5 top Linux server distros: How to choose the right one

What you need to know to choose among Ubuntu LTS, Oracle Linux, Fedora Server, Red Hat Enterprise Linux and SUSE Enterprise Server

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RHEL uses SELinux for Mandatory Access Control (MAC) host OS security, which is in "Enforcing" mode by default. RHEL comes with a host-based firewall, firewalld, installed and enabled by default.

Use case

RHEL is recommended for commercial enterprise-production applications where technical support is required to keep the mission-critical systems running. It is the best Linux OS for running production applications requiring high availability using the most stable OS.

CentOS Stream

CentOS (Community Enterprise Linux Operating System) is a community-supported open-source operating system based on RHEL. While Red Hat is the major sponsor of the OS, it is free to use and has a GNU GPLv2 license model.

Historically, CentOS and RHEL shared a version-naming convention, so CentOS 6.5 was built on source packages of RHEL 6.5, but that changed with the introduction last year of CentOS Stream. The new designation makes CentOS a rolling preview of what’s coming in the next RHEL release. The current version is called CentOS Stream 8, and that is what we are reviewing here. CentOS Stream 9 is due out later this spring.

The last version under the old naming scheme is CentOS 8, which was released in September 2020, and updates for it end Dec. 31, 2021, a major cut to the update window.

While CentOS doesn't come with formal software support, third-party vendor OpenLogic does provide commercial support. If more support is needed, another option is moving to RHEL, which does have commercial support. Also, because CentOS closely resembles RHEL, much of the RHEL 8 training materials would also be applicable to help configure and maintain CentOS systems.

There are many sources of documentation on the CentOS distribution, including a primary documentation website and a wiki site .  There are also community-monitored and maintained mailing lists, forums, and bug tracking to reach out to when you run into problems.

The CentOS Project doesn't offer its own training, but there are online classes offered by third parties.  CentOS is easy to download and get running in a testing environment.  It is important to make sure you are downloading the correct install image for the hardware you will run it on.  CentOS has narrowed the hardware architectures supported to x86-64 (the most popular), aarch64, and ppc64le.

Download and Install

For the review, we downloaded the CentOS-Stream-8-x86_64-20201210-dvd1.iso ISO image, a 9.37 GB file, and used it to create a new VM, powered it up, and used the quick installation procedure.

The default boot loader in CentOS is GNU GRand Unified Bootloader (GRUB), in this case GRUB 2.02-90. The Journaled File System supported by CentOS is XFS.

After installation completed, the size of VM without its ISO file was 14.5 GB while the root partition disk usage is 4.57 GB.  The steady-state memory usage after default install is 1.31 GB.

After installation, you can log into the graphical desktop environment.

Software

In this edition of CentOS Stream, the Linux kernel version is 4.18.0-257, which is only slightly newer than the RHEL version we tested.

GNOME 3.32.2 was the desktop that came with the distribution we tested, but KDE is also available.

Other default included software with this distribution include: Firefox, GNOME tools, and Cockpit (to control web services).  LibreOffice is available, but was not automatically included in the ISO we installed.

CentOS uses RPM, DNF, yum, and Flatpak for package management. CentOS has the ability to load RHEL 8-compatible software and use the Enterprise Linux (EPEL) packages/repositories because it has a great degree of RHEL compatibility.

Networking

The default interfaces are ens33, virbr0, and virbr0-nic. CentOS uses Network Manager for network interface configuration, but Netplan can be enabled and is installable with Snap.

CentOS is a fully dual-protocol OS with IPv6 installed and enabled by default.  CentOS supports static, SLAAC, or DHCPv6 address assignment.  When CentOS was on a network using IPv6 SLAAC, RDNSS, and DNSSL, it uses a stable-privacy address and RDNSS and DNSSL furnish the DNS info.

Security

During the installation process, a root password and a standard non-privileged user account was created, and that user was not added to the sudoers list. Also, the SSH daemon was installed and running by default.

