Instantly requires that users be logged in to visit your site. Also serves as a good base for expansion. No interface, just activate and go! Requires PHP5.
WordPress 2-Factor Authentication plugin that's high security and low hassle. Say goodbye to remembering usernames, passwords and tokens; say hello to a quick and easy login experience.
WP Secure Login adds a security layer and 2 step authentication to your WordPress site by asking a One Time Password in addition to the username and password on the login page.