This article describes how to find the interface's MAC address.
Go to Network -> Interfaces -> Edit Interface and along with the interface name hardware address also be added from version 5.4 onward.
In non VDOM mode.
# get hardware nic <if_name> | grep Hwaddr
In VDOM mode.
# conf global
get hardware nic <if_name> | grep Hwaddr
To see the firewall port2 MAC address:
# get hardware nic port2
FW version: N/A
You can also use fnsysctl utility. This will show you current HW address and it works also for virtual interfaces, like Vlan:
Technical Note: How to find the interface's mac address