Ubuntu, Debian and Rocky Linux run most Linux servers today, and CentOS still shows up in older documentation and legacy fleets. They all use the same Linux kernel and the same core tools, so the differences that matter are elsewhere: how long each release is supported, how packages are managed, which security features are on by default, and which software vendors certify against them. This guide compares them for server use and ends with a recommendation for common cases.
The two families
These distributions belong to two families:
- Debian family: Debian and its derivative Ubuntu. Packages are
.debfiles managed withapt. - Red Hat family: Red Hat Enterprise Linux (RHEL) and the distributions built from it or alongside it: CentOS Stream, Rocky Linux and AlmaLinux. Packages are
.rpmfiles managed withdnf.
Skills transfer well inside a family and reasonably well across them. The biggest day-to-day differences are the package manager, the firewall tool and the mandatory access control system.
To see which distribution and version a server runs, read /etc/os-release, which exists on all of them:
cat /etc/os-release
PRETTY_NAME="Ubuntu 24.04.3 LTS"
NAME="Ubuntu"
VERSION_ID="24.04"
VERSION_CODENAME=noble
ID=ubuntu
ID_LIKE=debian
...
The ID_LIKE field tells you the family: debian for Ubuntu, "rhel centos fedora" for Rocky Linux.
What happened to CentOS
CentOS Linux used to be a free, binary-compatible rebuild of RHEL. Red Hat ended it: CentOS Linux 8 reached end of life on December 31, 2021, and CentOS Linux 7 on June 30, 2024. Neither receives security updates any more, so any server still running them should be migrated.
The project continues as CentOS Stream, which is different in one important way: it sits slightly ahead of RHEL and is where upcoming RHEL minor releases are developed. It is stable enough for many uses but gets changes before RHEL does, and each major version has a shorter life (about five years) than RHEL.
Rocky Linux and AlmaLinux were created to fill the gap left by CentOS Linux. Both are free, community-run and aim for compatibility with RHEL, with the same ten-year support window per major version. For a server that previously ran CentOS 7 or 8, one of them is the natural replacement.
Comparison at a glance
| Ubuntu LTS | Debian stable | Rocky Linux / AlmaLinux | CentOS Stream | |
|---|---|---|---|---|
| Based on | Debian (unstable branch) | Independent | RHEL sources | Upstream of RHEL |
| Release cadence | LTS every 2 years (April) | About every 2 years | Follows RHEL: major about every 3 years, minor every 6 months | Rolling within a major version |
| Standard support | 5 years | About 3 years, plus 2 years of Debian LTS | 10 years per major version | About 5 years per major version |
| Extended support | Up to 10+ years with Ubuntu Pro (free for personal use on a few machines) | Extended LTS from third parties | Not needed for most | None |
| Package manager | apt (.deb), plus Snap | apt (.deb) | dnf (.rpm) | dnf (.rpm) |
| Default firewall tool | UFW (installed, inactive) | None enabled (nftables available) | firewalld (active) | firewalld (active) |
| Mandatory access control | AppArmor (enabled) | AppArmor (enabled) | SELinux (enforcing) | SELinux (enforcing) |
| Commercial backing | Canonical | Community | Community (RESF / AlmaLinux OS Foundation) | Red Hat |
Current releases
Versions you are likely to deploy in 2026:
| Distribution | Release | Kernel | Default Python | End of standard support |
|---|---|---|---|---|
| Ubuntu | 24.04 LTS "Noble Numbat" | 6.8 | 3.12 | April 2029 |
| Debian | 13 "Trixie" | 6.12 | 3.13 | 2028, then Debian LTS to 2030 |
| Debian | 12 "Bookworm" | 6.1 | 3.11 | June 2026, then Debian LTS to 2028 |
| Rocky Linux / AlmaLinux | 9 | 5.14 (with extensive backports) | 3.9 (3.11 and 3.12 available) | May 2032 |
| Rocky Linux / AlmaLinux | 10 | 6.12 | 3.12 | May 2035 |
RHEL-family kernel version numbers look old because Red Hat freezes the version at release and backports fixes and drivers into it for the whole lifecycle.
NoteRHEL 10 and Rocky Linux 10 require an x86-64-v3 capable CPU (roughly Intel Haswell or AMD Excavator and newer). AlmaLinux 10 also publishes x86-64-v2 builds for older hardware. Check this before choosing version 10 for older machines.
Package management
Both package managers handle dependencies, signatures and repositories well. The commands map almost one to one:
| Task | Ubuntu / Debian | Rocky Linux / CentOS Stream |
|---|---|---|
| Refresh metadata | sudo apt update | sudo dnf makecache (usually automatic) |
| Upgrade everything | sudo apt upgrade | sudo dnf upgrade |
| Install a package | sudo apt install nginx | sudo dnf install nginx |
| Remove a package | sudo apt remove nginx | sudo dnf remove nginx |
| Search | apt search nginx | dnf search nginx |
| Show package info | apt show nginx | dnf info nginx |
| Which package owns a file | dpkg -S /usr/sbin/nginx | rpm -qf /usr/sbin/nginx |
| List installed packages | apt list --installed | dnf list --installed |
Package names also differ for the same software. For example, development headers use -dev on Debian and Ubuntu (libssl-dev) and -devel on the Red Hat family (openssl-devel), and Apache is apache2 on one side and httpd on the other.
