System hardening means locking down a system and reducing its attack surface: removing unnecessary software packages, securing default values to the tightest possible settings and configuring the system to only run what you explicitly require.
Let’s take an example from daily life. A jewellery store and a grocery shop are located next to each other, but of course, you would expect that the jewellery store has much beefier bars and stronger locks that are shut when the shop is closed for the night as the contents are more valuable. In this case, the jewellery shop building has been hardened to protect precious products and deter thieves.
We can take a very similar approach to computer systems too. When software such as an operating system is published, anyone can download it and use it for playing games, running an online bank, and everything in between. But for running the bank, we need to take some additional precautions to harden the system above and beyond the default…
