How to create a Jailed SSH User with Jailkit on Debian 9 (Stretch)

This document describes how to install and configure Jailkit in Debian 9 (Stretch) Server. Jailkit is a set of utilities to limit user accounts to specific files using chroot() and or specific commands. Setting up a chroot shell, a shell limited to some specific command, or a daemon inside a chroot jail is a lot easier and can be automated using these utilities.