Use the following command from the DOS Command Line:
tracert x.x.x.x
where x.x.x.x is the IP you want to trace, this program will display the hops needed to get to the destination IP if under 30 hops. It might even show you the domain name of the IP.
You dont want to close an open port, you want to stealth it.
Two simple ways to do this are:
1) Disable port in hardware firewall rules (If you have a router).
2) Disable port through software firewall (I.E. ZoneAlarm, BlackIce)
You want stealth on your ports so that attackers do not even think your computer is there.
Check
www.grc.com for test of best known ports.
Hope this helps.