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

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 A+ Guide to Software, 4e

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) A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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) A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

Figure 9-31 Two or more networked computers can share a single Internet connection A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

Supporting Internet Clients Section task: support Internet clients Common Internet clients Web browsers E-mail FTP VoIP Windows XP Remote Desktop A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

Table 9-3 Suffixes used to identify top-level domain names A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

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 A+ Guide to Software, 4e

Figure 9-75 The desktop of the remote computer is available on your local computer A+ Guide to Software, 4e