I have a ZTE MF 823 4G stick which was working on an older version of IPFire for quite a long time now on a Raspberry PI B+ board. Some time ago, after updating IPFire from version 2.19 (core update 120) to a newer version which required a fresh install, I noticed, that the stick was not working as expected on the new IPFire version. Not having time to debug the issue, I reverted everything back to the working version and everything was fine.
Now the Raspberry PI board died (problems with USB power continuously resetting connecting USB devices), and I had no other choice, than to pick up a newer Raspberry PI’s and try it again.
The problem I am facing (even with IPFire 2.25 - core update 145) is, that the ZTE stick gets a new random MAC address at every reboot. This prevents the network configuration from finding the red0 device, resulting in:
Bringing up the red0 interface…
Interface red0 doesn’t exist.
If I run setup, remove red0 and re-add it again, everything works fine until the next reboot.
There have been other forum posts in the past, but I think they never realized, what caused the error.
https://forum.ipfire.org/viewtopic.php?f=27&t=20589&p=122253&hilit=zte#p122253
and
https://forum.ipfire.org/viewtopic.php?f=6&t=15281&p=127695&hilit=zte#p127695
As I didn’t get anywhere with this issue, I searched for other ways to use the stick. I found, that by setting it to “FACTORY” mode, I can use it as a dialup modem. This change survives a power failure or reboot, but the issue I am facing here is that after successfully connecting, the ppp0 device cannot be bridged:
Jun 11 08:34:51 firepdg chat[14882]: timeout set to 3 seconds
Jun 11 08:34:51 firepdg chat[14882]: report (CONNECT)
Jun 11 08:34:51 firepdg chat[14882]: abort on (\nBUSY\r)
Jun 11 08:34:51 firepdg chat[14882]: abort on (\nNO ANSWER\r)
Jun 11 08:34:51 firepdg chat[14882]: abort on (\nRINGING\r\n\r\nRINGING\r)
Jun 11 08:34:51 firepdg chat[14882]: abort on (\nNO CARRIER\r)
Jun 11 08:34:51 firepdg chat[14882]: send (+++ATZ^M)
Jun 11 08:34:51 firepdg chat[14882]: send (AT+ZOPRT=5^M)
Jun 11 08:34:51 firepdg chat[14882]: send (+++ATZ^M)
Jun 11 08:34:52 firepdg chat[14882]: expect (OK)
Jun 11 08:34:52 firepdg chat[14882]: ATZ^M^M
Jun 11 08:34:52 firepdg chat[14882]: OK
Jun 11 08:34:52 firepdg chat[14882]: – got it
Jun 11 08:34:52 firepdg chat[14882]: send (ATH0^M)
Jun 11 08:34:52 firepdg chat[14882]: expect (OK)
Jun 11 08:34:52 firepdg chat[14882]: ^M
Jun 11 08:34:52 firepdg chat[14882]: AT+ZOPRT=5^M^M
Jun 11 08:34:52 firepdg chat[14882]: OK
Jun 11 08:34:52 firepdg chat[14882]: – got it
Jun 11 08:34:52 firepdg chat[14882]: send (ATM0^M)
Jun 11 08:34:52 firepdg chat[14882]: expect (OK)
Jun 11 08:34:52 firepdg chat[14882]: ^M
Jun 11 08:34:52 firepdg chat[14882]: ATZ^M^M
Jun 11 08:34:52 firepdg chat[14882]: OK
Jun 11 08:34:52 firepdg chat[14882]: – got it
Jun 11 08:34:52 firepdg chat[14882]: send (AT+ZCDRUN=8^M)
Jun 11 08:34:52 firepdg chat[14882]: send (AT+CGDCONT=4,“IP”,“iliad”,0,0^M)
Jun 11 08:34:52 firepdg chat[14882]: send (sleep 5^M)
Jun 11 08:34:52 firepdg chat[14882]: timeout set to 45 seconds
Jun 11 08:34:52 firepdg chat[14882]: expect (OK)
Jun 11 08:34:52 firepdg chat[14882]: ^M
Jun 11 08:34:52 firepdg chat[14882]: ATH0^M^M
Jun 11 08:34:52 firepdg chat[14882]: OK
Jun 11 08:34:52 firepdg chat[14882]: – got it
Jun 11 08:34:52 firepdg chat[14882]: send (dATDT99#^M)
Jun 11 08:34:52 firepdg chat[14882]: expect (CONNECT)
Jun 11 08:34:52 firepdg chat[14882]: ^M
Jun 11 08:34:52 firepdg chat[14882]: ATM0^M^M
Jun 11 08:34:52 firepdg chat[14882]: OK^M
Jun 11 08:34:52 firepdg chat[14882]: AT+ZCDRUN=8^M^M
Jun 11 08:34:52 firepdg chat[14882]: Close autorun state result(0:FAIL 1:SUCCESS):1^M
Jun 11 08:34:52 firepdg chat[14882]: ^M
Jun 11 08:34:52 firepdg chat[14882]: OK^M
Jun 11 08:34:52 firepdg chat[14882]: AT+CGDCONT=4,“IP”,“iliad”,0,0^M^M
Jun 11 08:34:52 firepdg chat[14882]: OK^M
Jun 11 08:34:52 firepdg chat[14882]: ATDT99#^M^M
Jun 11 08:34:52 firepdg chat[14882]: CONNECT
Jun 11 08:34:52 firepdg chat[14882]: – got it
Jun 11 08:34:52 firepdg chat[14882]: send ()
Jun 11 08:34:52 firepdg pppd[14858]: Serial connection established.
Jun 11 08:34:52 firepdg pppd[14858]: Using interface ppp0
Jun 11 08:34:52 firepdg pppd[14858]: Connect: ppp0 <–> /dev/ttyUSB2
Jun 11 08:34:53 firepdg root: Could not find a bridged zone for ppp0
Jun 11 08:34:53 firepdg codel: Codel AQM has been enabled on ‘ppp0’.
Jun 11 08:34:53 firepdg pppd[14858]: CHAP authentication succeeded
Jun 11 08:34:53 firepdg pppd[14858]: CHAP authentication succeeded
Jun 11 08:34:55 firepdg vnstatd[1284]: Interface “ppp0” enabled.
This could be anything else, too, because I really have no experience with setting up dialup modems anymore 
What could be done to prevent the stick from changing MAC address at every boot?
Is there a way to tell IPFire to ignore MAC address binding for the RED interface?
What is causing IPFire in dialup mode to not work as expected?
Bye,
Oskar