Bridging Wifi to Ethernet on a Raspberry Pi (from https://sureshjoshi.com/development/raspberry-pi-wifi-to-ethernet-bridge)

bridge-wifi-to-eth-pi.sh

### NOTE: This is strictly a breakdown of the snippets from the blog article, not an automated script. 
### For automation, refer to the Ansible role

### Setup a Static IP

nano /etc/dhcpcd.conf
# Add these fields with your desired IP address
> interface eth0
> static ip_address=10.10.10.1/24
> static routers=10.10.10.0

# This command can kill Wifi, so you're probably just as well to reboot instead
service dhcpcd restart

## Enable IPv4 Packet Forwarding

nano /etc/sysctl.conf
# Uncomment this line or add it to the bottom
> net.ipv4.ip_forward=1

# For immediate access (without a reboot)
sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"

### Use iptables to Setup Data Forwarding

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

### Ensure iptables Are Run On Boot

# Save the rules we just added
iptables-save > /etc/iptables.ipv4.nat

nano /etc/rc.local
# Add this line to the rc.local just before 'exit 0'
> iptables-restore < /etc/iptables.ipv4.nat

### Setup dnsmasq to Provide IP Addresses

apt-get install dnsmasq

nano /etc/dnsmasq.conf
# Replace dnsmasq.conf with this
> interface=eth0                            # Use interface eth0
> listen-address=10.10.10.1                 # Specify the address to listen on (static ip_address from dhcpcd.conf)
> domain-needed                             # Don't forward short names
> bogus-priv                                # Drop the non-routed address spaces.
> dhcp-range=10.10.10.100,10.10.10.200,12h  # IP range and lease time (setting .100 to .200 as possible IPs)

service dnsmasq restart