The Internet

1. The Internet Chapter 25

2. Overview In this chapter, you will learn how to Explain how the Internet works Connect to the Internet Use Internet software tools

3. Internet Tiers Tier 1 (main tier) Seven to twelve companies Own long-distance, high-speed fiber-optic networks called backbones Interconnect at network access points (NAPs) in major citiesacross theglobe

4. Internet Tiers (continued) Tier 2 Smaller regional networks Larger ISPs that provide Internet access are often Tier 2 providers Tier 3 Even more regional networks Built-in redundancy Decentralized Can easily adapt to failures on network

5. TCP/IP: Language of the Internet TCP/IP is the common language of the Internet Suite of protocols Many services—such as HTTP—plus the capability to create new services This vast routed network, running TCP/IP is the Internet How do we tap into it?

6. Internet Service Providers Internet service providers (ISPs) gain access to the Internet from leased Tier 1 and Tier 2 connections Users gain access to the Internet by leasing connections from ISPs ISPs come in many sizes National companies Local shops

7. Connection Concepts Connecting to an ISP requires Hardware for connectivity Modem and working phone line DSL or cable modem Some other high-speed connection Software (protocols) Governs the connection and data flow Software (services) E-mail, browsing

8. Many Ways to Connect Dial-up Analog ISDN Dedicated DSL Cable Fiber LAN Wireless Wi-Fi Cellular Satellite

9. Dial-up Requires a Modem The term modem is an abbreviation for modulator/demodulator Enables computers to communicate with each other via standard telephone lines Converts analog signals into digital signals Converts digital signalsinto analog signals

10. Modems A modem uses serial communication Transmits data as a series of individual 1s and 0s Universal asynchronous receiver/transmitter (UART) Converts serial into 8-bit parallel data

11. Baud Rate Baud rate is the basic cycle of time that a modem uses as its carrier frequency Maximum baud rate of a phone line is 2400 baud The modem speed is measured in bits per second (bps) Modems can pack multiple bits into a single baud 14 bits × 2400 baud = speed of 33.6 Kbps

12. Communication Standards Modern modem standards are referred to as V standards Set by the International Telecommunication Union—Telecommunications Standardization Sector (ITU-T) Both standards offer download speeds of just under 56 Kbps V.90 upload speeds of up 33.6 Kbps V.92 upload speeds of up to 48 Kbps Rarely get download speeds greater than 48 Kbps

13. Modem Connections Modems connect to the PC in one of two ways Internal modems connect to a PCI or PCI Express expansion slot External modems connect through a serial port or USB port

14. Dial-up Networking Dial-up networking Uses information from your ISP The dial-up phone number, user name, password, and other special configuration parameters Configured in Network and Internet Connectionsoption in Windows XP Select Set up or change your Internet connectionand use the wizard Configured in the Networkand Sharing Center inVista Set up a connection or network

15. Dial-up Networking (continued) Uses PPP protocol Point-to-point protocol (PPP) Streaming protocol developed especially for dial-up Internet access Most dial-up errors are user errors Turn the volume up and verify the connection Listen for a dial tone Listen for “modem talk” instead of a person answering the phone

16. ISDN Integrated Services Digital Network (ISDN) Phone companies have upgraded their network infrastructures to all digital lines (except for the line from your phone to the central office) ISDN goes fully digital Uses channels B (Bearer) used for data and voice at 64 Kbps D (Delta) used for setup and configuration information at 16 Kbps Basic Rate Interface (BRI) Most common setup Two B (total of 128 Kbps) and one D channel ISDN uses terminal adapters rather than modems

17. DSL Digital subscriber line (DSL) Uses a regular phone line but special equipment at both ends Much faster than dial-up Upload: 128-384 Kbps Download: 2-6 Mbps or greater Installation requires a NIC and DSL receiver (often called a DSL modem) Must be within 18,000 feet from the closest main phone service switching center

18. Cable Uses cable TV connections Connect the RG-6 or RG-59 coaxial cable to a cable modem Connect modem to a NIC in the PC with UTP cable Very fast speeds—often much faster than DSL (20+ Mbps download) Bandwidth is shared with other users, which can affect performance

19. Fiber FiOS from Verizon Fiber direct to the home Download speeds vary from 5 Mbps down/2 Mbps up to 50 Mbps down/20 Mbps up Average is 15 Mbps down/5 Mbps up U-verse from AT&T Mix of fiber and local copper at the house Average download of 3-6 Mbps down/1 Mbps up, with 24 Mbps down possible

20. Other Internet Connections LANs Most companies connect their network to the Internet through an ISP Users connect through the LAN Wireless Wireless connections require access via wired network If wired network has access, wireless devices can use this wired network via a WAP Satellite Uploads previously done through modem Initial connections still must be made through a modem

21. Internet Connection Sharing Internet connection sharing (ICS) Allows one computer to share a single Internet connection with multiple devices Available since Windows 98 SE Requires a LAN between the devices

22. Hardware Connection Sharing SOHO routers like this WRT54G are very popular hardware connections between your network and the ISP Provide hardware firewall protection Built-in WAP Built-in switch

23. Network Address Translation (NAT) NAT enables multiple devices to share a single Internet address Most ISPs provide a single Internet address Without routers that supported NAT, you would have to purchase separate IP addresses for every device that needed Internet access Alternatively you could use your own IP addresses, but only if you didn’t connect to the Internet NAT = GOOD!

