linux - ITNotes

Systemd & Systemctl: Essential Guide to Managing Services on Modern Linux

March 12, 2026

Mastering Systemd and Systemctl is crucial for any Linux engineer facing critical service outages. This tutorial demystifies service management on modern Linux, providing practical commands and a step-by-step guide to creating your own custom services. Equip yourself with the knowledge to troubleshoot effectively and maintain system stability.

Linux

Linux Distro Comparison: Ubuntu vs CentOS vs Debian vs Arch

March 10, 2026

Navigating Linux distributions can be tough, especially when critical deployments are on the line. This guide compares Ubuntu, CentOS, Debian, and Arch, providing clear insights into their strengths and weaknesses. Learn which distro best suits your production servers, development environments, or personal use, complete with practical setup examples and commands.

Security

How I Detect and Prevent Brute-Force Attacks (A 6-Month Review)

March 10, 2026

A midnight brute-force attack forced me to get serious about server security. For the last six months, a layered strategy using Fail2ban and SSH keys has kept my systems secure and silent. This guide details my practical, battle-tested setup so you can do the same.

Linux

Linux Package Managers Compared: apt vs yum vs dnf vs pacman

March 8, 2026

apt, yum, dnf, and pacman all install software — but the commands, config files, and behaviors differ significantly across Linux distros. This guide covers installing, configuring, and monitoring packages on Debian, RHEL, Fedora, and Arch systems with practical side-by-side examples.

Linux

Apache Virtual Host Configuration: Host Multiple Websites on One Server

March 8, 2026

Learn how to configure Apache virtual hosts on Ubuntu 22.04 to host multiple websites on a single server. Covers installation, virtual host setup, HTTPS with Certbot, .htaccess rewrite rules, and practical production tips.

Networking

How to Set Up OpenVPN Server on Ubuntu: A Practical Guide

March 8, 2026

Setting up OpenVPN on Ubuntu means building a PKI, configuring server certificates, and generating per-client .ovpn files. This guide covers each step with real commands and the practical details that documentation usually leaves out.

Networking

How DNS Works: A Complete Guide for Developers and DevOps Engineers

March 7, 2026

DNS is the backbone of every internet connection — invisible until it breaks. This guide walks through how DNS resolution actually works, the key record types every developer should know, and the practical commands that make debugging fast and reliable.

Networking

How to Set Up a DHCP Server on Linux: A Field-Tested Guide

March 7, 2026

A field-tested guide to setting up a DHCP server on Linux using dnsmasq for quick deployments and ISC DHCP for production environments. Covers static leases, multi-subnet config, PXE boot, failover, and monitoring tips learned from six months of real-world use.

Networking

TCP vs UDP: Key Differences and When to Use Each in Your Network Stack

March 7, 2026

TCP guarantees delivery and ordering through a handshake and retransmission; UDP skips all that for raw speed. Knowing when to pick each protocol — and how to verify what your stack is actually doing — is foundational networking knowledge every engineer needs.

Networking

SSH Tunneling: Secure Access to Remote Services Over Any Network

March 7, 2026

SSH tunneling lets you securely forward ports between machines using an existing SSH connection — no VPN, no firewall changes, no extra software. This guide covers local, remote, and dynamic tunnels with practical examples, persistent setup using autossh, and a systemd service for production use.