Firewalld Download
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Firewalld provides a dynamically managed firewall with support for network/firewall zones that define the trust level of network connections or interfaces. It has support for IPv4, IPv6 firewall settings, ethernet bridges and IP sets. There is a separation of runtime and permanent configuration options. It also provides an interface for services or applications to add firewall rules directly.
With the firewalld D-Bus interface it is simple for services, applications and also users to adapt firewall settings. The interface is complete and is used for the firewall configuration tools firewall-cmd, firewall-config and firewall-applet.
The separation of the runtime and permanent configuration makes it possible to do evaulation and tests in runtime. The runtime configuration is only valid up to the next service reload and restart or to a system reboot. Then the permanent configuration will be loaded again. With the runtime environment it is possible to use runtime for settings that should only be active for a limited amount of time. If the runtime configuration has been used for evaluation, and it is complete and working, then it is possible to save this configuration to the permanent environment.
Our world has never been more connected than it is right now. Every person, business, government, etc. uses the web to communicate, exchange currency and data, and generally go through the motions of daily life and operations. However, these connections are not inherently safe, and because of this, we have to put defensive measures in place to keep our location, information, and money protected. In times past, when someone wanted to secure their possessions, they erected gates and fences to keep intruders at a distance. Today, we accomplish these same goals with the use of firewalls. Most Linux systems made use of the iptables utility, however, a new technology was on the horizon.
With the introduction of the Red Hat Enterprise Linux 7.0 (RHEL) in 2011, iptables was superceded as firewalld was born. At its core, firewalld is a zone-based firewall. Zone-based firewalls are network security systems that monitor traffic and take actions based on a set of defined rules applied against incoming/outgoing packets.
Firewalld provides different levels of security for different connection zones. A zone is associated with at least one network interface (eth0, for example). We see the preconfigured zones by using the following command:
Now, the good thing about firewalls is that they keep our networks safe. The bad thing is that there is no "one-size fits all" firewall that fits every situation. Because of this, firewalls are customized to fit the exact needs of the situation that they are employed in. For example, if I need to allow FTP (File Transfer Protocol) transfers in the external zone so that I can move a file over port 21, I might use something like this:
The new allow rule doesn't survive the reinitialization of the firewalld configuration. To ensure that our new rule persists, we need to add the --permanent option. The new command is:
Now, what happens when you need to allow traffic over a non-standard port? Imagine you have a backup service that needs to run over a dedicated UDP port. How would you add this exception to your zone? The syntax is very user friendly and is only slightly different from what we used for services. To add a port to your zone configuration, use the following:
If, after reading this article, you're wondering what to do with the information, I highly recommend firing up your favorite VM (RHEL, Fedora, CentOS, etc.) and start experimenting with the commands above. The best way to learn is to get hands-on experience. If you found this content interesting, keep an eye on Enable Sysadmin for part two, where you'll dive into creating custom zones and more advanced rule creation.
Tyler is the Sr. Community Manager at Enable Sysadmin, a submarine veteran, and an all-round tech enthusiast! He was first introduced to Red Hat in 2012 by way of a Red Hat Enterprise Linux-based combat system inside the USS Georgia Missile Control Center. More about me
The opinions expressed on this website are those of each author, not of the author's employer or of Red Hat. The content published on this site are community contributions and are for informational purpose only AND ARE NOT, AND ARE NOT INTENDED TO BE, RED HAT DOCUMENTATION, SUPPORT, OR ADVICE.
With the nftables backend, firewalld does not assume complete control over the hosts firewalling. Since nftables allows multiple "namespaces" via tables, firewalld will scope all of its rules, sets, and chains to the firewalld table. Firewalld does not do a complete flush of firewall rules, it will only flush rules in the firewalld table.
nftables allows multiple chains to hook into netfilter at the same point. Packets that are accepted by a chain are still subject to the rules of other chains hooked into the hook type and in the drop case processing always stops immediately and no other hooks will process the packet. To ensure predictability of the execution order of chains, firewalld gives its rules slightly lower precedence than default nftables hook priority values. Consequently, firewall rules created outside of firewalld (e.g. by libvirt, Docker, Podman, systemd-nspawn, etc.) will be processed before firewalld rules and packets accepted by them will still be subject to firewalld rules.
