[Replicant] Question regarding a freedom respecting modem

Denis 'GNUtoo' Carikli GNUtoo at cyberdimension.org
Mon May 10 15:38:28 UTC 2021


On Tue, 4 May 2021 12:20:16 +0000 (UTC)
m d <mdreplicantmd at yahoo.com> wrote:

> ##It's rather related to the cellular network architecture: you are
> ##connected to a given antenna / base station that knows at what
> distance ##of it you are. In addition you might move so there is a
> feature ##called handover that enables you to switch form one base
> station to the ##next one while moving. So you then have multiple
> base stations that ##knows the distance between you and them. With
> that it's trivial to get ##your position.
> 
> OK, is that distance known to the network via the RSSI?
> I think this handover feature might be somewhat related to this
> "triangulation" method, in which case what if the device remains
> static from within a building next to a window. Is it possible that
> the station could only connect to 1 base without providing distance
> information between the other ones?
I'm not an expert on that, as I lack low level knowledge on the
standards like GSM, GPRS, 3G, etc. 

If I recall well, the device sends distance measurements, but it's not
magic either as you probably cannot fake the distance too much else it
would probably stop working.

> ##I'm also unsure if there are more ways than the IMEI to identify
> ##devices. It's for instance possible to identify the family of WiFi
> ##chips being used just by looking at what is being transmitted. So it
> ##may be possible to still get some identifying information out of the
> ##device even if the IMEI has been changed.
> 
> Radio fingerprinting pointed above?
Yes, I wasn't aware of any papers for GSM. Thanks for the link, I'll try
to find the time to read it.

> One more thing, is the function to hide caller ID one of proprietary
> software? I'm unable to hide my caller ID on Replicant although the
> function was working as expected with proprietary ROMS. 

That's probably because it's not implemented yet.

There is some rough information on what is implemented and what is not
here:
https://redmine.replicant.us/projects/replicant/wiki/Libsamsung-ril

That list doesn't take into account the libsamsung-ipc part and how
things are implemented, so it's not very reliable but it still gives a
rough idea of the status.

Having a complete implementation could also enable projects like
LineageOS to reuse libsamsung-ipc and libsamsung-ril. 

This could then benefit the GNU/Linux distributions that use vendor
kernels too (or even upstream kernel once we make it work with that).

Denis.
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