So siehts ganz gut aus !

node_modules/mqtt/lib/connect/tcp.js

@@ -0,0 +1,19 @@
+'use strict'
+var net = require('net')
+
+/*
+  variables port and host can be removed since
+  you have all required information in opts object
+*/
+function buildBuilder (client, opts) {
+  var port, host
+  opts.port = opts.port || 1883
+  opts.hostname = opts.hostname || opts.host || 'localhost'
+
+  port = opts.port
+  host = opts.hostname
+
+  return net.createConnection(port, host)
+}
+
+module.exports = buildBuilder