[OpenWrt Wiki] Firewall overview
https://openwrt.org/docs/guide-user/firewall/overview02.08.2021 · Firewall overview OpenWrt uses the firewall3 (fw3) netfilter/iptable rule builder application. It runs in user-space to parse a configuration file into a set of iptables rules, sending each to the kernel netfilter modules. fw3 purpose The netfilter rule set can be very complex for a typical router. This is by necessity; each rule is tailored to a discrete capability provided by the …