cybersecuritysecurity

nftables

nftablessecurityfirewall
Plain English

nftables is the firewall engine inside the Linux kernel. Tools like UFW and Docker write rules into it; nft lets you see or write them directly.

Technical Definition

nftables organises rules into tables, chains (hooked at input, forward, output, prerouting, postrouting) and rules.

  • sudo nft list ruleset shows everything.
  • iptables on Ubuntu is iptables-nft, which translates into nftables.
  • Supports sets and maps for fast matching.

Source: nft(8)

nftables in practice

$ sudo nft list ruleset | head
$ sudo iptables -V
iptables v1.8.11 (nf_tables)
In the Wild

You rarely write nft by hand on Ubuntu, but listing the ruleset explains why traffic passes or drops when ufw and Docker both add rules.

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