centos

How to disable or enable the firewall on AlmaLinux

How to disable/enable firewall on AlmaLinux

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firewalld is the firewall manager that comes pre-installed on AlmaLinux, whether you’ve freshly installed AlmaLinux or migrated from CentOS to AlmaLinux. By default, the firewall is turned on, meaning that a very limited number of services are able to receive incoming traffic.

This is a nice security feature, but it means that the user must be knowledgeable enough to configure the firewall whenever they install a new service on the system, like HTTPD or SSH for example. Otherwise, connections from the internet can’t reach these services.

In this guide, we’ll see how to disable or enable the firewall in AlmaLinux, along with checking the status of the firewall. These are good troubleshooting options when trying to determine if a firewall rule is blocking traffic to or from a particular service.

DID YOU KNOW?
firewalld is simply a front end for the system’s nftables (formerly iptables) firewall. This makes the firewall easier to interact with, but essentially firewalld just translates all our commands into corresponding nft commands.

In this tutorial you will learn:

  • How to check the firewall status on AlmaLinux
  • How to stop firewall on AlmaLinux
  • How to start firewall on AlmaLinux
  • How to permanently disable firewall on AlmaLinux
  • How to enable firewall to start after reboot
How to disable or enable the firewall on AlmaLinux

How to disable or enable the firewall on AlmaLinux

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AlmaLinux download

AlmaLinux Download

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AlmaLinux is a Linux distribution based on Red Hat Enterprise Linux and maintained by CloudLinux, a company that provides server hosting and Linux software. For other most popular Linux distributions, please visit our dedicated Linux download page.

MIGRATE YOUR CENTOS TO ALMALINUX
Follow our guide to learn how to migrate CentOS to AlmaLinux, if you prefer convert your existing operating system instead of starting with a new AlmaLinux installation.

The motivation behind Alma’s release is to serve as a viable replacement for CentOS at the time of its shift from an enterprise-stable operating system to an upstream development branch of RHEL. Users can even switch from CentOS to AlmaLinux with just one command that will swap repositories and keys.

AlmaLinux functions very similarly to RHEL, but it’s completely free. It’s marketed to users and companies that need enterprise-level stability in a Fedora-like operating system. In other words, companies that want to use Red Hat but don’t want to pay the subscription fee and/or don’t need tech support can use AlmaLinux to fill the gap.

Being based on RHEL naturally makes AlmaLinux more geared towards servers and workstations, though it can still work well as a desktop operating system for some people. The full installation comes with the GNOME desktop environment and proves easy enough to use, but Linux newcomers will find a more welcoming experience in a user friendly distro like Ubuntu.

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Completing the merge from CentOS to AlmaLinux

How to migrate from CentOS to AlmaLinux

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The main motivation behind the creation of AlmaLinux was to be a viable replacement for CentOS Linux at the time of its shift from an enterprise-stable operating system to an upstream development branch of RHEL.

Now that AlmaLinux is released, it still leaves CentOS users wondering how to switch operating systems. Ideally, this should be done as seamlessly as possible, to prevent downtime, loss of data, etc. In this guide, we’ll show you the step by step instructions to migrate from CentOS to AlmaLinux with just a few commands.

In this tutorial you will learn:

  • How to migrate from CentOS to AlmaLinux
Completing the merge from CentOS to AlmaLinux

Completing the merge from CentOS to AlmaLinux

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AlmaLinux

AlmaLinux vs CentOS

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The release of AlmaLinux in 2021 was spurred by the change of CentOS Linux from an enterprise-stable operating system to an upstream development branch of RHEL.

With AlmaLinux being branded as a replacement for CentOS, and giving users the option to migrate to AlmaLinux from CentOS, you may be wondering what the differences are between these operating systems.

In this guide, we’ll look at what makes AlmaLinux and CentOS so similar, and why new differences between the distributions are causing many to distro hop.

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ERROR: Unable to find the kernel source tree for the currently running kernel error message on CentOS / RHEL

ERROR: Unable to find the kernel source tree for the currently running kernel – CentOS / RHEL / AlmaLinux

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This article will provide you with an information on how to install kernel source on CentOS/RHEL Linux system. Alternatively it will guide you through a simple troubleshootng process in case you have already installed kernel sources/headers and yest still receiving the bellow error message:

  ERROR: Unable to find the kernel source tree for the currently running kernel.  Please make sure you have installed the kernel     
         source files for your kernel and that they are properly configured; on Red Hat Linux systems, for example, be sure you have 
         the 'kernel-source' or 'kernel-devel' RPM installed.  If you know the correct kernel source files are installed, you may    
         specify the kernel source path with the '--kernel-source-path' command line option.

