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

Chapter 8 Activities on the Chapter 8 Activities on the InternetInternet

8.1 Tools and Services on the Internet8.1 Tools and Services on the Internet

8.28.2 Business on the InternetBusiness 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

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 videowith hyperlinks

Hypertext Transmission Protocol (HTTP) protocol for transferring documents on the Web

1. establishes a connection between client and server2. carries requests from the browser3. transports pages from Web server

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, byuser name and password

E-mail message simple text, and attachment

a file travelled with the e-mail message

Chapter 8 Activities on the Internet

8.1.2 E-mail (2/4)

E-mail servers SMTP server

kept by an ISP handles outgoing mailsSMTP (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 serverIMAP (Internet message access protocol)

• mail left in the server after downloaded

Chapter 8 Activities on the Internet

8.1.2 E-mail (3/4)

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 textfor transmitting photo, sound or word documentincludes information in the e-mail header

• for receiver’s e-mail software to reconstruct the original data

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 filesfile management tasks

• e.g. creating directory, deleting files, renaming files etc.

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”

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 filesrunning applicationsadminister the remote system

commands and passwords are sent in plain text without encryption

should be turned off, if not in use

Chapter 8 Activities on the Internet

8.1.5 Newsgroup (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

Chapter 8 Activities on the Internet

8.1.5 Newsgroup (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

Chapter 8 Activities on the Internet

8.1.6 IP 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

Chapter 8 Activities on the Internet

8.1.6 IP Phone (2/3)

A. Advantages Low cost Efficient user of connection

Packets can interleave along a communication line

Fault-tolerantvoice packets could bypass failed portion

Chapter 8 Activities on the Internet

8.1.6 IP 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 sequencePackets may use different routes and arrive out of sequencebut, impossible to re-assemble real-time data

C. Solutions Quality of Service (QoS) field

in each IP packet higher priority for time-sensitive data

Chapter 8 Activities on the Internet

8.1.7 Videoconferencing8.1.7 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

Chapter 8 Activities on the Internet

8.2 Business 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).

Chapter 8 Activities on the Internet

8.2 Business on the Internet

8.2.1 Business-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 purchasesa 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 datacredit card is widely used in e-commerce for payment

Chapter 8 Activities on the Internet

8.2 Business on the Internet

8.2.2 Business-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

Chapter 8 Activities on the Internet8.2 Business on the Internet

8.2.3 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

Chapter 8 Activities on the Internet

8.2 Business on the Internet

8.2.4 Pros and Cons of e-Commerce (1/2)

A. Business

Advantages Disadvantages

• Save the cost in setting up physical stores. No need to pay for rents and sales staff.

• Explore new market worldwide• Can provide latest information on

products and services• Establish corporate image, product

and service brand names through the Internet

• Sales data can produce statistics quickly

• Client’s purchase behaviour can be collected for future promotion

• Web sites must be updated regularly

• Programming staff are needed to maintain the Web sites and meet changes

• Investment on expensive server and high bandwidth communication channels

• Weak customer relationship due to lack of personal contact

Chapter 8 Activities on the Internet

8.2 Business on the Internet

8.2.4 Pros and Cons of e-Commerce (2/2)

B. Customers

Advantages Disadvantages

• Convenient to shop: no need to travel

• Can shop any time: e-stores are open 24 hours a day

• Easy to carry out price comparison

• Cannot see, feel or try the product before purchase

• Cannot easily return items

• Lack of personal contact

• Need to wait for delivery

• May need to pay for delivery cost

Chapter 8 Activities on the Internet

8.2.5 Security 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

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

A. 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 partnereasy for hackers to grab the key

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

A. Encryption (2/3)

Public Key Infrastructure (PKI) most secure encryption method involves a pair of keys:

public key • can be known to everyone,

private key• 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

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

A. Encryption (3/3)

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

B. 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 recipientonly the private key of the recipient can decrypt the message

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

C. 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”

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

C. 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

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

C. 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)

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

D. 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 applicantHK Post Office issues “e-Cert”

for everyone to query about the identity through the CAobtain the public key

can be viewed by clicking the “locked icon” in the status bar of a Web browser

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

E. 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

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

F. 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)

Chapter 8 Activities on the Internet

8.2.5 Security of e-commerce

F. 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 identityfraudulent credit cards cannot be usedcustomers cannot deny having confirmed the purchase