https://staging.unixworld.org/Notes on Linux, Unix, and open-source systems.HugoenSun, 11 Jan 2026 00:00:00 +0000https://staging.unixworld.org/high-availability-with-keepalived-on-rhel-rocky-linux-and-almalinux/Sun, 11 Jan 2026 00:00:00 +0000tsvetanhttps://staging.unixworld.org/high-availability-with-keepalived-on-rhel-rocky-linux-and-almalinux/Keepalived provides simple and robust facilities for load-balancing and high-availability. The load-balancing framework relies on the well-known and widely used Linux Virtual Server (IPVS) kernel module providing Layer4 load-balancing. Keepalived implements a set of checkers to dynamically and adaptively maintain and manage a load-balanced server pool according to their health. Keepalived also implements the VRRPv2 and VRRPv3 protocols to achieve high-availability with director failover [1]. Prerequisites Skills: Basic Linux administration. Operating System: RHEL, Rocky Linux, or AlmaLinux. Servers: 2x Nodes on the same subnet. Network: 1x Virtual IP (VIP) for the cluster. Keepalived installation Keepalived is available in the standard system repository, so the installation is straightforward. Execute the following command on both servers:https://staging.unixworld.org/automatically-start-podman-containers-with-systemd-on-rhel-10/Sat, 28 Jun 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/automatically-start-podman-containers-with-systemd-on-rhel-10/ Quadlet is a systemd generator that allows you to manage Podman containers, pods, and networks using systemd unit files. This is especially useful for running containers under systemd as user services in a rootless environment. This tutorial walks you through setting up and using Quadlet with rootless Podman containers on RHEL 10, Fedora 40+, and Rocky/AlmaLinux. Prerequisites RHEL/AlmaLinux/RockyLinux 10+ Podman (Container Management) Install Podman On RHEL 10, install Podman:https://staging.unixworld.org/how-to-import-gns3-vm-on-proxmox/Sun, 08 Jun 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/how-to-import-gns3-vm-on-proxmox/This tutorial will guide you step-by-step on how to set up the GNS3 VM on your Proxmox hypervisor. GNS3 (Graphical Network Simulator 3) is a network simulation tool that allows you to emulate complex network topologies. We will use the latest version of the GNS3 VM at the time of writing (2.2.54) as an example. Prerequisites Proxmox server. SSH access to your Proxmox server or direct shell access. Basic knowledge of Linux commands. Step 1: Download the latest GNS3 VM Open the terminal or web shell on your Proxmox server. You can also use ssh to connect to your server.https://staging.unixworld.org/mounting-qcow2-disk-images-and-resetting-the-root-password-without-booting-the-vm-in-ubuntu/debian/Sun, 01 Jun 2025 00:00:00 +0000martinhttps://staging.unixworld.org/mounting-qcow2-disk-images-and-resetting-the-root-password-without-booting-the-vm-in-ubuntu/debian/This guide explains how to mount a QCOW2 disk image on your host server and reset the root password without starting the virtual machine. Step 1 – Install the nbd package sudo apt install nbd-client qemu-utils Step 2 – Load the NBD kernel module sudo modprobe nbd Step 3 – Connect the QCOW2 image as a network block device sudo qemu-nbd --connect=/dev/nbd0 /PATH_TO_IMAGE/image.qcow2 Step 4 – Identify partitions in the QCOW2 imagehttps://staging.unixworld.org/from-qnap-to-truenas/Sun, 25 May 2025 00:00:00 +0000martinhttps://staging.unixworld.org/from-qnap-to-truenas/This is a short overview of how my QNAP server evolved into the system it is today. It received more memory, a new OS, an additional PCIe module, and more. Getting Started A few years ago, I decided to move out of the cloud and bring my data home. As an admin with limited experience at the time, I chose to play it safe and bought a QNAP TS-453B NAS. Here’s a quick hardware rundown:https://staging.unixworld.org/turning-laptop-into-proxmox-homelab-server/Sun, 18 May 2025 00:00:00 +0000martinhttps://staging.unixworld.org/turning-laptop-into-proxmox-homelab-server/ In 2025, almost everyone has a spare laptop collecting dust in a box. In this article, I’ll give a quick overview of how I saved mine by turning it into a test Proxmox node. 1. Hardware I’m listing only the components relevant to the Proxmox cluster. There’s extra disk that could be swapped with an SSD for a software RAID 1 setup—but since this is just a test Proxmox node, that’s not necessary (at least for now…).https://staging.unixworld.org/allowing-remote-access-to-the-opnsense-gui/Wed, 14 May 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/allowing-remote-access-to-the-opnsense-gui/OPNsense is a powerful and user-friendly open-source router solution based on FreeBSD. This article will show you the steps to configure a firewall rule in OPNsense to allow remote access to the OPNsense GUI remotely via WAN. Login to Your OPNsense Router Start by accessing your OPNsense router: Use the console or IPMI interface to log in to your OPNsense device. Enter your login credentials (username and password) to gain access. Disable the Firewall Temporarily If you don’t have local network access to the OPNsense router, you will need to temporarily disable the firewall to access the OPNsense GUI remotely through the WAN interface.https://staging.unixworld.org/moving-vm-from-xen-to-proxmox/Sun, 11 May 2025 00:00:00 +0000martinhttps://staging.unixworld.org/moving-vm-from-xen-to-proxmox/Migration Workflow: XenServer to Proxmox 1. Prepare on XenServer (source node) Turn off the VM and activate its LVM logical volume: xe vm-disk-list vm=source.host.name # get the logical volume ID lvdisplay | grep LV_DISK_ID # Activate the logical volume lvchange -a y /dev/VG_XenStorage-LV_DISK_ID/VHD-ID Tip: Replace LV_DISK_ID and VHD-ID with actual values from lvdisplay. 