Linux server distributions compared: support, updates and protection

A server distribution is a promise: for a fixed number of years, someone will publish security fixes for the packages you install. Choosing one is less about taste than about how long that promise lasts, how the fixes reach you and what protection is switched on before you change anything. This comparison covers the four families most small teams choose from: Debian, Ubuntu LTS, the RHEL-compatible Rocky Linux and AlmaLinux, and Alpine.

Support periods in autumn 2026

The dates below come from each project's release pages. Check them again before you plan a migration, because projects occasionally adjust them.

How security updates reach you

Debian's security team publishes fixes as Debian Security Advisories through a dedicated repository. Fixes are backported: the package keeps its version number apart from a suffix. A scanner that only compares upstream version numbers may therefore report problems that are already fixed, so check the advisory before you panic.

Ubuntu works the same way with Ubuntu Security Notices. The important detail is the repository split. Packages in main get five years of standard security maintenance, while long-term coverage for universe, which holds many popular tools, comes through Ubuntu Pro. Check which component your key packages come from.

Rocky Linux and AlmaLinux rebuild Red Hat Enterprise Linux and publish their own advisories. Each major version gets ten years: five of active support with new minor releases, then five of security fixes only. Fixes land in the latest minor release, so a normal dnf upgrade keeps you current. Pinning an old minor release means losing fixes.

Alpine creates a new stable branch every May and November. The main repository is supported for about two years, the community repository only until the next release. That rhythm suits containers that are rebuilt often and is demanding for a long-lived server, which needs a branch upgrade at least every two years.

Mandatory access control: AppArmor and SELinux

Mandatory access control (MAC) limits what a program may do, even when it runs as root. If an attacker takes over a web server process, a good MAC policy stops it from reading SSH keys or writing outside its directories.

Debian and Ubuntu ship AppArmor enabled, with profiles for selected programs. Profiles are path based and fairly readable, but many services run without one. Rocky Linux and AlmaLinux ship SELinux in enforcing mode, with a policy that covers most system services. SELinux is stricter and harder to learn. The classic mistake is switching it off when a web application cannot write to a directory, instead of setting the right file context with semanage fcontext and restorecon. Alpine enables no MAC system by default and relies on its small footprint instead.

# Rocky Linux and AlmaLinux: should print Enforcing
getenforce

# Debian and Ubuntu: list loaded AppArmor profiles and their mode
sudo aa-status

Footprint and container base images

Every installed package is code that may need a patch. Debian and Ubuntu offer minimal server installs, the RHEL family has a minimal install option, and Alpine is small by design, built on musl and BusyBox. Smaller is not automatically safer: musl behaves differently from glibc in some edge cases, and some software is less tested on it. But a small system is easier to inventory and quicker to patch.

For containers the same logic applies. Slim Debian and Ubuntu images, minimal Rocky Linux and AlmaLinux images and Alpine images all exist. Whichever you choose:

• Pick the base image whose update rhythm you will actually follow.
• Name a supported release in your build file rather than a moving latest tag.
• Rebuild images regularly so they pick up security fixes, even when your own code has not changed.
• Scan images for known vulnerabilities as part of the build.

An image built once and never rebuilt has no support period at all, whatever the distribution promises.

Automatic security updates

All of these systems can install security fixes on their own. On Debian and Ubuntu the tool is unattended-upgrades. Ubuntu Server enables it for security updates out of the box; on Debian, check that it is installed and active. On Rocky Linux and AlmaLinux the tool is dnf-automatic, which you limit to security updates and run from its systemd timer. Alpine has no built-in equivalent, so schedule apk upgrade yourself or rebuild images.

# Debian and Ubuntu
sudo apt install unattended-upgrades
sudo dpkg-reconfigure -plow unattended-upgrades

# Rocky Linux and AlmaLinux
sudo dnf install dnf-automatic
# then set in /etc/dnf/automatic.conf:
#   upgrade_type = security
#   apply_updates = yes
sudo systemctl enable --now dnf-automatic.timer

Kernel and core library updates only take effect after a reboot or a service restart. Plan a regular reboot window, otherwise automatic updates install fixes that never actually run.

An image built once and never rebuilt has no support period at all.

General information, checked on 31 October 2026. Test changes on one system first and keep a way back. Found something outdated? Tell the editors.