Raspberry Pi Internet Wifi to USB Adapter (wlan0 (pi) -> usb0 -> pc)

Raspberry Pi Internet Wifi to USB Adapter (wlan0 (pi) -> usb0 -> pc).md

Guide to connecting to wireless internet via raspberry pi!

Based on https://www.hardill.me.uk/wordpress/2019/11/02/pi4-usb-c-gadget/

Tested on DietPi (Janurary 2023) on a RPI Zero W.

Setting up your Pi

Download and install the latest DietPi and enable wifi configurations etc. Setup can be done headlessly - look in the boot partition of the sdcard

Setting up the usb ethernet

• Add dtoverlay=dwc2 to the /boot/config.txt
• Add modules-load=dwc2 to the end of /boot/cmdline.txt

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• Add libcomposite to /etc/modules
• (Rasberry Pi OS ONLY) Add denyinterfaces usb0 to /etc/dhcpcd.conf

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• Install iptables and dnsmasq with: apt install dnsmasq iptables
• Create /etc/dnsmasq.d/usb with following content

interface=usb0
dhcp-range=10.55.0.2,10.55.0.6,255.255.255.248,1h
dhcp-option=3,10.55.0.1
dhcp-option=6,9.9.9.9
leasefile-ro

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• Create /etc/network/interfaces.d/usb0 with the following content

auto usb0
allow-hotplug usb0
iface usb0 inet static
  address 10.55.0.1
  netmask 255.255.255.248

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Create /opt/usb.sh with the following content

#!/bin/bash
cd /sys/kernel/config/usb_gadget/
mkdir -p pi
cd pi
echo 0x1d6b > idVendor # Linux Foundation
echo 0x0104 > idProduct # Multifunction Composite Gadget
echo 0x0100 > bcdDevice # v1.0.0
echo 0x0200 > bcdUSB # USB2
echo 0xEF > bDeviceClass
echo 0x02 > bDeviceSubClass
echo 0x01 > bDeviceProtocol
mkdir -p strings/0x409
echo "fedcba9876543211" > strings/0x409/serialnumber
echo "Raspberry Pi" > strings/0x409/manufacturer
echo "PI USB Device" > strings/0x409/product
mkdir -p configs/c.1/strings/0x409
echo "Config 1: ECM network" > configs/c.1/strings/0x409/configuration
echo 250 > configs/c.1/MaxPower
# Add functions here
# see gadget configurations below
# End functions
mkdir -p functions/ecm.usb0
HOST="00:dc:c8:f7:75:14" # "HostPC"
SELF="00:dd:dc:eb:6d:a1" # "BadUSB"
echo $HOST > functions/ecm.usb0/host_addr
echo $SELF > functions/ecm.usb0/dev_addr
ln -s functions/ecm.usb0 configs/c.1/
udevadm settle -t 5 || :
ls /sys/class/udc > UDC
ifup usb0
service dnsmasq restart

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
iptables -A FORWARD -i wlan0 -o usb0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i usb0 -o wlan0 -j ACCEPT

• Make /opt/usb.sh executable with sudo chmod +x /opt/usb.sh

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• Add that script to /etc/rc.local:

#!/bin/bash
/opt/usb.sh
exit 0

• Make rc.local executable sudo chmod +x /etc/rc.local
• And reboot to finish!

Done! Enjoy your RPI Wifi Adapter

A few things to note:

• You can ssh into the rpi at dietpi@10.55.0.1
• This is designed for Linux clients - untested on windows etc.
• This guide should work with the following PIs:
  • Zero (although not that useful because no wifi)
  • Zero W
  • Zero 2 (aka 2W)
  • 4B (aka 4)