Fix The ICMP Destination Port Unreachable Error Message

Welcome to the network engineering training section by CoreNetworkZ Tech Solutions. We are happy to see the appreciation from our regular readers for our previous tutorial. So, today, we discuss another ICMP error -Destination Port Unreachable.

Team CoreNetworkZ explained various ICMP error messages in this blog. Our regular readers, John Zamoshchin and Oliver Anthony, requested that we explain this specific error message.

That is why we picked this topic. After reading this tutorial, you will learn the meaning and solution for this ICMP Port Unreachable reply.

Let us first check when we get this ICMP Reply Destination Port Unreachable.

Destination Port Unreachable is one of the ICMP error replies when we ping a remote device from our computers.

We will get this error while pinging a remote device or server from our PC.

Sandeep Kumar asked the meaning of this ping reply in the comment section. So, we check the meaning of the ICMP Error Reply Destination Port Unreachable.

The Destination Port Unreachable error tells us that the ping packet we sent failed to reach the desired destination and dropped.

Heera Lal asked us to explain in simple terms for our readers without having a technical background.

We will explain this with a real-world example. When someone pings a remote host, the ping packets will travel from his device to the destination.

Ping packets will reach the destination gateway, and the remote router redirects them to the exact host.

If the host is too busy or the device port does not support the type of packets we send, it will result in the reply Destination Port Unreachable.

So, this reply is from the host (not from the remote gateway) and different from the following ICMP replies.

One of our readers asked whether a Linux system will show the Destination Unreachable ( Port Unreachable) error.

Both the Windows and Linux PCs display this ICMP reply.

Now we check why a PC shows Destination Unreachable (Port Unreachable) Ping Reply.

Golagani Appa Rao asked us to explain the reasons for getting this error message. Let us explain them. The following reasons will cause the ICMP Reply Destination Port Unreachable.

1. Unaccepted Protocol Type-

   One of the main reasons for the Port Unreachable error is sending packets to a remote host without the required protocol to be accepted by the active port of the remote host.

   
   

2. Remote Port is Busy-

   If the port is busy while the ping packets reach, the chances of getting a rejection are very high. It may also result in the ICMP reply from the remote host on the sender with the message Destination Unreachable (Port Unreachable).

   
   

3. Possible Ban on Sender IP Address

   Another reason is the possible ban on the sender IP address configured at the remote host. Remote Port will reject packets sent from a banned address.

   
   

4. Remote Router Firewall Settings Changes Packets Encapsulation

   Our study shows the Remote Host Firewall (rarely) causes Destination Unreachable (Port Unreachable) error.

   To test it, we should ask the remote host admin to turn off the firewall (if you have such a privilege). Robert Waldinger, a web hosting company employee, confirmed it. You can read it in his comment.

   
   

5. Remote Port Might be Damaged

   If the remote port is damaged, you may receive a Destination Port Unreachable reply on your computer.

   
   

You have learned why your PC shows the Ping Destination Unreachable (Port Unreachable) message. Let us check the steps to fix it.

Troubleshooting the ICMP Port Unreachable error is a bit difficult because the issue lies with the remote device.

If you see the ICMP reply Destination Unreachable (Port Unreachable), follow the steps below.

1. Ping a Different Address

   When you see ICMP Destination Unreachable message, ping a different IP address or web URL.

   
   

   For example, if you receive the ICMP reply Port Unreacbale when you ping https:www.corenetworkz.com, try to ping https://www.google.com.

   
   

   If you get packet-received messages from the destination, you can verify the source of the problem.

   
   

2. Ping the Address From a Different IP address

   Ping packets from a banned IP will result in ICMP Port Unreachable Error.

   
   

   Ping the Remote IP (or hostname) from a different IP address to verify it.

   
   

3. Disable the Proxy and VPN Services

   Turn Off the Proxy and VPN services on your device and ping the remote server again.

   
   

   Occasionally Proxy networks cause the ICMP Destination Unreacbahle (Port Unreachable) error.

   
   

   You can resolve it by turning off the VPN. Niall Martin verified this solution, and you can read his experience in the comment section.

   
   

4. Check for Protocol Mismatch

   Kunzes Dolma asked what generated this error message. To answer it, you should understand this fact. ICMP requests do not use a port number, but TCP and UDP packets use port numbers.

   
   

   Theoretically, a Port Unreachable message comes with UDP and TCP connection failure.

   
   

   Destination Port Unreachable reply should not be from ICMP echo requests.

   
   

CoreNetworkZ.com has a collection of useful articles like how to open a port in Cox Modem and how to fix Acer Laptop hanging issues.

1. Error 769: The Specified Destination is not Reachable
2. Error 628: The Connection was Terminated by the Remote computer
3. How to Change the Default TTL Value Set On Ping Packets?
4. How to Fix 169.254.X.X (APIPA) Windows Automatic Private IP Address?

I believe that you enjoyed this tutorial. If anyone is interested in learning more, visit the following pages.

1. What is this Ping Destination Unreachable Error?
2. https://answers.microsoft.com/en-us/windows/forum/all/destination-port-unreachable/8a11ef11-0275-4f8a-b538-de75514adc92
3. https://unix.stackexchange.com/questions/287447/icmp-destination-unreachable-port-unreachable