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Chapter 7

Chapter 7. The Web and E-mail. Chapter Contents. Section A: Web Technology Section B: Search Engines Section C: E-commerce Section D: E-mail Section E: Web and E-mail Security. Web Basics. The Web is an interlinked collection of document, image, video, and sound files

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Chapter 7

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  1. Chapter 7 The Web and E-mail

  2. Chapter Contents • Section A: Web Technology • Section B: Search Engines • Section C: E-commerce • Section D: E-mail • Section E: Web and E-mail Security Chapter 7: The Web and E-mail

  3. Web Basics • The Web is an interlinked collection of document, image, video, and sound files • A Web site contains a collection of related information • Podcasts • RSS vs. Atom • Videocasting Chapter 7: The Web and E-mail

  4. Web Basics • A Web page is the product or output of one or more Web-based files displayed in a format similar to a page in a book • A Web browser is client software that displays Web page elements and handles links between pages • Every Web page has a unique address called a URL Chapter 7: The Web and E-mail

  5. HTML • Set of specifications for creating documents that a browser can display as a Web page • Markup language • HTML tags • XHTML – Extensible HTML • DHTML – Dynamic HTML • Ajax – Asynchronous JavaScript and XML Chapter 7: The Web and E-mail

  6. HTML UTA Example Chapter 7: The Web and E-mail

  7. HTTP HTTP messages flow between a browser and a Web server. Chapter 7: The Web and E-mail

  8. Web Browsers • Help you access Web pages • Upgrade to new browser versions as they become available • Popular browsers: • Internet Explorer • Mozilla Firefox • Apple Safari • Netscape Navigator • Opera Chapter 7: The Web and E-mail

  9. Cookies • Small chunk of data generated by a Web server and stored on computer’s hard disk • Fix problems caused by HTTP’s stateless protocol • Relatively safe • Your computer does not have to accept cookies Chapter 7: The Web and E-mail

  10. Web Page Authoring • Text editor • HTML conversion tool • Online Web authoring tools • Web authoring software • Microsoft FrontPage • Adobe Dreamweaver Chapter 7: The Web and E-mail

  11. HTML Scripts • HTML scripts can perform complicated tasks and respond to user actions • HTML forms • Server-side script • Client-side script • Java applet • ActiveX control • Digital Certificate Chapter 7: The Web and E-mail

  12. Search Engines • Search Engine Basics • Formulating Searches • Citing Web-based Source Material Chapter 7: The Web and E-mail

  13. Search Engine Basics • A Web crawler is a computer program that is automated to methodically visit Web sites • A search engine indexer is software that culls keywords from a Web page and stores them in a database • A search engine’s query processor looks for your search terms in search engine’s indexed database and returns list of relevant Web sites • Link popularity is measured by quantity and quality of links from one Web page to others • A meta keyword is entered into a header section of a Web page when it is created and is supposed to describe the page contents • Keyword stuffing Chapter 7: The Web and E-mail

  14. Formulating Searches • Most search engines work with keyword queries in which you enter one or more words, called search terms Chapter 7: The Web and E-mail

  15. E-commerce • E-commerce Basics • Online Shopping • Online Auctions • Online Payment Chapter 7: The Web and E-mail

  16. E-commerce Basics • Business transactions conducted electronically over a computer network • B2C (business-to-consumer) • C2C (consumer-to-consumer) • B2B (business-to-business) • B2G (business-to-government) Chapter 7: The Web and E-mail

  17. Online Shopping Transactions In a typical shopping session, you connect to an online storefront and use navigation controls to browse through the merchant’s catalog. As you browse, you can drop items into your electronic shopping cart. At the checkout counter, you enter the information necessary to pay for the items you selected. Chapter 7: The Web and E-mail

  18. Online Shopping Chapter 7: The Web and E-mail

  19. Shopping Carts Chapter 7: The Web and E-mail

  20. Online Payment • A secure connection encrypts the data transmitted between your computer and a Web site • SSL (Secure Sockets Layer) • S-HTTP (secure HTTP) Chapter 7: The Web and E-mail

