OpenSource tools/services for server monitoring

Question

I'm looking for an OpenSource server monitoring tool that allows the following:

• Monitor a variety of services on TCP, UDP.
• Supports custom port numbers.
• Supports some basic response checking (beyond initial connection checking).
• Basic dashboard overview of health status.
• Alert notifications via e-mail.

I could roll my own, but want to make sure I don't reinvent the wheel if there's a complete suite out there that does what I want (and maybe more!).

EDIT: Preferably software that runs on Windows.

Answer 1

I recommend the "mon" package (http://www.kernel.org/software/mon). It is pre-packages in most Linux distributions, and fairly customizable.

Answer 2

Nagios is the way to go. Very powerful and customizable. Has dashboards, history, alerts, graphs, and much more.

I you want something a bit fancier, there is Groundwork which is built on nagios and various other bits and pieces, but I didn't really like that after playing with it for a little bit. It also costs for anything but the community edition.