NetworkManager can assign different connection profiles to different zones. This allows for example, adding a home WiFi connection to the "home" zone, a work WiFi connection to the "work" zone, and all other WiFi connections to the default "public" zone.
Service or port can be added for a limited amount of time using --timeout=value option passed during addition command. Value is either number of seconds, minutes if postfixed with m or hours h. For example, adding SSH service for 3 hours:
The applet is not packaged separately from firewalld. The auto start script located at /etc/xdg/autostart/firewall-applet.desktop can be hidden, however: see XDG Autostart#Directories. Alternatively, exclude the file from being installed by adding it to NoExtract in /etc/pacman.conf.
Now - the reason that firewalld is chosen is the fact that UFW is creating issues - at least has been (it has been a while since I touched the subject) - when used in connection with a VPN. You can search the archived forum for topics related to UFW if you would like to confirm it.
Hello, I have questions about the effectiveness of ufw vs firewalld. I personally find firewalld to be more efficient but hard to use. I am curious what the overall consensus is on whether ufw or firewalld should be used and for what reasons. I know that Jay has a video on ufw that I have not watched as I usually just read the man page if I need to use ufw.
AFAIK, both use iptables or nftables backend inside the kernel. UFW is keeping it somewhat simple. FirewallD always seemed to me like a workstation type firewall, with a laptop that changes networks like office, home, public wifi etc., in which you need different firewall profiles (zones). You define what rules apply to which network you are on and firewalld takes care of applying new firewall rulesets.
Hopefully the OP did a little research and went with nftables. It is a lot nicer to work with than iptables, however, iptables is pretty darn straight forward if you edit the rules in a text file with vim. Doing the insert commands is impossible for me except for the most basic rule set. Just backup the file, open it and edit to your hearts content. It is all laid out there and organized. Reads like a book.
In a lot of ways it is easier to edit & comment than a GUI fw. I had one setup with over a couple hundred lines and using iptables in a text file was a breeze. For those reading this if you value your your sanity use a text file to config your rules. And use nftables in 2023.
That works but why add all the code? I like using as little extra code as possible. Every time you add code you extend trust to another person(s). You can do this with maybe 4-5 lines in your nftables config. I can post my config but googling it is easy enough too.
This is particularly why crowdsec is better, because that knowledge can be gathered from others when that happens, so you can potentially avoid all exploit hammering altogether, instead of just preventing the amount of hammering being done.
And doing it on a system (linux) that is used every where and by everybody (not just some of Netflix servers). But again, the nerd in me loves the technical challenge of it, so I understand why you are doing that.
To be as fair as I can be, you are asking for performance differences that are irrelevant in 2023. Security advantages too in a practical aspect. Arguments can be made in both sides, but we are only talking about stuff on the extreme margin.
With both source codes open to the public, any significant improvements get flat lined. At least on the linux side. The biggest issue I see is the developer momentum going towards linux. I wish the BSDs were healthier, but that just seems be getting worse as the years/decades roll on.
I hope you are right about the developer issue with the BSDs. My concern is the economics (monetary, academic, notoriety, etc) of kernel development favor a monopoly, but at least linux is an open source monopoly. Time will tell, but I hope you are right.
Even if I give the benefit of my doubt to grant openbsd a security edge, what are we talking about? Maybe 1%, or if we are being extremely generous 5%. So you learn a whole new OS and fw syntax for 1-5% bump in security? At best. And that is from a base (linux) that is already extremely secure, especially with a little configuration. The juice is not worth the squeeze. And that points back to the problem the BSDs have, even if they are better they are not better enough to change from the default. That goes for users and developers.
My firewall rule is a conditional allow, so skip past that and the default drop will do the same job. Again, even if I grant you the benefit of my doubt and say my rule is inferior. Well, how much better is the alternative? And at what cost (lots of new code running as root)?
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