USB ethernet gadget on Raspberry Pi OS example compatible with Windows 10 1709+ (driverless), MacOS, iOS 13+, Android

1. USB ethernet gadget on Raspberry Pi OS example compatible with Windows 10 1709+ (driverless), MacOS, iOS 13+, Android.md

USB ethernet gadget on Raspberry Pi OS compatible with:

• Windows 10 1709+ (driverless)
• MacOS
• iOS 13+
• Android (RNDIS is used for Android 6 and below) *1
• ChromeOS *2
• Linux 4.x+ *2

*1 Android will not request for an IP address if gateway is empty or internet is not found after the first connection, requiring a reboot. To mitigate, add captive portal redirect page or toggle airplane mode.

References:

https://jordemort.dev/blog/why-android-cant-use-cdc-ethernet/

https://news.ycombinator.com/item?id=44219405#:~:text=I%20wrote%20this,a%20CDC%20adapter)

TODO

• *2 Prefer EEM/ECM for Linux by taking down RNDIS on link up hotplug event

2. dietpi-usb-gadget-pizero2.sh

#!/bin/sh
set -e

BOOT_CFG="/boot/firmware/config.txt"
CMDLINE="/boot/firmware/cmdline.txt"

grep -q '^dtoverlay=dwc2' "$BOOT_CFG" 2>/dev/null || echo 'dtoverlay=dwc2' >> "$BOOT_CFG"

if [ -f "$CMDLINE" ]; then
    grep -q 'dwc2' "$CMDLINE" || sed -i '1 s/$/ modules-load=dwc2,libcomposite/' "$CMDLINE"
fi

cat >/usr/local/sbin/usb-gadget.sh <<'SH'
#!/bin/sh
set -e

CONFIGFS=/sys/kernel/config/usb_gadget
G=custom

mountpoint -q /sys/kernel/config || mount -t configfs none /sys/kernel/config

modprobe libcomposite

cd "$CONFIGFS"

if [ -d "$G" ]; then
    echo "" > "$G/UDC" 2>/dev/null || true
    sleep 1
    rm -rf "$G"
fi

mkdir "$G"
cd "$G"

echo "0x0200" > bcdUSB
echo "0x02" > bDeviceClass
echo "0x00" > bDeviceSubClass
echo "0x3066" > bcdDevice
echo 0x1d6b > idVendor
echo 0x0104 > idProduct

mkdir -p strings/0x409
echo "9112473" > strings/0x409/serialnumber
echo "Example" > strings/0x409/manufacturer
echo "Example Pi Edition" > strings/0x409/product

mkdir -p configs/c.1/strings/0x409
echo "CDC ECM+RNDIS" > configs/c.1/strings/0x409/configuration

mkdir -p functions/ecm.usb0
mkdir -p functions/rndis.usb0

echo "RNDIS" > functions/rndis.usb0/os_desc/interface.rndis/compatible_id
echo "5162001" > functions/rndis.usb0/os_desc/interface.rndis/sub_compatible_id

echo "b8:27:eb:c3:ba:09" > functions/rndis.usb0/host_addr
echo "f0:fe:9f:95:db:0a" > functions/rndis.usb0/dev_addr

echo "b8:27:eb:e8:05:0f" > functions/ecm.usb0/host_addr
echo "e4:d5:8e:eb:20:36" > functions/ecm.usb0/dev_addr

ln -s functions/rndis.usb0 configs/c.1/ 2>/dev/null || true
ln -s functions/ecm.usb0 configs/c.1/ 2>/dev/null || true

mkdir -p os_desc
ln -s configs/c.1 os_desc/c.1 2>/dev/null || true

echo 0x00 > bDeviceClass

for i in $(seq 1 50); do
    UDC=$(ls /sys/class/udc 2>/dev/null || true)
    [ -n "$UDC" ] && break
    sleep 0.1
done

echo "$UDC" > UDC

ip link add name br-usb type bridge 2>/dev/null || true
ip link set br-usb up 2>/dev/null || true
ip link set usb0 up 2>/dev/null || true
ip link set usb1 up 2>/dev/null || true
ip link set usb0 master br-usb 2>/dev/null || true
ip link set usb1 master br-usb 2>/dev/null || true

ip addr add 10.0.95.1/29 dev br-usb 2>/dev/null || true
SH

chmod +x /usr/local/sbin/usb-gadget.sh

cat >/etc/systemd/system/usb-gadget.service <<'SRV'
[Unit]
Description=USB Gadget ECM+RNDIS Bridge
After=systemd-modules-load.service local-fs.target

[Service]
Type=oneshot
ExecStart=/usr/local/sbin/usb-gadget.sh
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target
SRV

systemctl daemon-reload
systemctl enable usb-gadget.service
systemctl start usb-gadget.service

3. optional-dhcp.conf

#/etc/dnsmasq.d/usb-interfaces.conf

#Android won't setup routes without DHCP IPv4 on some phones, IPv6 only does not work.

interface=br-usb
dhcp-range=10.0.98.10,10.0.98.200,12h

bind-interfaces