zlacker

SSH is TCP though and the outside world can initiate a handshake, the point being that wireguard silently discards unauthenticated traffic - there's no way they can know the port is open for listening.

>>bjt123+(OP)
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.)

>>eqvino+i03
That's why you discard ICMP errors.

>>apstls+Ew5
If anything, that's why you discard ICMP port unreachable, which I assume you meant.

If you're blanket dropping all ICMP errors, you're breaking PMTUD. There's a special place reserved in hell for that.

(And if you're firewalling your ICMP, why aren't you firewalling TCP?)