Configure OpenWRT as a Router

So this particular How-To is written to be specific to how OpenWrt can be made to be a router instead of a network access device. This is a two-way communication between a host network that serves WIFI and the local network that runs off of the ethernet port.

Ironically, this is for a Raspberry Pi 4. It should work for any device though.

Make it a Router

First Steps

You should be on a machine that is connected to the etherport of the device in question, either through a switch or a good ole fashioned hub. You’ll need to point your browser to 192.168.1.1 and log in as root with no password.

Put a password in. Even a simple one that isn’t secure but that you’ll remember.

Configure the WIFI

Go to Network -> Wireless and choose the option to scan for radio0. Choose the your network and put the WIFI password in. Hit Submit. Then go to Save & Apply.

Configure the Local Network

Go to Network -> Interfaces and choose Edit on the LAN interface. Delete the entry in IPv4 address and put in the IP address and the correct subnet mask. Hit Save. Then hit Save & Apply

Quickly Now!

Renew the DHCP lease ( operating system dependent ) and change the address in the browser to be what ever you put in for the previous step and go to the new page. You should have a new IP address with the new network and you should be able to hit the router at the new address. If you can’t, then re-flash and try again.

Adjust the Firewall

Right now, the new network can see out, but the outside network cannot see if, which is fine if you want it that way. To make it a two-way street, go to Network -> Firewall and change the drop to be accept and then hit Save & Apply.

Testing

traceroute and ping are your friends here. You should be able to traceroute and ping back and forth across both networks, assuming you have hosts that you can contact. If nothing else, test against the individual routers that you have setup.