Display Current Config for all NIC's: ifconfig
Display Current Config for dc0: ifconfig dc0
Assign multiple IP's: ifconfig dc0:0 192.168.1.2
Assign second IP: ifconfig dc0:1 192.168.1.3
Disable network card: ifconfig dc0 down
Enable network card: ifconfig dc0 up
Assign IP/Subnet: ifconfig dc0 inet 192.168.1.2 netmask 255.255.255.0
Assign Gateway: route delete default && route add default 192.168.1.1
*You MUST be at the ROOT user to make/save any changes. You will need to save your changes in the /etc/rc.conf file. Network cards are referred to as dc0, dc1, dc2, etc based on their position on the PCI bus.
*Special thanks to Romanov Sergey Vladimirovich from Moscow for the UNIX commands!