  21. Web Technology (bonus) • The Internet Protocol Stack • Application Ports Chapter 7: The Web and E-mail

  22. Internet Protocol Stack • Nodes attached to the Internet implement a standard set of capabilities to allow communications between dissimilar systems across dissimilar communications links • The standard protocol “stack” is implemented in a layered design to support modularity and ease of implementation in many different environments. Chapter 7: The Web and E-mail

  23. HTTP, etc. TCP or UDP IP Ethernet UTP, fiber, etc. application transport network link physical Internet Protocol Stack • Think of each layer as a different system software program that runs on your computer. • The upper layers allow like applications to communicate • The lower layers allow like devices to communicate APPLICATION CATEGORY DEPENDENT OPERATING SYSTEM CONTROLLED NETWORKE HARDWARE DEPENDENT Chapter 7: The Web and E-mail

  24. application transport network link physical application transport network link physical packets packets Internet Protocol Stack Web browser, email client, etc. Web server, email server, etc. Target Server Application Your Client Application Your Messages Your Messages The Internet Chapter 7: The Web and E-mail

  25. Internet Ports Web Server Application Email Application File Transfer Application • The means by which a single physical node differentiates multiple requests, like email, web, file transfer, etc. • The transport layer passes requests to specific “ports” into the application layer 80 25 21 transport network link physical Chapter 7: The Web and E-mail

  26. E-mail • E-mail Overview • Netiquette • E-mail Technology Chapter 7: The Web and E-mail

  27. E-mail Technology • E-mail systems carry and manipulate e-mail messages • E-mail servers • Based on store-and-forward technology (SMTP) • Three types of e-mail client systems widely used today: • POP • IMAP • Web-based e-mail Chapter 7: The Web and E-mail

  28. E-mail Technology • A POP server is a computer that stores your incoming messages until they can be transferred to your hard disk • E-mail client software • An SMTP server is a server that forwards emails that you send Chapter 7: The Web and E-mail

  29. 1) Alice uses an email client program to compose a message and “to” bob@someschool.edu 2) Alice’s mail client sends the message to her mail server where it is placed in a message queue (SMTP) 3) Client side of opens a “connection” with Bob’s mail server 4) The client-side mail server sends Alice’s message over the connection (SMTP) 5) Bob’s mail server places the message in Bob’s mailbox on the server 6) Bob opens his email client program to download and read Alice’s message (POP3) user agent user agent mail server mail server E-mail Technology: SMTP mail 1 2 6 3 4 5 Chapter 7: The Web and E-mail Slide from Computer Networks: A Tops-Down Approach, Kurose and Ross

  30. Web Client user agent 1 mail server Web HTTP Mail SMTP 2 7 3 4 5 HTTP 6 SMTP E-mail Technology: Web mail • Web-based e-mail accounts allow you to use a browser to access your e-mail messages • Messages are sent as form data between the client and the server using HTTP (not SMTP/POP). • Your Web server re-formats and then forwards your email using SMTP. Chapter 7: The Web and E-mail

  31. Web and E-mail Security • Cookie Exploits • Fake Sites • Spam • Phishing Chapter 7: The Web and E-mail

  32. Cookie Exploits • An ad-serving cookie can track your activities at any site containing banner ads from a third party Chapter 7: The Web and E-mail

  33. Fake Sites • A fake Web site looks legitimate, but has been created by a third party to be a very clever replica of a legitimate Web site • Pharming is an exploit that redirects users to fake sites by “poisoning” a domain name server with a false IP address Chapter 7: The Web and E-mail

  34. Spam • Spam is unwanted electronic junk mail about medical products, low-cost loans, and fake software upgrades that arrives in your online mailbox • A spam filter is a type of utility software that captures unsolicited e-mail messages before they reach your inbox • Local filtering • ISP filtering Chapter 7: The Web and E-mail

  35. Phishing • Phishing is an e-mail based scam designed to persuade you to reveal confidential information, such as your bank account number or Social Security number • If you don’t want to become a phishing victim, be suspicious of e-mail messages that supposedly come from banks, ISPs, online payment services, operating system publishers, and online merchants Chapter 7: The Web and E-mail

  36. Chapter 7 Complete The Web and E-mail

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