public void Start()
{
_device = Open();
if (_device == null) throw new Exception("Cannot open Ethernet interface");
_deviceMac = _device.Interface.MacAddress.GetAddressBytes();
// filter to only bacnet packets
_device.Filter = "ether proto 0x82";
System.Threading.Thread th = new Threading.Thread(CaptureThread);
th.IsBackground = true;
th.Start();
}