In this tutorial you will learn:

  • How to install kernel-headers
  • How to install kernel-devel
  • How to check kernel version
  • How to check for installed kernel-devel version

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Lets Encrypt on CentOS 8

Install Let’s Encrypt on Centos 8

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SSL encryption for your website is extremely important. It prevents man in the middle attacks, helps your page’s SEO, and browsers like Firefox won’t warn users that your site is insecure.

Best of all, you can get all these advantages for just a few minutes of your time. In this guide, we’ll show you how to install Let’s Encrypt on Centos 8, and how to use it to configure SSL encryption for your website. In a few steps, your site will become accessible via HTTPS, with HTTP links (optionally) redirecting to the secure protocol as well.

In this tutorial you will learn:

  • How to install Let’s Encrypt
  • How to configure Let’s Encrypt SSL

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CentOS Linux

CentOS vs Fedora

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CentOS and Fedora are two of the most well known and widespread Linux distributions. They’re both based on Red Hat Enterprise Linux (RHEL), which means Fedora and CentOS bear a lot of similarities to their ancestor, but also to each other.

In this guide, we’ll be comparing the two distributions across a few key areas and giving a brief review of both distros. Read on to learn more about CentOS and Fedora and how they compare. By the end of this article, you’ll be armed with enough information to choose the best distro for your needs.

In this tutorial you will learn:

  • CentOS and Fedora background information
  • CentOS and Fedora similarities and differences
  • Which distro should I use, CentOS or Fedora?

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Red Hat Enterprise Linux

Oracle Linux vs Red Hat (RHEL)

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Oracle Linux and Red Hat Enterprise Linux (RHEL) are well-known Linux distributions, often used in the business world. Each distro has their own pros and cons, differences, and similarities to the other.

In this guide, we’ll be comparing the two distributions across a few key areas and giving a brief review of both distros. Read on to learn more about Oracle Linux and RHEL and how they compare. By the end of this article, you’ll be armed with enough information to choose the best distro for your needs.

In this tutorial you will learn:

  • Oracle Linux and RHEL background information
  • Oracle Linux and RHEL similarities and differences
  • Which distro should I use, Oracle Linux or RHEL?

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Apache Solr installed on Linux

Apache Solr Linux install

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Apache Solr is open source search software. It’s capable of being implemented as an enterprise-level search engine thanks to its high scalability, advanced indexing, fast queries, and ability to integrate with a large variety of applications. It’s capable of tackling big data and also has high availability with its load balancing and failover configurations.

The platform is written in Java and can be installed on Linux systems. In this guide, we’ll show the step by step instructions for installing Apache Solr on some of the most popular Linux distros, including Ubuntu, Debian, CentOS, and Red Hat.

In this tutorial you will learn:

  • How to install Apache Solr on Debian based systems
  • How to install Apache Solr on Red Hat based systems
  • Initial configuration of Apache Solr
Apache Solr installed on Linux

Apache Solr installed on Linux

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firewalld on CentOS

Install firewalld on CentOS Linux system

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firewalld is a front-end for the built in netfilter firewall on Linux systems. The main advantage of firewalld over using raw nftables/iptables commands is that it’s easier to use, especially for more complex firewall features like timed rules. In this regard, it’s similar to the uncomplicated firewall (ufw) that comes installed by default on Ubuntu systems.

On CentOS, firewalld is the default firewall interface and should already be installed on your system. In this guide, we’ll take you through the installation of firewalld on CentOS, which includes some basic usage commands so you can get started managing the firewall.

In this tutorial you will learn:

  • How to install and update firewalld
  • firewalld basic usage commands

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How to update CentOS

How to update CentOS

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Like all Linux distros, it’s important to keep your CentOS system up to date in order to make sure that you have the latest security updates and newest features. Updating the system usually involves simply upgrading all installed packages to their latest versions. Every few years, there’s a new version of CentOS released, which requires a more involved update process to install.

In this article, we’ll cover updating a CentOS system on a per package basis and upgrading the entire operating system. This can be done via command line and GUI. Both methods will be shown in this guide, so you can pick whichever is easier for you.

The process for upgrading a CentOS system is a little different depending on which version you have installed. The latest version of Centos has moved to the dnf package manager. Previous to Centos 8, yum was the package manager used. Regardless of which version you’re running, we’ll show you the proper commands so you can update your system.

In this tutorial you will learn:

  • How to update CentOS packages via command line
  • How to update CentOS packages via GUI
  • How to upgrade entire CentOS system

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