<?
# from http://patrick.vande-walle.eu/internet/test-your-ipv6-connectivity/
function is_connected_ipv6() {
	return (substr_count($_SERVER['REMOTE_ADDR'], ":") > 0 && substr_count($_SERVER['REMOTE_ADDR'], ".") == 0);
}
$host  = $_SERVER['HTTP_HOST'];
$uri   = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Pragma: no-cache");
header("Location: /blog/".(is_connected_ipv6() ? "images/ip-v6.png" : "images/ip-v4.png"));
?>