2018-06-27 (last updated at June 28th, 2018) Michael BoelenKernel, Linux 14 comments

Livepatch: Linux kernel updates without rebooting

If you run a Linux server, software patching is a task that will have to be performed on a regular basis. Although most programs can be auto-restarted with a tool like needrestart, there is one exception: the kernel. Wouldn’t it be a nice if we could update the kernel without the mandatory reboot? Here is livepatch, the feature of the Linux kernel that makes it possible. Let’s discover how it works and if you can use it on your system. […]

2016-10-24 (last updated at June 25th, 2018) Michael BoelenKernel 2 comments

Linux and ASLR: kernel/randomize_va_space

Configuring ASLR with randomize_va_space The Linux kernel has a defense mechanism named address space layout randomization (ASLR). This setting is tunable with the randomize_va_space setting. Before making changes to this setting, it is good to understand what this Linux security measure actually does and how it works. Understanding ASLR In 2001 the term ASLR was first introduced as a patch to the Linux kernel. Its main goal was to randomize memory segments to make abuse by malicious programs harder. A […]

2016-07-07 (last updated at July 6th, 2018) Michael BoelenKernel Leave a comment

Linux hardening with sysctl settings

The GNU/Linux kernel powers a lot of systems, from big mainframes to the Android device in your pocket. If you want to achieve more security on your Linux systems, it would make sense to start hardening there, right? While securing the kernel looks easy at first sight, there is more to it than initially meets the eye. We will have a look at some kernel options and how to select the best sysctl values for Linux systems. After reading this article […]

2015-07-03 Michael BoelenAuditing, Kernel, Software, System Administration 2 comments

Monitor file access by Linux processes

Process Auditing: Disk and File Activity Processes are the running workforce on a Linux system. Each process has a particular goal, like forking child processes, handling incoming user requests of monitoring other processes. As a system administrator or IT auditor, you might want to know at some point what disk activity occurs in a process. In this article, we have a look at a few options to quickly reveal what is occuring in a process, including disk and file activity. Monitor syscalls […]

2014-04-27 (last updated at June 26th, 2018) Michael BoelenHardening, Kernel, Linux

Linux kernel security and how to improve it

Every system is as strong as its weakest link. In the case of an operating system like Linux, one weakness in the kernel could result in a security breach. This article covers the Linux kernel features and how they work. Kernel features Live kernel patching As the kernel is similar to other software, it receives updates to improve it. Now and then a security weakness is discovered in one of the subsystems of the Linux kernel. This means that Linux […]