FreeBSD - Enhancing firewall security with port knocking

Port knocking is known since at least the early 2000's as a way to increase firewall security. The main idea is to open certain ports for certain IP addresses, when a given set of ports is addressed in a given sequence. Traditionally in FreeBSD we can use knockd; however, in this video, I show how to achieve the same effect using only the pf firewall and expiretables, to achieve a more robust solution. #FreeBSD #BSD #Unix #pf #firewall