The reason for this is because UDP is a "connectionless" protocol, which means that the operating system does not try to establish a link for the socket until it actually needs to send or receive data.
?php $fp = fsockopen( "udp: / /127.0.0.1", 13, $errno, $errstr); if (!$fp) {echo "ERREUR: $errno - $errstr br \n";} else {fwrite($fp ,"\n"); echo fread($fp, 26); fclose($fp);}?