Secure Shell is a specialized cryptographic protocol. It creates a secure environment for the interaction of a client with a server.
If SSH packages are not included in your server, it is necessary to install them. First, you need to install the SSH package. Start with the installation of both the Open SSH Client apps and the server daemon.
Once downloaded, start the daemon. Make sure the SSHD status is active. Stop the daemon. Set up the OpenSSH Service to start running each time after the server reboot. Make sure the SSH is configured properly. It will serve as an additional security level. To do so, disable root login. Change the number of the port for the SHH to run in a non-standard port. Provide access to particular users only.
Don’t forget to save the modifications.
After that, install and configure a firewall. There are plenty of options available. Just make sure that the firewall configurations are compatible with the installed SSH. If you want to secure your server more, you can restrict an IP address. For it, edit the file iptables. Check whether you are going to use IPv6 and if yes, edit IP6tables to accept it. Save the changes. Don’t forget to restart iptables. It will apply the modifications.