Raspberry pi - Huawei HiLink (E8372 LTE usb dongle) to ethernet adapter - tested on raspbian buster

usbLTEtoEthernet.md

1. Set static ip address to raspberry pi eth0 (ethernet) in /etc/network/interfaces.d/eth0 :

   auto eth0
   iface eth0 inet static
       address 192.168.1.20/24

2. Uncomment IP forwarding from /etc/sysctl.conf :

   net.ipv4.ip_forward=1

   save & reboot.

3. Enable nat with iptables:

   sudo iptables -t nat -A POSTROUTING -j MASQUERADE

4. Now connect raspberry pi ethernet cable to your computer or switch device then assign ip like this :

   ip : 192.168.1.21/24
   gw : 192.168.1.20
   dns: 1.1.1.1,1.0.0.1

   You can also automate ip address assignment by setting up an dhcp server!

5. Save iptables config & make it persistent by installing iptables-persistent package.

   sudo apt install iptables-persistent

   during installation process it will ask you by prompting a dialog to save previous iptables config. Answer yes. if you forgot you can run this process again by running :

   sudo dpkg-reconfigure iptables-persistent

   iptables-persistent package will save iptables configs in /etc/iptables/rules.v4 & /etc/iptables/rules.v6 and it will automatic loading of the saved iptables rules on boot time.