// the find
trimstray/iptables-essentials
Iptables Essentials: Common Firewall Rules and Commands.
A reference document — not a library or tool — collecting common iptables rules and sysctl hardening settings in one place. Aimed at sysadmins and developers who manage Linux servers and need a quick command lookup rather than digging through man pages.
The coverage is genuinely broad: basic traffic control, connection tracking, brute-force and SYN flood mitigations, bogus TCP flag drops, and the less-obvious mangle table rules that belong in PREROUTING rather than INPUT. The sysctl section pairs each setting with a concrete explanation of what it actually does, not just what to copy-paste. The NFQUEUE examples with working Python scripts are a cut above most cheatsheets — port knocking via userspace packet inspection is niche but well-executed. Rules consistently use conntrack state matching rather than the deprecated state module, which is the correct modern approach.
The repo is essentially a single README and hasn't been meaningfully updated since 2024, with no tooling to validate that any of these rules actually work as advertised. There is no mention of nftables, which has been the default on most major distros since 2020 and is where Linux firewall development actually happens now — recommending iptables for new setups in 2026 is quietly steering people toward legacy infrastructure. The load balancing section mixes nth and random modules without explaining that nth is deterministic round-robin while random is probabilistic, which matters a lot if you're debugging why traffic isn't balanced. The TODO list has been half-complete for years, which suggests the project is in maintenance-at-best mode.