A simpler packet filter
Save and Restore
Similar to iptables, the nftables configuration can be saved to a file. Line 1 in Listing 4 writes the current ruleset to the firewall.config
file, and line 2 reads the configuration back in.
Listing 4
Saving nftables Configuration
01 # nft list ruleset > firewall.config 02 # nft -f firewall.config
To make sure that there are no other (possibly interfering) rules left in the cache before initializing the firewall, you should add the line flush ruleset
at the beginning of the configuration file firewall.config
.
Creatures of habit, humans have a hard time with change. To help out with the transition from iptables to nft
, the iptables-translate
and ip6tables-translate
commands convert the spelling of iptables firewall rules to those of nftables (Listing 5). This works for both individual instructions and complete rulesets.
Listing 5
Converting Rules
$ iptables-translate -A INPUT -p tcp --dport 22 -m conntrack --ctstate NEW -j ACCEPT nft add rule ip filter INPUT tcp dport 22 ct state new counter accept $ ip6tables-translate -A FORWARD -i eth0 -o eth3 -p udp -m multiport --dports 111,222 -j ACCEPT nft add rule ip6 filter FORWARD iifname eth0 oifname eth3 meta l4proto udp udp dport { 111,222} counter accept
Conclusions
Nftables helps to group several complex tools under a common umbrella, making it easier to secure the network. To thoroughly test the new firewall ruleset, you can, for example, use a bunch of Raspberry Pis on a small, dedicated network. Alternatively, you can create a virtual test network using VirtualBox or the smart Mininet [16] application.
Acknowledgements
The author would like to thank Axel Beckert and Werner Heuser for feedback during the preparation of this article.
Infos
- LPIC-2: https://www.lpi.org/our-certifications/lpic-2-overview
- netfilter project: https://netfilter.org
- IPFilter: https://en.wikipedia.org/wiki/IPFilter
- nftables: https://netfilter.org/projects/nftables
- "What comes after iptables?": https://developers.redhat.com/blog/2016/10/28/what-comes-after-iptables-its-successor-of-course-nftables
- "Why you will love nftables": https://home.regit.org/2014/01/why-you-will-love-nftables
- Debian relies on nftables: https://wiki.debian.org/nftables
- "Hello nftables, Goodbye iptables": https://linuxnewbieguide.org/hello-nftables-goodbye-iptables
- libmnl: https://git.netfilter.org/libmnl
- libnftnl: https://git.netfilter.org/libnfnetlink
- "IPtables vs. nftables": https://digitalglarus.ch/en-us/cms/blog/2018/08/19/iptables-vs-nftables
- BPF: https://en.wikipedia.org/wiki/Berkeley_Packet_Filter
- tcpdump: https://www.tcpdump.org
- "Differences between iptables and nftables explained": https://linux-audit.com/differences-between-iptables-and-nftables-explained/
- ISO/OSI specification: https://en.wikipedia.org/wiki/OSI_model
- Mininet: http://mininet.org
« Previous 1 2
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Endless OS 6 has Arrived
After more than a year since the last update, the latest release of Endless OS is now available for general usage.
-
Fedora Asahi 40 Remix Available for Macs with Apple Silicon
If you've been anticipating KDE's Plasma 6 for your Apple Silicon-powered Mac, then you're in luck.
-
Red Hat Adds New Deployment Option for Enterprise Linux Platforms
Red Hat has re-imagined enterprise Linux for an AI future with Image Mode.
-
OSJH and LPI Release 2024 Open Source Pros Job Survey Results
See what open source professionals look for in a new role.
-
Proton 9.0-1 Released to Improve Gaming with Steam
The latest release of Proton 9 adds several improvements and fixes an issue that has been problematic for Linux users.
-
So Long Neofetch and Thanks for the Info
Today is a day that every Linux user who enjoys bragging about their system(s) will mourn, as Neofetch has come to an end.
-
Ubuntu 24.04 Comes with a “Flaw"
If you're thinking you might want to upgrade from your current Ubuntu release to the latest, there's something you might want to consider before doing so.
-
Canonical Releases Ubuntu 24.04
After a brief pause because of the XZ vulnerability, Ubuntu 24.04 is now available for install.
-
Linux Servers Targeted by Akira Ransomware
A group of bad actors who have already extorted $42 million have their sights set on the Linux platform.
-
TUXEDO Computers Unveils Linux Laptop Featuring AMD Ryzen CPU
This latest release is the first laptop to include the new CPU from Ryzen and Linux preinstalled.