https://www.grc.com/x/ne.dll?rh1dkyd2
It test you ports against probing. Maybe you've seen it, maybe it is bunk, I thought it was interesting.
Your system has achieved a perfect "TruStealth" rating. Not a single packet — solicited or otherwise — was received from your system as a result of our security probing tests. Your system ignored and refused to reply to repeated Pings (ICMP Echo Requests). From the standpoint of the passing probes of any hacker, this machine does not exist on the Internet. Some questionable personal security systems expose their users by attempting to "counter-probe the prober", thus revealing themselves. But your system wisely remained silent in every way. Very nice.
It test you ports against probing. Maybe you've seen it, maybe it is bunk, I thought it was interesting.