vlan_mon and ipoe kernel modules not loaded

[MD1614-TUD]

At present vlan_mon cannot be loaded in the kernel.

[butjar]

Reproduce:

$ docker logs accel-pppd
[2019-06-07 10:52:57.947] accel-ppp version ae4c3be6ba262224a0f934bc980db9a729ba96a6
[2019-06-07 10:52:57.948] genl: error talking to kernel
[2019-06-07 10:52:57]: error: genl: error talking to kernel
[2019-06-07 10:52:57.948] ipoe: unclassified packet handling is disabled
[2019-06-07 10:52:57]:  warn: ipoe: unclassified packet handling is disabled
[2019-06-07 10:52:57.970] genl: error talking to kernel
[2019-06-07 10:52:57]: error: genl: error talking to kernel
[2019-06-07 10:52:57.970] vlan_mon: kernel module is not loaded
[2019-06-07 10:52:57]:  warn: vlan_mon: kernel module is not loaded

[butjar]

I think #7 is related. It seems that accel-ppp uses genl to check if the kernel modules are loaded:
see https://github.com/xebd/accel-ppp/blob/f5d5b536c381db907ac92878221a3790f2f15842/accel-pppd/vlan-mon/vlan_mon.c#L521 ff

[butjar]

Turning on debuging I suspect the error comming from here: https://github.com/xebd/accel-ppp/blob/363ac4b5603e0f18d1e1e3e8466a3983b88ce375/accel-pppd/libnetlink/libnetlink.c#L386

[butjar]

Error message with debug log enabled:

[2019-06-07 13:31:58.400] accel-ppp version ae4c3be6ba262224a0f934bc980db9a729ba96a6
[2019-06-07 13:31:58.401] open ns (null)
[2019-06-07 13:31:58.402] libnetlink: RTNETLINK answers: No such file or directory
[2019-06-07 13:31:58]: debug: libnetlink: RTNETLINK answers: No such file or directory
[2019-06-07 13:31:58.402] genl: error talking to kernel
[2019-06-07 13:31:58]: error: genl: error talking to kernel
[2019-06-07 13:31:58.402] ipoe: unclassified packet handling is disabled
[2019-06-07 13:31:58]:  warn: ipoe: unclassified packet handling is disabled
[2019-06-07 13:31:58.431] libnetlink: RTNETLINK answers: No such file or directory
[2019-06-07 13:31:58.431] genl: error talking to kernel
[2019-06-07 13:31:58]: debug: libnetlink: RTNETLINK answers: No such file or directory
[2019-06-07 13:31:58]: error: genl: error talking to kernel
[2019-06-07 13:31:58.431] vlan_mon: kernel module is not loaded
[2019-06-07 13:31:58]:  warn: vlan_mon: kernel module is not loaded
[2019-06-07 13:31:58.431] ipoe: start interface eth0 ()
[2019-06-07 13:31:58]:  info: ipoe: start interface eth0 ()
[2019-06-07 13:31:58.433] libnetlink: RTNETLINK answers: No such device
[2019-06-07 13:31:58]: debug: libnetlink: RTNETLINK answers: No such device