Course Content

Module 1: The Internet

• What is the Internet?

• Client/Server Computing

• Connecting to the Internet

• Security

Module 2: Email

• Introduction to email

• Choosing an email program

• How email is sent and received

• Email addresses

• Mailing List

What is the Internet ?

The Internet is a global network of computers that allows rapid, worldwide communication.

• It means network between networks

• but we also think of it as the

International network

It is also called Net, Cyberspace, Superhighway etc.,

• More than 250 million people connected to the Internet

What is the purpose ?

• To communicate and share information.

Who runs or is in charge of it ?

• No one is in charge of the Internet

• No centralized management of the Internet exists

• The Internet backbone, through which internet traffic flows, is owned by private companies.

• Private companies oversee the registering of Internet domains.

• InterNIC is responsible for registering the domains

Registrars

The companies which are allowed to oversee registration of domains are called registrars.

• All computers on the Internet communicate with one another using the Transmission Control Protocol/ Internet Protocol suite, abbreviated to TCP/IP.

Services:

• electronic mailFile transfer

Information resources

Group membership,

Multimedia displays,

News,

and much more

The Web operates on a client / server model

When many people use the word "Internet", they are really talking about the World Wide Web.

Internet services use a Client-server model for distributed computing

Client / Server Computing :

It is a computational architecture that involves client processes requesting service from server processes

• Client and server software programs allow computers to "speak the same language,"

• Processes are divided between the client and server. The relationship is based on as series of requests and responses.

• Clients:– Netscape– Internet Explorer etc.,

• The language contains commands that tell your

browser how to display – text, – graphics,

and multimedia files

• Commands contains linking the page to other pages, and to other Internet resources

• They can also display applications, programs, animations, and similar material created with programming languages such as Java and ActiveX, and scripting languages such as JavaScript.

• Home pages contain links to files that the Web browser can't play or display. In that case, you'll need a plug-in.

• Web Browser has become complete software suites – Can do everything from video conferencing to

letting you create and publish HTML pages

Web sites uses three kinds of organizational structure to organize their pages – Tree structure – Linear structure– Random structure

One common complaint about the Internet is that connections are too slow.

Connecting to the Internet:

Computer can connect to the Internet, ranging from dialup PPP connections to LANs.

• The most common option is to find an ISP that lets you dial into it with your home computer.

Connection Establishes:

SLIP

PPP

• Using one of the ISP, computer will becomes part of the Internet and can access all of its vast resources, such as browsing the Web.

• ISDN (Integrated Services Digital Network) lines provide high-speed connections to the Internet using copper cables telephones wires.

• DSL technologies will enable you to use the Internet at high speeds and simultaneously talk on your telephone, using the same single phone line

• ADSL (Asymmetric Digital Subscriber Line) , a newer technology, allows for very high-speed connections over existing telephone wires, but your ISP will have to support the technology.

• VDSL (Very high data rate DSL) primarily used by large corporations because of its cost.

• The newest way to connect to the Internet and browse the Web are via satellite connections, and via so – called Palmtop computers

Everyone who connects to the Internet need security

Internet Security can be achieved as given below:

• Firewalls.

• Password Selection

• Document Protection

• Program updates

• Viruses

Firewall:

Firewall are often used to keep the network safe and free of intruders and viruses

• A firewall should monitor incoming and outgoing traffic.

• Some Firewalls are more secure than others (ICSA Certified, etc)

• Most firewall do not protect against viruses

• All firewall require administration– Set-up – Configuration – Updates– Making holes for applications

• Events logs

• Many "alerts" come from infected machines doing random scanning

Password Selection:

Good Password:

• Contain both upper and lower case characters.

• Have at least two numbers and / or punctuation characters.

• Are easy to remember, so you don't have to write them down

• Are at least seven characters long

• Can be typed quickly, so that no one can read them over your shoulder.

• Are changed at least every 60 days.

• Are not used on more than one system

• Are not shared with anyone.

