This simple plugin enables logging of failed authentication attempts in Matomo (Piwik), nothing more, nothing less. Failed login attempts are logged like this:
WARNING LoginFailLog[2017-07-22 23:35:20] [b215d] Failed login from 22.214.171.124 'patrick'. WARNING LoginFailLog[2017-07-22 23:35:20] [b215d] Failed login from 126.96.36.199 with username 'patrick'.
This is useful if you want to secure your Matomo instance with fail2ban or similar tools that work on log files. For example, the following filter can be used with fail2ban to detect and count login fails:
# Fail2Ban configuration file for Matomo with LoginFailLog plugin [Definition] failregex = .* Failed login from <HOST> with username .*