This document provides an overview of email and telnet. It defines email as allowing users to exchange messages through a user agent program. It describes the basic components and processes for sending, receiving, and addressing emails. It also discusses email security protocols and mailing lists. For telnet, the document explains that it allows remote logging into another computer through a network virtual terminal. It compares local versus remote logging and describes basic telnet user commands.

1. M. DHARANI M.SC (CS),
NADAR SARASWATHI COLLEGE OF
ARTS AND SCIENCE, THENI
EMAIL AND TELNET

2. INDEX
 DEFINTION
 USER AGENT
 SENDING MAIL
 RECEIVING MAIL
 ADDRESS
 MAILING LIST OR GROUP LIST
 SECURITY
 TELNET DEFINITON
 LOCAL VERSUS REMOTE LOGGING
 NETWORK VIRTUAL TERMINAL
 USER INTERFACE

3. DEFFINTION
Electronic mail allows user to exchange
message .
In an application such us HTTP or FTP,
the server program is running all the
time, waiting for a request from a
client.
There is a request and there is a
response.
First email is considered a one-way
transaction

4. USER AGENT
The first components of a electronic
mail system is the user agent (UA) .
A user agent is a software package
(program) that composes , reads ,
replies to, and forward message.
There are two types of user agent,
1. command- driven
2. GUI based

5. SENDING MAIL
 To send mail, the user , through the
UA, creates mail that looks very similar
to postal mail.
The envelope usually contains the
sender address, the receiver address
and other information.
 The message contains the header and
body.
The body of the message contains the
actual information to be read by the

6. RECEIVING MAIL
 The user agent is triggered by the user.
 If a user has mail, the UA informs the
user with a notices.
 If the user is ready to read the
information, a list is displayed in which
each lines contains the summary of
information about a particular message
in the mail box.
 In the user can select any of the
message and display it contains on

7. ADDRESSES
 To deliver mail, a mail handling system
must use an addressing system with
unique addresses.
 The addresses consists of two parts,
1. local part
2. Domain name
 The domain name assigned to each mail
exchanger either comes from the DNS
at database.

8. MAILING LIST OF GROUPING
LIST
 Electronic mail allows one name, an alias
to represents, several different email
address .
 This is called mailing list or grouping
list.
 Every time a message is to be send ,
the system check the recipients name
against the alias database.

9. EMAIL SECURITY
 The protocol does not provide any
security provisions per second.
 However, the email exchange can be
secure using to application layer
security design is particular for email
system.
 Two protocols,
1. Pretty good privacy (PGP)
2. secure / multi purpose internet
mail extensions ( S /MIME)

10. TELNET
 A server program can provide a specific
service to its corresponding client
program.
 TELNET FOR TWO REASONS:
 The simple plaintext architecture of
telnet allows as to explain the issues
and challenges related to the concept
of remote logging.
 Network administration of an use telnet
for diagnostic and debugging purposes.

11. LOCAL VERSUS REMOTE
LOGGING
 When a user logs into a local system, its
is called local logging.
 The terminal drives the process the
character to the operating system.
 The operating system turn , interprets
the combination of character and
invokes the design application program
or utility.

12. NETWORK VIRTUAL
TERMINAL (NVL)
 The mechanism to access a remote
computer is complex .
 We are dealing with heterogeneous
system.
 The server telnet on the other hand
translate data and commands from
NVT form into the form acceptable
by the remote computer.

13. USER INTERFACE
 The Operating system ( UNIX, FOR
EXAMPLE ) Defines and interface with
user- friendly command.
 OPEN -- connect to a remote computer
 CLOSE – close the connection
 DISPLAY – show the operating
parameters
 MODE – change to line or character
mode
 QUIT – To exit telnet

14. THANK YOU !!!