Bad Password

• Use personal information that others can easily figure out such as your name (or even an acquaintance's name, phone number, license plate or birth date).

• Are place names

• Are the same as your account name.

• Are easy to spot when typing such as '12345' 'qwerty' etc.,

Document Protection

• Always turn off file sharing

• Backup your data files regularly.

• Use Windows NT/2000/XP for paper security

Program Updates

• Register your software.

• Windowsupdate.microsoft.com

• Keep internet Explorer up to date even if you don't use it!

Viruses

A virus is a program that performs a task that you have not requested or require.

Viruses come from:

E-mails

Internet programs

"Off the shelf" programs

Always need for:

• Automatic scanning of all incoming emails.

• Automatic and frequent updating via Internet.

• Well known company.

• Able to scan Zip files.

• Automatically check files when opened/copied/moved.

• Start Automatically when OS starts.

To protect the computers

• Install Anti-Virus software today.

• Install a Firewall today.

• Use good passwords

• Keep all software up to date

Proxy

• A Proxy is a central machine on the network that allows other machines in that network to use a shared Internet connection.

• Proxy servers are intermediate servers which accept requests from clients and forward them to other proxy servers, a source server, or service the request from their own cache.

• The proxy is also called 'server' or 'gateway'..

• Proxy allows users on a network to browse the Web, send files over FTP, and work with E-mail and other Internet services

• Proxy server work by opening a socket on the server and allowing the connection to pass through.

• Only one computer in a company with direct Internet connection.

• The same proxy is used by all the clients on the network.

• Enables the proxy to efficiently cache documents that are requested by several clients

A Proxy basically does the following:

• Receives a request from a client inside the firewall

• Sends this request to the remote server outside of the firewall

• Reads the response

• Sends it back to the client

E-mail

E-mail:

Email is an e-mail, which stands for 'electronic mail'.

• Typed into a message window on the computer screen

• A message which also includes your own 'reply-to' email address

• Sent and received through your modem connection to your ISP, whose mail server computer is in turn connected to the rest of the Internet

• Incredibly cheap: you pay for your local phone call to connect to your local ISP

Choosing Email Software (emailer)

• An emailer is a computer application that allows a user to store, send and access messages electronically.

• There are many different emailers (eg: pine, elm, mush, Eudora, Netscape Messenger, zmail, mm, Microsoft outlook, etc., )

• Emailer can run either from client or a server.

• Emailer receive and send mail through a computer called a Mail Server.

Client Emailer Using POP (Post Office Protocol)

• Email is received and stored on a mail server.

• When the user starts their client-side emailer, the emailer retrieves the mail from the server to the client to be stored and read on the client

• A copy of the email can be kept on the server or deleted.

Client Emailer using IMAP (Internet Mail Access Protocol)

• Email is received and stored on a mail server

• When the user starts their client-side emailer, the emailer can read, delete, save and send email on server without retrieving a permanent copy of the messages to client machine.

• IMAP was developed in response to the limitations of POP.

Client using Web mail

• Email is received and stored on a mail server.

• When the user starts their client-side emailer, the emailer can read, delete, save and send email on server without retrieving a permanent copy of the messages to client machine.

• Web Interface email is similar to IMAP in function and capabilities.

Functions of Email Software

– Read a Message– Send a Message– Reply – Quote– Forwarding– Address Books– Folder Maintenance– File Attachment

Email Addresses

An email addresses consists of two to three parts.

LoginID, Host, Domain

Sometimes no host is indicated.

eng@sun1.ksu.edu.saeng : login ID

sun1: host

ksu.edu.sa: Domain

eng@ksu.edu.saeng: loginID

ksu.edu.sa: Domain

Mailing Lists

• A mailing list is a group of email addresses which can be reached by sending an email message to a single address.

• A mailing list is maintained by a software program which is administered by a person called the listowner

• A mailing list can be a discussion forum, a support group, a guide, or an electronic publication.

Think Before you Send!

Questions ?