I use port knocking as an emergency backup measure on my bastion host (OpenBSD w/pf). The regular sshd runs on a non standard port with key authentication only. The backup sshd needs to be knocked and allows password authentication. I only use it in emergencies when I don't have my key handy.
I have used it in the past and has saved me a few times. This is only on the bastion.
"Who said the Unix philosophy was the be-all, end-all?"
I didn't and I don't know anyone that has. I was comparing systemd and SysV.
"Unix is just a collection of random decisions made by various people over the years."
"Linux has never been about quality. There are so many parts of the system that are just these cheap little hacks, and it happens to run." - Theo de Raadt
"The layout of /usr/bin, /usr/sbin, /usr/local/bin"
I don't agree with you. Having base in a directory and having user installed bins in another makes sense. I don't understand why most modern Linux distros install on only one partition by default. You lose the ability to mount with flags ie noexec,nosuid,nodev.
NFS is horrible. Unix/Linux is a multi-user operating system why would you not want to have groups?
I have used it in the past and has saved me a few times. This is only on the bastion.