To log in to your WordPress site you visit the wp-login.php URL on your website. Normally you arrive directly at the Log in page. BUT…
To avoid performance problems that can be created by a rather nasty botnet, your hosting company may add an additional check that prevents you from accessing the wp-login.php page until you have authenticated.
Authentication Required – added protection against the botnet attack
The dialog box message is intended for humans to read and understand. The text could be better couldn’t it?
This dialog protects your site against the botnet attack.
Please enter the User Name and Password shown.
WordPress login wp-login.php
Make sure your username is NOT admin and that your password is strong.