code: function () { // Enter passive mode
      var socket = this
        , dataServer = net.createServer()
      socket.passive = true
      dataServer.on('connection', function (dataSocket) {
        dataSocket.setEncoding(socket.dataEncoding)
        dataSocket.on('connect', function () {
          // Unqueue method that has been queued previously
          if (socket.dataTransfer.queue.length) {
            socket.dataTransfer.queue.shift().call(dataSocket)
          } else {
            dataSocket.emit('error', {"code": 421})
            socket.end()
          }
        }).on('close', function () {
          socket.reply(this.error ? 426 : 226)
          dataServer.close()
        }).on('error', function (err) {
          this.error = err
          socket.reply(err.code || 500, err.message)
        })
      }).on('listening', function () {
        var port = this.address().port
          , host = server.address().address
        socket.dataInfo = { "host": host, "port": port }
        socket.reply(227, 'PASV OK (' + host.split('.').join(',') + ',' + parseInt(port/256,10) + ',' + (port%256) + ')')
      }).listen()
    }
docs: Passive mode