What is a firewall, exactly? Is a Linux firewall required? This post will answer all of your questions about how to set up and configure a Linux firewall.



Firewall:

  
There is a lot of information about firewalls, as well as long-standing discussions about the need for a firewall in Ubuntu. We recommend enabling it because you have open ports if you are reading this page. Traffic can enter and exit this port unimpeded without a firewall. Malware can open random ports unless you have a firewall to block them. 

  A NAT router can provide an additional layer of security, but it cannot replace a firewall. More information may be found in this supplemental guide. Make appropriate use of your firewall. Don't just set it up and forget about it; study how it works and establish some reasonable guidelines. A guide on how to enable the Ubuntu firewall may be found here. Adding port numbers, on the other hand, can be perplexing. Consider it this way if it helps: You're reading this tutorial because you went to the wiki.ubuntu.com website. You must connect your browser to this site by navigating to port 80 to make the connection (and so show the content).
Another instance is when you go to get your email. The computer creates a connection to the mail server on port 110. The other port numbers that you add provide similar functionality.

What is a firewall in Linux?

A firewall is a set of software filters that control inbound and outbound traffic on your computer. Simply put, it is a kind of wall between your computer and the outside world.



Do you need a firewall in ubuntu?

This is a question I get practically every day from new users. In a nutshell, you don't need it, but you should buy it anyhow. Please allow me to explain why. By default, almost all Linux distributions do not have a firewall. They have an inactive firewall in order to be healthy. This is not set and activated because the Linux kernel contains a built-in firewall, and theoretically all Linux distributions have a firewall.

That, I believe, is due to the fact that utilizing a firewall requires some practice. But don't panic; even without an active firewall, your Linux system is safe.

By default, most distributions, such as Ubuntu and Linux Mint, do not have open ports, so hackers cannot access your computer. However, I recommend enabling the firewall. You better be sure that sorry. 

The firewall doesn't use a lot of resources, but it does add an extra layer of security. An inexperienced user may accidentally open some ports without knowing it, for example, install samba, ssh, apache. In this case, the firewall will continue to protect the system from external access.

How to set up a firewall in Linux / Ubuntu?

In Linux, you may setup and run the firewall using a variety of applications. However, I'll just show you two of the greatest programs.
  • UFW – It is perhaps the easiest to use firewall available on Linux. If you are a complete beginner or just want to use your Linux system without getting too deeply into setting it up, use UFW.
  • iptables - It is a more advanced but likely suitable method for configuring a Linux firewall. If you really want to learn Linux and intend to become a Linux expert then you should learn iptables.

UFW - the uncomplicated firewall

As I previously stated, UFW is the simplest and most straightforward approach to set up a Linux firewall. It may be used both from the command line and with a graphical front-end. In the first scenario, you must use your program manager to install the GUFW software. Install UFW exclusively in the latter scenario, i.e. without G and hence without GUI.

GUFW


Let's begin with the user interface. Simply download, open, and activate GUFW. This is the case. The firewall is turned on, and most users will be OK with the default settings of denying incoming connections and allowing outbound connections. No one will be able to log into your computer, but any program installed on it will have access to the internet. Go to the Rules tab and open the ports for a specific application if you need to connect to your computer from the outside.

GUFW Graphical Interface

GUFW is a graphical user interface for the ufw command line tool. Although Ubuntu does not provide a graphical user interface, gufw is available in Ubuntu's software repositories. In the script, GUFW is listed as a program named Firewall Configuration. GUFW, like ufw, has a straightforward and user-friendly interface. You can quickly switch on or off the firewall, change the default policy for inbound and outgoing traffic, and create new rules.

Iptables - advanced Linux firewall

Instead, Iptables are intended for server use where you need to configure complex network routing. For the average desktop user, the iptables firewall is not easy to understand. Honestly, I've tried iptables a few times on my system and always go back to UFW. You have to read a lot to understand how iptables work and how to configure it according to your needs.

Logs

Firewall logs are required for detecting attacks, troubleshooting firewall rules, and detecting anomalous network behavior. However, registry rules must be included in the firewall before any applicable termination rules, and registry rules must be provided before any applicable termination rule (a rule with a destination that specifies the destination of the package, such as accept, drop, or reject).

The Netfilter subsystem of the Linux kernel is used to process or determine the destination of network traffic destined for or passing through your server. This mechanism is used to filter packets in all contemporary Linux firewall systems.

Administrators who do not have a user space interface to operate the kernel packet filtering mechanism will find it useless. This is what iptables is for: when a package arrives on your server, it is given to the Netfilter subsystem for acceptance, tampering, or rejection according on the rules provided to it via iptables from the user space. If you're familiar with iptables, that's all you'll need to administer your firewall, although there are numerous front-end interfaces available to make things easier.

By default, Ubuntu comes with a firewall configuration tool called UFW (Uncomplicated Firewall). UFW is an easy to use front-end iptables firewall rule management tool whose main purpose is to facilitate managing iptables or as the name suggests without hassle.

The Netfilter subsystem of the Linux kernel is used to process or determine the destination of network traffic destined for or passing through your server. This mechanism is used to filter packets in all contemporary Linux firewall systems. Administrators who do not have a user space interface to operate the kernel packet filtering mechanism will find it useless. This is what iptables is for: when a package arrives on your server, it is given to the Netfilter subsystem for acceptance, tampering, or rejection according on the rules provided to it via iptables from the user space. So, iptables is all you need to manage your firewall, if you know this, but there are several front-end interfaces available to simplify the task.

Ubuntu comes with a firewall setup tool named UFW by default (Uncomplicated Firewall). UFW is a user-friendly front-end iptables firewall rule management application whose major goal is to make administering iptables as painless as possible.

Firewalls aren't required for most Linux desktop users. The only time you'll need a firewall is if you're using your computer to run a server application... The firewall in this scenario restricts inbound connections to certain ports, guaranteeing that they can only communicate with the relevant server application.



How do I know if my firewall is on Linux?

If your firewall uses the built-in kernel firewall, sudo iptables -n -L lists all iptables contents. If there is no firewall, the output will be nearly blank. Your VPS might already have ufw installed so try the ufw case.

What is firewall in Ubuntu?

UFW is a firewall setup tool included with Ubuntu (Hassle-Free Firewall). UFW is a user-friendly front-end iptables firewall rule management application whose major goal is to make managing firewall rules as simple as possible. It is very advised to keep the firewall turned on.

Ubuntu comes with a firewall called ufw, which stands for 'Hassle-Free Firewall.' For the basic Linux iptables commands, Ufw is the most user-friendly interface. You may even use a graphical interface to operate ufw. Ubuntu Firewall was created to make basic firewall activities simple without having to understand iptables. It doesn't have the same potency as the normal iptables commands, but it's a lot easier to use.

Security Updates for Ubuntu

When Ubuntu developers find and patch vulnerabilities, they provide security updates. If you do not install the patches, the vulnerability will remain. Ubuntu allows you to automatically install security updates; once enabled, you won't have to resume security updates manually. Locate the update manager on your desktop and select "Settings" to customize how Ubuntu handles updates. You may also use the gadget to set up automatic updates.