Linux Firewall - What is it? What are the best options?

Do you already know what the Linux Firewall is? To better understand, it is enough to analyze how much the internet and data sharing have grown over the years since they were developed in the 90s.

Today, according to the Insper Institute, there are already about 5 billion active users - more than 60% of the world’s population. This is a major social and economic advance!

However, with so much growth and distribution of information, malicious systems also emerged.

They seek to illegally steal and manipulate data, harming not only the online universe, but affecting lives in the “real world”.

For this reason, some actions needed to be taken to protect users and the confidential information they share.

In the Linux system, for example, highly structured firewalls are used, capable of keeping the entire system safe and intact. Despite being something very useful, many still have questions about it, such as:

• What is the Linux Firewall, after all?
• What is the importance of Linux Firewall?
• What is the best firewall for Linux?
• How to structure the Linux Firewall?

All of these questions will be answered in today’s article! The Linux Certification team developed this comprehensive article, with everything you need to know. Follow and check it out!

What is a Linux Firewall?

A Linux Firewall is an automatic defense system, implemented on Linux and administered by the main user, that defines what data will be allowed and what rules will be applied.

From this initial definition, the system “learns” and performs the steps alone, protecting your network.

To make it easy, remember a firewall as a “wall of fire” that protects the flow of data. Before any user or information can access your network, it must go through it.

The importance of having knowledge about Linux Firewall

Information security on Linux has been increasingly discussed — it’s really a hot topic. Therefore, if you are an IT professional, understanding how to apply the Linux Firewall methodology can be a major difference in your career.

It also allows sensitive data from companies and networks to be kept secure, preventing attempted attacks and malicious intrusions.

Thus, you can specialize in the methodology and stand out in the labor market, in addition to protecting and guaranteeing a good result for companies in this segment.

What is the best firewall for Linux?

Photo: Pexels | How to choose the best one?

The best Firewall for Linux is, without a doubt, Iptables. Iptables is nothing more than a tool for filtering packets and deciding what their destination will be.

In addition, it allows several different configurations when treating packets, which can be stylized and filtered as part of an entire network, of a system or just of equipment, for example.

The cost-benefit of this system, in particular, draws attention. It can be easily adapted to any type of company, network or need, according to the reality encountered by the professional.

How to set up iptables Linux firewall on CentOS

When we talk about iptables, a very common question is how to configure it on CentOS, which is one of the operating system options for Linux.

The truth is that configuring it is very simple. First, however, it is important to uninstall any other Firewall that already exists on the machine, so that there is no conflict.

Do this through the sudo privilege and “systemctl stop firewalld”, triggering the command “sudo yum install iptables-services”.

4 Linux Firewall that also deserve your attention

Although iptables is the best of all, there are still other viable options in Linux Firewall that you can choose from. We have listed the 4 most famous ones below.

UFW

UFW is the firewall for Ubuntu, another Linux distribution. Its abbreviation UFW comes from the name Uncomplicated Firewall, and promises to simplify this system for the user.

For this reason, it is easier to use than iptables and can be a great alternative if you are still learning and immersing yourself in the subject.

It also provides detailed information on incoming and outgoing events, IP addresses, packet sizes found, response and expiration times, protocols and communication ports.

Douane

Douane is yet another viable alternative, which allows the control of situations such as the blocking of applications and network connections.

All of this is defined very simply, using the “allow” and “deny” button interface offered by the system itself, in order to create pre-programmed rules.

This interface is the main differentiator of the system. Despite this, another situation makes it inaccessible to novice users: the installation and lack of updates to download automatically.

The downside is having to manually download each system package and install it separately - something that can be cumbersome and time consuming.

IPFire

The advantage of IPFire is its agility and versatility. Despite being classified as an operating system such as Ubuntu or Debian, it is famous for being perfect for use as a Firewall.

For this reason, it is extremely complete and has unique resources, which can be applied in various contexts to promote safety.

With it, the user can create networks, servers and rules for the network application, in addition to hosting services on other servers.

pfSense

The pfSense firewall has router functions and is based on FreeBSD. In addition, it presents a more “clean” and accessible interface.

Also, due to so much history and development processes, pfSense is one of the best documented. Because of this fact, there is also a large community of support and users of pfSense - ideal for answering questions.

Keep an eye on Linux Firewall forums and communities

Photo: Pexels | Forums may be the best way out.

If you want to stay up to date with everything that happens with Linux Firewalls and get answers to your main questions about the topic, you need to check out the forums and communities of each firewall.

If you have decided that iptables is the perfect one for you, for example, visit the forums about it.

There, it will be possible to follow the main updates, bugs, and solutions found by other users and even by software developers.

In addition, you can choose more comprehensive community forums, which talk about all types of firewalls, to stay aware of trends and possibilities.

In it, you will find various topics from old and recent discussions on the topic, with the aim of learning more and more.

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Conclusion

Did you notice how simple understanding Linux Firewall is? It is enough to acquire the exact knowledge on the subject from a reliable source such as the Linux Certification!

You learned about the importance of these systems and which are the main ones, as well as how to set up and use information forums to your advantage.

If you like content about Linux, technology trends, and career in the IT market, you need to check out the our Linux Certification blog!

In it, we share free articles that help you in a practical and applicable way. At the end of each reading, you will have a totally different view on the topics!

Some that may interest you, especially if you are starting out in the Linux universe, are:

• Systemd: how it works, differences for sysvinit and commands;
• Guide to process management in Linux with a list of 13 commands;
• Why learn Linux? See the advantages and the operating market and much more!