I have 2 droplets. Lets say FWserver and APPserver. I want to make sure that all inbound and outbound traffic in my private networking is going via FWserver. on FWserver,eth0 is connected to internet (ip 139.59.x.x) and eth1 is connected internally to private network (10.139.y.y).

on FWserver, I did the following
echo 1 > /proc/sys/net/ipv4/ip_forward
route add -net 10.0.0.0./16 dev eth0
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

From APPserver

I am able to ping and connect to private networking ip 10.139.y.y
However I am unable to reach the public ip 139.59.x.x

I guess that is the first step before I can connect to internet from APPserver via FWsever

Please help. this is urgent for me to setup my private networking

thanks
UK