Comparing Linux-Based Network Firewall Software
Implementing a firewall is crucial for securing your Linux system. There are an array of popular software firewalls to choose from, and each offers unique features. So understanding how these tools compare can help you choose the best firewall for your needs.
In this guide, learn more about each of the most common software firewall tools on Linux and how they compare. When available, follow links to our in-depth guides on each of these tools and compare examples of how each handles common firewall configurations.
Netfilter is a packet-filtering framework included in the Linux kernel (since 2.4.0). This framework provides kernel-level hooks that are used to implement packet filtering and network address and port translation (NAT and NPT). Ultimately, it is this framework that all firewall tools leverage for managing packets.
Low-level tools, like nftables and iptables, are the default interfaces for Netfilter. These tools provide a lot of control over firewall rules but they can also be difficult to learn and work with. You can also find high-level tools, like UFW and firewalld, built on top of these low-level tools. Such high-level tools can further simplify firewall configuration.
Linux utilizes dedicated packet classification tools for users to manage network/firewall rules. These tools — nftables and iptables — are built on Netfilter and provide low-level firewall configurations. They are especially helpful when you need fine-grained control of your network’s package filtering.
nftables has become the default low-level packet classification tool, replacing iptables. Leveraging the Netfilter framework, nftables allows users to configure network rulesets that filter and route packets and ultimately define network traffic.
nftables uses a tables -> chains -> rules structure for managing network rules. Tables organize sets of chains, and each chain consists of a list of rules, processed in order.
Because nftables has superseded iptables, you should opt to use it when possible. The main exception is older Linux systems, many of which do not support nftables. Alternatively, you may prefer a high-level tool like those covered below.
You can learn more about nftables and its usage in our Getting Started with nftables guide.
iptables traditionally filled the space now occupied by nftables. iptables is, like nftables, a low-level tool for packet classification, providing firewall and network traffic management through the configuration of rulesets. iptables uses a similar tables -> chains -> rules hierarchical model as well.
Even though nftables has replaced iptables as the default, some systems, particularly ones using older Linux versions, only support iptables. Unless you are looking for higher-level firewall configuration (see High-Level Firewall Configuration Managers section below), you need to use iptables in those cases.
You can learn more about iptables and how to configure network rules with them in our Controlling Network Traffics with iptables guide.
To some users, low-level tools may prove overly cumbersome. High-level tools offer simpler solutions for implementing firewalls that may better fit your needs. By abstracting lower-level details, these tools can make it easier to manage network rules.
UFW (short for UncomplicatedFirewall) offers firewall management in a user-friendly command-line interface. It comes by default on Ubuntu systems and is typically the go-to choice on Debian and Arch Linux systems as well.
What especially sets UFW apart is the simplicity its commands bring to firewall configuration. Setting up your desired firewall rules and enabling the firewall follows an uncomplicated set of commands.
See more on UFW and steps for getting started in our How to Configure a Firewall with UFW guide.
Firewalld provides an interface for configuring firewall rules both dynamically and persistently. The dynamic configuration feature allows firewalld to set up rules that apply immediately, without having to restart the service or interrupt existing connections. Additionally, firewalld’s zones system provides convenience for categorizing and managing levels of trust.
Firewalld supports most Linux distributions, and it is included by default on RHEL-related systems (e.g., CentOS, Fedora, AlmaLinux, Rocky Linux) and openSUSE.
Take a look at our Configure a Firewall with Firewalld guide to find out more about using firewalld.
Cloud firewall services, like Akamai’s Cloud Firewall, offer a different approach to cloud security and have some advantages over local software firewalls. For instance, Akamai’s Cloud Firewall can configure and manage firewall rules across multiple cloud instances.
That said, cloud firewalls often do not cover all of the features of software firewalls. Typically, a software firewall can offer more configuration options and advanced control of network traffic.
One solution — cloud or software firewall — is likely to better fit your needs than the other. But often you can get the best results by using both together. As an example, you can use a cloud firewall to apply “absolute” network rules across multiple cloud instances and prevent unwanted traffic from ever reaching your servers. Then, use a software firewall to fine-tune your network filtering on each server.
Learn more about cloud firewalls and how they compare to software firewalls in our Comparing Cloud Firewalls to Linux Firewall Software guide.
To further compare the software firewall tools, what follows are a series of example network filtering rules. Each covers a common scenario and shows how each of the four tools above implements the necessary ruleset. These examples offer a sense of how the tools differ, and for even more, you can refer to the guides linked above.
Whether at the outset of configuring a firewall or when revising an existing configuration, it is helpful to get an overview of existing settings.
For firewall configuration, it is crucial to be able to block traffic. The examples that follow first show how to block all traffic, then show the more typical policy configuration — denying incoming traffic and allowing outgoing.
Tighter network security stipulates specifically which IP address has access to the system. Denying incoming traffic by default — as shown above — and adding exceptions as needed helps to ensure access only by known systems.
Each firewall management tool covered here offers an option for blocking traffic from a given IP. Recommended setups and some default policies in these tools may already block all incoming traffic that is not explicitly approved. However, being able to explicitly block a given IP address gives you much more control and may be particularly useful in certain setups.
Allowing traffic on specific ports is common, especially for web servers. Opening ports allow access for SSH connections (port
22) and for web application usage (ports
443), among other use cases.
In addition, the firewall tools covered here can use port specifications alongside IP address specifications. Doing so can ensure even tighter security, relegating incoming traffic from specific addresses to specific ports.
This page was originally published on