如何通过服务器隧道浏览器端 mqtt？

Question

Browser uses this to connect to a mosquitto (websockets mode):

new Paho.MQTT.Client('localhost', 9001, '');

As I understand, it's a direct connection from the browser to the broker. It won't work in the normal setup when the browser is on a different machine.

In normal setup nodejs and the broker are on the same machine. How to route that via nodejs, so nodejs could forward the connections to the localhost:9001 ? And I don't want to write a lot of code for repacking messages and reimplementing different subscription API.

Answer 1

localhost is a special case hostname that refers to the machine some code is running on.

Assuming the broker you want to connect to is on the same machine that hosted the webpage you can use the location variable to get the information you need.

var client = new Paho.MQTT.Client(location.hostname, 9001, '');

Assuming you are proxying the webapp then the websockets can be proxied as well on the same port which would end up with:

var client = new Paho.MQTT.Client(location.hostname, parseInt(location.port), '');

To proxy the mqtt as well (using nginx):

location /mqtt {
    proxy_pass          http://127.0.0.1:9001/;
    proxy_http_version  1.1;
    proxy_set_header    Upgrade $http_upgrade;
    proxy_set_header    Connection "upgrade";
}

Answer 2

You could just open up another port and then setup an SSH Tunnel (ie SSH Tunnel the MQTT Data). The advantage of doing this is that it allows you to exposed or not expose this port to the internet with ease and it is secure (encrypted).

This tutorial explains how to do this. Obviously as the MQTT data is transmitted over SSH (through the SSH Tunnel) it is 100% encrypted and therefore secure. Also you could of course use RSA keys (making the SSH connection very secure indeed) and then write a simple BASH script to automation all of this process I guess. Tutorial Link: SSH Tunnel MQTT