If you have a computer with access to a WiFi and want to share to a local LAN and say you are booting off a ubuntu usb stick.

1. Boot the compute freshly
2. Put the computer on the WiFi
   1. Bring up a browser and log into the network
3. Change the computer's wired connection to
   1. IP4 Manual instead of DHCP
   2. Set IP to 10.4.1.254 / 255.0.0.0 with no DNS or Gateway required
4. Enable NAT network sharing with the following two commands

   ifconfig
   sudo /sbin/iptables -t nat -A POSTROUTING -o wlp6s0 -j MASQUERADE
   echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

5. Set any LAN computers to us 10.4.1.254 as gateway (and DNS to 8.8.8.8)