Tethering data allowance from phone to laptop via usb

Question

I don't have a problem doing this, I can use my phone and connect to the data allowance from my sim card and I can also connect my phone to a wireless network. I can then plug my phone into my laptop via a usb cable and I can enable tethering from the phone. I then end up with internet connection on my laptop.

That is all well and good. However, when I click the connected connection on my phone, it comes up as 192.168.0.5 and when I check ifconfig on my laptop, it shows up as 192.168.42.209.

Why is that happening, shouldn't my laptop also be showing at 192.168.0.5 as I am using the internet connection on my laptop via the phone?

This really isn't a problem in terms of using the internet on the laptop via the phone as it works nicely. The problem is when I try to configure my home router to do some port forwarding. My router has an ip address range from 192.168.0.1-254, so I can't port forward using the 192.168.42.209.

I have tried setting up a static ip address for my laptop using the routers ip address range, i.e. I tried 192.168.0.50, and the internet stops working.

I clearly don't understand all this, why is this happening?

So basically, why is the ip address on my phone different to the ip address on my laptop even though i am connecting to the internet on my laptop via the phone, and why does my internet connection stop working on the laptop if I tried giving the laptop a static ip address within the routers ip address range?

I have an old phone with Froyo 2.2 and I have a laptop with Ubuntu 12.04

Answer 1

Let me see if I understand you:

[Router] <--Wifi--> [Phone] <--USB tether --> [PC]

If this is your setup, then what is happening is the Phone is acting like a router. It has multiple ways to connect to the internet (3G and Wifi) and it does not simply bridge the connection for the PC. Instead it does the same thing that your router does, which is NAT, or Network Address Translation. Basically, you have two networks: the network that's connected to the router, and the network that's connected to the phone's USB port (which has only one machine on it). There is probably no easy way to port-forward from your router to your PC in this configuration. The phone is its own computer; it is not a wifi-adapter, even though your PC sees it as just a network device.