Masscan: TCP port scanner, scanning entire Internet in under 5 minutes

A very nice and well-built tool. Excellent use of sequence numbers for stateless send/receive (SYN cookies): https://github.com/robertdavidgraham/masscan/blob/master/src... (very well-documented source too, a pleasure to read). I once (2016) used it to scan port 22 on the whole ipv4 (had to experiment with rate limits to not trigger alarms and get complaints forwarded by my VPS provider; the clever ip+port randomization technique helps a lot with that). Then took the ~22m (iirc) IPs which responded and ran…

Note: your ISP and third-parties probably won't like this very much.

What's impressive about this or zmap? they do not magically invent bandwidth. Zmap requires a 1 Gbps connection or more, this will require 10X the bandwidth. Those projects are basically dumb packet generators, what I find really impressive is the Internet routing infrastructure that can accept those outputs.

Don't get me wrong, I think this is some great coding, but I'm just wondering... what might be a legal/ethical use this? I'm thinking that most companies own at most a couple thousand machines, so something more traditional like nmap might do just fine.