Nftables vs Iptables: Why Linux Admins Are Making the Switch

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Firewall wall with digital particles.

The End of an Era

For nearly two decades, iptables was the ubiquitous tool for packet filtering on Linux. It was reliable, but it was also a product of its time—designed for a simpler internet and a less modular kernel. In 2025, the transition to nftables is essentially complete. If you are starting a new server build today, sticking with iptables is like building a car with a carburetor in the age of fuel injection.

1. Why Iptables Is Failing the Modern Web

As networking became more complex (IPv6, bridging, ARP, traffic shaping), iptables struggled to scale.

Fragmentation: Iptables is actually four different tools: iptables, ip6tables, arptables, and ebtables. Maintaining four different rule sets is a nightmare for consistency.
Packet-by-Packet Overhead: Iptables rules are verified sequentially for every packet. If you have 1,000 rules, the kernel has to check them one by one.
Destructive Updates: To change even one rule, the iptables utility has to download the entire rule set from the kernel, change it, and upload it back. This causes a “blip” in protection and massive CPU spikes on busy servers.

2. The Nftables Revolution: The Virtual Machine Approach

nftables solves these problems by moving the logic from the user-space utility to a specialized Virtual Machine inside the kernel.

When you run an nft command, it compiles your human-readable rule into byte-code. The kernel’s nf_tables engine then executes this byte-code. This is fundamentally more efficient because the kernel no longer has to “comprehend” rules; it just executes pre-compiled tasks.

Side-by-Side Syntax Comparison

Feature	Iptables Syntax	Nftables Syntax
Add Rule	`iptables -A INPUT -p tcp --dport 80 -j ACCEPT`	`nft add rule ip filter input tcp dport 80 accept`
Drop Source IP	`iptables -A INPUT -s 1.2.3.4 -j DROP`	`nft add rule ip filter input ip saddr 1.2.3.4 drop`
View Rules	`iptables -L -n -v`	`nft list ruleset`
Unified Table	Impossible (IPv4 and IPv6 are separate)	`nft add table inet my_table` (Handles both!)

3. High-Performance Features of Nftables

Incremental Updates

Unlike its predecessor, nftables supports atomic, live updates. You can push a single rule into the kernel without affecting existing connections or putting load on the CPU.

Set-Based Matching

One of the most powerful features of nft is the use of Sets. In iptables, if you wanted to block 100 IPs, you needed 100 rules. In nftables, you create one set and one rule:

nft add set ip filter banned_ips { type ipv4_addr; }
nft add rule ip filter input ip saddr @banned_ips drop

This is drastically faster because the kernel uses a hash table or a red-black tree to check the set in $O(1)$ or $O(\log n)$ time, rather than checking 100 rules sequentially.

4. A Modern Web Server Config (`nftables.conf`)

Here is what a robust, modern firewall config looks like in nftables syntax:

table inet filter {
    chain input {
        type filter hook input priority 0; policy drop;

        # Allow established connections (crucial!)
        ct state established,related accept

        # Allow loopback
        iif lo accept

        # Allow SSH and Web
        tcp dport { 22, 80, 443 } accept

        # Accept ICMP (Ping) with rate limiting
        icmp type echo-request limit rate 5/second accept
    }
}

Conclusion: Should You Switch?

If you are on Debian 10+, Ubuntu 20.04+, RHEL 8+, or Arch, the “switch” has already happened behind the scenes. Your iptables commands are likely being translated to nftables by the kernel.

However, to gain the performance benefits of sets, unified tables, and incremental updates, you must discard the legacy wrapper and learn the nft language. It’s cleaner, faster, and built for the next 20 years of Linux networking.