Portqry Udp 🎁 Certified

portqry -n 192.168.1.1 -p udp -e 33456 You might get:

UDP port 33456: FILTERED or NOT LISTENING (no response) Or with a host that sends ICMP unreachable: portqry udp

Here’s an interesting angle on that often surprises people: Why portqry over UDP is tricky Unlike TCP, UDP is connectionless — no handshake, no ACK. So portqry can’t just “connect” to a UDP port to see if it’s listening. portqry -n 192

UDP port 53 (domain service): LISTENING Because Google DNS replies to a proper DNS query. But if you send to a random high UDP port with no service: UDP is connectionless — no handshake

UDP port 33456: NOT LISTENING (ICMP Port Unreachable) Want to see if something on your own machine is bound to UDP but not responding?