检查ip6是否已关闭

Question

I'm trying to check if ip6 is not connected in my code using php. My idea now is to calculate the loading if it is going to connect. I try to use this code.

$file = file_get_contents('http://ip6.me/');

// Trim IP based on HTML formatting
$pos = strpos( $file, '+3' ) + 3;
$ip = substr( $file, $pos, strlen( $file ) );

// Trim IP based on HTML formatting
$pos = strpos( $ip, '</' );
$ip = substr( $ip, 0, $pos );
$ipaddress = $ip;
$ip_get = explode('.',$ipaddress);

this work fine with me if will get ip address. But there is a time that ip6 down and it load to much. What is the best way to check if ip6 is down? I try to calculate the load of browser, but I have no idea how to do it.

Answer 1

I would ping a server over IPv6. On linux, you can use the following code.

exec('ping -6 -c 1 2001:4860:4860::8888', $lines, $exit); // ping will return 0 if ping succeeds
if($exit == 0) {
    // up
    echo "up
";
} else {
    //down
    echo "down
";
}

EDIT:

Samuel's answer tests whether a TCP port is reachable over IPv6. In some cases, because of firewall configuration, only one of the methods may work.