Currently I have a computer which is connected to the internet (via ppp0) and dhcp server (via eth0) (Debian 6.0.3). The dhcp server IP address is 192.168.2.1. On the other hand I have another computer which is also connected to the server with IP: 192.168.2.167. I want to do port forwarding from the internal port 16000 of the 192.168.2.167 to the external port 13201 which is of ppp0. I tried the iptables command meant for this operating in Debian but nmap can't see port 13201 opened. Does anyone know why it is not do port forwarding.