Hi!
Check whether this command
# cat /proc/sys/net/ipv4/ip_forward
1
yields 0 or 1. It should be 1.
Do this:
# echo 1 > /proc/sys/net/ipv4/ip_forward
to enable ip forwarding.
This setting won't survive across reboots; for that, edit /etc/sysctl.conf, like this:
net.ipv4.ip_forward = 1
(See
http://www.cyberciti.biz/tips/linux-as-router-for-dsl-t1-line-etc.html for reference).
Hope that it helps.
Cheers!
BTW, are you in Quito?