A FORWARD -i '$INTIF' -o '$EXTIF' -j ACCEPTĮcho -e ' rc.firewall-iptables v$FWVER done. '

A FORWARD -i '$EXTIF' -o '$INTIF' -m conntrack -ctstate ESTABLISHED,RELATED -j ACCEPT #= No editing beyond this line is required for initial MASQ testing =Įcho ' - Verifying that all kernel modules are ok'Įcho '-'Įcho ' Clearing any existing rules and setting default policy.' Then save the following script (which comes from the Ubuntu wiki) as nat.sh, and make it executable with chmod +x nat.sh: echo -e ' Loading simple rc.firewall-iptables version $FWVER. '

Reload dhcpcd with: sudo systemctl daemon-reload & sudo systemctl restart dhcpcd. Since the OS uses DHCPCD to manage network interfaces, edit /etc/nf and add in a static IP address configuration for the 2nd ethernet interface: interface eth1 The 'LAN' side interface (which I'm assuming is eth1) will connect through to another computer or a switch so it can distribute connections to one or more computers. That will be the 'WAN' side of the router. I'm going to assume you're okay with the first interface ( eth0) using DHCP to get an IP address from a DCHP server, router, or modem it's plugged into. These instructions work on that OS, as well as Debian, Ubuntu, and derivative distros. look at the picture-the thing's about to fall off my desk!), and I had two network interfaces on a Raspberry Pi running the 64-bit build of Raspberry Pi OS.

I should note that for more complex use cases, or where you really need to worry about security and performance, you should use something like OpenWRT, pfSense, or VyOS-or just buy a decent out-of-the-box router!īut I needed a super-simple router setup for some testing (seriously. I needed a very basic 'Internet sharing' router setup with one of my Raspberry Pis, and I thought I'd document the setup process here in case I need to do it again.

Raspberry pi router os