Create signup codes for every website in a multisite network, so that only specific users can register on your website. You can create different signup codes for different sites so that the bots can be restricted from accessing members pages. It adds security to your website and the configuration of the plugin is extremely easy. The plugin is fully compatible with other themes and plugins.
This is the EXACT same plugin as distributed by the developer on WPMU DEV. The developers’ links are provided above.