1) - Connect to the server via console.
2) - Open the ssh config file with the command below.
nano /etc/ssh/sshd_config
3) - Change the PermitRootLogin prohibit-password part to PermitRootLogin yes
4) - Delete the # sign in front of the #PasswordAuthentication yes section and save.
5) - Restart the ssh service with the following command.
service sshd restart
6 - Now you can access it with putty.
