I was trying to test out my friend's computer (with agreement) by using nmap remotely. But the result I got seems kinda awkward to me. It only showed 1900 as tcpwrapper and all other ports were no responded. And OS detection was 3Com router not the machine I thought.
Is it because it blocks nmap scanning at router? I tested same network and other machines were revealed with various ports/services.
Any idea how to interpret this result and do some further testing on this machine?