CentOS uses SELinux for Mandatory Access Control (MAC) host OS security, and it is in enforcing mode by default.

CentOS comes with a host-based firewall (firewalld) installed and enabled by default.

Use case

CentOS is recommended when you needed a Linux distribution that has excellent compatibility with RHEL and EPEL packages but don't want to spend money. CentOS could be ideal for a dev/test OS or for a lab environment that might be preparing to eventually move on to RHEL.  If you are going to use CentOS for production applications, use RHEL and purchase a support subscription.

Debian

Debian is the Linux version that spawned other distributions including Ubuntu and Raspberry Pi OS and is overseen by the Debian Project, which maintains the ideal of free and open software. It is developed by volunteers from the open-source community.

The current version, released September 26, 2020, is Debian 10.7, also called Buster, named for the dachshund in Toy Story. (Other Debian code names – Lenny, Squeeze, Wheezy, Jessie – are also character in the movie made by Pixar, where Debian was used. It is rumored that the curly Debian logo is the same as the curl on Buzz Lightyear's chin.)

Debian has no commercial support, but does a support page with links to help options including a mailing list monitored by the open-source community, an IRC chat channel, user forums, and a bug-tracking system. You can also hire third-party Debian consultants.

Documentation and training

Debian offers a wealth of free downloadable documentation, which includes helpful manuals, guides, and release notes. The Debian Project doesn't offer training, but there are third-party online training classes.

Download and Install

Debian is easy to download and get running in a testing environment, but it is important to download the correct install image for the hardware and desktop environment you will run it on. It supports a variety of hardware architectures but the primary ones are x86, x86-64, and Arm. Others include i386, i686, aarch64, armel, armhf, mips, mipsel, ppc64el, and s390x.

In our test we went to the official download site, selected the DVD/USB option, and downloaded the Debian ISO image via BitTorrent using the Transmission client. We selected a hybrid ISO image file and chose our architecture--amd64.  The 2.59GB file was debian-live-10.7.0-amd64-gnome.iso.torrent. We created a new VM using this ISO image, powered on the VM and went through the quick installation procedure.

The default boot loader in Debian is GNU GRand Unified Bootloader (GRUB), and the GRUB version is GRUB 2.02. The default Journaled File System that came with the version we tested was EXT4, but Btrfs, EXT3, JFS, and XFS are also available.

After installation completed, the size of VM without its ISO file is 11.3 GB while the root partition disk usage is 7.63 GB.  The steady-state memory usage (after default install) is 0.71 GB, the smallest storage and memory utilization of all the distros we tested. In this edition of Debian, the Linux kernel version is 4.19.0-13.

Software

After installation, you can log into the graphical desktop environment,  in this case GNOME 3.30.2.  There is a wide variety of window managers available with the ISO downloads including Cinnamon, Gnome, kde, lxde, lxqt, mate, standard, and xfce. Other default software includes LibreOffice, Firefox, Evolution, Thunderbird, and some games.

Debian and its contributors have written packages of precompiled software that are available for easy installation. Debian's package management options include APT and dpkg.

Networking

The default network name is ens33. Debian uses Network Manager for network interface configuration, but Netplan can be enabled.

Debian is a fully dual-protocol OS with IPv6 installed and enabled by default. Debian supports static, SLAAC, or DHCPv6 address assignment. When Debian was on a network using IPv6 SLAAC, RDNSS, and DNSSL, it used a temporary privacy address, and RDNSS and DNSSL furnished the DNS info.

Security

During the installation process, a root password and a standard non-privileged user account were created, and that user was not added to the sudoers list.  Also, the SSH daemon was not installed and running by default so we had to add it before we could SSH into the OS.

Debian uses AppArmor for Mandatory Access Control (MAC) host OS security.

