*NVT (Network Virtual Terminal)
*How the Telnet Works
*The Telnet host works
● What is telnet:Teletype network
○ Telnet is a network protocol used on the Internet or local area
networks to provide a bidirectional interactive communications
● First you need to know the Internet address of the host.(want to use)
● When you contact the host
○ Negotiate communicate each other.
○ Decide terminal emulation which will be used.
*terminal emulation:how your keybord will transmit information.
and how information will be displayed on your screen.
● Terminal emulation example:
○ VT-100 : the most common type
● Quotation by
NVT (Network Virtual Terminal)
● The Telnet is a kind of NVT.
● The Telnet protocol assumes that each end of the
connection - the client and the server – is a NVT.
● Each NVT has a virtual “printer” and a virtual
● The keyboard sends data from one NVT to the
● The printer is not really a printer at all it receives
and displays the data on the computer screen.
How the Telnet Works
Do you know , typed text in a Telnet session accumulate in a
buffer on your computer ?
When a complete line of data is ready for transmission or when
you give a command to transmit data, the data is sent across the
Internet from your NVT keyboard.
● The transmit data such as pressing the Enter key
Your IP address is also sent, so that information can be routed
back to you. Additionally , specific Telnet commands are sent that
the other NVT uses to decide what to do with the data or how to
respond to the data.
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The Telnet host works
The Telnet hosts processes the data you've sent.
And it returns to your screen the results of using the
data or running the command on a distant computer.
This action has a delay between the time you send a
command and the time you see the results on your
Because packets must go through many Internet routers
in each direction between your computer and the host.