Use SHA key authentication
For additional security, it is highly recommended to use SHA key authentication, i.e. setting up SSH (Secure Shell) on your server. SSH is a popular software package which enables secure system administration and file transfers over insecure networks, meaning that it uses encryption to secure the connection between a client and a server. All user authentication, commands, output and file transfers are therefore protected from attacks in the network.
All details about implementation and configuration can be found on the SSH official website.