Detecting if a mobile phone internet is used by a connection to pc?

Question

Just wondering how phone/internet providers can detect if a mobile phone's internet connection is used as a modem connected to a computer, or just browsing internet by itself?

Is that information stored in packets, if so what type of packets and how does it look?

Thanks.

Answer 1

Yes, it most likely is stored in the IPv4 Packet header. You will probably find that the providers can examine the TTL (Time-To-Live). Detecting a TTL difference from that set as the default on the device you have, they should be able to sort out your packets as either originating from the mobile device or from a network device beyond it.

Note, you can obviously fake this if you know what your doing (and as long the default isn't 255, due to it being an 8bit field), so it is not a guaranteed solution.

Outside of this, they could always inspect the User-Agent strings on any HTTP requests to see if you are using a PC-based browser. Once again, this is obviously not a guaranteed solution if someone is determined enough to change all this.