Set-up Laptop as Wired Router

First set up a network configuration as follows:

IP: 192.168.128.1
netmask: 255.255.255.0
gateway: 192.168.128.1

Then run the following command:

sudo iptables -A FORWARD -o <WIFI_MAC> -i <ETHERNET_MAC> -s 192.168.128.0/24 -m conntrack --ctstate NEW -j ACCEPT
sudo iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
sudo iptables -t nat -F POSTROUTING
sudo iptables -t nat -A POSTROUTING -o <WIFI_MAC> -j MASQUERADE