24. Basic Router Configuration All routers have an administrative user name/password that enables you to configure the router Change from the default

25. DHCP or Not DHCP All home routers are DHCP servers by default You should only have one DHCP server Disable DHCP if you already have a DHCP server

26. Set the WAN Address WAN addresses can be static or dynamic If you’re allocated a static IP address, update your WAN connection per ISP instruction

27. Updating Firmware SOHO routers often have firmware updates – check with the manufacturer

28. Internet Software Tools Once you’ve made the connection to the Internet, you can now use the thousands of Internet applications CompTIA wants you to know about the following applications World Wide Web (HTTP and HTTPS) E-mail (POP and SMTP) Newsgroups FTP Telnet VoIP

29. TCP/IP Ports Every Internet application is assigned one or more TCP/IP port number(s) 1-65536 The first 1024 port numbers are reserved for the most popular and common applications

30. World Wide Web The World Wide Web (Web) provides a graphical face for the Internet Web servers house Web sites Web browsers access the files on Web servers Web browsers are highly configurable A proxy server enables multiple connections to the Internet to go through one protected PC Similar to ICS, but more sophisticated Typically used in corporate connections Uses Layer 7 – browsers communicate directly with the proxy server software when desiring a Web site

31. Proxy Server A proxy server is a device or software that acts as an intermediary between Internet servers and clients Commonly used to filter Internet access Clients must be configured to use a proxy server

32. Security and scripts Active programs and scripts such as Java and Active Server Pages Can be useful and powerful Can be malicious Internet Explorer has configurable options Tools | Internet Options| Security tab lets you set security levels World Wide Web

33. HTTP vs. HTTPS HTTP provides no encryption HTTP over Secure Sockets Layer (HTTPS) Provides encryption Use when submitting personal information such as credit card numbers, phone numbers, etc. Verify HTTPS is being used two ways Lock icon HTTPS appears in address bar

34. E-mail Popular e-mail programs Microsoft Outlook Mozilla Thunderbird E-mail protocols Post Office Protocol version 3 (POP3) Used for receiving e-mail Internet Message Access Protocol (IMAP) Used for receiving mail, but with more features than POP3 Simple Mail Transfer Protocol (SMTP) Used for sending e-mail

35. Configuring e-mail Can use name or IP E-mail (continued)

36. Web Mail Available anywhere you have Internet access Free, but requires some sort of connection Most services offer lots of storage, searchable messages, flagging of messages for follow-up, etc. Most popular Gmail Hotmail Yahoo! Mail

37. E-mail Security Digital signaturesconfirm identity of sender of e-mail Concepts are simple, implementations not so much Requires that you get a certificate from an issuing authority (same folks who create certificates for secure e-commerce) Try Thawte’s Personal e-mail certificates http://www.thawte.com/resources/personal-email-certificates/index.html Then must add to e-mail application Easy in Outlook, barely possible in Web mail

38. Newsgroups Use a newsreader program to access newsgroups Outlook Express was common newsreader (free) News servers run Network News Transfer Protocol(NNTP) Get NNTP address from ISP

39. FTP File Transfer Protocol (FTP) Used to share files Address usually ftp.[whatever].com Requires an FTP server on one end and an FTP client on the other WS_FTP is a popular client Some Web browsers also support FTP Public FTP servers allow anonymous login User Name: Anonymous Password: e-mail address Sends user name and password in clear text

40. Telnet and SSH Text-based terminal emulation programs for controlling a remote computer They look the same but Telnet is unencrypted SSH is encrypted

41. VoIP Voice over IP (VoIP) Enables voice calls over the network Works with any type of high-speed connection DSL, cable, satellite, etc. VoIP is a collection of protocols Not a single protocol Vendors Skype Vonage

42. Terminal Emulation Enables access to other computers as if you were there Windows Remote Desktop University of Cambridge’s VNC Free and totally cross-platform Can run and control Windows from a Macintosh system andvice versa

43. Terminal Emulation (continued) • Remote Desktop • Microsoft’s implementation • Free and built into system • Remote Assistance • End user requests help • Helper can take control of desktop • If permission granted

44. Remote Desktop Remote Desktop enables you to access computers over the network Excellent tool for managing headless servers Here’s how to get there Start | Run or Start Search | mstsc Start | All Programs | Accessories | Communications | Remote Desktop

45. Virtual Private Networks (VPN) Allows you to connect to a private network via the Internet

46. Beyond A+ Online gaming World of Warcraft (WoW) Counter-Strike Chat Internet Relay Chat (IRC)

47. Beyond A+ File sharing Allows users to share files with other users Users can access any shared files (such as MP3s) on any computer anywhere on the Internet Napster and Kazaa are file-sharing programs Music industry trying to stop file sharing BitTorrent protocol to counter music industry Also used for Linux distributions µTorrent is one program using BitTorrent protocol