RHCSA(26A): Locking Down Your RHCSA Linode Lab Server

Podcast: The RHCSA Series Podcast
Season: 2 (Episodes 26A - 50)
Episode: 26A
Title: RHCSA(26A): Locking Down Your RHCSA Linode Lab Server
Release date: January 6, 2026
Produced by: Djere Services Group

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Associated article: https://djere.com/rhcsa26a-locking-do...

NOTE: This podcast is 100% independent, and is in no way affiliated with Red Hat.

Mission: This podcast is 100% focused on 1 goal: providing knowledge to help its listeners pass the RHCSA exam.

Executive Summary
To secure and maintain your RHCSA practice environment, this guide outlines a three-pronged approach: 1. network-level security, 2. instant system resets, and 3. automated cleanup. This approach was chosen after local virtualization attempts with Gnome-Boxes, virt-manager, and VirtualBox on a PopOS 24.04 desktop failed, likely due to the experimental Cosmic desktop. By using Linode, a cost-effective alternative, you can still protect your lab from threats, recover from errors quickly, and practice critical skills in a clean, repeatable environment.

The foundational strategy is to lock down network access using the Linode Cloud Firewall. This is done by setting the Default Inbound Policy to Drop, which blocks all incoming connections and effectively makes your Linode invisible to bots and scanners. You then add specific "Accept" rules for SSH (TCP port 22) from your home IP addresses. While you can use single-address rules with /32 for IPv4 and /128 for IPv6, the recommended and more stable approach for dynamic IPv6 is to whitelist the entire IPv6 network prefix (/64), as this block remains consistent. A placeholder example is 2001:db8:a0b:12f0::/64. Should your IP change and you get locked out, Linode's LISH Console serves as a vital safety net, providing direct, out-of-band access.

For major system changes or mistakes, a master snapshot provides a powerful solution. After configuring your lab's perfect starting point, you power down the Linode and take a snapshot. This creates a point-in-time image of the disk, allowing you to instantly revert the server to a clean state rather than rebuilding it from scratch.

Finally, for minor adjustments, a simple Bash script can automate cleanup tasks. This script can be written to undo common practice tasks such as stopping services (httpd, nfs), removing practice users, and resetting firewall rules (firewalld). This saves time and reinforces the valuable skill of automation, which is critical for the exam.

By combining these three techniques, you create a professional-grade, secure lab environment perfect for focused RHCSA study!!!