iptables

["Alexandre Carlos" <alexandre@redes.unb.br>]

Hi all

My experimental backbone is the following:

           67.91  4.2     4.3   1.3   1.1    10.1
             --------        ------       --------
 67.90- | ingress |----| core |----| egrees |-----10.2
             --------         -----        --------


I´m using IPTABLES version 1.2.4-dscp do set up the tos value of the
packets. I´m creating the following rule on the ingress and the egress
hosts.

iptables -A PREROUTING -t mangle -p icmp -j FTOS --set-ftos 0x28 or
iptables -A FORWARD -t mangle -p icmp -j FTOS --set-ftos 0x28

But when i try do ping from 67.90 to 10.2

The chechshum of the ip on the reply message is incorrect, so the packet is
droped on core hosts.

I would like to know, how can i avoid dropping the packet and still using
the same version of iptables and rules

Alex