XTABLES-LEGACY(8)

✨ XTABLES-LEGACY(8) ✨

Okay bestie, the manual name is xtables-legacy, and it's giving "iptables but make it old-school" 💅 It's iptables using the old getsockopt/setsockopt-based kernel API 🦋

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🌸 NAME 🌸

xtables-legacy — iptables using old getsockopt/setsockopt-based kernel API 🎀

💖 DESCRIPTION 💖

okay so, xtables-legacy are the original versions of iptables, and they talk to the kernel through the old getsockopt/setsockopt interface ✨ That interface has some limitations, which is why iptables can also be used with the newer nf_tables based API. For the xtables-nft variants of iptables, check out xtables-nft(8) 🧚

🦋 USAGE 🦋

so the xtables-legacy-multi binary can be linked to the traditional names, like this:

/sbin/iptables -> /sbin/iptables-legacy-multi
/sbin/ip6tables -> /sbin/ip6tables-legacy-multi
/sbin/iptables-save -> /sbin/ip6tables-legacy-multi
/sbin/iptables-restore -> /sbin/ip6tables-legacy-multi

The iptables version string tells you which API you're on, legacy (get/setsockopt) or the new nf_tables one 👀 Check it with:

iptables -V
iptables v1.7 (legacy)

🚨 LIMITATIONS 🚨

⚠️ bestie, this part is important: when you insert a rule with iptables -A or iptables -I, iptables first has to grab the current active ruleset, tweak it to include your new rule, and then commit the result back. So if two instances of iptables are running at the same time, one of the updates might get lost 😭 The --wait option can help with this, but only partially 🙈

also, there's no built-in way to watch for changes to the ruleset 💀 Your only real option is periodically running iptables-legacy-save and checking for differences in the output. xtables-monitor(8) needs the xtables-nft(8) versions to work, so it can't show changes made with the iptables-legacy tools. Not it, not that 💅

🔗 SEE ALSO 🔗

xtables-nft(8), xtables-translate(8) 🫶

👑 AUTHORS 👑

Rusty Russell originally wrote iptables, in early consultation with Michael Neuling. Iconic origin story, no cap 🔥

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💜 Source: System Manager's Manual · xtables-legacy(8) · dated June 2018, periodt ✨