In normal mode, our equipment behaves like the keyboard of the computer we connect to. OPEN: This command establishes a connection to a remote computer.SET ECHO: If we cannot see what we are writing or, on the contrary, we double it, this command corrects the situation.
If you are connected to a remote computer, this command closes the connection and then the application. CLOSE: Closes the Telnet connection to the remote computer and returns to command mode (if started in command mode) or closes the application.
Command mode allows you to use a series of commands that affect the operating mode, including connection and disconnection. To use Telnet, it is very important to note that its client has two ways to work: Command mode and normal use mode. The basic features of the Telnet protocol are available in RFC 854. Therefore, byte 255 is called IAC (Interpret as Command). When byte 255 is transmitted, the next byte should be interpreted as a command. Data transmission consists of only byte transmission in the TCP stream. Port 23 is assigned to this protocol when it is used to connect the remote host to a computer running as a server.Īpart from the associated options and negotiation rules, these protocol features are essential. Also, it is not a secure data transfer protocol because the data it transmits travels over the network as unencrypted text. It does not mention authentication because it is completely separate from the applications that use it. This is a basic protocol to which other protocols of the TCP/IP set ( FTP, SMTP, POP3, etc.) are implemented.
So, for example, you use Serial Cable to initially configure a Cisco Router, and then you can configure this protocol remotely from the local or remote network without being next to this device. This protocol is used to configure remote hosts. Thus, it provides an easy-to-implement 8-bit coded, bidirectional (half-duplex) communication system.
It is implemented over a TCP connection to send data in an 8-bit encoded ASCII format with verification sequences between them. The protocol provides basic rules that allow a client (a system consisting of a screen and keyboard) to connect with a command interpreter (on the server-side). Telnet is a standard Internet protocol that allows terminals and applications to connect to the Internet. Using pre-web computing terminology, we can say that a client is actually a teleprocessor terminal emulation program adapted to the Internet system, that is, the TCP / IP protocol. TELecommunication NETwork is one of the oldest protocols on the Internet, extends to the time of ARPANET and is used to connect to a remote computer over the Network so that the client computer acts as a terminal connected to the remote computer.Īll it takes is a Telnet client.