Automatic APN

[Ben Chan]

On Thu, Nov 15, 2018 at 12:46 AM Aleksander Morgado
<aleksander at aleksander.es> wrote:
>
> Hey,
>
> > My engineering team has been looking at implementing automatic APN detection and I wanted to reach out and see if anyone has thoughts on where(MM/NM) or if this would belong.
> >
> > We're looking at using the Android APN/carrier lookup table via MCC/MNC & IMEI.
> > https://android.googlesource.com/device/sample/+/master/etc/apns-full-conf.xml
> >
> > We've got to do it, I'd like it to go open-source if it can be done without too much hackyness. Thoughts?
>
> We already have our own database here:
> https://gitlab.gnome.org/GNOME/mobile-broadband-provider-info/blob/master/serviceproviders.xml
>
> This database is used e.g. when creating a new network connection for
> a modem via NetworkManager, it allows the user to select which APN to
> use based on the SIM card MCCMNC. Beware, not IMEI, that would be very
> wrong!!!
>
> We don't have an "automatic" selection procedure, because multiple APN
> configurations may match the same MCCMNC, so which one would you use?

There are definitely edge cases, such as MVNOs, where MCCMNC isn't
sufficient for determining the right APN. Other signals like IMSI,
EFspn, EFgid need to be taken into account. Unfortunately, MNOs/MVNOs
tend to choose different approaches. As MNOs merge and split over
time, APNs may change over time.

It'd be much simpler if they all go with one common default APN.
There is another annoying bit, APN authentication, where in many cases
the username and password are just known values and really serve no
purposes :(