Guard

Guard protects your wp-admin against bruteforce attacks.

Features:

• Max retries: You have the power to choose how many attempts a user can make before the user is blocked;
• Lockdown: This prevents the user from being able to use the login form after too many retries;
• Email notifications: We'll report a user lockdown to you via email;
• Hide lost password: Hides the "Forgot your password?" link from the login form page.

This plugin does not make any changes to core: When you delete/uninstall the plugin, everything will revert back to normal.