When a router forwards traffic between two interfaces (such as from LAN to WAN), it uses the forward chain. HTTP traffic initiated by users destined to external servers passes through this chain.
* A.#prerouting - Used mainly for routing decisions and NAT, not filtering.
* B.#forward - Used to filter transit traffic.
* C.#output - For traffic originating from the router itself.
* D.#input - For traffic destined to the router itself.
Extract from MTCNA Course Material - Firewall Chains:
"Client-to-server traffic, like browsing the web, passes through the forward chain when routed through the router." Extract from Rene Meneses Study Guide - Firewall Structure:
"To block or allow traffic passing through the router (LAN to Internet), use the forward chain." Extract from MikroTik Wiki - Firewall Filtering Overview:
"forward: filters all transit traffic routed through the router."