Phase 1 · Free

Lab: Phase 1, Get a Machine Running

A clean Ubuntu install you built yourself, verified, snapshotted, and documented.

90 minPhase 1: Get a Machine RunningFree

Cost: $0. Tools: VirtualBox or UTM, Ubuntu 26.04 LTSLong Term Support: a software release that receives security and bug-fix updates for an extended period, typically years, without major changes. Read more → ISOA single file that holds an exact copy of an optical disc's contents, used to distribute operating system installers and boot virtual machines. Read more →. Bare metal optional.

Goal

A clean Ubuntu install you built yourself, verified, snapshotted, and documented.

Steps

  1. Download the Ubuntu ISO and verify its SHA-256A cryptographic hash function that turns any input into a fixed 256-bit fingerprint, used to verify downloads, sign certificates, and secure blockchains. Read more → against SHA256SUMS (lesson 1.3). Paste the hash comparison output into your log.
  2. Create the VMA software-based emulation of a complete computer that runs its own operating system and applications, isolated from the host hardware. Read more →: 4 GB RAMRandom Access Memory: the fast, temporary working memory that holds the programs and data a computer is using right now, cleared when power is lost. Read more →, 2 CPUs, EFI on, 30 GB disk (lesson 1.4).
  3. Install Ubuntu with a user you can sudo with.
  4. Update: sudo apt update && sudo apt upgrade -y.
  5. Prove UEFIUnified Extensible Firmware Interface: the modern firmware standard that tests the hardware at power on and starts the bootloader, replacing legacy BIOS. Read more →: [ -d /sys/firmware/efi ] && echo UEFI || echo BIOS.
  6. Take a snapshot named clean-install.

Worked troubleshooting: the checksum does not match

Symptom. sha256sum -c prints FAILED for your ISO.

Hypothesis. Either the download is damaged or incomplete, or you compared against the wrong line (a different version or architecture).

Test. This is what a mismatch looks like. It was reproduced on the course VM with a small test file standing in for the ISO:

t.iso: FAILED
sha256sum: WARNING: 1 computed checksum did NOT match

The command exits with code 1. Now check the cheap explanations first. Does the file name in SHA256SUMS exactly match yours, including desktop versus live-server and amd64 versus arm64? Is the file size the same as on the download page? A short file means the download stopped early.

Fix. If the names match and it still fails, delete the ISO and download it again, ideally from a different mirror. Never “try it anyway.” A failed check is the reason the check exists.

Why it worked. A hash changes completely if a single byte changes, so there is no “close enough.” Either the file is the published one or it is not.

Proof (put in ~/course-notes/phase-1-install/)

  • screenshot-uname.png: desktop with a terminal showing uname -a.
  • install-log.md with:
    • Machine: host make/model/RAM/CPU, and hostnamectl output from the guest.
    • Path chosen (VirtualBox, UTM, or bare metal) and why.
    • The checksum you verified and the command you used.
    • Every step, in your own words.
    • Three problems you hit and how you solved them, in the format from lesson 1.5. If nothing went wrong, deliberately try one thing (boot with the ISO detached, give the VM 1 GB RAM) and record what happens.

Done when

  • uname -a shows Linux and your hostname.
  • lsb_release -a shows 26.04 LTS (or 24.04 LTS).
  • The snapshot exists.
  • The log has three real problems with fixes.

Hard mode (optional)

Do it on bare metal. Record your firmware setup key, the boot order before and after, and whether Secure Boot was on.