PF has always been my “only” choice of firewall when I’m on OpenBSD or FreeBSD. My PF kungfu is just enough to use it as a host firewall though. Recently I needed to level up my PF skill in order to use it on one of my hobby project. This book came in the right time.
The release candidate for DragonFly 4.0 came out last week, and normally the release would happen after a week. There’s still a few people reporting an odd freeze, so until we can find a cause, we’ll continue to wait.