Where can I check a open or not port ?

Go to http://grc.com and find Shields Up! (towards the bottom of the main page). That'll tell you what ports you have open and closed.

Thanks, cprompt.

But do we have the way under W2K3 ( from a built in software ) to check ports status ?

I'm sure Rabbit will correct me, but while you can use netstat to view listening connections (ie open ports), I don't think there's any way of telling if the ports are physically closed off higher up the chain (by using IPSEC/RRAS firewall or something).

Well, I need to open a outgoing TCP port 5224 as Plesk request me to update the license key, so how can I do it ?

Umm, open the firewall port.

I tend to like Blue's Port Scanner for all my port scanning needs.

What have you used to close it off in the first place?

That's a great bit of software, even if it does use the smallest, non-sizeable, window known to mankind

Don't know, the DC deliver me the server and Plesk notice that the port 5224 was close !?!...

You can use the scanning tool in Orbit.