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Saving a server at 2 AM: A detailed guide to DNF Package Manager on RHEL/Rocky Linux

By admin March 19, 2026

At 2 AM, the server reported an error, and DNF was my savior. This article shares practical experience using DNF on RHEL/Rocky Linux, from basic commands to advanced tips, helping you confidently troubleshoot issues.

Linux

Optimize Linux server performance for production: A detailed guide for beginners

By admin March 17, 2026

This article provides a detailed guide on how to optimize Linux server performance for a production environment. From resource monitoring to fine-tuning CPU, RAM, Disk I/O, and Network, it's aimed at beginners.

Network

Free Online Network Tools for SysAdmins: Subnet Calculator, DNS Lookup, IP Converter

By admin March 15, 2026

Free online network tools I keep bookmarked for emergency troubleshooting: Subnet Calculator for CIDR/overlap, DNS Lookup for propagation checks, IP Converter for cross-platform configs — all run directly in the browser, no installation needed.

Linux

How to Configure sudo and the sudoers File on Linux: Safe Permission Management for Each User

By admin March 15, 2026

A comparison of 3 approaches to granting sudo access on Linux: adding users to the wheel/sudo group, editing /etc/sudoers directly, or using /etc/sudoers.d/. Covers the pros and cons of each approach along with practical configuration guides using visudo, Command Aliases, and NOPASSWD for team-based production environments.

Network

Basic Network Knowledge for SysAdmins: IP, Subnet, Gateway – Indispensable Foundations

By admin March 12, 2026

This article delves into three foundational concepts of computer networking: IP Address, Subnet Mask, and Gateway. You'll understand how they work, why they're crucial for SysAdmins, and how to configure them on Linux, along with practical experiences from a SysAdmin managing office and datacenter networks.

Centos

Migrating from CentOS 8 to AlmaLinux 9: Comparing 3 Methods with Step-by-Step Instructions

By admin March 7, 2026

A step-by-step guide to migrating your server from CentOS 8 to AlmaLinux 9 using a safe 2-step process: convert to AlmaLinux 8 with the official script, then upgrade to AlmaLinux 9 with ELevate. Compares all 3 migration methods, analyzes trade-offs, and provides a complete post-migration checklist.

Linux

Securing Your SSH Server: Essential Steps to Prevent Getting Hacked

By admin March 4, 2026

A hands-on guide to SSH server security: comparing 4 common approaches, analyzing their trade-offs, and concrete configuration steps from SSH keys to Fail2ban. Prioritize in the right order to protect your server as effectively as possible.

Linux

Installing and Configuring NTP Server on Linux: Fixing Time Sync Issues in Production

By admin March 2, 2026

A guide to installing chrony and configuring internal NTP server/client on Linux, drawn from real production operations experience. Covers cluster configuration, firewall setup, offset verification, and a basic monitoring script.

Fedora

Configuring SELinux on Fedora: From Enforcing Mode to Custom Policies for Your Application

By admin March 1, 2026

SELinux on Fedora is often disabled the moment it causes the first error — but doing so removes the most important security layer. This guide walks you through debugging denial logs, fixing file contexts, leveraging built-in booleans, and creating custom policies with audit2allow so your app runs correctly and your server stays secure.

Network

Setting Up a DNS Server with Bind9 on Ubuntu/Debian

By admin February 28, 2026

A step-by-step guide to setting up an internal DNS server with Bind9 on Ubuntu/Debian: installation, forward and reverse zone files, forwarder and ACL configuration, testing, and troubleshooting. Written from real-world experience managing an office network.