Re: Setup for multiple different gsm.sim-operator-id?

[Einar Jón <tolvupostur gmail com>]

Hi Dan

You've answered a bunch of my questions on modemmanager-list.
Thanks for your patience.

On Wed, 11 Sep 2019 at 15:14, Dan Williams <dcbw redhat com> wrote:
> On Wed, 2019-09-11 at 13:01 +0200, Einar Jón via networkmanager-list
> wrote:
> > On Wed, 4 Sep 2019 at 22:43, Thomas Haller <thaller redhat com>
> > wrote:
> > > On Wed, 2019-09-04 at 21:59 +0200, Einar Jón wrote:
> > > > On Wed, 4 Sep 2019 at 17:11, Thomas Haller <thaller redhat com>
> > > > wrote:
> > > > > On Wed, 2019-09-04 at 16:46 +0200, Einar Jón via
> > > > > networkmanager-
> > > > > list
> > > > > wrote:
> > [snip]
> > > > > I think that is not possible, you would need a different
> > > > > connection
> > > > > profile for each operator.
> > > >
> > > > I was thinking of doing that, creating profiles
> > > > modem12345.nmconnection
> > > > modem22334.nmconnection
> > > > modem556677.nmconnection
> > > > etc...
> > > >
> > > > But grabbing
> > > > IMSI=$(mmcli -m XX| awk /operator id/ ...)
> > > > and calling
> > > > nmcli c do-stuff modem$IMSI
> > > > seems to be the wrong way to use NetworkManager.
> > >
> > > Hi,
> > >
> > > I think you would create each profile only once.
> > >
> > > Afterwards, you should be able to
> > >
> > >   nmcli device connect $MODEM
> > >
> > > and then (depending on the SIM), only one of the profiles is a
> > > suitable candidate to activate. You can set properties in the
> > > profile
> > > that tie to the operator, can't you?
> > >
> > > The only problem is that you have a larger number of profiles,
> > > and that you need to create them (once).
> >
> > I think we are talking about the same thing. Or I don't understand.
> > My device ($MODEM) is always cdc-wdm0. I have a python script
> > that creates multiple profiles that are identical apart from the
> > [gsm] block that has different values for sim-operator-id, apn
> > (and optional username, password and network-id).
> >
> > I tried the multi-setup stuff, and it is much easier than I thought.
> > So now I have 7 mobileXXXX profiles and NM is smart enough
> > to get the correct one and connect on startup, without even needing
> > nmcli device connect $MODEM
> >
> > $ nmcli connection
> > NAME                UUID                                  TYPE      D
> > EVICE
> > eth0                7f79871d-15ff-446a-b1c3-
> > 5978c81c176b  ethernet  eth0
> > eth1                5317eb97-1514-4852-b120-
> > ab4fa9173350  ethernet  eth1
> > mobile20404         ef48d247-00df-433a-bf6a-
> > 97ad54e3b757  gsm       cdc-wdm0
> > mobile21407         b9d37621-32c9-4073-8848-86dd8814f503  gsm       -
> > -
> > <snip> 4 similar lines <snip>
> > mobile234507        3d473ad6-7a25-4130-bc61-c2e987bcfa2a  gsm       -
> > -
> > Wired connection 1  d82449b5-69e2-33c3-944d-c132881f9052  ethernet  -
> > -
> >
> > So... Now I just need a way to get the connection name. Is there a
> > better way than
> > nmcli c | awk '/cdc-wdm0/ {print $1}'
> > ?
> >
> > And I managed to make a case when none of the profiles connects (set
> > gsm.network-id to a provider that isn't in range).
> > Then it doesn't activate any profile, and it seems like there is no
> > hope to start the modem.
> > This is a feature our customers need, that instead of connecting to
> > the IMSI of the sim card (like 21407), we prefer to roam with
> > operator
> > 12345.
> > If that fails, fall back on normal roaming. Is that doable? Am I
> > using
> > gsm.network-id wrong?
>
> network-id locks that connection to the given operator, and if the
> modem cannot register with that network, then the connection will fail.
> For example, if you are near a border and an international roaming
> provider is stronger than your preferred network, and for whatever
> reason your device always connects to the roaming provider and costs
> you more. That kind of thing.
>
> You could duplicate each connection and leave the network-id empty or
> set to the SIM preferred operator. Then set the autoconnect priority of
> that connection "worse" than the connection for the roaming operator.
> NM should then try the roaming connection first, and if that fails fall
> back to the non-roaming connection.
>
> Does that work for you?

Actually, it seems to work fine. It's a brilliantly stupid solution.
I just added an additional profile roaming${IMSI} without the
network-id, and it works.
$ nmcli c s
NAME           UUID                                  TYPE  DEVICE
roaming21407   b9d37622-32c9-4073-8848-86dd8814f503  gsm   cdc-wdm0
mobile20404    ef48d247-00df-433a-bf6a-97ad54e3b757  gsm   --
mobile21407    b9d37621-32c9-4073-8848-86dd8814f503  gsm   --
....

Since I'm started, I still have a few more questions:
1) How does NetworkMananger decide which connection to try?
I.e. how do I set the priority of mobile21407 higher than roaming21407?
2) I notice that my up, down lines in /etc/network/interfaces.d/wwan0 and
scripts in /etc/network/if-*.d/ are ignored.
How do run extra stuff on ifup/ifdown?
managed=true in the [ifupdown] section doesn't seem to help.
3) NetworkMananger either clobbers /etc/resolv.conf or ignores it.
Is there any way to get NetworkMananger to get along with udhcpc?
I could probably use rc-manager=resolvconf, but then I need to
rework udhcpc and udhcpc6 to work with openresolv, which is a PITA.

-- 
Regards
Einar Jón