The operating system comes with a host-based firewall (netfilter) installed with iptables and ip6tables, and it is enabled by default.  However, there aren't any iptables or ip6tables rules installed by default.

Use case

Debian is recommended if you needed a stripped down, back-to-basics OS and preferred Debian packages.  If you are already familiar with Linux and like having full control and no cruft to get in your way, then Debian is a great way to go.  However, it’s not recommended for mission-critical application.

Ubuntu

Ubuntu is a free, Debian-based Linux operating system, originally developed to be a desktop and server OS that now has an Ubuntu Core edition for IoT applications.

Ubuntu has a free-software license model which means it is free to use Ubuntu and run it wherever. We reviewed Ubuntu 20.04.1 LTS, a.k.a Focal Fossa, that was released April 23, 2020 and has general support until April 2025. There is a newer version, Ubuntu 20.10 (Groovy Gorilla) that was released Oct. 22, 2020, but its support runs out in July 2021. (Ubuntu versions are released periodically, and alternating versions are intended to have a longer lifespan, and also have long-term support (LTS). If you intend to run a system for many years and require software updates, then the LTS versions are recommended. The next one, Ubuntu 21.04 (Hirsute Hippo) will be available sometime around April 2021.)

Licensing and support

Canonical Ltd. publishes and provides commercial services for Ubuntu, including Ubuntu Advantage 24x7 technical support, which is available in flavors to address the needs of applications and the needs of infrastructure. Ubuntu documentation is available online, and the CommunityHelpWiki provides helpful tips and hacks. There are also Ubuntu mailing lists, Ubuntu Forums, Ask Ubuntu, and a bug tracker. Canonical offers basic and advanced  Ubuntu Server training classes.

Download and install

It is easy to download Ubuntu and quickly get it running on a physical or virtual server, and we downloaded Ubuntu 20.04.1 LTS desktop, which is supported by x86-64 and Arm architectures. We downloaded the 2.71GB filename ubuntu-20.04.1-desktop-amd64.ISO, used the image to create a virtual machine, powered it up and installed it.

The default Ubuntu boot loader is GNU GRand Unified Bootloader (GRUB) and the version is GRUB 2.04. The default Journaled File System in the version we tested was EXT4.  However, Btrfs, EXT3, JFS, and XFS are available.

After installation, the size of the VM without its ISO file is 12.1 GB, and the root-partition disk usage is 8.42 GB.  The steady-state memory usage after default install is 0.97 GB. After installation, you can log into the graphical desktop environment.

Software

The Linux kernel version for the OS is 5.4.0-58, and the version of GNOME, the desktop environment, is 3.36.3. LibreOffice, Firefox, Thunderbird, Transmission, and several games come installed by default. Ubuntu uses APT, dpkg, and Flatpak for package management.           

Networking

The default interface is ens33. Ubuntu uses Network Manager for network interface configuration, but it comes with Netplan support installed by default. Netplan is also supported by Canonical.

Ubuntu is a dual-protocol OS with IPv6 installed and enabled by default.  Ubuntu supports static, SLAAC, or DHCPv6 address assignment.  When Ubuntu was on a network using IPv6 SLAAC, RDNSS, and DNSSL, it used a temporary privacy address. RDNSS and DNSSL furnish the DNS info.

Security

During the installation process, a root password and a standard non-privileged user account was created, and that user was automatically added to the sudoers list. The SSH daemon was not installed and running by default so we had to add it before we could SSH into the OS.

Ubuntu uses AppArmor for Mandatory Access Control (MAC) host OS security. The operating system comes with a host-based firewall (UFW) installed with iptables and ip6tables enabled by default, but without iptables or ip6tables rules installed.

Use case

Ubuntu is one of my favorite Debian OSs that has a solid community of support.  It is the extremely popular, de facto OS for network engineers, and has a broad application package to choose from. I would recommend it to those interested in learning about Linux, on a budget, but want a simple, yet modern, GNOME desktop experience.

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