Centreon won't run with PHP 5.4 or 5.5 in Ubuntu 14.04
Centreon is a nice, open source GUI over Nagios and allowes you to do 100% of your day to day monitoring setup and operation inside the GUI. Nice, that is, once it runs. Before that, it is a nightmare - but there is help.
The requirements page states that required PHP version is 5.3, excluding 5.3.2. Also, I am not sure if later versions of 5.3 will work. If you need some info from deeper down the rabbit hole, try