Authorizer Access Restriction Plugin for WordPress
Most of us have our website available to everyone on the internet. In certain cases, it makes sense to restrict access to your website to only certain users. Authorizer is just the plugin for the job. It lets you give access to your site only to approved users.
Authorizer supports authentication through Google, CAS, and LDAP accounts. It can also limit invalid login attempts to keep bad bots away. Webmasters can change default new users, login setting, and other settings in the back-end. They can also choose which pages should be available to everyone (public & private pages).