Node.js TCP client and server example

nodejs-tcp-example.js

/*
In the node.js intro tutorial (http://nodejs.org/), they show a basic tcp 
server, but for some reason omit a client connecting to it.  I added an 
example at the bottom.

Save the following server in example.js:
*/

var net = require('net');

var server = net.createServer(function(socket) {
	socket.write('Echo server\r\n');
	socket.pipe(socket);
});

server.listen(1337, '127.0.0.1');

/*
And connect with a tcp client from the command line using netcat, the *nix 
utility for reading and writing across tcp/udp network connections.  I've only 
used it for debugging myself.

$ netcat 127.0.0.1 1337

You should see:
> Echo server

*/

/* Or use this example tcp client written in node.js.  (Originated with 
example code from 
http://www.hacksparrow.com/tcp-socket-programming-in-node-js.html.) */

var net = require('net');

var client = new net.Socket();
client.connect(1337, '127.0.0.1', function() {
	console.log('Connected');
	client.write('Hello, server! Love, Client.');
});

client.on('data', function(data) {
	console.log('Received: ' + data);
	client.destroy(); // kill client after server's response
});

client.on('close', function() {
	console.log('Connection closed');
});

This is really fun, I have been playing with this today and you have definitely distracted me. Ignore my previous issue, I have progressed and now have a basic “chat room” with multiple clients.. I have been using ncat as the client, but I need more logic so I’m trying to implement your node client. So far it works, connects to the server and writes the initial text..

But all subsequent message don’t seem to go back to the server?

Apart from the very first client.write how do I send a mother client.write after the user hits enter?

This is really fun, I have been playing with this today and you have definitely distracted me. Ignore my previous issue, I have progressed and now have a basic “chat room” with multiple clients.. I have been using ncat as the client, but I need more logic so I’m trying to implement your node client. So far it works, connects to the server and writes the initial text..

But all subsequent message don’t seem to go back to the server?

Apart from the very first client.write how do I send a mother client.write after the user hits enter?

newbies who visit this many years later may find this video on youtube helpful to get started with the server side https://www.youtube.com/watch?v=HyGtI17qAjM

Is Hello, server! Love, Client. guaranteed to print? It seems like there's a race condition.

Actually, is anything other than E guaranteed to print?

Hi, is it possible to use this to connect to a network share (smb1)?

The output:

Connected
Received: Echo server
Hello, server! Love, Client.
Connection closed

all is fine

this gist was really helpful for me, thank you dude

Hi guys and gals,
I'm trying to create a simulator using Javascript for the front end which I can do, but I'm having a hard time with Node.js for the backend. When I click on, say, a Cisco router icon, I want the a physical connection to occur between my PC and the physcial router that is connected via ethernet. It is a laboratory router (no internet connection). I was thinking that I should download the NPM package telnet-client and require it in the node.js file. I don't know what to do from there. I assume I have to require net as well. Will someone help me. Please... Pretty please :)

Please use arrow functions!

hello, how can you prevent DDOS attacks on this code?

how to set tcp headers on request and receive in the server

how to set tcp headers on request and receive in the server

I don't think you can set headers with TCP. HTTP maybe what you are looking for

'Received: ' + data

I also have a same issue.......

require("net") is not working in 16.13.1
when i move to 18.x now it says digital envelope routines unsupported
.......

you try to connect to another pc port? if yes, make sure to allow inbound firewall

this gist was really helpful for me, thank you dude

same! thank you!

I have multiple simultaneous connections. how can I write to a particular client if the remotePort and remoteAddress is stored to the DB. the new Socket() command does not work in my case because it creates a new instance of this.