GRC
Is this better tool than Gibson Reseach's one (which maybe just looks for uPNP stupid settings, though they can scan all your ports.)?
https://www.grc.com/default.htm
Scroll down to ShieldsUp!
Compared to GRC's site they want far too many different domain's scripts enabled according to NoScript.
It also gives false positives!
"The scanner couldn't access the device on your IP address [redacted], possibly as a result of it being infected with the Mirai malware.
Please restart your connected device to enable scanner access. Why?"
Either it's incompetent or a scam to sell cloud services.
"Q: I restarted my device but the scanner still can't access it. What should I do?
Nothing, you're good. If after rebooting the scanner still can't access your device, it's because the remote access ports are closed and your device is secure from Mirai injection attacks."
Well, I don't have anything exposed by my Router/Firewall (Open WRT on a PCEngines SBC)