How to connect to Telnet server from Node.js ?

In this article, we will see how to connect the Telnet server with Node.js application.

Telnet: The telnet is an application protocol over the Transmission Control Protocol (TCP) used on the internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. Telnet is used to share a terminal with someone far from us. They provide lots of benefits like virtual terminals and real-time execution on command on the shared terminal. if you have more curious about the telnet refer to this article.

NodeJS: Node.js is a runtime environment for javascript, based on the V8 engine the executes javascript on the server-side. So with the help of nodejs we also create an event-driven application,if you have more curious about the telnet refer to this article.

Program Approach:

• Firstly declare the same global variable for further use.
• Import or require two modules for work with telnet server, first one is the net module the help to manage the network and the second one telnet-stream is used for establishing a connection with a telnet server.
• Initialize net socket object with IP and port number of the telnet server.
• Create a telnet client and connect this above socket.
• After connection, the socket listing some events is as close for if connections are closed and data for collecting data from the telnet server last but not a least do and will event to occur every new step in telnet server create a log.

Connect the Telnet server from Node.js

Step 1: Run the below command for initializing npm.

npm init -y

Note: -y is used for all settings are default.

Step 2: install some packages.

npm install telnet-stream

Note: telnet-stream is used to connect the telnet to our node application.

Step 3: Create a file with the below code. Here, the filename is index.js

Javascript

// Some global variable for further use
var TelnetSocket, net, socket, tSocket;

// Require the net module for work with networking
net = require("net");

// Require and create a TelnetSocket Object
({ TelnetSocket } = require("telnet-stream"));

// Initialize the socket with the our ip and port
socket = net.createConnection(22, "test.rebex.net");

// Connect the socket with telnet
tSocket = new TelnetSocket(socket);

// If the connection are close "close handler"
tSocket.on("close", function () {
    return process.exit();
});

// If the connection are on "on handler"
tSocket.on("data", function (buffer) {
    return process.stdout.write(buffer.toString("utf8"));
});

// If the connection are occurred something "doing handler"
tSocket.on("do", function (option) {
    return tSocket.writeWont(option);
});


tSocket.on("will", function (option) {
    return tSocket.writeDont(option);
});

// If the connection are send the data "data handler"
process.stdin.on("data", function (buffer) {
    return tSocket.write(buffer.toString("utf8"));
});

Step 4: Run index.js file.

node index.js

Output: Finally, you have connected your node application to telnet.