Hello everybody!,
I have a doubt about this, because when i set up a machine to forward packets with IP_FORWARD module, it just decreases the TTL, and forwards the packet to the target.
But when i use iptables filters and NAT, i have to disable ICMP Redirects, because other routers consider it a "router", and they send redirects to client hosts in the network.
In neither cases the host uses routing protocols or something like that, so, what's the difference between them? What does iptables or NAT do to make the other routers consider the host a "router" and what IP_FORWARD module does not?