Fix "ssh_init: host not found" Error in SSH

Table of Contents: Introduction Use IP Address Instead of Hostname Verify DNS Resolution Manually Add Hostname to Hosts File Flush DNS Cache Restart Network Services Check Firewall & SSH Port Check SSH Configuration Summary of Fixes

The "ssh_init: host not found" error occurs when SSH cannot resolve the hostname, usually due to:

• Incorrect hostname (misspelled or nonexistent domain)
• DNS resolution failure (host cannot be found)
• Firewall/network issues (blocked SSH connections)
• Misconfigured SSH settings

1. Use IP Address Instead of Hostname

To bypass DNS resolution issues entirely, try connecting with your server's IP address instead of its hostname.

nslookup yourserver.com

dig yourserver.com +short

host yourserver.com

192.168.1.10

Use the IP Address in SSH Instead

Instead of connecting with the hostname:

ssh user@yourserver.com

Try connecting with the IP address:

ssh user@192.168.1.10

Diagnostic Result:

• If the IP connection works, the issue is definitely with DNS resolution.
• If SSH still fails even with the IP, the problem may be network-related, firewall-related, or the SSH service might not be running on the server. Proceed to the next steps.

2. Verify DNS Resolution

If the hostname is not resolving, check your system's DNS settings directly.

nslookup yourserver.com

systemd-resolve yourserver.com

host yourserver.com

Expected Results:

• If an IP address is returned (e.g., 192.168.1.10), DNS is working correctly from your system's perspective.
• If you see "host not found", "NXDOMAIN", or no IP address appears, DNS is failing and you should move to the next step.

3. Manually Add Hostname to /etc/hosts

If DNS is not resolving the hostname, you can manually map it to its IP address on your local system. This is a reliable workaround that bypasses external DNS entirely.

sudo nano /etc/hosts

192.168.1.10 yourserver.com

Now SSH should recognize the hostname by checking this local file first.

4. Flush DNS Cache

Clear old or corrupted DNS records from your system's cache to force it to retrieve fresh information.

ipconfig /flushdns

sudo killall -HUP mDNSResponder

sudo systemd-resolve --flush-caches

After running the appropriate command for your OS, retry your SSH connection.

5. Restart Network Services

Restarting your network interface can refresh all connection settings, including DNS.

sudo systemctl restart networking

nmcli networking off && nmcli networking on

ipconfig /release
ipconfig /renew

Now try connecting again with SSH.

6. Check Firewall & SSH Port

If DNS is working but SSH still fails, the connection might be blocked by a firewall.

Test If the SSH Port Is Open

Run one of these diagnostic commands:

nc -zv yourserver.com 22

or

telnet yourserver.com 22

Interpretation:

• If it connects successfully, the SSH service is reachable on port 22.
• If you see "Connection refused" or it times out, the SSH port is blocked, the service is not running, or the host is unreachable.

Allow SSH in Firewall (Server-Side Configuration)

sudo ufw allow 22/tcp
sudo ufw reload

sudo firewall-cmd --add-service=ssh --permanent
sudo firewall-cmd --reload

Now try SSH again from your client machine.

7. Check SSH Client Configuration

Your SSH client may have incorrect settings in its configuration file that are causing the hostname resolution to fail.

1. Open your user-specific SSH configuration file:

   nano ~/.ssh/config

2. Verify the host entry for your server is defined correctly. A standard entry looks like:

   Host myserver
       HostName yourserver.com
       User username
       Port 22
       IdentityFile ~/.ssh/id_rsa

3. Save the file (Ctrl+O, then Enter, then Ctrl+X).
4. Now test the connection using your configured alias:

   ssh myserver

Ensure the HostName directive contains the correct, resolvable address.

8. Summary of Fixes

By systematically following these troubleshooting steps, SSH should work without the "ssh_init: host not found" error!