Ubuntu Server — Canonical, LTS versions and the link with Debian

Objective

Learn to recognize an Ubuntu Server version, understand how long it stays maintained, and place Ubuntu in relation to Debian. This is the basis for deciding which version to install on a server… and when to replace it.

Key points

Ubuntu is published by the company Canonical. The distribution is free; Canonical sells support and services (Ubuntu Pro).
The version number is a date: 24.04 = released in April 2024.
An LTS version (Long Term Support) comes out every two years, in April of even years: 20.04, 22.04, 24.04, 26.04.
An LTS receives 5 years of standard security updates, then up to 10 years with ESM (Expanded Security Maintenance), included in Ubuntu Pro.
Ubuntu is built from Debian: same .deb packages, same dpkg and apt tools.

1. Canonical and the birth of Ubuntu

In 2004, South African entrepreneur Mark Shuttleworth founded Canonical. His idea: take Debian, known to be solid but slow to release new versions, and turn it into a system that is easy to install, released on a fixed schedule.

The first version, Ubuntu 4.10 ("Warty Warthog"), came out in October 2004. The word ubuntu comes from the Bantu languages of southern Africa and expresses the idea of solidarity between people.

Today, Ubuntu is one of the most widespread systems on web servers and in the cloud. When you rent a virtual machine from a hosting provider, Ubuntu is very often the default image.

2. Reading a version number

The format is always YY.MM: the year in two digits, then the month of release.

Version	Code name	Release	Type
20.04	Focal Fossa	April 2020	LTS
22.04	Jammy Jellyfish	April 2022	LTS
23.10	Mantic Minotaur	October 2023	interim
24.04	Noble Numbat	April 2024	LTS
26.04	Resolute Raccoon	April 2026	LTS

Each code name combines an adjective and an animal starting with the same letter. In configuration files, only the adjective is used, in lowercase: focal, jammy, noble. You will find it everywhere, for example in the package repositories.

After the release, Canonical publishes point releases: 24.04.1, 24.04.2… This is not a new version of Ubuntu, only an updated installation image, which saves you from downloading hundreds of fixes right after installation.

cat /etc/os-release       # name, version, code name (present everywhere)
lsb_release -a            # same information, if the lsb-release package is installed
hostnamectl               # system, kernel and architecture (machine with systemd)
uname -r                  # kernel version only

3. LTS or interim version?

Ubuntu releases a version every six months, in April and October.

Interim versions (23.10, 24.10, 25.04…) are maintained for only 9 months. They are for trying new features.
LTS versions come out every two years, in April of even years, and are maintained for at least 5 years.

On a production server, you install an LTS. Think of the invoicing server of an SME in Casablanca: nobody wants to reinstall it every nine months.

4. How long is an LTS maintained?

Version	End of standard support	End of ESM (Ubuntu Pro)	Original kernel
20.04	May 2025 (ended)	2030	5.4
22.04	2027	2032	5.15
24.04	2029	2034	6.8

Standard support (5 years, free): security and bug fixes for the packages in the main repository, the one Canonical maintains itself.
ESM, with Ubuntu Pro (up to 10 years): security fixes continue after the end of standard support. Ubuntu Pro also covers the community universe repository and adds other services, such as Livepatch (patching the kernel without rebooting).
Ubuntu Pro is free for personal use on a small number of machines; companies pay a subscription. Beyond 10 years, Canonical still offers a paid option called Legacy.

pro status                # status of Ubuntu Pro and its services (ESM, Livepatch…)
sudo pro attach <jeton>   # attach the machine to an Ubuntu Pro subscription (<jeton> = your token)

Concrete example. A school in Rabat still has a server on 20.04. Since June 2025, this server no longer receives free fixes. Two options: enable Ubuntu Pro to buy time, or plan the migration to 24.04.

5. Moving from one LTS to the next

The upgrade tool is do-release-upgrade. To be safe, it only offers to move from one LTS to the next starting from the first point release (for example 24.04.1), once the first bugs have been fixed.

sudo apt update && sudo apt full-upgrade   # first: update the current version
sudo do-release-upgrade                    # then: move to the next LTS

On a server, always make a backup (or a snapshot of the virtual machine) first.

6. Ubuntu and Debian: one family

Ubuntu did not start from scratch. At each new cycle, Canonical imports packages from Debian (from its unstable development branch, nicknamed sid), then adapts them, tests them and adds its own tools.

This is why the file /etc/debian_version exists on Ubuntu: it shows the Debian branch it started from, for example trixie/sid on a 24.04.

What is identical to Debian:

.deb packages, dpkg, apt;
the file layout: /etc/apt/, /etc/default/, /var/log/…;
service names: ssh, apache2, cron…

What Ubuntu adds or does differently:

Area	Ubuntu Server
root account	locked; you administer with `sudo`
Installer	Subiquity (since 20.04), LVM offered by default
Network	netplan (YAML files in `/etc/netplan/`)
Firewall	ufw installed, but inactive at first
Security	AppArmor active
Cloud	cloud-init prepares the machine at first boot
Additional software	snap, in addition to `apt`
Schedule	a version every 6 months, an LTS every 2 years

Each of these tools has its own lesson in this course.

By version

	20.04	22.04	24.04
Status in October 2026	ESM only (Ubuntu Pro)	standard support	standard support
Repository list	`/etc/apt/sources.list`	`/etc/apt/sources.list`	`/etc/apt/sources.list.d/ubuntu.sources`
Python 3 provided	3.8	3.10	3.12
Server installer	Subiquity	Subiquity	Subiquity

Common pitfalls

Installing an interim version in production. A 24.10 is no longer maintained after 9 months: your server is left without fixes.
Confusing the kernel version with the Ubuntu version. uname -r gives the kernel (6.8.0-…), not the distribution version. For Ubuntu, read /etc/os-release.
Forgetting the end-of-support date. Write it down in your server inventory: a 20.04 server without Ubuntu Pro no longer receives free fixes.
Believing that Ubuntu is Debian. The base is shared, but the network tools, the firewall and the installer differ. A Debian procedure does not always work as is.

Lab

Your lab machine runs Ubuntu 24.04. Before you start, explore it:

cat /etc/os-release       # look for VERSION_ID, VERSION_CODENAME and ID_LIKE
cat /etc/debian_version   # the Debian branch it started from
uname -r                  # the kernel (the host machine's kernel, in a container)

Then complete the tasks: save the identity card, note the code name, find the Debian base and work out the end of standard support. Click Check my work after each step.

Quiz

What does the version number 22.04 mean?
How often does an LTS version come out, and in which month?
How long does the standard support of an LTS last? And with ESM?
A customer asks you to install Ubuntu 24.10 on their production server. What do you answer?
Name two tools that Ubuntu shares with Debian, and two tools specific to Ubuntu.

Answers

A version released in April 2022 (year 22, month 04). It is an LTS (Jammy Jellyfish).
Every two years, in April of even years.
5 years of standard support; up to 10 years with ESM, included in Ubuntu Pro.
That an interim version is maintained for only 9 months: it is better to install the LTS 24.04, maintained until 2029 (2034 with ESM).
Shared: dpkg, apt, .deb packages. Specific to Ubuntu: netplan, Subiquity, snap, ufw as the default firewall, Ubuntu Pro.

Reference source: Ubuntu Server Guide (Canonical, CC BY-SA 3.0). Original MasterLinux text.