The Internet

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The Internet

• Chapter 10

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Overview

• In this chapter, you will learn to
• Explain how the Internet works
• Connect to the Internet
• Configure Internet software tools

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Understanding the Internet
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Root Servers and Backbones

• University mainframe and mini computers make up
  the majority of root servers on the Internet
• Internet was designed to survive a catastrophic
  war or devastating natural disaster by being
  extremely decentralized
• The Internet uses TCP/IP as its language
• Every backbone server leases connections to the
  Internet to companies called Internet Service
  Providers (ISPs)

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TCP/IP Language of the Internet

• TCP/IP is the common language of the Internet
• Hypertext Transport Protocol (HTTP) is the TCP/IP
  service that provides structure for the World
  Wide Web
• An Internet browser uses HTTP

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Internet Service Providers

• Internet backbone servers lease connections to
  the Internet to Internet Service Providers (ISPs)
• Users gain access to the Internet thru ISPs that
  sit on the edge of the Internet backbone

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Connection Concepts

• Connecting to an ISP requires
• Hardware for connectivity
• Modem and working phone line
• DSL or cable modem
• Software
• Governs the connection and data flow

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Connecting to the Internet
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Ways of Connecting

• Dial-up
• Analog
• ISDN
• Dedicated
• DSL
• Cable
• LAN
• Wireless
• Satellite

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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
• Convert analog signals into digital signals that
  can be understood by the PCs COM ports
• Convert digital signals from the
  PCs COM ports into analog
  signals for standard telephone lines
• Transmit data as a series of individual 1s
  and 0sserial communication

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Serial and Parallel Communication

• Serial Communication
• Transmits data as a series of 1s and 0s

• Parallel Communication
• Transmits data in discrete 8-bit chunks

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UART Chip

• Both internal and external modems convert data
  between analog and digital
• CPUs must receive data in 8-bit parallel chunks
• Serial bits are converted into 8-bit parallel by
  the Universal Asynchronous Receiver/ Transmitter
  (UART) chip

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UARTS on Modems
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Baud Rate

• Baud rate is the basic cycle of time that a modem
  uses as its carrier frequency
• The modem speed is measured in bits per second
  (bps)
• A 2400 baud rate modem that transmits 2 bits per
  time cycle has a speed of 4800 bits per second

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Communication Standards

• Current V standards for modems, which include
  modem speed, data compression, error correction,
  and fax were set by the International
  Telecommunication Union Telecommunications
  Standardization Sector (ITU-T)
• Current standards include V.90 and V.92
• Download speeds of about 56 Kbps
• Upload speeds of 33.6 Kbps and 48 Kbps

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Flow Control (Handshaking)

• Flow control, also known as handshaking, is the
  process by which two serial devices manage a
  conversation
• PCs handle local flow control using hardware or
  software

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Flow Control (Handshaking)

• Hardware flow control uses extra wires called
  ready to send (RTS) and clear to send (CTS)
• Called RTS/CTS
• When in doubt, use hardware flow control

• Software flow control uses special characters
  called XON and XOFF to signal the beginning and
  end of data transmission respectively
• Called XON/XOFF
• Slower than hardware flow control and rarely used
  today

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Modem Connections

• Modems connect to the PC in one of two ways
• Internal modems connect to a PCI expansion slot
• External modems connect thru a serial port or a
  USB port

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Dial-up Networking

• Dial-up networking
• Uses information from your ISP such as the
  dial-up phone number, username, password, and
  other special configuration parameters
• To configure in Windows XP select Network and
  Internet Connections in Control Panel, then
  select Set up or change your Internet connection
  and follow the wizard
• Uses Point-to-Point Protocol (PPP)

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Dial-up Networking
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Dial-up Networking
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ISDN

• Integrated Services Digital Network (ISDN)
• Phone companies have upgraded their network
  infrastructure to all digital lines except for
  the line from your phone to the central office
• To meet the demand for higher speed access to the
  Internet, phone companies began offering ISDN
  service
• ISDN makes that last mile from your phone to the
  phone companys Central Office digital as well

