Install Ubuntu LTS and open a terminal

02Identify and verify the image

Download means saving a file from a remote service onto your computer. For this route, choose the official Ubuntu 24.04 LTS Desktop amd64 ISO and record its full filename and point release. A point release is an update within the same release line. Check the release directory and filename together; do not substitute a Server, WSL or ARM image.

A checksum is a value calculated from file contents. SHA-256 produces a digest written as 64 hexadecimal digits: 0–9 and a–f. Compare the complete digest of your download with the entry for that exact filename in SHA256SUMS. A match shows that the file agrees with that checksum.

A digital signature is a separate check on who published the checksum file. SHA256SUMS.gpg contains its signature. Canonical's verification guide explains the signing key and its fingerprint, an identifier used to check the key. Complete that official workflow as well as the file comparison. A hash match alone does not establish publisher identity or guarantee harmless software. If you cannot complete verification, defer installation and use the text route.

The worksheet contains one hash command for each host OS. This is optional preparation for the live route. On Windows, open PowerShell to enter commands; on Linux or macOS, open Terminal. Replace ISO-FILENAME.iso with the full path to your saved ISO, keeping straight quotes around the path so spaces stay together. A path identifies the file's location. On Windows, File Explorer's Copy as path can help; on Linux/macOS, use your file manager's properties or location view. If it supplies surrounding double quotes, use the path text inside the worksheet's single quotes rather than nesting quotes.

Get-FileHash reads a file; -Algorithm SHA256 chooses the hash method and -LiteralPath supplies its exact path. The Linux sha256sum command calculates SHA-256; macOS shasum uses -a 256 to select it. Run only the command matching your host. Read the resulting digest without copying any surrounding labels into your comparison. If locating the file or using a command window is unfamiliar, continue with the no-install route and revisit verification after the shell lessons.

Verify an Ubuntu installation image
Use the lesson's text route if these host commands are unfamiliar.
No image, checksum or observed command result is supplied here.

For the x86-64 route, use Ubuntu 24.04 LTS Desktop amd64 media:
https://releases.ubuntu.com/24.04/
Check the complete filename and release before downloading.
Use SHA256SUMS and SHA256SUMS.gpg for that same release.
Do not use a checksum belonging to another filename or point release.

A checksum describes file bytes. SHA-256 produces 64 hexadecimal digits.
A digital signature helps establish who published the checksum file.
Follow Canonical's signature and key-fingerprint instructions:
https://ubuntu.com/tutorials/how-to-verify-ubuntu
If you cannot complete them, defer installation and use the text case.

Hash commands (read the lesson's explanation first):
Replace ISO-FILENAME.iso with the exact full path to your downloaded ISO.
Keep the straight quotes around the path, including any spaces.
Choose ONLY the line for your host's command window.

Windows PowerShell:
Get-FileHash -Algorithm SHA256 -LiteralPath 'ISO-FILENAME.iso'
Linux terminal:
sha256sum 'ISO-FILENAME.iso'
macOS Terminal:
shasum -a 256 'ISO-FILENAME.iso'

Compare all 64 digits with the SHA256SUMS line for that exact image.
Hexadecimal letter case does not change the value.
Mismatch: stop; check filename, release and download completeness.
Match: the file agrees with that checksum. This alone does not establish
publisher identity or guarantee software free of harmful behavior.
Record what you checked; do not mark an unchecked image verified.

03Choose the guest resources and boundary

The planning values here are 4 GiB RAM, two virtual CPUs and a new 30 GiB virtual disk. Use them only if the host has adequate spare resources. A dynamically allocated disk grows as data is written, up to its chosen maximum. That maximum is not all allocated RAM, and growth still needs real host storage for the disk, downloads, updates and snapshots.

