Troubleshooting 'ssh: connect to host [ip] port 22: No route to host' on Ubuntu

Encounter the "ssh: connect to host [ip] port 22: No route to host" error on Ubuntu? Learn about possible causes and troubleshooting steps in this guide. Resolve connection issues and get your SSH working smoothly again.
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If you've encountered the error message "ssh: connect to host [ip] port 22: No route to host" on your Ubuntu system, it indicates that your machine is unable to establish a connection to the specified IP address on port 22. This error can be frustrating, but it often has straightforward causes and solutions. In this guide, we'll explore some common reasons for this issue and steps you can take to troubleshoot and resolve it.

Check Network Connectivity
The first step is to ensure that your Ubuntu machine has a working network connection. Verify that you can reach other websites and services. If your network connection is unstable or disconnected, address that issue first.

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Verify SSH Service Status
Ensure that the SSH service is running on both the local and remote machines. Use the following commands to check the status:

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If the service is not running, start it with:

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Firewall Configuration
Firewall settings could be blocking the SSH connection. Check the firewall status and make sure that port 22 is open. If you're using UFW (Uncomplicated Firewall), you can check its status with:

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Open port 22 if it's not already open:

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IP Address and Hostname
Ensure that you are using the correct IP address and hostname for the remote machine. Double-check your SSH command to confirm that the target address is accurate.

Routing Issues
The "No route to host" error suggests a routing problem. Check the routing table on your Ubuntu machine using:

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Ensure that there is a route to the destination IP address.

Physical Connection
If you're connecting to a remote machine, confirm that the physical connection to the network is secure. If possible, try connecting to the network locally to rule out any issues with intermediate devices.

Security Groups (AWS EC2)
For those using cloud services like AWS EC2, verify that your security group rules allow incoming SSH traffic on port 22.

Conclusion
The "ssh: connect to host [ip] port 22: No route to host" error on Ubuntu can result from various issues, including network connectivity problems, firewall configurations, or incorrect SSH settings. By systematically checking and addressing each potential cause, you can troubleshoot and resolve the error, ensuring a successful SSH connection.

Remember to adapt these troubleshooting steps based on your specific environment and circumstances. With diligence and attention to detail, you can overcome this error and regain seamless SSH access to your Ubuntu system.