Send an « HTTP/1.1 403 Forbidden » header on a failed login instead of « HTTP/1.1 200 OK », which is the WordPress default header on failed login. This is a tremendously simple plugin that does only that and absolutely nothing else.
The purpose of this plugin is to provide a way to allow external tools like fail2ban to get a message of a failed login e.g. to prevent a brute-force attack on a firewall level.
For the public domain.
Uses PHP5.3 anonymous functions and will not work on earlier versions of PHP