How do I get the external IP of my server using PHP?

Question

I often hear people say to use \"$_SERVER[\'SERVER_ADDR\']\", but that returns the LAN IP of my server (e.g. 192.168.1.100). I want the external IP.

Answer 1

This is an old thread, but for what it's worth, I'm adding a simple function that I use. It uses outside services (which is inevitable it seems), but it provides a backup service as well, and local caching to avoid repetitive HTTP calls.

/*
USAGE
$ip = this_servers_public_ip(); // Get public IP, and store it locally for subsequent calls.
$ip = this_servers_public_ip(true); // Force remote query and refresh local cache if exists.
*/
function this_servers_public_ip($purge=false) {
    $local = sys_get_temp_dir().'/this.servers.public.ip';
    if ( $purge===true && realpath($local) ) {
        unlink($local);
    }
    if ( realpath($local) ) {
        return file_get_contents($local);
    }
    // Primary IP checker query.
    $ip = trim( file_get_contents('https://checkip.amazonaws.com') );
    if ( (filter_var($ip, FILTER_VALIDATE_IP) !== false) ) {
        file_put_contents($local,$ip);
        return $ip;
    }
    // Secondary IP checker query.
    $ip_json = trim( file_get_contents('https://ipinfo.io') );
    $ip_arr = json_decode($ip_json,true);
    $ip=$ip_arr['ip'];
    if ( (filter_var($ip, FILTER_VALIDATE_IP) !== false) ) {
        file_put_contents($local,$ip);
        return $ip;
    }
    return false; // Something went terribly wrong.
}