I’m not sure whether “WordPress Simple Firewall” is still an apt description for this plugin or not; there are lots of options that can be configured and functions that can be turned on or off!  This plugin works best in conjunction with the iControlWP WordPress Management Control Panel. I’m still at the early stages of testing and implementing this across the WP sites I manage, but it appears to be a valuable addition to a suite of products to manage/maintain and secure WordPress.