How to solve an expired key (KEYEXPIRED) with apt

Updating expired keys on Debian and Ubuntu   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. root# 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] […]

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How much system hardening should you do?

System Hardening When it comes to Linux system hardening there is a lot to do. From the almost book-like CIS benchmarks to following best practices found all over the web. Recently someone new to the field of information security asked me a simple, yet important questions: how much system hardening should you be doing? When is it enough? Since there was no easy answer, I have written down my thoughts to help others in the future. Time and Effort To understand […]

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Difference between CentOS, Fedora, and RHEL

Difference between CentOS, Fedora, and RHEL The biggest open source company is nowadays Red Hat. It is known for its contributions to many open source projects, including the Linux kernel itself. Less known is that Red Hat is involved in different Linux distributions, directly or indirectly. Fedora Fedora has received many updates and individual releases over the years. It is a playground for new functionality. Often new technology is found here. It can be compared with other distributions like Arch […]

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Linux and rise of Ransomware

Ransomware on the Linux Platform Times are changing when it comes to Linux malware. Since a long time we had backdoors, PHP shells, and even rootkits. But it won’t take long that ransomware will catch up on the Linux platform. We hope you are reading this to counter the threat, not because it is already too late. Ransomware Invasion Ransomware is a little devil. It encrypts your valuable data and protects it with a generated key. This key is then […]

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Migration tips for Lynis to version 2.3.1 and beyond

Lynis migration tips Usually a lot of work is put into new releases. So it is a shame if most users don’t use the latest version, right? Surprisingly, that still happens a lot. In the recent past, users of Lynis had to rely on external package maintainers, custom package building, or manually downloading the latest release. Debian and RPM packages If you are running a system that uses the DEB or RPM format, you might want to use our new […]

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Unused Linux Users: Delete or Keep Them?

What to do with unused Linux users? We get often the question what one should do with unused users on Linux. Everyone who looked in the /etc/passwd file will recognize them, strange usernames. A great example is UUCP, or Unix-to-Unix Copy. Once used for communication on direct lines, now another piece of history in our password files. The Options Before we make any decision on dealing with unused Linux accounts, we should look at the most obvious choices we have. The […]

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