如何檢查服務器或主機上的開放端口？

Question

對於iPhone通知我們需要2195端口是開放的。我們如何檢查2195端口是否在該服務器或主機上打開？

Answer 1

$host = 'stackoverflow.com'; 
$ports = array(21, 25, 80, 81, 110, 443, 3306); 

foreach ($ports as $port) 
{ 
    $connection = @fsockopen($host, $port); 

    if (is_resource($connection)) 
    { 
     echo '<h2>' . $host . ':' . $port . ' ' . '(' . getservbyport($port, 'tcp') . ') is open.</h2>' . "\n"; 

     fclose($connection); 
    } 

    else 
    { 
     echo '<h2>' . $host . ':' . $port . ' is not responding.</h2>' . "\n"; 
    } 
} 

出把看這個

stackoverflow.com:21 is not responding. 
stackoverflow.com:25 is not responding. 
stackoverflow.com:80 (http) is open. 
stackoverflow.com:81 is not responding. 
stackoverflow.com:110 is not responding. 
stackoverflow.com:443 is not responding. 
stackoverflow.com:3306 is not responding.