Originally posted here by Maestr0
A. He has a weird ass firewall running,
B. His ISP is blocking well known trojan ports at their perimeter to avoid problems for their customers (which is what I believe is happening).
C. Something else I didn't think of.

i guess the answer is B.
my isp is filter that kind of port..... so if being port scanned it will show filtered. although that pc doesn't open that port.