Ubiquiti - Security Gateway - Change the MAC Address

SSH into the Cloud Key.

Create a /usr/lib/unifi/data/sites/default/config.gateway.json file:

/usr/lib/unifi/data/sites/default/config.gateway.json

{
    "interfaces": {
        "ethernet": {
            "eth2": {
                "mac": "00:00:00:00:00:00"
            }
        }
    }
}

NOTE:

Change that MAC address to whatever you need it to be.

Change the NIC (eth2 in the example) to whichever is the WAN Port.
- On the USG 4 Pro, eth2 is the WAN1 port. eth0 is LAN1. But this may differ.
  - Check by ssh into the USG, then grep for that interface:
```
ip addr|grep -A2 eth2:
4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet 1.2.3.4/22 brd 255.255.255.255 scope global eth2
```
    - The 1.2.3.4 should be the external IP.
    - The 00:00:00:00:00:00 should be the correct MAC address.