ICMP Destination unreachable (Port unreachable) Networking Origin: Network OSI layer 4 · Transport Last updated 5 Nov 2026

Networking: ICMP Destination unreachable (Port unreachable) — UDP packet sent to a port where nothing is listening

A host answered a UDP packet with an ICMP message saying no program is listening on that port.

Exact message you may see ICMP Destination unreachable (Port unreachable)Port unreachableICMP port unreachabletype 3 code 3ICMP Destination Port Unreachable
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Seen on: Linux Networking

Meaning

The target machine is up but the service isn't running or isn't bound to that address/port, so UDP clients (DNS, NTP, syslog, SNMP, game servers) get "port unreachable" or ECONNREFUSED on connected UDP sockets. Start the service, bind it to the right interface, and check the firewall.

Common causes

  • UDP service not running
  • Service bound to 127.0.0.1 only
  • Wrong port number
  • Firewall REJECT rule
  • Container port published only for TCP

⚡ Quick fix

  1. Check the listener: ss -ulnp | grep PORT
  2. Bind the service to the right interface
  3. Publish UDP in containers: -p 53:53/udp

Detailed fix by platform

Linux

  1. bash
    ss -ulnp | grep :514
sudo tcpdump -ni any icmp

How to diagnose

  1. Listener — UDP port open?
  2. Bind address — Reachable?
  3. Docker — /udp published?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Network. Errors that are often confused with or caused by this one (click to open):

dig: status: REFUSED (recursion not available) — Networking: dig: status: REFUSED / recursion requested but not available — the DNS server won't resolve queries for you (Networking)dig: status: REFUSED …Frag needed and DF set (ICMP type 3 code 4) — Networking: ping: local error: message too long, mtu=1500 / Packet needs to be fragmented but DF set (Networking)Frag needed and DF se…nc/telnet hangs: firewall DROP vs REJECT — Networking: nc -vz hangs then times out — firewall silently DROPs packets (REJECT would answer "Connection refused") (Networking)nc/telnet hangs: fire…Ping: Request timed out — Networking: ping — Request timed out / 100% packet loss (host drops or filters ICMP) (Networking)Ping: Request timed o…PING: transmit failed. General failure. — Networking: PING: transmit failed. General failure. / ping: sendmsg: Operation not permitted (Networking)PING: transmit failed…Reply from 192.168.1.1: Destination host unreachable — Networking: ping — Destination Host Unreachable / Destination net unreachable (ICMP type 3) (Networking)Reply from 192.168.1.…Reply from x: TTL expired in transit — Networking: TTL expired in transit — routing loop between routers (Networking)Reply from x: TTL exp…UDP RcvbufErrors / packet receive errors — Networking: netstat -su: packet receive errors, receive buffer errors — UDP datagrams dropped by a full socket buffer (Networking)UDP RcvbufErrors / pa…ICMP Dest…

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