> non-damaging protscan

Tell that to every corporation on Earth, especially to Banks, that "port scanning your perimeter is an innocent thing". Tell that your employer as well and do tell us what's your job status afterwards.

(I am not downvoting the utterly silly grey comments - I want them to be visible to a) ;)

Then they need to disclose that behavior. Because my firewall marks portscans as a malicious activity.

Since the portscan happens clientside on 127.0.0.1 I doubt your firewall will be able to notice the portscan.

That depends if you use IPv4 with NAT like almost everyone on a residential Internet uplink or IPv6 with a public routed address...

127.0.0.1 (aka localhost) isn't affected by your NAT setup. Your browser initiates this scan on the local loopback device, so the traffic will never even leave your computer (even on linux, it's somewhat difficult to get it to route 127.0.0.1 to another computer and it'll break a lot of applications in the process or make them insecure).

IPv6 with a public routed address still means there is a firewall, just like with NATv4. NATv4 just also has a NAT router with that firewall.