPS protocol)
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4. 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
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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5. 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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6. 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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7. 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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8. 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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9. 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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10. 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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11. 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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12. 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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13. 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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14. Figure 9-31 Two or more networked computers can share a single Internet connection
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15. 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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16. 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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17. 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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18. 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 ( )
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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19. 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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20. Supporting Internet Clients
Section task: support Internet clients
Common Internet clients
Web browsers
FTP
VoIP
Windows XP Remote Desktop
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21. 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:
Name resolution service relates name to IP address
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22. Figure 9-49 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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23. Table 9-3 Suffixes used to identify top-level domain names
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24. 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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25. 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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26. 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
Client sends to client server using SMTP
Client server sends to recipient with SMTP
Recipient’s server forwards to recipient
Recipient’s server uses POP or IMAP4
Recipient must first login and request from server
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27. Supporting FTP File Transfer Protocol (FTP) FTP server (or FTP site)
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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28. 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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29. Figure 9-75 The desktop of the remote computer is available on your local computer
A+ Guide to Software, 4e