Uh, you know you can scan UDP ports just fine, right? Hosts reply with an ICMP destination unreachable / port unreachable (3/3 in IPv4, 1/4 in IPv6) if the port is closed. Discarding packets won't send that ICMP error.
It's slow to scan due to ICMP ratelimiting, but you can parallelize.
(Sure, you can disable / firewall drop that ICMP error… but then you can do the same thing with TCP RSTs.)
It's slow to scan due to ICMP ratelimiting, but you can parallelize.
(Sure, you can disable / firewall drop that ICMP error… but then you can do the same thing with TCP RSTs.)