how to fix ssh: connect to host <server IP address> port 22: No route to host

Question

I got hired as a Linux  system engineer at a technology company. I received a task today to connect from my office computer to a remote server within the company for configuration and management purposes. I knew I could use SSH protocol to connect to the server on port 22.

I opened the terminal and entered the SSH connection command, including the IP address of the target server. However, after running the command, I encountered a perplexing error message: "ssh: connect to host <server IP address> port 22: No route to host."

Any idea how to fix this?

Answer 1

Hello 守山 李

Welcome to Microsoft Q&A Platform, thanks for posting your query here.

This error message indicates that your computer is unable to reach the target server. There could be several reasons for this, such as incorrect IP address, network connectivity issues, or firewall restrictions.

To troubleshoot this issue, you can try the following steps:

-From this link (https://ping.eu/port-chk/) please check if your VM Public IP is accessible on port 22. If this is closed, which means the NSG is not set correctly.

-Also, check if there are any firewall restrictions that are blocking your connection. You can try disabling your firewall temporarily and see if you are able to connect to the server. If you are able to connect after disabling the firewall, you need to configure your firewall to allow SSH traffic on port 22.

Hope this helps.

Answer 2

hello .

I think you can troubleshoot this issue from the following three items. Hope it can help you. You can copy the command output here. Let's figure out the issue together.

• Verify the IP Address: Double-check that you've entered the correct IP address for the destination server. You can get the ip address with command ip addr after you login your Linux VM from console or you can get it from VM portal.
  https://www.howtouselinux.com/post/check-ip-address-in-linux
• Check Network Connectivity: Make sure your computer has a working network connection. Type the following command telnet server_address 22
  https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/troubleshoot-ssh-connection
• Check Firewall Settings: Ensure that there are no firewalls or security groups blocking outgoing SSH connections from your computer. You may need to modify the firewall rules to allow SSH traffic. You can disable firewall for testing.
  https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/detailed-troubleshoot-ssh-connection