Because our Smart-TV had only LAN built in I wanted to use the RPi 3 to bridge WiFi to LAN.
This tutorial worked for me before I updated to a later raspbian version:
https://www.raspberrypi.org/forums/viewtopic.php?f=36&t=132674
I adapted it a bit until it worked for me on raspbian stretch 2017-07-09

The configuration file of the DHCP Client (dhcpcd5) /etc/dhcpcd.conf is used instead of /etc/network/interfaces.

Preparation

Upgrade everything. Install rpi-update and dnsmasq. Run rpi-update => reboot.

sudo apt-get update && sudo apt-get upgrade -y && sudo apt-get install rpi-update dnsmasq -y
sudo rpi-update
sudo reboot

Connect to WiFi

Edit wpa_supplicant.conf

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Add your network credentials

network={
    ssid="mynetwork"
    psk="secret"
}

Static DHCPCD Configuration

Edit dhcpcd.conf

sudo nano /etc/dhcpcd.conf

Add this OR uncomment the example and modify

interface eth0
static ip_address=172.24.1.1/24
static routers=172.24.1.0
static domain_name_servers=172.24.1.0 8.8.8.8

DHCP Server

Backup dnsmasq.conf and create new

sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig
sudo nano /etc/dnsmasq.conf

Add configuration for DNS & DHCP-Server (dnsmasq)

interface=eth0      # Use interface eth0  
listen-address=172.24.1.1 # Explicitly specify the address to listen on  
server=8.8.8.8       # Forward DNS requests to Google DNS  
domain-needed        # Don't forward short names  
bogus-priv           # Never forward addresses in the non-routed address spaces.  
dhcp-range=172.24.1.50,172.24.1.150,12h # Assign IP addresses between 172.24.1.50 and 172.24.1.150 with a 12 hour lease time

Enable IPv4 forwarding

Edit sysctl.conf

sudo nano /etc/sysctl.conf

Uncomment this line

net.ipv4.ip_forward=1

IP Tables

sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"
sudo nano /lib/dhcpcd/dhcpcd-hooks/70-ipv4-nat
iptables-restore < /etc/iptables.ipv4.nat

3 thoughts on “RPi 3 – WiFi to Ethernet Bridge”

  1. Ran through this guide and everything seemed to work well, but I lose internet connection on the pi whenever I connect the ethernet device to the pi. Can’t tell if device is getting internet(it’s an IP camera), got any ideas?

    1. What do you mean by “the raspberry loses internet connection”?
      Does the IP Camera use DHCP and can you maybe reset it?
      Have you tried a different device on the ethernet port (a laptop,…)?

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