全面披露：有一个类似的问题
here.
有什么办法可以测试一个特定的端口是否打开并使用PHP正确转发？具体来说,如何使用套接字连接给定给定端口的给定用户？
一个例子是WhatsMyIP.org/ports的“自定义端口测试”部分.
我不知道你的意思是“正确转发”,但希望这个例子可以做到这一点：
$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";
}
}
输出：
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.
有关端口号的完整列表,请参见http://www.iana.org/assignments/port-numbers.