How to fix error: connect_to hostname port port: failed. in SSH

First, double-check the hostname and port you're using. The default SSH port is 22, but some servers use non-standard ports:

# Test with explicit hostname and port
ssh -p 22 [email protected]
ssh -p 2222 [email protected]  # If using non-standard port

Verify you have the correct hostname. Try using the IP address directly to rule out DNS issues:

ssh -p 22 [email protected]

Verify that the hostname resolves to an IP address:

nslookup example.com
dig example.com
# On Windows:
nslookup example.com

If the hostname doesn't resolve, it won't work. Check:
- The hostname spelling is correct
- You have an active internet connection
- Your DNS resolver is working
- The domain actually exists

If DNS resolution fails, either use the IP address directly or fix your DNS settings.

Test if the remote host is reachable at all:

ping -c 4 example.com
# On Windows:
ping example.com

If ping fails, the host is unreachable due to network issues. Check:
- The host is actually online
- Network cables/WiFi connection is active
- No firewall is blocking ICMP traffic
- The IP address/hostname is correct

If the host is offline or unreachable, that's the root cause of the SSH connection failure.

Test if the specific SSH port is open and accepting connections:

# Using telnet (if available)
telnet example.com 22
# Or using nc (netcat)
nc -vz example.com 22
# Or using timeout + bash
timeout 2 bash -c 'echo > /dev/tcp/example.com/22' && echo "Port open" || echo "Port closed"

If this succeeds, you should see a response like:

Connected to example.com.
Escape character is '^]'.
SSH-2.0-OpenSSH_7.4

If it fails, the SSH port is not accessible. This confirms the network/firewall issue.

Run SSH with verbose flags to see exactly where the connection fails:

ssh -vvv [email protected]

The -vvv flag provides maximum verbosity. Look for lines like:
- Trying 192.168.1.100... - Shows if it found an IP
- Connection refused - Server is reachable but SSH port closed
- No route to host - Network unreachable
- Connection timed out - Server not responding

The verbose output will tell you exactly where the connection process fails, helping identify if it's DNS, routing, firewall, or the SSH service.

If the host is reachable by ping, verify the firewall allows SSH on port 22:

On the remote host (Linux):

# Check if SSH port is listening
sudo netstat -tlnp | grep ssh
# Or using ss:
sudo ss -tlnp | grep ssh

Should show something like:

tcp  0  0 0.0.0.0:22  0.0.0.0:*  LISTEN

Check firewall rules:

# UFW (Ubuntu/Debian)
sudo ufw status
sudo ufw allow 22/tcp

# iptables (general Linux)
sudo iptables -L -n | grep 22

# firewalld (CentOS/RHEL)
sudo firewall-cmd --list-all
sudo firewall-cmd --permanent --add-service=ssh
sudo firewall-cmd --reload

Verify your local firewall isn't blocking outbound SSH connections:

On Linux:

sudo iptables -L -n
sudo firewall-cmd --list-all  # For firewalld

On macOS:
Open System Preferences > Security & Privacy > Firewall and check if it's blocking SSH.

On Windows:
Open Windows Defender Firewall > Advanced settings and check for outbound rules blocking port 22.

Most modern firewalls allow outbound connections by default, but corporate networks may restrict them. If behind a corporate firewall, check with your IT department.

If you have access to the remote host console or through another method, restart the SSH daemon:

# On Linux/Unix
sudo systemctl restart ssh
# Or:
sudo systemctl restart sshd

# Check if it's running:
sudo systemctl status ssh

The SSH service might have crashed or stopped. Restarting it may resolve the issue. If you can't access the console, you may need to:
- Request the system administrator restart SSH
- Reboot the server if necessary
- Check cloud provider console (AWS, DigitalOcean, etc.) for the host status