help needed in n/w

Hi all,

Iam new to netfilters and iam trying to play around to
understand a few things. By default when no policies are specified then it allows all traffic to go out and in to the n/w. I want to change this to default as deny.
That is when there is no policy all should be default deny.

So in order to achieve that i tried to change the code a little.
In the file iptable_filter.c there is a variable called
static int forward = NF_ACCEPT
I changed this to NF_DROP and when i compiled and used it
sure i was not able to send any or recv any packets
but even after i give a policy like iptables -t filter -A
INPUT -j ACCEPT
Nothing changes. So achieve what i want what should i do?
And where do i change?

Another thing is that in normally when i put a policy like
iptables -t filter -A OUTPUT -j REJECT
Even my own self IP doesnt ping? Why should this happen?
Isint it ok to ping local ip and loopback ip?
If i want such implementation where i should be able to
ping to self and local but not any other ip?
Is it possible?
I dont want to add policies rather is it possible just by
changing the iptables kernel code?

Please help me on this?

Varun