Sharing Internet Connection with Embedded Devices

As an engineer working with embedded devices, I’ve often encountered situations where I needed to update Docker images on devices like the Jetson Xavier, which lacked a WiFi card due to size constraints in our DAQ kit. After hours of searching for a solution, I’ve compiled this guide to help others facing similar challenges. There are two main methods to share your laptop’s internet connection with an embedded device connected via Ethernet:

1. Bridging: This method places the embedded device on the same local subnet as your laptop.
2. NAT (Network Address Translation): Your laptop acts as a router, forwarding traffic between networks.

Bridging

On your laptop, run the following commands:

brctl addbr mybridge
brctl addif mybridge eth0
brctl addif mybridge wlan0

Note: This method may not work with all WiFi cards. If you encounter issues, delete the bridge using brctl del mybridge and proceed to the NAT method.

NAT

1. Enable IP forwarding on your laptop:

echo 1 > /proc/sys/net/ipv4/ip_forward

For IPv6, replace ipv4 with ipv6 in the command.

2. Set up iptables rules:

iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
iptables -A FORWARD -i wlan0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth0 -o wlan0 -j ACCEPT

3. Configure the gateway on your embedded device (Xavier or Raspberry Pi):

 route add default gw 192.168.1.254 eth0

4. Test it by quickly pining an external ip address

With these steps, you should be able to run sudo apt update and resolve any issues without reinstalling the WiFi card on your embedded device. This guide provides a quick and efficient solution for sharing internet connections with embedded devices, saving time and effort in development and testing scenarios.