Monitorix is a free, open source, lightweight system monitoring tool designed
to monitor as many services and system resources as possible. It has been
created to be used under production Linux/UNIX servers, but due to its
simplicity and small size can be used on embedded devices as well.

It consists mainly of two programs: a collector, called monitorix, which is a
Perl daemon that is started automatically like any other system service, and a
CGI script called monitorix.cgi. Since 3.0 version Monitorix includes its own
HTTP server built in, so you aren't forced to install a third-party web server
to use it.

Note:

There are several runtime dependencies (like pflogsumm) I'm unable to test for
all services. Keep an eye on /var/log/monitorix which will tell you.