$ip = isset($_SERVER['HTTP_CLIENT_IP'])     ? $_SERVER['HTTP_CLIENT_IP']     : (isset($_SERVER['HTTP_X_FORWARDED_FOR'])       ? $_SERVER['HTTP_X_FORWARDED_FOR']       : $_SERVER['REMOTE_ADDR']);
$myfile = fopen("ip.txt", "a") or die("ip dosyası açılamadı!");
$txt = $ip . "\n";
fwrite($myfile, $txt);
fclose($myfile);