How to fix ERR_CERT_COMMON_NAME_INVALID when trying to connect to a node.js server (not hosted on localhost)?

Question

So I'm trying to create a script in Tampermonkey (JavaScript) to send data to a node.js server. For those who don't know what Tampermonkey is, it's basically an extension to run JavaScript scripts on websites to add stuff (ex make an overlay on a .io game). However, along with this I'm trying to send the data from the node.js server to another client on a different computer (not the problem). My problem arises when I stop hosting the node.js server on localhost and instead on the computer's address (so it can communicate with client on computer #2) Here is my code for the server

const app = require('express')();
const https = require('https');
const fs = require('fs');

const httpsServer = https.createServer({
    key: fs.readFileSync('./server.key'),
    cert: fs.readFileSync('./server.crt')
});

const port = 4000;

httpsServer.listen(port, "192.168.1.38", function () {
    console.log('LISTENING');
});

const ioServer = require( "socket.io" );
const io = new ioServer();
io.attach( httpsServer );

io.on( "connection", function( socket ) {
    console.log('client connected');
});

The code for the Tampermonkey client is:

// ==UserScript==
// @name         testscript
// @namespace    http://tampermonkey.net/
// @version      1
// @description  try to take over the world!
// @author       user12751150
// @match        *://diep.io/#*
// @grant        none
// @require      https://cdnjs.cloudflare.com/ajax/libs/socket.io/1.4.5/socket.io.min.js
// ==/UserScript==



var socket = io.connect('https://192.168.1.38:4000');;
function socketThing() {
    socket.emit('test', {"test": "data"});
}
setInterval(socketThing, 500);

(it's just a test script, so it doesn't actually do anything useful)

Whenever the script is running it shows this in console:

GET https://192.168.1.38:4000/socket.io/?EIO=3&transport=polling&t=M_5NBeo net::ERR_CERT_COMMON_NAME_INVALID

I have tried many solutions, such as How can I create a self-signed cert for localhost? and How to generate a self-signed SSL certificate using OpenSSL? and many others, but they don't work. I'm not sure if I should make a self signed certificate for localhost and then just change it to my computer's IP, or if I have to create something completely different.

I have currently tried:

creating a certificate with common name as 192.168.1.38
creating a certificate with everything as 192.168.1.38
creating a certificate with 192.168.1.38 and https://192.168.1.38 as alternate IPs

score 1 · Answer 1 · answered Jan 10 '22 at 07:47

I am working on a personal project and had the same issue. What worked for me: I replaced the IP adress with my actual domain name.

var socket = io.connect("https://ip:4000");

to:

var socket = io.connect("https://actualWebsiteAdress:4000");

Maybe you give that a try.

score 0 · Answer 2 · answered Apr 14 '20 at 14:12

I faced the error while working on a project and I resolved it by specifying the correct ip on the client side. I had before something like what what you wrote

    var socket = io.connect('https://192.168.1.38:4000');

then my colleague who was assisting me said the error might be because of subnet differences. I didn't understand that much but He suggested I change to something like this below

    var socket = io.connect('https://OurAlreadyHostWebsite.org:4000/');

And it worked. So just in case this provides a hint you can use to find a solution.

How to fix ERR_CERT_COMMON_NAME_INVALID when trying to connect to a node.js server (not hosted on localhost)?

2 Answers2