Conclusion You've seen three ways of hardening SSH access to your machine: modification of sshd configuration parameters, selecting which users can log in by me

Conclusion You've seen three ways of hardening SSH access to your machine: modification of sshd configuration parameters, selecting which users can log in by means of PAM, and use of port-knocking sequences to hide the existence of SSH access. Although I mentioned that there is no way to secure fully any machine, adding these three layers will make your server more than just a little safer.