PFSense impersonate MAC

[Stonent]

My internet comes in via an RJ45 to a ISP provided "modem" that also has gigabit ports and wifi. I suspect like many it is MAC locked to that device. I would like to insert a firewall before the "modem" and was wondering if anyone had done this before? I assume the "modem" is required because it has so much ISP related stuff in the menus. It's a Calix Gigacenter.

Basically I'm wondering how PFSense can deal with impersonating a MAC of a device that's on its output port, if that will cause strange issues or not and hopefully trick the modem into not seeing it.

 

[RTM]

If you want to use a different MAC Address than the original one, you can change it quite easily:
Open the interface under the "Interfaces" dropdown and edit the "MAC address" field.

TL;DR: Interfaces -> WAN (probably) -> MAC Address field

BTW: If this works, then I doubt you'll need to use the "modem".