Exploring the new nftables firewall tool – a successor to iptables

Save and Restore

As with iptables, the nftables configuration can be saved to a file. The first command from Listing 4 writes the current ruleset to the firewall.config file, while the second command reads the configuration again.

Listing 4

Writing the Ruleset to a File

# nft list ruleset > firewall.config
# nft -f firewall.config

To make sure that there are no other (possibly interfering) rules in the cache before initializing the firewall, add a line that reads flush ruleset at the beginning of the firewall.config configuration file.

Translation

Humans are known to be creatures of habit who have difficulty with change. The iptables-translate and ip6tables-translate commands are two tools that help you get used to the new environment. These commands convert the nomenclature of iptables firewall rules to nftables format (Listing 5). You can convert both for individual statements and complete rulesets.

Listing 5

Converting Iptables 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 you accommodate several complex tools under one roof, thus making it easier to secure the network. You'll want to try out the new firewall rules before you deploy them on your network. One option is to create a virtual test network using VirtualBox or the smart application Mininet [12]. Or, you could set up a pack of Raspberry Pis on a small, isolated network to simulate a real-world configuration.

Acknowledgements

The author thanks Axel Beckert and Werner Heuser for their suggestions and criticism during the preparation of the article.

The Author

Frank Hofmann works on the road, preferably in Berlin, Geneva, and Cape Town, as a developer, trainer, and author. He is coauthor of the Debian Package Management Book (http://www.dpmb.org/index.en.html).

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
 
SUBSCRIPTIONS
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • New Kernel Firewall Nftables to Succeed Netfilter

    The Netfilter team has long been mulling over rework of firewall code in the Linux kernel. Now team lead Patrick McHardy ends months of work by announcing nftables.

  • Persistent iptables

    The Linux iptables packet filter lacks an easy way to load rules automatically after restarting a system, but you can automate this process several ways.

  • FAQ

    Nftables promises to be the future of Linux firewalls. Meet iptables' replacement.

  • Netfilter's Recent Module

    Netfilter’s Recent module builds a temporary blacklist to keep intruders off your network.

  • KTools: KMyFirewall

    Linux has a fantastic selection of firewalls for securing stand-alone computers or whole networks. Although you can use IPTables to set up a firewall, the configuration is often the most difficult step. KMyFirewall offers a powerful, user-friendly, GUI-based approach.

comments powered by Disqus

Direct Download

Read full article as PDF:

Price $2.95

News