On the plus side this ( https://www.debian.org/doc/manuals/securing-debian-manual/index.en.html ) Securing Debian Manual isn't slop.
On the downside it is from 2012 and I have no idea how much has changed since then.
(Trying to set up an internet accessible file server for the first time)
Securing Debian Manual
This document describes security in the Debian project and in the Debian operating system. Starting with the process of securing and hardening the default Debian GNU/Linux distribution installation, it also covers some of the common tasks to set up a secure network environment using Debian GNU/Linux, gives additional information on the security tools available and talks about how security is enforced in Debian by the security and audit team.







