Below I am going to show you how to share your wi-fi internet with an ethernet device using a raspberry pi. This is a simple task to get an ethernet-only device online or in my case a host computer for a mesh network.
If you don’t have your raspberry pi SD card configured to run Raspian click here
sudo apt-get -y update; sudo apt-get -y upgrade; sudo reboot
What does it do: update your software to the latest saying Yes to all prompts. (most are just it is this size are you sure) then reboot
Once your system is back up and running lets configured the DHCP host for the ethernet port.
Let’s install the DNS server
sudo apt-get install dnsmasq -y
Let’s deny the ethernet for requesting DHCP
sudo nano /etc/dhcp/dhcpd.cfg
sudo nano /etc/network/interfaces
Under auto eth0 I used the following settings
allow-hotplug eth0 iface eth0 inet static address 192.168.1.1 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255
Now configure the DHCP service for eth0
sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.bak
now create a new file and add the following code
sudo nano /etc/dnsmasq.conf interface=eth0 listen-address=192.168.1.1 dhcp-range=192.168.1.100, 192.168.1.200, 12h server=126.96.36.199 bind-interfaces domain-needed bogus-priv
to set up port forwarding run the following command
sudo nano /etc/sysctl.conf
Un-comment out the following line
This should be the last line on your terminal when you open the file but if you cant find it just place it at the bottom of the page.
Protip: Ctrl + W the alt + W (represented as ^W) to rerun the search
Next step is setting up the communication between the Ethernet and the Wireless chip. They are called eth0 and wlan0 respectively.
sudo iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE sudo iptables -A FORWARD -i wlan0 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT sudo iptables -A FORWARD -i eth0 -o wlan0 -j ACCEPT
Almost there last few steps
Run this command to back up the configuration.
sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"
Then add the following to the end of the file /etc/rc.local to ensure the IPtables are always set on boot:
up iptables-restore < /etc/iptables.ipv4.nat
Finalize everything with a
sudo reboot n
Check to make sure your client can get online when connected to the raspberry pi and you are good to go.