Telnet is a network protocol used to provide interactive communication between computers over TCP/IP networks. It allows users to connect to remote hosts and use their resources through terminal emulation. During a Telnet session, the client and host computers negotiate terminal emulation and communicate by sending text between a virtual terminal on the client and the host. There may be delays between sending commands and receiving responses due to buffering and transmission times.

1. Understanding Telnet
● How to use Telnet
● The Telnet protocol and NVT(Network Virtual
Terminal)
● The details of a Telnet session
● How receive Telnet?

2. How to use Telnet
● If I know the Internet address of
the host whose resources I want
to use, I will use Telnet.
● When I contact the host, other
computer and my computer
negotiate how they will
communicate with each other.
● They decide which terminal
emulation will be used. Terminal
emulation will be displayed on
my screen.

3. The Telnet protocol and
NVT(Network Virtual Terminal)
● Telnet is a network protocol
used on the Internet or local
area networks to provide a
bidirectional interactive
communications facility.
● Telnet client applications are
available for virtually all
computer platforms.
● The Network Virtual Terminal
(NVT) is a bi-directional
character device. The NVT has
a printer and a keyboard.

4. The details of a Telnet session
● The text you type on the client
computer is stored temporarily in
a buffer on your computer.
● Completing the data on the
buffer, it is sent to the
destination which is represented
as the host's IP address.
● The client's IP address is also
sent with the data to send back
the results to the client.
● Besides, additional Telnet
command might be sent to
perform specific behavior.

5. How receive Telnet?
● The Telnet host receives the
data.
● That computer also returns to
your screen the dir command
and sends the results.
● A delay might occur between the
time you send a command and
the time you see the results on
your own computer screen.

6. References
● http://security.web.cern.ch/security/ssh/Encrypting_Connections/encry
http://docstore.mik.ua/orelly/networking_2ndEd/fire/figs/fire2.180
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● http://docstore.mik.ua/orelly/networking_2ndEd/fire/figs/fire2.040
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