Make mobile phone (e.g., Android) USB tethering "just work"

[louies0623]

When the mobile phone is connected to the computer with usb tethering, it does not working the computer to connect to the network.

[probonopd]

Can you please provide specifics: Android/iOS version? Do you see anything related to it when you type dmesg?

[louies0623]

Galaxy A70, android 11, No

[probonopd]

Please check

https://docs.freebsd.org/en/books/handbook/advanced-networking/#network-usb-tethering

[probonopd]

I wonder whether we should set all of

if_urndis_load="YES"
if_cdce_load="YES"
if_ipheth_load="YES"

by default...

[louies0623]

Haven't work.

[probonopd]

Here is a Hardware Probe of someone who is using an Android phone connected via USB and using dhclient ue0:

https://bsd-hardware.info/?probe=8ae819f673

Note the SOV41 RNDIS Communications Control RNDIS Ethernet Data.

https://www.freebsd.org/cgi/man.cgi?query=urndis&sektion=4

So it seems we have at least some support for Android USB tethered phones.

[probonopd]

Tried this, it works for me with an Android phone

• On the Android phone, connect to cellular or to WLAN
• On helloSystem, sudo kldload /boot/kernel/if_urndis.ko
• Attach the Android phone via USB
• On the Android phone, enable "USB Tethering". How to do this may depend on the Android version. In the Android settings app, search for "Tethering". This needs to be switched on manually each time, as it it seems to switch off itself each time the device is disconnected from the computer (to be confirmed). On my phone, the switch to enable this is greyed out until the device is connected to a computer via USB
• sudo dmesg | tail should show ue0: <USB Ethernet> on urndis0
• (Not needed, done automatically?) Enable the network interface with ifconfig ue0 up
• Get an IP address with dhclient ue0 At this point you should be connected.

Note that this works not only for using cellular but also for using the Android device to access WLAN, which might come handy in situations where the WLAN hardware on your device is not supported by FreeBSD yet.

[probonopd]

Now the question is, how can we automate all of this so that no commands need to be typed in by the user?

• Load the kernel module. Can we do so "on the fly" whenever a corresponding device is attached? Otherwise, add in /boot/loader.conf:

  kld_list="<...> if_urndis if_cdce if_ipheth"

For all kernel modules that are not essential for mounting the root device use kld_list, because

kld_list (str) A list of kernel modules to load right after the local disks are mounted. Loading modules at this point in the boot process is much faster than doing it via /boot/loader.conf for those modules not necessary for mounting local disk.

• Run the ifconfig and dhclient commands whenever a ue* device shows up. Probably we can do this with devd(8)? Strangely, the default /etc/devd.conf does not seem to handle these devices?

[probonopd]

Inspecting what udev does when a tethering device is attached with sudo service devd stop && sudo devd -d 2>&1 | grep Executing, then switing on tethering on the Android device shows:

Executing '/etc/pccard_ether $'ue0' start'
Executing '/usr/libexec/hyperv/hyperv_vfattach $'ue0' 0'

So what is missing is sudo service dhclient quietstart ue0. To change that, create /usr/local/etc/devd/android_tethering.conf with the following content (tested):

# DHCP for USB Ethernet devices, e.g., Android phones with USB Tethering
notify 100 {
        match "system"          "ETHERNET";
        match "subsystem"       "(ue)[0-9]+";
        match "type"            "IFATTACH";
        action "/usr/sbin/service dhclient quietstart $subsystem";
};

---

For iOS devices it may be more complicated, as it may be necessary to run usbmuxd(1) (from comms/usbmuxd): https://man.freebsd.org/cgi/man.cgi?query=if_ipheth&sektion=4.