Linux Firewall: What It Is and the Best Options
Do you already know what the Linux Firewall is? To better understand it, just analyze how much the internet and data sharing have grown over the years, since they were developed in the 90s.
Today, according to Insper Institute, there are already about 5 billion active users — more than 60% of the world population. This is a great social and economic advance!
However, with so much growth and distribution of information, malicious systems have also emerged.
They seek to steal and manipulate data illegally, harming not only the online universe, but also affecting lives in the "real world".
That's why 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 secure and intact. Although it is something very useful, many people still have doubts about it, such as:
- So, what is the Linux Firewall?
- What is the importance of the Linux Firewall?
- What is the best firewall for Linux?
- How to structure the Linux Firewall?
All these questions will be answered in today's article! The Certificação Linux team has developed this complete article, with everything you need to know. Follow along and check it out!
What is a Linux Firewall?
A Linux Firewall is an automatic defense system, implemented in Linux and administered by the main user, that defines which data will be allowed and which rules will be applied.
From this initial definition, the system "learns" and executes the steps on its own, protecting your network.
To make it easy, remember firewall as a "fire wall" that protects the data flow. Before any user or information can access your network, it must pass through it.
The importance of having knowledge about Linux Firewall
Information security in Linux has been increasingly discussed — it is really a hot topic. That's why, if you are an IT professional, understanding how to apply the Linux Firewall methodology can be a great differentiator in your career.
It also allows confidential data from companies and networks to be kept secure, preventing malicious attack and intrusion attempts.
That way, you can specialize in the methodology and stand out in the job market, in addition to protecting and ensuring good results for companies in this segment.
What is the best firewall for Linux?
The best Firewall for Linux is, without a doubt, Iptables. Iptables is nothing more than a tool to filter packets and decide what their destination will be.
It also allows several different configurations when dealing with packets, which can be styled and filtered as part of an entire network, a system, or just one device, 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 found by the professional.
How to configure Linux Iptables firewall on CentOS
When we talk about iptables, a very common doubt 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. However, it is important to first uninstall any other Firewall already on the machine, so that there is no conflict.
Do this through sudo privilege and "systemctl stop firewalld", running the command "sudo yum install iptables-services".
4 Linux Fw 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. We listed the 4 most famous below.
UFW
UFW is the firewall of Ubuntu, another Linux distribution. Its abbreviation UFW comes from the name Uncomplicated Firewall, and it promises to simplify this system for the user.
Because of that, it is simpler to use than iptables and can be a great alternative if you are still learning and diving into the subject.
It also offers detailed information about 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 control of situations such as blocking applications and network connections.
All of this is defined in a very simple way, using the "allow" and "deny" button interface that the system itself offers, in order to create pre-programmed rules.
This interface is the great differentiator of the system. Despite that, another situation makes it inaccessible for beginner users: the installation and lack of updates for automatic download.
The negative point is having to manually download each system package and install it separately — something that can be laborious and time-consuming.
IPFire
The advantage of IPFire is agility and versatility. Despite being classified as an operating system just like Ubuntu or Debian, its fame is for being perfect for use as a Firewall.
For this reason, it is extremely complete and has unique features, which can be applied in various contexts to promote security.
With it, the user can create networks, servers, and rules for network application, in addition to hosting services on other servers.
pfSense
The pfSense firewall has router functions and is based on FreeBSD. Furthermore, it has a more "clean" and accessible interface.
Also, due to its long history and development processes, pfSense is one of the most well-documented ones. For this reason, there is also a large support and user community for pfSense — something ideal for clearing doubts.
Read more: pfSense Firewall: what it is, advantages, and how to install the software
Keep an eye on Linux Firewall forums and communities
If you want to stay on top of everything that happens with Linux Firewalls and get answers to your main questions about the topic, you need to check the forums and communities for each firewall.
If you have decided that iptables is the perfect one for you, for example, access the forums about it.
There, you will be able to follow the main updates, bugs, and solutions found by other users and even by software developers.
Also, you can choose forums from broader communities that talk about all kinds of firewalls, to stay up to date on trends and possibilities.
A good example of a forum to stay updated is the Brazil Firewall And Router, from the Viva o Linux community.
In it, you will find various discussion topics, old and recent, about the topic, with the goal of learning more and more.
Conclusion
Did you see how understanding Linux Firewall is simple? You just need to acquire the exact knowledge about the topic from a reliable source like Linux Certification!
You learned about the importance of these systems and what the main ones are, as well as how to install and use information forums in your favor.
If you like content about Linux, technology trends, and career in the IT market, you need to check the 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 completely different view on the subjects!
Some that may interest you, especially if you are starting in the Linux universe, are:
Prof. Uirá Ribeiro
Chair do Board do Linux Professional Institute
After years of watching professionals waste hours on simple tasks because they didn't know the right Linux tools, I decided to teach.
Today I'm the author of most of LPI's official Learning Materials and mentor to over 14,000 certified students.
That was just one piece. The course teaches the whole path — from your first command to exam day.
