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Chapter 8 Activities on the Internet

Chapter 8 Activities on the Internet. 8.1 Tools and Services on the Internet 8.2 Business on the Internet. Chapter 8 Activities on the Internet. 8.1 Tools and Services on the Internet. WWW e-mail File Transfer Telnet Newsgroup IP Phone VideoConferencing.

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Chapter 8 Activities on the Internet

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  1. Chapter 8 Activities on the Internet 8.1 Tools and Services on the Internet 8.2 Business on the Internet

  2. Chapter 8 Activities on the Internet 8.1 Tools and Services on the Internet • WWW • e-mail • File Transfer • Telnet • Newsgroup • IP Phone • VideoConferencing

  3. Chapter 8 Activities on the Internet 8.1.1 WWW • Web browser • major Internet application • supports interactive, visual, animated interface. • Web pages • documents written in HyperText Markup Language (HTML) • present text, images, sound, animation and video • with hyperlinks • Hypertext Transmission Protocol (HTTP) • protocol for transferring documents on the Web • 1. establishes a connection between client and server • 2. carries requests from the browser • 3. transports pages from Web server

  4. Chapter 8 Activities on the Internet 8.1.2 E-mail (1/4) • E-mail (electronic mail) • exchange of messages with other users via a computer network • using store-and-forward mode • E-mail user • has an account from an organisation • e.g. ISP, school, Web mail company • login to send and receive mail, by • user name and password • E-mail message • simple text, and • attachment • a file travelled with the e-mail message

  5. Chapter 8 Activities on the Internet 8.1.2 E-mail (2/4) • E-mail servers • SMTPserver • kept by an ISP • handles outgoing mails • SMTP (simple mail transfer protocol) • protocol for routing e-mails • POP (or IMAP) server • kept by an e-mail service provider (e.g. a school) • stores the incoming mails (store-and-forward) • POP3 (Post office protocol version 3) • protocol for downloading e-mails from the server • IMAP (Internet message access protocol) • mail left in the server after downloaded

  6. Chapter 8 Activities on the Internet 8.1.2 E-mail (3/4)

  7. Chapter 8 Activities on the Internet 8.1.2 E-mail (4/4) • Attachment and MIME • SMTP • handles text-based messages only • MIME (Multi-purpose Internet mail extension) • a protocol • disguises other data as plain ASCII text • for transmitting photo, sound or word document • includes information in the e-mail header • for receiver’s e-mail software to reconstruct the original data

  8. Chapter 8 Activities on the Internet 8.1.3 File Transfer (1/2) • File Transfer Protocol (FTP) • defines how to send and receive files between a client and a server. • FTP client program • allows user to access an FTP server • functions : • uploading/downloading files • file management tasks • e.g. creating directory, deleting files, renaming files etc.

  9. Chapter 8 Activities on the Internet 8.1.3 File Transfer (2/2) • Private FTP site • needs authentication • Anonymous FTP site • publicly accessible • read only • user name : “anonymous”

  10. Chapter 8 Activities on the Internet 8.1.4 Telnet • Telnet • a protocol • enables users to log on and control another computer via the Internet. • simulates a text-based terminal screen • users can perform tasks • managing files • running applications • administer the remote system • commands and passwords are sent in plain text without encryption • should be turned off, if not in use

  11. Chapter 8 Activities on the Internet 8.1.5Newsgroup (1/2) • Newsgroup • a forum on the Internet • threaded discussion • on a specified range of subjects • Thread • is a collection of related messages • the original article, and • postings responding to the original article

  12. Chapter 8 Activities on the Internet 8.1.5Newsgroup (2/2) • Usenet • a worldwide forum with over 30,000 newsgroups • many Usenet servers all over the world • with the same set of messages • Network News Transfer Protocol (NNTP) • protocol for Usenet newsgroups • A moderated newsgroup • managed by somebody who filters the messages • but, contents can be inaccurate • postings will be maintained for a week or less

  13. Chapter 8 Activities on the Internet 8.1.6IP Phone (1/3) • Circuit-switching • for Normal telephone • a circuit is set up and maintained until the communication is finished • does not make full use of available bandwidth • conversations have a lot of silent space • IP Phone (also called voice over IP, VoIP) • TCP/IP-based packet-switching technology • converts analog voice data into digital data • breaks into packets

  14. Chapter 8 Activities on the Internet 8.1.6IP Phone (2/3) • A. Advantages • Low cost • Efficient user of connection • Packets can interleave along a communication line • Fault-tolerant • voice packets could bypass failed portion

  15. Chapter 8 Activities on the Internet 8.1.6IP Phone (3/3) • B. Problems • No guarantee of packet delivery • Packets may be damaged • but, impossible to re-transmit real-time data • Packets arriving out of sequence • Packets may use different routes and arrive out of sequence • but, impossible to re-assemble real-time data • C. Solutions • Quality of Service (QoS) field • in each IP packet • higher priority for time-sensitive data

  16. Chapter 8 Activities on the Internet 8.1.7 Videoconferencing • Videoconferencing • meeting of people at different locations • using computer networks • with visual image and sound • Hardware • microphone, speakers and Web cam • Software features • transmit video and sound • users can write/ view whiteboard notes • exchange files • share an application

  17. Chapter 8 Activities on the Internet 8.2Business on the Internet • Electronic commerce (e-Commerce) • doing business on the Internet • Three modes of e-commerce: • business-to-customer (B2C) • business-to-business (B2B) • customer-to-customer (C2C).

