I am somewhat in tears now seeing this. I spent weeks at work trying to backwards analyze GCP IAP, which apparently uses this in the background (invoked via the gcloud CLI).

Almost like a lost art, it was impossible to find serious tutorials other than Michael W. Lucas’s book of a couple of years ago or the O’Reilly book from 2006.

Very much appreciated. Thank you for documentation on these very important systems that many of us sysadmins who came into the field later in life missed (other than when we connect to our cloud servers). Soon, even the cloud part I mentioned will be gone mostly to because of ‘kubectl’, as Kelsey Hightower has said.