Causes and solutions of Putty's failure to connect to the server

Putty is our common SSH server remote connection tool, but sometimes there is a problem that we cannot connect to the server. Generally, software problems are relatively minor, and most problems are server problems. Here, if Putty fails to connect to the server, we can solve the following problems.

1. Network connection problem

Ensure that our server is currently available, and check whether the server is powered on. Check whether your network connection is normal, for example, by trying to visit other websites or using the ping command to test the accessibility of the target host.

2. Firewall blocks connection

Firewall settings may prevent Putty from establishing a connection with the target host. You can check your local firewall settings to ensure Putty is allowed to pass. We can check whether the server has a security group and pass the SSH port. Some ports are 22 by default, while others have been modified by the service provider by default.

3. Host configuration problem

The target host may not have the SSH service configured correctly or started. Ensure that the target host has correctly installed and configured the SSH service, and that the service is running.

4. Connection port error

Ensure that you are using the correct SSH port number on the target host. By default, SSH uses port 22 for connection. If the target host has changed the SSH port, you need to modify Putty's connection settings accordingly.

5. User name and password error

Confirm that the user name and password you entered are correct. If we don't know the password of the server, we can replace it with a new one at the service provider.

6. SSH key verification problem

If the target host requires SSH key for verification, and you do not configure or provide the correct key correctly, the connection will fail. Ensure that you have configured the SSH key correctly, and provide the correct key information according to the relevant instructions.

The above six problems are the reasons why we may not be able to PUTTY connect to the server and the solutions.