Apt cheat sheet

The package manager apt gots much more options than one could think. In this cheat sheet they get uncovered.


Managing packages

Ubuntu system hardening guide for desktops and servers

Step by step guide to secure any Ubuntu desktop or server. Harden your Ubuntu during installation and afterwards with the available security tips.


The system hardening process of a system is critical during and after installation. It helps the system to perform its duties properly. This blog post shows you several tips for Ubuntu system hardening. It will dive into the most critical steps to take first. Then more specific hardening steps can be added on top of these. As most security guides only tell you what to do, we will also go into more detail on why a specific security measure is important.

How to solve an expired key (KEYEXPIRED) with apt

Software updates and package management is easy, until you get a KEYEXPIRED message. In this article we should how it happens and the way to solve it.


Software updates and package management is easy with systems based on Debian or Ubuntu. Just apt-get update (or apt update) and run an upgrade. But sometimes you may encounter the following situation: a KEYEXPIRED message. KEYEXPIRED message # apt-get update && apt-get upgrade Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB] Hit:2 http://nl.archive.ubuntu.com/ubuntu xenial InRelease Get:3 http://nl.archive.ubuntu.com/ubuntu xenial-updates InRelease [95.7 kB] Hit:4 http://nl.archive.ubuntu.com/ubuntu xenial-backports InRelease Hit:5 https://packages.cisofy.com/community/lynis/deb stable InRelease Get:6 http://nl.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages [373 kB] Ign:7 http://nginx.