Nidan is an active network monitoring system.
Nidan consists in a scanning agent, written in Python, and a web controller, written in PHP. Nidan scanning agent use REST to connect, via HTTP, to the controller. so you can install it into a different remote servers (also behind a NAT). In most case, both are on the same server. Nidan agent can be run also as non-privileged users, but scanning tecniques will be not accurate as running as root