Create a normal virtual disk, the mode included in snapshots. In VirtualBox's Storage settings, check that only the new guest disk and the ISO are attached; do not attach a physical disk or a personal virtual disk. In Settings > General > Advanced, leave shared clipboard and drag and drop disabled. Keep Shared Folders empty and attach no USB device in the USB settings. These features can expose host data or devices to the guest.

In Settings > Network > Adapter 1, choose NAT and leave the Port Forwarding rules empty. As the earlier boundary lesson explained, NAT allows guest connections through the host. Use it for ordinary installation downloads only. It does not authorize scans or tests of other systems. After setup, you may disconnect the virtual network when no download is needed.

Install Ubuntu inside a new virtual machine
Fill actual values only after observing them. Otherwise write pending.

Host OS / architecture / hypervisor full version:
Ubuntu 24.04 LTS Desktop amd64 ISO (for the x86-64 route):
Exact point release / filename / official release URL:
Same-release checksum file / signature / verification result:
New VM name: yanosec-ubuntu
Guest RAM / virtual CPUs / virtual disk maximum:
New normal virtual disk filename and location:
NAT selected, no forwarding; all host sharing and USB attachment off:
Only installer target: this new empty guest disk
Installed guest version shown in Settings > About:
Terminal opened inside Ubuntu:
Guest shut down normally; manager shows Powered Off:
Result: observed installation / no-install reasoning only

Conceptual sequence, not recorded screens:
New VM -> attach ISO -> boot guest installer -> language and keyboard ->
interactive/default installation -> choose new guest disk ->
private guest account -> install -> restart without ISO -> sign in ->
Settings About -> Terminal -> guest shutdown.
Do not make a host USB installer or change a physical host disk.

Separate question case:
Windows shows the outer VM viewer window.
Ubuntu shows a Terminal window inside that viewer.
No remote login or host integration is in use.
Where do commands in the Ubuntu terminal run?
Answer format: host or guest.

04Try the new guest installation

Continue only after the host and image checks succeed. Use a new guest with no important files and keep its window boundary visible.

1. Open VirtualBox Manager on the host and choose New. Name the VM yanosec-ubuntu, attach the verified Desktop ISO and select the matching Ubuntu 64-bit guest type. Choose Skip Unattended Installation when offered. This keeps installation interactive so you can review each disk decision.
2. Assign resources that fit your host budget. Create a new dynamically allocated virtual disk; VDI is VirtualBox's native disk-image format. New disks use normal mode by default; leave that mode unchanged. Record the file location and maximum size. Review Storage, Network and sharing settings before starting. If you cannot establish which disk is new, stop here.
3. Start this VM. In the Ubuntu installer choose your language, accessibility needs and keyboard layout. Choose interactive installation and the default application selection. Extra third-party drivers are not needed for this walkthrough. Follow labels for the 24.04 installer; another release can show different screens.
4. At the disk selection screen, confirm the target is the one new empty virtual disk with the capacity you recorded. Erase disk writes a new installation to that selected disk. It is appropriate here only because this VM exposes the new disposable disk. If the target is unclear, do not confirm erasure. This lesson does not create a USB installer, boot host installation media or change a physical disk.
5. Create a local Ubuntu guest account with a private password. Review the target once more, then install and restart. When requested, remove the ISO from the VM's virtual optical drive; this is the drive presenting the image as installation media. Start from the installed virtual disk and sign in. Record the result you actually see.
6. Inside Ubuntu, open Settings and find System > About or About. Record the guest OS version. Use Ubuntu's application search to find Terminal and open it within the guest desktop. Expected: a text window waiting for input. No command or particular prompt text is required.
7. Close Terminal and shut down Ubuntu normally through its system power menu. Confirm Powered Off in the VM manager. Saved means a suspended running state and is different. Keep the guest for the snapshot lesson. If abandoning setup, leave it powered off until you can review the manager's removal options for this VM alone.

05Complete the no-install route

Read the checklist's conceptual sequence. Draw boxes for the existing host, the guest installer and the new guest disk. Place the hypervisor installer, Ubuntu ISO and installation target in the appropriate boxes. Mark which disk receives the installation and where the terminal later opens.

