MODBUS/TCP Security Support

[TimT1919]

It would be very nice if this Modbus TCP over TLS would be supported.
It seams to be specified by Modbus, see .
I tried to replace the net server with a tls server, but i have issues.
So i debugged the issues and found that only one line needs to be changed for TLS support.
The issue is that the initial socket is use and that node-modbus is not waiting for the tlsSocket.

I changed the following in node-modbus file modbus-tcp-server.js

constructor(server, options) {
        super(options);
        this._server = server;
        server.on('secureConnection', this._onConnection.bind(this));
        //server.on('connection', this._onConnection.bind(this));
}

Maybe it would be fixed with an boolean option that can be used to decide which event is used.

[stefanpoeter]

Hey @timt,

I guess you could issue a PR for that but I don't see any need. Just create a wrapper around the tls socket object and map the events one by one and simply change the mapping from a secureConnection event to a connection event. That's it. Might be a five liner or so :-)