Installing Debian and CentOS Virtual Machines in VirtualBox

BeginnerLinux~3 hours
VirtualBoxDebian 12CentOS StreamISO

I installed Debian 12 and CentOS Stream 9 VMs in VirtualBox with sensible partitioning, bridged networking, and guest additions. A clean base image cloned in minutes became the reproducible starting point for every later lab.

Objective & Context

A disposable VM is the safest place to learn. This lab builds both a Debian- and an RHEL-family base so commands can be tested across package managers, the substrate for the server-admin and KVM labs.

Environment & Prerequisites

  • VirtualBox 7.x with VT-x/AMD-V enabled.
  • Debian 12 and CentOS Stream 9 ISOs.
  • At least 4 GB RAM and 20 GB disk to spare.

Step-by-Step Execution

1. Create the VM disk from CLI

VBoxManage createvm --name debian12 --register && VBoxManage createmedium disk --filename debian12.vdi --size 20480

2. Verify the install booted

cat /etc/os-release | head -2

3. Snapshot the clean base

VBoxManage snapshot debian12 take clean-base
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
Snapshot taken: clean-base

Validation & Testing

Boot each VM, confirm networking reaches the internet, and clone from the snapshot to verify reproducibility. Pass criteria: both distros install cleanly, have working bridged networking, and a snapshot restores a pristine base.

Advanced: Troubleshooting
  • No 64-bit option: enable VT-x/AMD-V in the host BIOS.
  • No network: switch the adapter to bridged or confirm NAT DNS.
  • Slow VM: install Guest Additions and allocate more vCPU/RAM.

Key Results

  • Built reproducible Debian and CentOS base images.
  • Captured clean snapshots that clone in minutes.
  • Verified bridged networking on both distros.
  • Established a safe, disposable lab environment.

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