Allow access to Wordpress only if user has passed thru another page first and gathered a special cookie

nginx-wordpress.inc

set $cicciopasticcio 0;
if ($request_uri ~* "/wp-admin|/wp-login.php") {
        set $cicciopasticcio 1;
}
if ($request_uri ~* "/wp-admin/admin-ajax.php") {
        set $cicciopasticcio 0;
}
if ($cookie_cicciopasticcio != "nginx") {
        set $cicciopasticcio "${cicciopasticcio}1";
}
if ($cicciopasticcio = 11) {
        return 404;
}

location = /cicciopasticcio.php {
        add_header X-Debug "cicciopasticcio" always;
        set $cache_skip 1;
        set $cache_uri '';
        add_header Set-Cookie "cicciopasticcio=nginx;path=/;max-age=3153600000";
        return 302 /wp-login.php;
}