Git concepts, and abbreviated notes on the important commands.
There are many, many articles on configuring particular software or operating systems for security. The quality varies widely, and most of them miss out one or more important points. Perhaps a better approach might be to start with the basic concepts, and then apply those to the system, rather than just working with lists of tweaks. Here is an attempt to define some of the basic technical issues of computer security, in plain language.
An introduction to the security facilities of Open Source UNIX-like operating systems, focusing on Linux distributions.
The VNC (Virtual Network Computing) facilities provide remote access to desktops, and allow your Linux systems to act as terminal servers, running many network-accessible desktops simultaneously. Unfortunately the flexibility of VNC makes it less approachable than other remote desktop solutions.
There are many service monitoring products, but Monit is unusual. It tests for specific conditions and carries out actions when they occur, rather than collecting for analysis and graphing. Monit is frequently used to improve the robustness of systems.
A tutorial on how to configure a fresh Linux installation for greater security.