title: Check if a remote port is UP(listening) on UDP?
body: <p>I've to detect if a remote host is UP, based on it's a service(IP+Port) running. I can't use a ping because we need to make it works even the ICMP port is blocked.</p>
  
  <p>Sometime the service is using TCP, sometimes UDP(but when I've to check, I know if the server has to run on UDP or TCP, it's depending of it's type). I've no issue checking the TCP port(based on <a href="https://stackoverflow.com/a/7605428/397830">https://stackoverflow.com/a/7605428/397830</a> ). But since UDP is not a connection oriented protocol, how could I be sure that the remote host is listening on UDP on this port?</p>
  
  <p>Thank you!</p>