There is a PC behind a cable modem. The cable modem is "blocking" port 161 snmp. I know this because it defines that in teh cable modem config file from the ISP. But, when I port scan the PC from the internet, my scanner reports that port 161 is OPEN. So, is it possible that port 161 traffic is blocked but the port scanner uses some other mechanism to see that 161 is open on the PC? I'm confused.