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DSL

• Digital Subscriber Line (DSL)
• Uses a regular phone line
• Needs special equipment at both ends
• Much faster than dial-up
• Upload 384 Kbps
• Download 2 Mbps
• Installation requires a NIC and DSL receiver
  (called a DSL modem) and proper
  TCP/IP settings
• Must be within 18,0000 feet from
  the closest frame

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Cable

• Cable
• Uses cable TV connections
• Very fast speedsas fast as DSL or faster
• Installation involves connecting the RG-6 or
  RG-59 coaxial cable coming in for cable TV to a
  cable modem to a NIC in the PC
• Bandwidth is shared with other users which could
  affect performance

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Other Internet Connections

• LANs
• Most companies connect their network to the
  Internet thru an ISP
• Users connect thru the local LAN
• Wireless
• Wireless connections are great when they work,
  but the technology isnt quite there yet
• Security may be an issue
• Satellite
• Uploads used to require a modem but not anymore
• Initial connections still must be made thru a
  modem

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Internet Connection Sharing

• Internet Connection Sharing (ICS) allows one to
  share one Internet connection with multiple
  devices
• Windows Me, 2000, and XP all provide ICS
• Requires a local LAN between the devices first
• Windows XP includes the Internet Connection
  Firewall (ICF) to increase security

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Internet Connection Sharing
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Internet Software Tools
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Internet Software Tools

• World Wide Web (www)
• HTTP and HTTPS
• E-Mail
• PostOffice Protocol version 3 (POP3) or Internet
  Message Access Protocol (IMAP) for incoming email
• Simple Mail Transfer Protocol (SMTP) for outgoing
  email
• Newsgroups
• File Transfer Protocol (FTP)
• Telnet

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World Wide Web

• The World Wide Web (WWW) 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 is software that enables multiple
  connections to the Internet to go through one
  protected PC
• Most of the time you can allow automatic
  configuration
• Security and scripts
• In Internet Explorer youll find Internet Options
  on the Tools menu the Security tab lets you set
  security levels

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E-mail

• The two most popular e-mail programs are
• Microsofts Outlook Express
• Netscapes Messenger
• To configure your e-mail program use Outlook
  Express Internet Connection wizard to configure
  the following
• Incoming mail server PostOffice Protocol version
  3 (POP3) or Internet Message Access Protocol
  (IMAP)
• Outgoing mail server Simple Mail Transfer
  Protocol (SMTP)

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E-mail
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Newsgroups

• To access a newsgroup you must use a newsreader
  program such as Outlook Express (handles e-mail
  also)
• News servers run Network News Transfer Protocol
  (NNTP)

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File Transfer Protocol

• File Transfer Protocol (FTP)
• Used to share files
• Requires an FTP server on one end and an FTP
  client on the other
• WS_FTP is a popular client
• Internet Explorer and other web browsers also
  support FTP transfers
• Public FTP servers allow a login using the
  username anonymous and your e-mail address as the
  password

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Beyond A
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Telnet / Terminal Emulation

• Telnet is terminal emulation software that allows
  you to exchange keystrokes and screen shots with
  a distant computer its like having an extra
  long cable on your keyboard and mouse
• Its like sitting in front of the distant
  computer
• Windows includes telnet at the command prompt and
  HyperTerminal in the GUI
• Other popular terminal emulators include
• TeraTerm
• Putty
• VNC from the University of Cambridge

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Pop-Ups and Spyware

• Pop-ups are those surprise browser windows that
  pop up automatically
• Use AltF4 to close active pop-up windows do
  not click anywhere inside the window
• Zero Popup, Googles Toolbar, xFXJumpStart Popup
  Killer, AdSubtract
• Spyware sends information to a company about your
  browsing habits
• Could be used to capture keystrokes, steal
  passwords, reconfigure dialup settings, and more
• Offer as free software to provide some other
  benefit you may want but then begin spying once
  installed

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Spyware Programs

• If you see a Security Warning screen popup, this
  is a clue that you dont want to proceed
• Programs that warn that your Internet activities
  are being spied on are usually seeking to do just
  that themselves
• Dont install any plug-in unless you know what it
  is
• Removing spyware
• Lavasofts Ad-aware
• PepiMKs Spybot Search Destroy
• Some spyware programs to avoid include
• Kazaa
• E-wallet
• Gator

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Beyond Browsing

• Online Gaming
• Chat
• File Sharing

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