🔐SSH Troubleshooting 101: Your Path to Secure Remote Connectivity 🔐

SSH (Secure Shell) is a widely used protocol for secure remote access to servers and systems. However, sometimes we may encounter issues while trying to establish an SSH connection. Here's a comprehensive guide to help you troubleshoot common SSH problems. 🔍

1. 🕰️ Connection Timeout

• This is usually a security group issue.

• Ensure your security group is correctly configured and assigned to your EC2 instance.

• Your security group should allow inbound traffic on port 22 (SSH) from the appropriate IP range (e.g., your IP or 0.0.0.0/0 for anywhere).

2. ⏳ Connection Timeout Persists

• If your security group is properly configured and you still face connection timeout issues, it could be due to a corporate or personal firewall blocking the connection.

• In such cases, consider using EC2 Instance Connect as an alternative.

3. 🪟 SSH Not Working on Windows

• If you encounter the error "ssh command not found" on Windows, it means you need to use a dedicated SSH client like PuTTY.

• Follow the instructions provided in the video or use EC2 Instance Connect.

4. ❌ Connection Refused

• This error indicates that the instance is reachable, but no SSH service is running on it.

• Try restarting the instance.

• If the issue persists, terminate the instance and create a new one, ensuring you're using Amazon Linux 2.

5. 🔑 Permission Denied (publickey, gssapi-keyex, gssapi-with-mic)

• This error can occur due to two reasons:

  • You're using the wrong security key or not using a security key at all. Verify the correct key is assigned to your EC2 instance.

  • You're using the wrong user. Ensure you've started an Amazon Linux 2 EC2 instance and are using the 'ec2-user' when connecting (e.g., ec2-user@<public-ip>).

6. 😖 Nothing is Working

• Don't panic! Use EC2 Instance Connect as an alternative method for connecting.

• Ensure you've started an Amazon Linux 2 instance a

7. 🔄 Connection Issues After Instance Restart

• If you were able to connect yesterday but can't today, it's likely because your EC2 instance's public IP has changed after restarting.

• Update the new public IP in your SSH command or PuTTY configuration.

8. 🔍 Check SSH Service Status

• Ensure the SSH service is running on the remote server by checking its status (e.g., sudo systemctl status sshd on Linux).

• If the service is not running, start it using sudo systemctl start sshd.

9. 🔑 Key Permissions

• Verify that your private key file has the correct permissions (600 or 400).

• Use chmod 600 your_private_key_file to set the appropriate permissions.

10. 🔁 Try a Different Port

• If the default SSH port (22) is blocked, try using a different port.

• Edit the SSH configuration file (/etc/ssh/sshd_config) on the server to change the port, and update your client accordingly.

11. 🕵️‍♀️ Enable Verbose Logging

• Turn on verbose logging on the SSH client (ssh -vvv user@host) to get more detailed information about the connection attempt.

• This can help identify the root cause of the issue.

12. 🚫 Disable Strict Host Key Checking (Temporary)

• If you encounter a "REMOTE HOST IDENTIFICATION HAS CHANGED" error, try disabling strict host key checking temporarily (ssh -o StrictHostKeyChecking=no user@host).

• This can help you connect and update the known hosts file.

13. 📡 Check Network Connectivity

• Ensure the remote server is reachable by pinging its IP address or hostname.

• If the ping fails, there might be a network or firewall issue.

14. 🔄 Restart SSH Service/Network

• Sometimes, restarting the SSH service (sudo systemctl restart sshd) or the network interface can resolve connectivity issues.

15. 📚 Consult Documentation and Logs

• Refer to the SSH client and server documentation for specific troubleshooting guidance.

• Check system logs (e.g., /var/log/secure or /var/log/auth.log) for any relevant error messages.

Remember, SSH troubleshooting can be a complex process, but with the right approach and tools, you can overcome even the toughest challenges. Stay patient, methodical, and keep learning! 📚🚀

Thank you for joining me on this journey through the world of cloud computing! Your interest and support mean a lot to me, and I'm excited to continue exploring this lfascinating field together. Let's stay connected and keep learning and growing as we navigate the ever-evolving landscape of technology.

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Feel free to reach out to me directly at spujari.devops@gmail.com. I'm always open to hearing your thoughts and suggestions, as they help me improve and better cater to your needs. Let's keep moving forward and upward!

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Thank you for reading and happy deploying! 🚀

Best Regards,

Sprasad