Category Archives: Security

Set the iLO password from Linux using hponcfg

No matter if you are looking for a way to manage the iLO settings from the Linux command line or just have lost or forgotten the iLO password, as long as you have access to the Linux system running on … Continue reading

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Manage SELinux boolean policies

Configuring a new service often means dealing with SELinux. The easiest way is most of the time to set an SELinux boolean. But what are SELiunx booleans and what exactly do they do? I will try to shed a little … Continue reading

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Auditing Linux system security using lynis

Lynis is a security auditing tool for UNIX and Linux based systems. It performs a security scan on the system and provides suggestions for best practices for system hardening. The report from lynis shows a lot of suggestions to harden … Continue reading

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Apache document root in users home directory with SELinux

Serving web-content from a user’s home directory allows the user to conveniently upload files. By default, the apache configuration in many Linux distributions assumes content is uploaded to a single directory owned by the webserver’s user, but it might be … Continue reading

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Create GnuPG key with sub-keys to sign, encrypt, authenticate

In order to use a GnuPG key on a smartcard or Yubikey, a GnuPG key needs to be created. This post will show you how to create a GnuPG key with sub-keys for signing, encryption and authentication. The authentication key can … Continue reading

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apt – install the package that contains a specific file

Sometimes a command that you execute complains about a dependency being missing on the system. From the file name in the error message it is often not possible to know exactly which package needs to be installed to resolve the … Continue reading

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Increase the size of a LUKS encrypted partition

Even encrypted discs or partitions sometimes need to have their size increased. A LUKS encrypted volume consists of different layers which all need to be resized. To resize an encrypted volume, multiple steps have to be performed to use the additional … Continue reading

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Certificate Transparency and unauthorized certificates

I own a domain which was bought a few months back which is managed by CloudFlare’s service in DNS-only mode. As I intended to only use CloudFlare’s DNS service, I disabled every option except the DNS related features. You can imagin the surprise to see certificates issued for my domain without my knowledge. Continue reading

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Verifying SSH configuration with a scan

Managing a number of Linux servers and keeping them secure can be a challenge. Certain tools can make the life of an admin a lot easier. To ensure an ssh daemon complies with a desired security configuration the admin can use a scanner … Continue reading

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Debug SSH Connection issue in key exchange

Securing a server means hardening the SSH server settings, but doing so can also cause issues with ssh clients. Finding the cipher or algorithm causing a failled connection can be tricky. Depending on the client used, the error message might be very … Continue reading

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