Repository coverage
Ubuntu and Debian ship a very large official archive, so most open source server software is one apt install away. Ubuntu's universe component is community maintained and receives fewer security updates unless you enable Ubuntu Pro.
The RHEL family ships a smaller, carefully maintained base. Most extra software comes from EPEL (Extra Packages for Enterprise Linux), maintained by the Fedora project. On Rocky Linux 9, enable the CodeReady Builder (CRB) repository, which EPEL depends on, and then EPEL itself:
sudo dnf install dnf-plugins-core
sudo dnf config-manager --set-enabled crb
sudo dnf install epel-release
Third-party vendors (Docker, PostgreSQL, Nginx, Grafana and others) publish official repositories for all of these distributions, so the latest version of a mainstream tool is rarely a deciding factor.
Security defaults and updates
Mandatory access control. Ubuntu and Debian use AppArmor, which confines programs based on file paths and ships profiles for a limited set of services. Rocky Linux and CentOS Stream use SELinux in enforcing mode with a policy that covers most system services. SELinux is stricter and more complex: when a service cannot read a file or bind to a port, check sudo ausearch -m avc -ts recent before anything else, and fix the label or boolean rather than disabling SELinux.
Firewall. Rocky Linux enables firewalld at install, allowing only SSH and a few defaults. Ubuntu includes UFW but leaves it inactive, and Debian ships no active firewall rules. On the Debian family, enabling a firewall is a step you have to remember.
Automatic updates. Ubuntu installs security updates automatically through unattended-upgrades, enabled by default. On Debian, install and enable the same package:
sudo apt install unattended-upgrades
sudo dpkg-reconfigure -plow unattended-upgrades
On Rocky Linux, use dnf-automatic. Set apply_updates = yes in /etc/dnf/automatic.conf, then enable the timer:
sudo dnf install dnf-automatic
sudo systemctl enable --now dnf-automatic.timer
Live kernel patching. Ubuntu offers Livepatch through Ubuntu Pro. On the RHEL side, kpatch is part of RHEL subscriptions; community rebuilds do not provide an equivalent live patching service.
Upgrading between major versions
This is one of the biggest practical differences over a server's life:
- Ubuntu: in-place upgrades between LTS releases are supported with
sudo do-release-upgrade, usually offered after the first point release of the new LTS. - Debian: in-place upgrades are supported and well documented in each release's notes: switch the suite name in the APT sources, then run
apt upgradefollowed byapt full-upgrade. - Rocky Linux and AlmaLinux: major upgrades (9 to 10) are not supported in place by Rocky Linux; the recommended path is a fresh install and migration. AlmaLinux supports in-place major upgrades with the ELevate project, with caveats.
Because of the ten-year lifecycle, many RHEL-family servers are simply replaced at the end of their life rather than upgraded.
Which one should you choose
- Ubuntu 24.04 LTS is the safest default for most new servers. It has the largest amount of current documentation and tutorials, up-to-date packages at release, first-class support from cloud tooling, container runtimes and GPU drivers, and an easy in-place upgrade path. Choose it for web applications, containers, Kubernetes nodes and general-purpose VPS workloads.
- Debian 13 suits you if you want a lean, conservative system without Snap or commercial add-ons, with predictable behavior across its life. It is a common base for container images and appliance-like servers that should change as little as possible.
- Rocky Linux 9 or AlmaLinux 9 (or 10 on modern CPUs) are the right choice when software you run is certified for RHEL, when your team already operates RHEL systems, when you need SELinux, or when you want a ten-year lifecycle without major upgrades. They are the direct replacement for CentOS Linux 7 and 8.
- CentOS Stream makes sense for testing software against upcoming RHEL changes, or if you contribute to RHEL development. For production servers that should just run, prefer Rocky Linux or AlmaLinux.
- CentOS Linux 7 or 8: do not deploy them. Migrate existing servers to Rocky Linux or AlmaLinux.
Consistency often matters more than the choice itself. Running one distribution across your fleet means one set of automation, one patching process and one set of habits for your team.
Conclusion
Ubuntu and Debian share apt, AppArmor and a quick upgrade path, while Rocky Linux, AlmaLinux and CentOS Stream share dnf, SELinux, firewalld and RHEL compatibility. For most new servers Ubuntu 24.04 LTS is a sound default, with Rocky Linux or AlmaLinux as the choice for RHEL-oriented environments. As next steps, deploy a test server with your chosen distribution, apply basic hardening (SSH keys, firewall, automatic security updates), and plan the migration of any remaining CentOS Linux machines.