DNAT Problems

["Rafael Paris" <raparis@gmail.com>]

Good morning everyone...

I have been trying to have access to my internal mail server from
internet but always get connection timed out.
This is a very short set of rules being used for testing purposes with
no success:

iptables -P FORWARD ACCEPT
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT

iptables -t nat -A PREROUTING -p tcp -i ppp0 -d <external_fixed_ip>
--dport 110 -j DNAT --to-destination <internal_ip:110>
iptables -t nat -A PREROUTING -p tcp -i ppp0 -d <external_fixed_ip>
--dport 25 -j DNAT --to-destination <internal_ip:25>

iptables -t nat -A POSTROUTING -o ppp0 -j SNAT --to <external_fixed_ip>

I'm using one ethernet device with my lan ip address and I can reach
the mail server from this host.
My kernel is 2.6.19.2 with iptables 1.3.7

I also used these rules with kernel 2.4.34 and nothing.

Thanks in advanced for any comments.

Cheers,
Rafael