netfilter logging at the NF_IP_POST_ROUTING hook ?

[Shavian Shakes <shavian78@gmail.com>]

New to netfilter/iptables. I am writing a small kernel module using
netfilter hooks. For debugging I need to log the packets at the hooks
NF_IP_POST_ROUTING and NF_IP_PRE_ROUTING.

From what I understand, the iptables chains "INPUT" and "OUTPUT" in
the "filter" table are hooked in at NF_IP_LOCAL_IN and NF_IP_LOCAL_OUT
respectively. So if I try to do something like :

iptables -A OUTPUT  -j ULOG --ulog-nlgroup 1 --ulog-prefix foo 

this will log the packets from the NF_IP_LOCAL_OUT hook. But I would
like to log them from the NF_IP_POST_ROUTING (and  NF_IP_PRE_ROUTING
too) hooks. Is there a simple way to achieve this using
iptables/netfilter?

thanks for any help/pointers.

Shavian. 

ps: I tried to do this (without fully understanding if it will work ):
iptables -A POSTROUTING -t nat  -j ULOG --ulog-nlgroup 1 --ulog-prefix foo
but it didnt..