How To Fix SSH Could Not Resolve Hostname

Secure Shell (SSH) is an essential tool for secure remote login and other secure network services over an insecure network. However, users sometimes encounter the “Could not resolve hostname” error.

This article provides methods for troubleshooting and resolving this common SSH issue.

Understanding the Error

The “Could not resolve hostname” error occurs when the SSH client is unable to resolve the domain name of the SSH server into an IP address.

This issue can stem from various sources, including DNS problems, incorrect SSH command usage, or issues with the SSH configuration.

How To Fix SSH Could Not Resolve Hostname

Do each method below until one fixes the problem.

Step 1: Verify the Hostname

First, ensure you’ve entered the correct hostname. Typographical errors are common and can lead to this error. Double-check the hostname for accuracy.

Step 2: Check DNS Resolution

If the hostname is correct, the issue may lie with DNS resolution. Use the ping command to check if your system can resolve the hostname to an IP address:

ping hostname

If the ping command fails to resolve the hostname, there’s a DNS resolution issue. In this case, try the following:

• Use a Fully Qualified Domain Name (FQDN): Ensure you’re using the full domain name (e.g., server.example.com instead of server).
• Check DNS Servers: Verify that your DNS servers are correctly configured in /etc/resolv.conf or through your network settings.
• Use an Alternate DNS Server: Temporarily switch to a public DNS server like Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1) to check if the issue is with your DNS provider.

Step 3: Check SSH Command Syntax

Ensure that you’re using the correct syntax for the SSH command. The basic format is:

ssh username@hostname

Mistakes in the command syntax might lead to resolution errors.

Step 4: Edit /etc/hosts (Optional)

If DNS resolution is not possible or you need a temporary workaround, you can manually add the hostname and its corresponding IP address to your /etc/hosts file:

123.45.67.89 hostname.example.com hostname

This step bypasses DNS resolution for the specified hostname.

Step 5: Check SSH Configurations

Misconfigurations in your SSH client config file (~/.ssh/config) can also lead to hostname resolution issues.

Check if there are any incorrect entries for Host or HostName that might be causing the problem. A correct entry should look like this:

Host servername
  HostName server.example.com
  User username

Step 6: Verify Network Connectivity

Sometimes, network issues can prevent hostname resolution. Ensure your device is connected to the internet and can reach external networks. Use tools like traceroute to diagnose connectivity problems to the target server.

Step 7: Use IP Address

As a last resort, try connecting to the server using its IP address instead of its hostname. This method bypasses DNS resolution:

ssh username@IP_address

Conclusion

Resolving the “Could not resolve hostname” error in SSH usually involves checking the hostname, verifying DNS resolution, ensuring correct SSH command syntax, and possibly editing network configurations.

By using the steps above, you can identify and resolve the root cause of the issue, ensuring a secure and stable connection to your remote server.