Problem mit TCP Port-Checker

<?

$server = "die IP des Servers"; //serverip  
$max_port = "200";  

function on(){
	global $server, $port;
	$c = @fsockopen("$server", $port, $errorno, $errorstr,0.5);  
	if($c){@fclose($c);return true;} else return false;
}

	for ($port=0;$port < $max_port;$port++)
			{
				echo "<font color='red'>Port: $port</font><br>";  
				if (on()) echo"<font color='green'>offener Port: $port</font><br>";  
				if ($port==$max_port) echo "Alle Ports getestet";  
			}

?>