Log Message:
Import net/fwknop version 2.6.9 from wip

fwknop stands for the "FireWall KNock OPerator", and implements an \ 
authorization
scheme called Single Packet Authorization (SPA). This method of authorization is
based around a default-drop packet filter (fwknop supports iptables and
firewalld on Linux, ipfw on FreeBSD and Mac OS X, and PF on OpenBSD) and
libpcap. SPA is essentially next generation port knocking.