[Leo28C]

I'm trying to set up a hardware firewall to go between my modem and DD-WRT router. However the firewall machine can't seem to reach the router no matter what I try. I should at least be able to telnet into the ports I regularly access from the outside (those that are open in DD-WRT) but I get no response. It could be an issue on the firewall side but I want to make sure everything's fine on the DD-WRT side before I go back to losing hair fiddling with FreeBSD.

I have DD-WRT set to:

Connection Type: Static IP
WAN IP Address: 4.2.2.2/24
Gateway: 4.2.2.1
Static DNS 1: 192.168.1.78

I chose the 4.2.2.0/24 subnet randomly. I don't know what else one is supposed to do when there's no DHCP server on either side. Is this the correct way to go about it? In addition to the /24 above I've also tried /32 and even /23 with no success.

For reference, on the firewall side the network adapter is manually set to IP 4.2.2.1 subnet 255.255.255.0.

edit: I shouldn't need a crossover cable for this, right? Connecting a router's WAN port to a regular LAN port on a computer?

[kernel-panic69]

You may require a crossover cable between modem and firewall PC, but not PC and DD-WRT router. Need much more details about modem, ISP service, etc. For local side subnets, you must use a private IP address range.

https://stackoverflow.com/questions/81350/private-ip-address-ranges

https://en.wikipedia.org/wiki/Reserved_IP_addresses

https://www.subnet-calculator.com/

https://www.calculator.net/ip-subnet-calculator.html

[uvz123a]

Network ports recognizes pinout and any UTP cable will work.
On older network cards you need to use correct cable, on newer this is not the case anymore.
You can use crossover or straight cable and it should work in any case.

[Leo28C]

[Leo28C]