@rico24 and here is an updated node_helper, that rejects connecting clients if they don’t send the right kind of identifier (ends with a digit)
var NodeHelper = require('node_helper');
var request = require('request');
module.exports = NodeHelper.create({
		initial_counter:10000,
        start: function() {
			this.countDown = {} 				
	},
	isDigit: function(x){
			return (x>='0' && x< ='9')  // watch out for spaces after < , forum hides it all
	},
        socketNotificationReceived: function(notification, payload) {
                console.log("Payload: =" + JSON.stringify(payload));
                switch(notification){
                        case "DO_YOUR_JOB":
				if(this.isDigit(payload.identifier.slice(-1))){
					if(!this.countDown.hasOwnProperty(payload.identifier+this.ourpage)){
				           this.countDown[payload.identifier]=this.initial_counter;
					}
				let return_payload={identifier: payload.identifier, value:(this.countDown[payload.identifier] - payload.value)}									 
                            this.sendSocketNotification("I_DID",return_payload )
			        console.log("Payload 2: = " + JSON.stringify(return_payload));
			}
			else
				this.sendSocketNotification("I_DID_REJECTED_INVALID_IDENTIFIER",payload )
                                break
                }
        },
});