When attempting to connect to a remote machine via SSH (Secure Shell), you may encounter an error that reads:
##[error]Error: Failed to connect to remote machine. Verify the SSH service connection details. handshake timeout
This error message can be perplexing, especially for those new to SSH and remote server management. In this article, we will break down the issue, explain potential causes, and provide solutions to help you resolve the error efficiently.
Understanding the Problem
The error "Failed to connect to remote machine. Verify the SSH service connection details. handshake timeout" indicates that the SSH client was unable to establish a connection with the remote server. This timeout signifies that the server did not respond in the expected timeframe, preventing a successful handshake.
Common Causes of Handshake Timeout
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Network Issues: The most common reason for a handshake timeout is network connectivity issues. The remote machine may not be reachable due to network outages or misconfigurations.
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Firewall Restrictions: Firewalls can block the SSH port (default is port 22), preventing the SSH client from connecting to the server.
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Incorrect SSH Details: Misconfigurations in the SSH connection settings, such as using the wrong IP address, username, or authentication key, can lead to timeouts.
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SSH Daemon Not Running: The SSH service (sshd) might not be running on the remote machine. If the service is stopped, you won't be able to establish a connection.
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High Server Load: If the server is under heavy load, it may be slow to respond or may drop the connection attempt altogether.
Solutions to Fix Handshake Timeout
1. Verify Network Connection
Ensure that the remote machine is reachable from your network. You can use the ping command to check for connectivity:
ping [remote-IP-address]
If the ping fails, check your network connection and ensure that the remote server is online.
2. Check Firewall Settings
Make sure that your firewall allows traffic on the SSH port (22). You can adjust the settings accordingly:
- For Linux, check
iptablesorufwsettings. - For Windows, check the Windows Defender Firewall or any third-party firewalls you might be using.
3. Confirm SSH Details
Double-check your SSH connection details:
- IP Address: Ensure you are using the correct IP address.
- Port: Make sure the port is set correctly (default is 22, but it may differ based on server configurations).
- Username and Authentication Key: Confirm that you are using the correct username and authentication methods.
4. Check SSH Service Status
On the remote machine, verify if the SSH daemon is active. For systems running Linux, you can use:
sudo systemctl status sshd
If it is not running, start the service:
sudo systemctl start sshd
5. Investigate Server Performance
If the server is under heavy load, consider checking the load average and system performance. You can log in to the server console (if possible) and use commands like top or htop to monitor server resources.
Conclusion
The "handshake timeout" error in SSH is typically a result of network issues, firewall restrictions, incorrect details, the SSH service being down, or server overload. By methodically following the troubleshooting steps outlined in this article, you can identify and resolve the underlying issue.
Additional Resources
By referring to these resources, you can gain a deeper understanding of SSH, its functionalities, and how to prevent common connection issues.
Feel free to reach out with any further questions or troubleshooting concerns!
