Port-Knocking
guest@6admin.io:~$ ls ~/tags/port-knocking
Security Through Obscurity Is Not Security, Digital Hygiene Is
Twenty years of comments on port knocking, port 22 and photos of house keys: why obscurity alone is vain, why Kerckhoffs doesn't extend everywhere and why the real question is called digital hygiene.
Portknocking: automatic combination generation
Automatic portknocking sequence generation from the system date, with mandatory NTP and an encrypted USB key.