That depends on what OS Distribution you're running.
If you're running a recent version of Linux you can find out what it's allowing/blocking with:
Code:
# iptables -L
You do NOT type the #; it's just there to show you that you run the command as root.
It still won't tell you how those commands got there. If you built the server yourself you should know what you set up. If someone else did it for you, ask them.