December 2025

How to upgrade our Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release (page 4)

botond published 2025/12/12, p - 18:32 time
How to upgrade your Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release (page 4) | Linuxportál
In the final part of our Debian 11 to 12 upgrade process, we focus on resolving the deepest technical challenges and reviving services. We take a detailed look at how to fix a stubborn Grub/OpenSSL issue that was blocking package management using a unique "Dummy Script" trick. Next comes fine-tuning the server environment: setting the system's default PHP versions, then running the ISPConfig upgrade script to restore website and control panel availability, correcting Apache configuration changes. Finally, we verify phpMyAdmin functionality and fix the Roundcube webmail 404 error, completing the system's operation in the new Debian 12 environment.

How to upgrade our Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release (page 3)

botond published 2025/12/12, p - 18:32 time
How to upgrade your Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release (page 3) | Linuxportál
After a successful reboot of the Debian 11 to 12 upgrade, we will perform a system health assessment and mandatory post-installation tasks on this page. We will verify that the new kernel and services are running, and then perform a thorough system cleanup to remove unnecessary dependencies and "orphaned" configuration files. We will demonstrate in detail how to restore previously disabled external package repositories (e.g. Ásbrú, Sublime Text) and how to fix errors (GPG keys, 404 paths) from the command line. Finally, we will use aptitude to find and selectively remove obsolete packages that are no longer in the Debian 12 repositories, thus ensuring complete system cleanliness and stability.

How to upgrade our Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release (page 2)

botond published 2025/12/12, p - 18:31 time
How to upgrade your Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release (page 2) | Linuxportál
In the process of a major system upgrade from Debian 11 to 12, after the preparations, we have reached the most critical stage: performing a full distribution upgrade (dist-upgrade). On this page, we will start the process by switching to the Konsole terminal and go through all the configuration file conflicts in detail. We will pay special attention to the services that are vital for ISPConfig servers (MariaDB, Pure-FTPd, Dovecot, Apache), showing in which cases we should stick to our own settings to maintain functionality, and when we can safely accept new versions (e.g. Jailkit, Roundcube, GRUB). At the end of the steps, we will close the stage with a successful reboot, entering the world of Debian 12.

How to upgrade our Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release

botond published 2025/12/12, p - 18:30 time
How to upgrade your Debian 11 (Bullseye) based system to Debian 12 (Bookworm) major release | Linuxportal
Upgrading from Debian 11 (Bullseye) to Debian 12 (Bookworm) is a crucial step in securing and modernizing your servers. This guide will walk you through the entire process using a complex hybrid system running both a desktop environment and ISPConfig server services, and will also cover specific pitfalls. On this page, we will cover the basic steps: assessing your system, securely managing external package repositories, and properly modifying your APT sources list (sources.list), including adding the new non-free-firmware repository. Finally, we will kick off the process by updating your package lists and performing a safe, minimal system upgrade, creating a solid foundation for the full version change.

CORS (Cross-Origin Resource Sharing)

botond published 2025/12/02, k - 17:57 time
Encyclopedia - CORS (Cross-Origin Resource Sharing) | Linuxportal
This encyclopedia entry introduces the CORS (Cross-Origin Resource Sharing) standard, a key element of modern web security. The description clarifies the most common misunderstanding: the restriction is enforced not by the server, but by the browser to protect the Same-Origin Policy. We discuss the operating mechanism in detail, distinguishing simple requests from complex calls that require preflight. We introduce the HTTP headers required for regulation and discuss the security risks arising from incorrect configuration (for example, using the * wildcard together with authentication). The article provides a practical guide to correctly configure the most popular web servers (Apache, Nginx) and PHP applications. Finally, we provide troubleshooting tips, highlighting why API clients (e.g. Postman) and web browsers behave differently.