Is it possible to access a computer connected to the internet through an Android phone? (the internet goes through the phone by tethering)

I want to use ssh to connect to the computer (from a different computer in the same network), but I am not able to access the computer.

Is it possible to portforward, use some kind of transparent proxy or to use DMZ?

My phone is rooted and I have Cyanogenmod installed and I can use iptables.

EDIT: The changed title completely changed the question!

My setup is the following: I have an android phone connected to a computer through the usb cable tethering internet from the phone, I wanted to ssh into the computer behind the android phone from another computer in the same network as the android phone. This was not possible, because the android phone creates a separate network for the connected computer, effectively shielding it from any incoming signals.

It turned out to be quite simple to fix by just using iptables.