> […] rendered unusable for attackers by using port knocking. Port knocking renders SSH unusable: I'm not going to tell my users "do this magic network incanta

> […] rendered unusable for attackers by using port knocking. Port knocking renders SSH unusable: I'm not going to tell my users "do this magic network incantation before running ssh". They want to open a terminal and simply run ssh. See the A in the CIA triad, as well as U in the Parkerian hexad.