Passionate about Linux hardening, compliance, security management and new technologies.

Linux System Integrity Explained: Ensure Data, Logging and Kernel Integrity

Linux System Integrity Explained From Data and Logging, up to Kernel Integrity Systems exist for one primary goal, which is processing data. Information security helps protecting this valuable data, by ensuring its availability, integrity, and confidentiality. In other words, data should be available when we need it. Then it should be properly transmitted and stored, without errors. Our last goal ensures that it is only available to those with a need to know. Many open source software components are available […]

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Installing ClamAV on CentOS 7 and Using Freshclam

Install and Configure ClamAV on CentOS 7 Including the usage of Freshclam   To get ClamAV on CentOS installed, we have to use the EPEL repository (Extra Packages for Enterprise Linux). Fortunately, the Fedora project provides this with an easy installation. Unfortunately the default configuration is not properly working. In this post we collect some of the issues and required changes. Let’s start with installing the EPEL support. yum install epel-release Next step is installing all ClamAV components. yum install […]

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How to Promote your Open Source Project

Getting more users with project promotion Nowadays it is easy to start an open source project. People over the world start new projects daily, as can be seen on the popular site GitHub. Unfortunately, many of these projects simply don’t get traction and end up as inactive ideas on the web. Traction is everything Traction in software projects is similar to speeding up a car. If you give too much gas, you might end at undesired places, too little and it takes too long […]

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Determine Processes Which Need a Restart with checkrestart/needrestart

Determine which processes need a restart after software patching Proper software patch management helps reducing weaknesses on your systems. But even if you patched an outdated system, old processes and libraries can continue to run in memory. For example when a library is updated, an active program might still use the old version. To really finish the process of software patching, we have to do more. This includes preparation, performing the update and finally check if we need a restart […]

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Budgeting for Techies: How to Get Money for a New Security Tool

Budgeting for techies How to Get Money for a New Security Tool We all know the common answer when asking for a new software tool: “sorry, no budget”. But why is that? Often because we, as technical oriented people, simply don’t know how budgeting works. Not surprising, as no one taught us. The downside is that it limits us seriously, to obtain the right tools for the job. Time to combine tech, money, and skills, to get finally that new […]

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Kernel hardening: Disable and blacklist Linux modules

Disable and black Linux kernel modules The Linux kernel is modular, which makes it more flexible than monolithic kernels. New functionality can be easily added to a run kernel, by loading the related module. While that is great, it can also be misused. You can think of loading malicious modules (e.g. rootkits), or unauthorized access to the server and copy data via a USB port. In our previous article about kernel modules, we looked at how to prevent loading any […]

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Increase kernel integrity with disabled Linux kernel modules loading

Increasing Linux kernel integrity Disable loading kernel module on Linux systems The Linux kernel can be configured to disallow loading new kernel modules. This feature is especially useful for high secure systems, or if you care about securing your system to the fullest. In this article, we will have a look at the configuration of this option. At the same time allowing legitimate kernel modules to be loaded. Disable kernel modules Newer kernel modules have a sysctl variable named kernel.modules_disabled. Sysctl […]

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Logging root actions by capturing execve system calls

Logging root actions Capturing execve system calls and store them in the audit log For compliance or security reasons you might want to capture all commands executed by the root user. Fortunately enough the Linux audit framework helps with capturing the right system calls and log it to the audit file. Configure audit To enable auditing, use the following commands: auditctl -a exit,always -F arch=b64 -F euid=0 -S execve -k root-commands auditctl -a exit,always -F arch=b32 -F euid=0 -S execve […]

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