  18. Chapter 8 Activities on the Internet 8.2Business on the Internet8.2.1Business-to-customer (B2C) • Business-to-customer (B2C) • involves an online storefront • a Web site with the following: • 1. electronic catalogue • showing the products and price • 2. virtual shopping cart • for customers to collect purchases • a set of records storing the product ID, price and quantity etc. • 3. secure Web connection • for financial transaction • encryption on customer’s personal and financial data • credit card is widely used in e-commerce for payment

  19. Chapter 8 Activities on the Internet 8.2Business on the Internet8.2.2Business-to-business (B2B) • Business-to-business (B2B) • carried out in private networks • authentication is required • business partners are given login username and password • transactions may be carried out without human intervention

  20. Chapter 8 Activities on the Internet 8.2Business on the Internet8.2.3 Customer-to-customer (C2C) • Customer-to-customer (C2C) • involves an online agent Web site • e.g. eBay • customers post their products online for other customers to bid

  21. Chapter 8 Activities on the Internet 8.2Business on the Internet8.2.4 Pros and Cons of e-Commerce (1/2) • A. Business

  22. Chapter 8 Activities on the Internet 8.2Business on the Internet8.2.4 Pros and Cons of e-Commerce (2/2) • B. Customers

  23. Chapter 8 Activities on the Internet 8.2.5Security of e-commerce • Security is important for e-commerce • involves transmission of sensitive data over the Internet • company must show its identity • for customers to have confidence • 2 major secure transmission: • SSL and SET • both involve • encryption, and • digital certificate

  24. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceA.Encryption (1/3) • Encryption • converts text data into scrambled characters • needs a key to read • Symmetric key encryption • encryption and decryption use similar keys • e.g. Shifting letters in message by certain positions • can be cracked easily by • analysing the frequency of each letter • The key must be sent in plain text to a new partner • easy for hackers to grab the key

  25. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceA.Encryption (2/3) • Public Key Infrastructure (PKI) • most secure encryption method • involves a pair of keys: • public key • can be known to everyone, • privatekey • must be kept secret • Data encrypted by one key can only be decrypted by the associated key: • Data encrypted by a public key must be decrypted by the private key, and vice versa

  26. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceA.Encryption (3/3)

  27. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceB.Integrity and Confidentiality • Integrity • ensures that a message is not modified • Using PKI, if an encrypted message is modified, it cannot be decrypted • Confidentiality • ensures that the message is protected • To send confidential message, encrypt it using the public key of the recipient • only the private key of the recipient can decrypt the message

  28. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceC. SSL (1/3) • Secure Sockets Layer (SSL) • ensures secure transmission of data between • a Web site and its clients • using PKI • identified by • lock icon in the status bar, or • protocol prefix “https”

  29. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceC. SSL (2/3) • After connection, • the Web site will send its public key to the client’s Web browser • Data from the client will be encrypted by the public key • only the company can view the data using its private key • Problems of PKI • PKI involves a lot of processing, and • data transmitted from the Web site cannot use PKI • because users do not have digital certificate • Solution: • After secure connection, the client’s computer • will generate a new symmetric key • send it to the Web site with encryption using the public key of the Web site • All the subsequent transmissions will use symmetric encryption until the connection is over

  30. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceC. SSL (3/3) • Problem of credit card in e-commerce • credit card information of customers are stored in the company’s database • privacy is not fully protected • This problem is solved by SET (see below)

  31. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceD.Digital Certificate • Digital certificate • provides an identity of an individual/organisation • issued by a Certificate Authority (CA) • together with a pair of keys to the applicant • HK Post Office issues “e-Cert” • for everyone to • query about the identity through the CA • obtain the public key • can be viewed by clicking the “locked icon” in the status bar of a Web browser

  32. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceE.Digital Signature • Digital signature • a portion of a message encrypted • by the sender’s private key • The receiver can decrypt the data by the sender’s public key • either obtained from CA or • included along with the message • Digitally signed document • represents non-repudiation • e.g. the client cannot deny having confirmed a purchase

  33. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceF. SET (1/2) • Secure Electronic Transaction (SET) • designed by credit-card firms • provides higher security than SSL • Both client and company must have their own • digital certificates • data sent is encrypted by both • public key of the company , and • private key of the client (digital signature)

  34. Chapter 8 Activities on the Internet 8.2.5Security of e-commerceF. SET (2/2) • Secure Electronic Transaction (SET) (cont’) • credit card information are sent to a bank • to avoid abuse of credit card information by companies • Advantages of SET: • company can verify customer’s identity • fraudulent credit cards cannot be used • customers cannot deny having confirmed the purchase

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