This is Jeba Limit Login Attempts wordpress plugin. Automatically lock the system for 30 minutes if a user attempts to login and fails after 3 tries.
Plugin Tag: Login Attempts
-

Limit Login Attempts (Spam Protection)
Limit rate of login attempts, including by way of cookies, for each IP. Fully customizable.
-

WP Login Attempts
WP login attempts is a very lightweight plugin that lets you customize your WordPress admin login page easily and safely.