DEBIAN

How to create a virtual machine with virt-install

After installing KVM on your Ubuntu or Debian system, the next step is to create a virtual machine using the virt-install command-line tool. Check existing virtual machines Before creating a new VM, check if there are any existing ones: sudo virsh list --all If no machines exist, the list will be empty. Create a virtual machine with virt-install The virt-install command allows you to specify all the VM’s properties. For example:

Monday, October 13, 2025 | 2 minutes Read

How to install KVM, QEMU and libvirt on Linux

To install KVM on Ubuntu or Debian, you need to prepare the system with the required packages, verify hardware virtualization support, and authorize users to run virtual machines. Below are the steps to install KVM on Ubuntu 24.04 (Noble Numbat) or recent Debian releases. Step 1: Update the system Before installing KVM, update your package repository information: sudo apt update Step 2: Check virtualization support 2.1 Verify CPU compatibility Check if your CPU supports hardware virtualization:

Monday, October 13, 2025 | 2 minutes Read

How to validate the KVM host installation

Before creating and running virtual machines with KVM, it’s essential to validate that the host meets the required hardware and software capabilities to ensure optimal performance. This guide describes how to verify system capabilities using tools such as virt-host-validate and virsh. 1. Validating CPU virtualization support KVM requires processors with hardware virtualization extensions: Intel: VT-x AMD: AMD-V To check if your CPU is compatible, run: grep --color -Ew 'svm|vmx|lm' /proc/cpuinfo vmx → Intel CPU with VT-x svm → AMD CPU with AMD-V lm → 64-bit support If your CPU lacks these extensions, only CPU emulation will be available and performance will be significantly reduced.

Monday, October 13, 2025 | 2 minutes Read

Key components of a virtual machine in KVM

In KVM (Kernel-based Virtual Machine), a virtual machine is composed of several elements that interact to emulate a complete hardware environment. Understanding each component helps you manage, troubleshoot, and optimize your VMs more efficiently. 1. Main components Component Description Virtual CPU (vCPU) Cores assigned from the physical host to the guest. Defined with --vcpus when creating the VM. Memory (RAM) Amount of memory assigned. Configured with --ram or can be hot-adjusted with virsh setmem. Virtual disk Storage file (.qcow2, .raw, etc.) used as the guest disk. Managed with virsh vol-* or virt-manager. Network interface Virtual connection (usually virtio or e1000) attached to a libvirt network (default, br0, etc.). Graphics device / console VNC, SPICE, or text mode (no graphical console). Controllable with --graphics or virsh vncdisplay. Firmware / BIOS / UEFI Defines the boot mode (traditional BIOS or UEFI with OVMF). Additional devices CD-ROM, USB controllers, serial channels, sound interfaces, etc. 2. Essential commands to retrieve VM information Once the VM is created, you can use virsh to inspect and manage all its details.

Monday, October 13, 2025 | 3 minutes Read

Installation and Configuration of MariaDB in Debian 12

MariaDB installation and configuration in Debian 12 To install MariaDB in Debian 12, follow these steps: 1.Update the repositories and install the MariaDB package: First, update your system repositories and install MariaDB: javiercruces@jcruces:~$ sudo apt update javiercruces@jcruces:~$ sudo apt install mariadb-server 2.Enable and start the MariaDB service: Once installed, set MariaDB to automatically start the start and then start the service: javiercruces@jcruces:~$ sudo systemctl start mariadb javiercruces@jcruces:~$ sudo systemctl enable mariadb 3.Configure MariaDB:

Sunday, September 1, 2024 | 2 minutes Read

Interconnection of database servers

This post addresses how to configure and manage connections between different databases, both homogeneous and heterogeneous, to facilitate interoperability between various database systems. Throughout the article, different connection scenarios are explored, starting with configurations between databases of the same type, such as Oracle to Oracle or PostgreSQL to PostgreSQL, and then moving towards heterogeneous connections between different technologies, such as Oracle to MySQL, PostgreSQL to Oracle, and vice versa. It also covers the steps needed to configure links, create users, and modify key configuration files, allowing remote consultations.

Sunday, September 1, 2024 | 9 minutes Read

Oracle installation 19c under Debian 12

Installing Oracle 19c on Debian 12 may seem complicated, but don’t worry, I’m here to guide you in every step. In this post, I will explain to you in a simple way how to prepare your system and make the installation of Oracle 19c in Debian 12. Update the repositories The first thing is to update the repositories of our virtual machine and in case we don’t have any packages we update it:

Sunday, September 1, 2024 | 4 minutes Read

PostgreSQL installation in Debian 12

In this post, I will guide you through the process of installing PostgreSQL in Debian 12, creating a user with basic permissions, and how to create and consult a database. #1. PostgreSQL installation To install PostgreSQL in Debian 12, follow these steps: Update the repositories and install PostgreSQL * *: First, make sure your system is updated and install PostgreSQL: ```bash sudo apt update sudo apt install postgresql ``` Verifies that the service is in operation * *: After installation, make sure that the PostgreSQL service is in operation:

Sunday, September 1, 2024 | 3 minutes Read

Remote access configuration in MariaDB

To allow remote access to your MariaDB server, follow these steps: Configure the MariaDB configuration file First, edit the MariaDB configuration file to allow connections from specific IP addresses. Open the file /etc/mysql/mariadb.conf.d/50-server.cnf with a text editor, for example, nano: sudo nano /etc/mysql/mariadb.conf.d/50-server.cnf Find the line that starts with bind-address and change it to accept connections from any IP address. You can have him accept connections from all the PIs with:

Sunday, September 1, 2024 | 2 minutes Read

Remote Access Configuration in Oracle

To configure remote access in Oracle, it is essential to correctly adjust the network files located in $ORACLE_HOME/network/admin. These files, such as listener.ora and tnsnames.ora, allow us to define how clients will connect to the database and which equipment will have access. Remote Access Configuration The Oracle configuration with respect to the network is saved in the directory that we have defined as the Oracle home: $ORACLE_HOME/network/admin.

Sunday, September 1, 2024 | 2 minutes Read

Comparative between OpenVPN and Wireguard

The goal of this post is to compare the different VPNs software most used by seeing which is faster, for which we will support in speed test using iperf3. [NOTE] The comparative part of the posts in this section in which we mount each type of VPN. Speed without VPN I’m gonna start by comparing the speeds of these 2 systems, using iperf3. For this I have removed the cisco router as I had it configured with FastEthernet interfaces and changed it to a Linux router with GigabitEthernet interfaces.

Thursday, March 28, 2024 | 9 minutes Read

Create certification authority (CA) and self-signed certificates in Linux

At first a student will establish a Certified Authority and sign a certificate for the other student’s page. We will then test it on the Apache and Nginx web servers. Create the certifying authority Step 1: Creating directories and files The first step will be to generate a directory in which you will locate your certification authority, in order to maintain an organization at all times. The directory name will be CA /. In turn, you have to generate several subdirectories within it:

Thursday, March 28, 2024 | 15 minutes Read