What is the Destination Port Unreachable Error Message

I used Wireshark to help me debug the above problem. The symptom of the problem seemed to be that my HOST was generating a lot of ICMP Destination unreachable (Port unreachable) packets that were being sent back to my DNS server. Over the last few hours, my DNS resolution seems stable and the number of these packets has reduced significantly. ICMP Destination Unreachable (Host administratively Apr 25, 2013 What is the Destination Port Unreachable Error Message ICMP requests do not use a port number, but both TCP and UDP packets use port numbers. Theoretically, Port Unreachable message comes with UDP and TCP connection failure. Destination Port unreachable reply should not from ICMP echo requests. Other Important ICMP Replies . PING: Transmit failed. General Failure; Ping Request Could Not Find Host.

[SOLVED] Destination host unreachable - CentOS

If you do not specify which ICMP message to reject with, the server by default will send back ICMP port unreachable (type 3, code 3).--reject-with modifies this behaviour to send a specific ICMP message back to the source host.

Destination Host Unreachable – Reasons and Fixes – HeelpBook

Destination Unreachable ICMP Message - Interface Ethernet