QUOTE (SuperBaby)
As a newbie, I am cusious to know how you can tell if your server is under attack. What to observe?
The first line would be to check if your site or server is reachable. If not, something is probably wrong.
If you can get in, SSH into your machine and do a
CODE
netstat -a
You should see the current connections and if you see a lot of SYN then well, it is sure sign you are under attack. But most of the time if you are under attack you will probably not be able to get in.
The other method would be to visit Orbit (remember Orbit is your friend). Under Hardware, Resource Utilization you will see long sustained spike in traffic, either incoming or outgoing. If it shows as outgoing, it would mean that your server is under attack. If it shows it as incoming, then you are attacking others.