Set MC7455 to go throught VPN (tap mode)

IoT Modules
1

Hello,

I’m using sientific datalogger that use an integrated sierra module to communicate.
The MC7455 only autorize communication throught VPN;
I successfully use an OpenVPN cloud server but now, our lab’s IT want to use there homemade VPN (and they’re right).
The thing is, to allow the device to get an IP from the VPN server, in addition with the certificate (client.conf file), you need the MAC address.

But, the module display 2 devices, one seem get an IP but have no MAC address, the other have a MAC address but no IP.

It seem to be somehow related with the integrated proxy to protect the module. But how can I repeat the mac address on both devices wwan0 and wwan 1 ?

I made a straight and short explanation because I’m expect that people know well the stuff, but I can be more specific and detailed if needed.

Bye

2

I used the GobiNet driver in Ubuntu 16, no problem is found for those MAC address:

https://source.sierrawireless.com/resources/airprime/software/usb-drivers-linux-qmi-software-s2,-d-,42n2,-d-,64/#sthash.8WEpkj5G.dpbs



[  102.362928] usb 2-1.1: Product: MC7455
[  102.362934] usb 2-1.1: Manufacturer: Sierra Wireless, Incorporated
[  102.362940] usb 2-1.1: SerialNumber: LQ53010055012345
[  103.147723] usbnet: loading out-of-tree module taints kernel.
[  103.179311] GobiNet: 2020-08-17/SWI_2.64
[  103.180033] GobiNet 2-1.1:1.8 eth1: register 'GobiNet' at usb-0000:00:1d.0-1.1, GobiNet Ethernet Device, 26:db:2e:ff:ac:08
[  103.181464] USB Speed : USB 2.0
[  103.182661] GobiNet 2-1.1:1.10 eth2: register 'GobiNet' at usb-0000:00:1d.0-1.1, GobiNet Ethernet Device, 26:db:2e:ff:ac:0a
[  103.184672] USB Speed : USB 2.0
[  103.184719] usbcore: registered new interface driver GobiNet
[  103.219280] usbcore: registered new interface driver usbserial
[  103.219616] usbcore: registered new interface driver usbserial_generic
[  103.219758] usbserial: USB Serial support registered for generic
[  103.239098] usbcore: registered new interface driver GobiSerial
[  103.239116] usbserial: USB Serial support registered for GobiSerial
[  103.239332] GobiSerial 2-1.1:1.0: GobiSerial converter detected
[  103.239448] usb 2-1.1: GobiSerial converter now attached to ttyUSB0
[  103.239573] GobiSerial 2-1.1:1.2: GobiSerial converter detected
[  103.239651] usb 2-1.1: GobiSerial converter now attached to ttyUSB1
[  103.239977] GobiSerial 2-1.1:1.3: GobiSerial converter detected
[  103.240147] usb 2-1.1: GobiSerial converter now attached to ttyUSB2
[  103.240156] GobiSerial: 2020-08-17/SWI_2.42:GobiSerial
[  103.295353] IPv6: ADDRCONF(NETDEV_UP): eth2: link is not ready
[  103.295498] GobiNet 2-1.1:1.10 eth2: kevent 12 may have been dropped
[  103.295502] IPv6: ADDRCONF(NETDEV_UP): eth2: link is not ready
[  103.305146] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
[  103.305360] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
[  115.620541] creating qcqmi0
[  115.620808] RawIP mode
[  119.052643] creating qcqmi1
[  119.053131] RawIP mode


owner@owner-ThinkPad-X220:~$ ifconfig eth0
eth0      Link encap:Ethernet  HWaddr f0:de:f1:63:3f:7a  
          inet addr:192.168.0.146  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::f2de:f1ff:fe63:3f7a/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:699 errors:0 dropped:0 overruns:0 frame:0
          TX packets:360 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1010319 (1.0 MB)  TX bytes:30611 (30.6 KB)
          Interrupt:20 Memory:d2400000-d2420000 

owner@owner-ThinkPad-X220:~$ ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 26:db:2e:ff:ac:08  
          UP BROADCAST NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

owner@owner-ThinkPad-X220:~$ modinfo GobiSerial | grep version
version:        2020-08-17/SWI_2.42
srcversion:     2395A30B92A702B5F7C46D1
vermagic:       4.4.0-189-generic SMP mod_unload modversions 
owner@owner-ThinkPad-X220:~$ modinfo GobiNet | grep version
version:        2020-08-17/SWI_2.64
srcversion:     5ED702AD99CB9320C5015A4
vermagic:       4.4.0-189-generic SMP mod_unload modversions 
owner@owner-ThinkPad-X220:~$ 


                                                                             
ati3                                                                         
Manufacturer: Sierra Wireless, Incorporated                                  
Model: MC7455                                                                
Revision: SWI9X30C_02.38.00.00 rE3F3E55C03AE94 jenkins 2022/01/13 05:16:00   
MEID: 35907206012345                                                         
ESN: 12800003752, 80000EA8              
IMEI: 35907206012345                  
IMEI SV: 22                             
FSN: LQ530100512345                     
+GCAP: +CGSM                            
                                        

OK
                                                                         
at!entercnd="A710"                                                              
OK                                                                              
at!usbcomp?                                                                     
Config Index: 1                                                                 
Config Type:  1 (Generic)                                                       
Interface bitmask: 0000050D (diag,nmea,modem,rmnet0,rmnet1)                     
                                                                                
OK
3

Hello jyijyi,

thanks for your answer.
I’m not sure to install any new driver 'cause it’s a manufacturer device, I’d like as much as possible not to have to install this on every devices. In a near future we could receive hundred of these and I can’t spend time to custom every device or create an image to install on it.

There must to be a solution with the default installation using the default driver.
But by the way, I don’t know what is exactly my driver, maybe I could find it in order to search somewhere on the net a solution.
How to know which driver is actually used ?

bye

4

You can check in dmesg

5

Weird. But that’s up to you to decide of course.

4G connections are point to point IP tunnels. There is no mac address associated with such a tunnel, obviously. A modem module could have had a permanent mac address programmed for its ethernet inside, but AFAIK the MC7455 doesn’t. It doesn’t need to since it doesn’t support any ethernet emulation modes at all. Only raw IP over USB. No L2 headers anywhere. And therefore no mac address.

This sounds like your module is configured for 2 RMNET functions. This was a documented setting in (a least some) MC7455 firmwares. But I believe it was mostly by accident and never actually supported (could be wrong on this - trying to remember almost 10 years back).

In any case - the driver must be configured for ethernet mode on one of those functions. That’s not going to work with the MC7455. It can only support raw IP. If you look up the mac address you’ll probably see that’s a locally generated random address, invented by the driver. That’s not going to bring you any success wrt your VPN policy.

6

Hi,
thanks for your detailed answer.
Actually our IT manager was able to find the MAC address of the device (the MC7455 or other part, can be more specific) by watching VPN connexion attempt on the openvpn server.
We needed to tinker a bit more to operate a DHCP connexion, but it works now.

It seem to have a really poor speed rate, which is strange, but we’ll continue development and keeping in mind the technical information you give to me !

Bye.