Now predict the result of two choices: attaching only a new empty guest disk, or attaching an existing personal disk whose contents matter. The first matches the practice boundary; the second is a reason to stop before installation. Neither a guessed disk label nor a VM window makes erasure safe.

Review your diagram: the manager runs on the host; the ISO supplies the guest installer; only the new virtual disk receives Ubuntu; Terminal belongs to the Ubuntu guest. Write image verification, installation and terminal opening deferred. You have practiced the choices without claiming to observe a completed installation.

06Optional challenge

Write a setup note that another learner could interpret: host OS and architecture, hypervisor version, image filename and checksum source, guest resources, disk target, network mode and result. Label unobserved values pending. Explain why a version number copied from a tutorial would not describe your own machine.

07Fresh cases for the checks

Use these fictional cases for the checks below. They have different inputs from the worked examples. Read them here or make notes; no installation or external service is needed.

Reading exercise only. Do not download an image or write a disk.
The case requires Ubuntu 24.04.3 Desktop amd64 media for an already checked x86-64 route.
I1: release directory 24.04.3; ubuntu-24.04.3-desktop-amd64.iso; Desktop; amd64.
I2: release directory 24.04.3; ubuntu-24.04.3-live-server-amd64.iso; Server; amd64.
I3: release directory 24.04.3; ubuntu-24.04.3-desktop-arm64.iso; Desktop; ARM64.
I4: release directory 24.04.2; ubuntu-24.04.2-desktop-amd64.iso; Desktop; amd64.
Treat these labels as supplied case metadata, not a claim about today’s available images.
Selecting an identity does not complete checksum or publisher verification.

Host hypervisor installation and guest image verification have passed in this fictional case.
The new disposable VM is field-lab. Its recorded new disk is field-empty.vdi, maximum 36 GiB.
Storage review:
D1: field-empty.vdi; new empty normal virtual disk; 36 GiB; attached to field-lab.
D2: personal-notes.vdi; existing virtual disk containing personal notes; 36 GiB; not attached.
D3: host physical disk; contains the existing host OS and files; not attached to the VM.
M1: verified Ubuntu ISO; attached as virtual optical installation media.
Only D1 and M1 are attached. The guest installer offers D1 as its disk target.
Predict the correct target in this text exercise; do not confirm an actual erasure.

The filename, release directory, Desktop edition and amd64 architecture match this case’s intended image.
The checksum file’s publisher signature and key fingerprint have already been checked in this fictional report.
Entry for the exact intended filename:
0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef
Digest calculated from the saved file:
0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdee
A note claims: verified; the first 63 digits agree.
These are invented 64-digit comparison values, not checksums of a real image.

Windows is the host OS. The VM viewer remains open on an Ubuntu desktop.
The learner clicks the Windows taskbar and opens Windows PowerShell outside the viewer.
Keyboard focus is in that PowerShell window.
No remote login, guest integration, container or WSL session is active.
Do not type a command; reason from the supplied window ownership.

The intended image’s complete filename, release, edition and architecture match.
Its full calculated SHA-256 digest matches the entry for that exact filename.
The checksum file’s signature and publisher key fingerprint have not been checked.
No other evidence about the checksum publisher is supplied.

08Explain source, destination and command context

Optional self-check: write a setup note that separates the host hypervisor installer, guest ISO and new virtual disk. Explain the evidence needed before choosing an image and before writing an installation target, then explain the terminal decision on card D.

Review your note: the host installer sets up the manager; the ISO supplies the guest installer; the recorded new empty virtual disk receives Ubuntu. Match exact image metadata, compare the full digest for that filename, and verify the checksum publisher separately. A VM name, capacity or open viewer alone proves neither a safe target nor a running installed guest. Record live installation and terminal opening as deferred in this reading exercise.