are you sure the edit you made in /etc/ipf/ipfnat.conf covers the 2 ways of communication?
i.e. does it cover the return path from 10.142.201.71 to your machine? NB: I'm not an expert on NAT!
I would have used an ssh tunnel to achieve the same result:
from the machine where you have firefox or other browser running, in a terminal, run this:
Code:
ssh -f -N -L2081:10.142.201.71:8090 root@10.71.0.228
then access
http://localhost:2081
NB: it's different from your NAT architecture, but at least it lets you access the server.