Sysadmin

A Practical Introduction to eBPF

Linux Sysadmin

Have you ever wanted to enhance your favorite distribution kernel with debugging, tracing, networking, security or plenty of other features without going through a long approval/testing/integration process managed by the Linux community? The extended Berkeley Package Filter (eBPF) is a Linux kernel feature that aims at running user-space code (eBPF programs) in the kernel, safely and efficiently, via the in-kernel eBPF machine. Let's discover how to build such programs.

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Performance of virtual storage (part 2) : QEMU

Virtualization Linux Sysadmin

In a previous blog post, I evaluated the performance penalty of virtual storage. I compared different host filesystems and different hypervisors (including QEMU). The conclusion was pretty harsh: in all tested configurations, virtual disks are almost 10 times slower than host drives. In this blog post, I will test additional QEMU configuration options, to see if I can get better results...

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Create a Linux kernel module

Linux Sysadmin

In a previous blog post, I presented how to build your own Linux kernel. This time I will show how to create, compile and load a very simple kernel module...

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Compile and install the Linux kernel

Linux Sysadmin

In this blog post I will show how to configure, compile and install a custom Linux kernel.

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Systemd : Basic concepts

Linux Sysadmin

Systemd is now the defacto standard init process on Linux systems. It is responsible for starting all required services... In this blog post we will present the basic concepts of systemd : basic usage, units and dependencies.

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Standalone Security Onion, a perfect SIEM solution for small networks

Sysadmin Network analysis and visualization Linux Monitoring SIEM

Security Onion is a free and open platform built by defenders for defenders. It includes network visibility, host visibility, intrusion detection honeypots, log management, and case management.

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Add modules to your micro-Linux

Linux Sysadmin

In a previous blog post, we have built a micro-Linux system relying on initramfs. In this blog post, we will add modules to this minimal system.

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GitLab : fix "cgroups: cgroup mountpoint does not exist: unknown"

GitLab Sysadmin Docker

If you use GitLab pipelines to build Docker image, you may encounter the error "cgroups: cgroup mountpoint does not exist: unknown". Here is how to fix...

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Benchmark Linux systems with sysbench

Linux Sysadmin

In this blog post, I will show how to use sysbench to test the CPU, memory and storage performance of a Linux system. I also had the chance to access some diverse hardware (laptop, desktop, servers). So I'll also give some results for you to compare with.

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Build a kernel, initramfs and Busybox to create your own micro-Linux

Linux Sysadmin

A regular Linux user will probably never have to compile it's own Linux kernel. But doing so is actually a great way to discover the features and working of the Linux kernel. So in this blog post we will guide you to compile a small kernel, create a minimal root filesystem that fits into memory, and finally create a micro-Linux system based on Busybox...

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Network boot for UEFI devices with iPXE

Sysadmin Linux

In a previous blog post, we have seen how PXE network boot works, and how to implement PXE boot for devices with a (classical) BIOS. For this purpose, we used SYSLINUX/PXELINUX. However, SYSLINUX/PXELINUX is usually not working well with modern UEFI devices. Hence in this blog post, we will show how to use iPXE to implement network boot for UEFI devices.

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Understand and implement PXE network boot

Linux Sysadmin

PXE is a powerful system that allows to boot a system from the network. The applications are numerous : install a system from the network, create diskless or kiosk systems. But the system is pretty complex! In this blog post we will explain how network booting works, and show an example to allow interactive installation of Ubuntu 22.04 server from the network...

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