Today I read about port-knocking for the first time. It has been a pretty known concept for more than ten years, but I don't know anybody who uses it for their servers.
How common is the usage of port-knocking?
4
closed as primarily opinion-based by TildalWave, David, Adi, Iszi, Rory Alsop♦ Sep 19 '14 at 15:16
Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.
-
I've never seen it used in an enterprise. However, I have seen firewall which lay dormant and can be enabled after telnet authentication (on page 463 of this). – JZeolla Sep 19 '14 at 13:19
1
Port-knocking is often used in 'closed' designs to assure network integrity. In the meantime it evolved into single-packet authentication.
Check here for the source of sources on the topic :)
0
To my knowledge, this is pretty uncommon.
What I remember about it from what I learned in college is it has a pretty big downside : it's easy to deny someone access by sending a packet to a random port using his adress, and thus breaking the "knock" sequence.
However its evolution, single-packet authorization, is much more solid (though I have no idea if it is commonly used in practice).
