WPsyslog2 is a global log plugin for Wordpress. It keeps track of all system events and log them to syslog. It tracks events such as new posts, new profiles, new users, failed logins, logins, logouts, etc.
OSSEC is an Open Source Host-based Intrusion Detection System. It performs log analysis, file integrity checking, policy monitoring, rootkit detection, real-time alerting and active response.