ModemManager 1.16.2 connection issue for EM7455 Sierra Modem

Aleksander Morgado aleksander at
Mon Jul 5 20:03:39 UTC 2021


> After making more tests and checking the logs more carefully I have found differences between the connection sequence , specifically regarding the bearer options.
> When a bearer is created with no auth options, like following the next command  ( 'allowed-auth' methods are not set):
> mmcli -m 0 --create-bearer="apn=myapn,user=myuser,password= mypassword,ip-type=ipv4"
> If we try to connect afterwards using the recently created bearer:
> mmcli -m 0 -b 0 -c
> Behaviour in ModemManager 1.10:
> ModemManager[5096]: <debug> [1625232197.783697] Using default (PAP) authentication method
> ModemManager[5096]: <debug> [1625232197.783715] Launching ipv4v6 connection with APN
> Behaviour in ModemManager 1.16.2:
> ModemManager[15247]: <debug> [1625483530.597060] [modem0/bearer0] using default (CHAP) authentication method
> ModemManager[15247]: <debug> [1625483530.597085] [modem0/bearer0] launching ipv4 connection with APN ''
> And this is causing my modem to fail when attempting a connection. If I create the bearer in ModemManager 1.16.2 specifying "allowed-auth=pap", it works.
> Therefore, before it was not needed to specify the authentication method if it was PAP, now it seems to be a need.

Ohh, true. Default when none specified was switched to CHAP in 1.16.0:
Quoting from the release notes: "If the connection attempt includes
user/password information but no explicit authentication type, CHAP
will now be used by default instead of PAP."

That change was risky but I believe it made sense; also, ideally the
user should always provide the exact auth type needed, so changing the
default looked like a not very critical thing... sorry for that.


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