Chapter 4

Communicating on the Internet

How E-Mail Works?

Most used Feature TCP breaks & reassembles messages into

packets IP delivers packets to the proper location Binary files can be attached:

- Pictures- Video- sounds

How E-Mail Works?

How E-Mail Works?

Encoding schemes: MIME - UUencode Gateways perform translating email formats Mailing List: connects a group of people Everyone in the mailing list receive the sent

message Moderated mailing list: screened by Admin Unmoderated mailing list: wide open List server

How Spam Works? Spam:- Unsolicited junk e-mail sent by commercial

companies for some services- Unwanted mail, making another information

slower to send- E-mail filters block Spam from known

spammers

Spam Mails

How Usenet Newsgroups Work?

The world biggest discussion forum Special software, online services Thread: grouped conversation by topics FAQ: Many newsgroups have a list of

Frequently Asked Questions to read before submitting messages

Moderated newsgroups: screened by Admin

Unmoderated newsgroups: Automatically posted

Usenet Newsgroups

Usenet Server: you can subscribe to any interested newsgroups or cancel it

You can post Binary files UUencode: common used encoding scheme

for Usenet newsgroups

Usenet Newsgroups

Internet Relay Chat

Communicating with others (keyboard conversation)

IRC: Internet Relay Chat, the most popular chatting way

Channels: many different topics in chat rooms

IRC follows a client/ server model:

IRC ServerIRC Client

Making Phone Calls on the Internet

Sounds are broken into packets, which delivered by TCP/IP protocols

Free calls Making phone calls and receiving calls from

someone who has an Internet address WebTalk Speaking into microphones, listening from

speakers