Netfilter: The Hooks
- You can register with netfilter to see packets at various points
in the stack (similar to old firewall.h hooks).
- For IPv4: PRE_ROUTING, LOCAL_IN, FORWARD, LOCAL_OUT, POST_ROUTING.
- Each hook can alter packets, return NF_DROP, NF_ACCEPT or
NF_QUEUE.
- We can also register new get/setsockopts.
On Top of Netfilter...