[nos-bbs] iptables help...

[jerome schatten]

Hi...

I'm trying to write some firewall rules to keep the bad guys out of my 
jnos  system running on a Raspberry Pi.  So far, I've been reasonably 
successful -- nice improvements, but I've hit a brick wall.

I'm stuck trying to write a rule that does the following:

In the FORWARD chain, take an IPIP ( protocol 4) packet that is found on 
the jnos side of tun0 interface and examine the encapsulated source 
address.  If it is not a 44.0.0.0/8 address, drop it; if it is, send it on.

There are ipip packets that appear on the jnos side of tun0 that are 
encapping a commercial ip address with another commercial ip address and 
then targeting my 44 address -- this is what I'm trying to get rid of at 
the moment.

Maybe this is not possible with iptables?

Ideas?

Thanks
jerome - ve7ass