2. Export over the network (Xen to Proxmox) Start listener on destination (Proxmox): nc -l -p 5000 | pv | dd bs=4096 of=/dev/mapper/vg-vm--111--disk--0 Then send the raw disk from source (XenServer):https://staging.unixworld.org/build-your-proxmox-templates-with-packer/Wed, 07 May 2025 00:00:00 +0000martinhttps://staging.unixworld.org/build-your-proxmox-templates-with-packer/In the world of virtualization and infrastructure as code (IaC), automating the creation of virtual machine templates is a critical time-saver. This article introduces my open-source project that uses HashiCorp Packer to create standardized VM templates in Proxmox Virtual Environment (PVE). The Problem with Manual Templates Creating VM templates manually in Proxmox is time-consuming and error-prone. Each time you need a new template, you must: Download the ISO Create a new VM Install the operating system Configure basic settings Convert to template This process becomes tedious when managing multiple distributions or versions, and it’s difficult to ensure consistency.https://staging.unixworld.org/rebooting-a-linux-with-i/o-errors/Wed, 07 May 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/rebooting-a-linux-with-i/o-errors/When a Linux system encounters I/O errors and becomes unresponsive, rebooting it gracefully might not be possible. In such scenarios, you can use the SysRq mechanism to reboot the system forcibly. This tutorial explains how to reboot a Linux system with I/O errors using SysRq commands. Steps to Reboot the System 1. Enable SysRq Commands The SysRq mechanism must be enabled to allow low-level system commands. To enable it, run the following command as root or using sudo:https://staging.unixworld.org/rebuilding-initramfs/Sun, 04 May 2025 00:00:00 +0000martinhttps://staging.unixworld.org/rebuilding-initramfs/Admins migrating VMs between different hypervisors often forget to rebuild the initramfs, which leads to missing drivers required by the target environment—causing the VM to fail to boot. Here’s a quick summary of how to fix that: We’ll use SystemRescue (sysrescue) instead of a CentOS installation CD for rebuilding initramfs—and in many cases, it’s even better because: It’s lightweight and fast to boot Includes all common tools: chroot, dracut, lvm2, mdadm, etc. Actively maintained and not tied to a specific distro **Steps Using SystemRescue to Rebuild **initramfs Boot the VM with the SystemRescue ISO Identify and mount your root filesystem lvm vgchange -ay # Activate LVM volumes, if needed lsblk # Identify root and boot partitions mount /dev/mapper/centos-root /mnt mount /dev/sda1 /mnt/boot # if /boot is separate Chroot into your system mount --bind /dev /mnt/dev mount --bind /proc /mnt/proc mount --bind /sys /mnt/sys chroot /mnt Rebuild initramfs with needed drivers dracut -f -v # Or specify kernel version: dracut -f -v /boot/initramfs-$(uname -r).img $(uname -r) Exit and reboot exit reboothttps://staging.unixworld.org/how-to-configure-bridge-on-bond-with-networkmanager/Sat, 29 Mar 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/how-to-configure-bridge-on-bond-with-networkmanager/Setting up a Linux bridge on a bonded interface improves network reliability and performance. Bonding combines multiple network interfaces into one for better speed and failover protection, while a Linux bridge acts like a virtual switch, connecting devices or virtual machines. In this guide, you’ll learn how to create a Linux bridge over a bonded interface, ensuring a stable and efficient network setup. Let’s get started! Network Diagram eth0 ---| | --+-- bond0 --+-- br0 eth1 ---| Create bridge nmcli connection add type bridge \ ifname br0 \ ipv4.method manual \ ipv4.addresses 192.168.0.40/24 \ ipv4.gateway 192.168.0.1 \ ipv4.dns "192.168.0.1" \ ipv6.method ignore \ ipv6.never-default true \ bridge.stp no \ con-name br0 I use a static IP address for my bridge. You will need to adjust the settings to match your needs.https://staging.unixworld.org/how-to-install-gns3-on-fedora/Sat, 29 Mar 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/how-to-install-gns3-on-fedora/What is GNS3 ? Graphical Network Simulator-3 (shortened to GNS3) is a network software emulator first released in 2008. It allows the combination of virtual and real devices, used to simulate complex networks. It uses Dynamips emulation software to simulate Cisco IOS (WikiPedia). How to install GNS3 I will show you how to install GNS3, dynamips, vpcs and ubridge on Fedora. Enable RPMFusion repositories Note: Non-free RPMFusion repository is required for dynamips. If you don’t need it, you can skip this step.https://staging.unixworld.org/how-to-install-node-exporter-on-truenas-scale/Sat, 29 Mar 2025 00:00:00 +0000tsvetanhttps://staging.unixworld.org/how-to-install-node-exporter-on-truenas-scale/On TrueNAS Scale, Graphite is the only current supported option to export metrics, but in this tutorial we will setup node_exporter and prometheus to get metrics and setup alerts for our NAS. This will also allow us to use standard Node Exporter and ZFS dashboards in Grafana. Download Node Exporter Before proceeding, it’s recommended to store the Node Exporter and any configuration files on your storage pool. In this example, the storage pool is named tank, which is mounted under /mnt/tank. This ensures the files are stored persistently and are safe from potential system upgrades or reconfigurations.