DigitalOcean Droplet SSH Failed

Troubleshooting DigitalOcean Droplet SSH Connection Failures

Encountering SSH connection issues with your DigitalOcean Droplet can be frustrating. This article provides a practical guide to diagnose and resolve common causes. Remember to back up critical data before making significant changes.

Common Causes and Solutions

Several factors can prevent you from successfully SSHing into your Droplet. Here's a breakdown of the most frequent culprits and how to address them:

• Incorrect SSH Key: This is a very common issue. Double-check that the public key you added to your Droplet matches the private key you're using on your local machine. Consider regenerating your SSH key pair (ssh-keygen) and adding the new public key to your Droplet via the DigitalOcean control panel.
• Firewall Restrictions: Your Droplet's firewall (ufw or iptables) might be blocking SSH traffic on port 22 (or a custom port if you've changed it). Use the DigitalOcean console (recovery console) to log in and configure your firewall. For ufw, allow SSH with sudo ufw allow ssh or sudo ufw allow 22/tcp.
• SSH Service Not Running: The SSH daemon (sshd) may have stopped running on your Droplet. Using the DigitalOcean console, restart the service with sudo systemctl start sshd. Check the service status using sudo systemctl status sshd to identify any errors.
• Incorrect SSH Configuration: The /etc/ssh/sshd_config file might contain errors that prevent SSH from working correctly. Review the file for any misconfigurations, especially related to port number, authentication methods, and allowed users. A common mistake is disabling password authentication without having a valid SSH key configured.
• Network Connectivity Issues: While less common, ensure your local machine has a stable internet connection. Try pinging your Droplet's IP address (ping your_droplet_ip) to verify basic connectivity. If you cannot ping the Droplet, there may be a network issue on your end or with DigitalOcean's infrastructure. Check DigitalOcean's status page for any reported outages.

Advanced Troubleshooting Techniques

If the basic solutions don't resolve the issue, consider these advanced troubleshooting steps:

1. Check the SSH Logs: Examine the SSH logs (usually located in /var/log/auth.log or /var/log/secure) for detailed error messages. These logs can provide valuable clues about the cause of the connection failure. Use the DigitalOcean console to access and analyze these logs.
2. Use Verbose SSH Mode: Connect using the -v option in your SSH command (e.g., ssh -v root@your_droplet_ip). This will display verbose output, showing the steps SSH takes during the connection process and highlighting any errors. Up to three -v options can be used for increased verbosity.
3. DigitalOcean Recovery Console: As mentioned previously, the DigitalOcean recovery console provides direct access to your Droplet, bypassing the need for SSH. This is invaluable for troubleshooting network and SSH-related issues.
4. Contact DigitalOcean Support: If you've exhausted all troubleshooting steps, contact DigitalOcean support for assistance. Provide them with detailed information about the problem, including the steps you've already taken.

By systematically investigating these potential causes and utilizing the tools provided by DigitalOcean, you can effectively diagnose and resolve SSH connection problems with your Droplets.