ssh into Raspberry Pi connected via a Huawei E3131 USB modem and prepaid SIM card (orange)

Question

I managed to connect my Raspberry Pi to the Internet (accessing web pages, ssh to a known server,...). Everything works fine.

Now what I would like to do is connecting into the device from a remote network.

The external IP I get is dynamic, but I simply read it using "whatismyip.com" accessed from the raspberry Pi, say it is 231.55.176.169 (this is just an example, not a real IP!)

However when I try:

ssh -l pi 231.55.176.169

or even:

ping 231.55.176.169

from a computer connected to the Internet on a remote network, the connection is not working (timing out). It is as if all outgoing connections were allowed and all incoming connections disabled.

Is this a restriction from my provider (Orange?), a limitation of the Huawei dongle, or am I missing something?

Eventually I would like to use no-ip.com to connect to the Raspberry but before that I need the test above to work.

Answer 1

This is due to the fact the 3g networks typically don't assign a single IP to every terminal device. Effectively, you are behind Orange´s "NAT".

To be able to access it, you need some kind of VPN solution.