Hi,
I prepared bash script in order to check connection to server and I would like to find some Nagios-like monitoring solution without having to install any agent/collector on the server.
Do you have any experience with something like that?

Thanks...

snmp would work, but you'd have to write your own fancy front-end.

I solved it like this (port version):

if
((nc localhost 22 </dev/null 2>&1 | grep -q SSH) && \
(nc localhost 25 </dev/null 2>&1 | grep -q fix) && \
(nc localhost 21 </dev/null 2>&1 | grep -q 220));
then
sudo echo "<p align="left"><font size="9">`date +%R`</font></b></p>" > /var/www/html/front.html
sudo echo '<p align="center"> <img src="/pix/ok.png" /></p>' >> /var/www/html/front.html
else
sudo echo '<p align="center"> <img src="/pix/ko.png" /></p>' >> /var/www/html/front.html
fi

It is a little "amateur" but it suits my needs