A simple security plugin for WordPress
Although this plugin has not been updated in over 2 years it’s still very popular and has over 1 million installs. Why? Because it does a very simple job. It limits the number of unsuccessful attempts to access your WordPress site, just like a cashpoint machine will refuse access if you enter the wrong pin number 3 times. You can change settings as to how many attempts and the lockout period before allowing further attempts.
Read more here: wordpress.org/plugins/limit-login-attempts