Scenario 1 - Wi-Fi (red) and Ethernet (green)
This sub-section offers an out-of-the-box configuration of the Raspberry Pi and enables your IPFire system to connect to the Internet via a wireless network (802.11). This can be your own wireless network or your neighbors. You will be able to connect to it as a client and IPFire will route your local networks through this wireless link. See Wireless Client.
In the IPFire setup Extended Network Menu the GREEN network is the on-board Ethernet port and is known as usb: Standard Microsystems Corp. SMSC9512/9514... The RED network is the wireless/WiFi and is known as sdio: brcmfmac.
After complete then configure the Wireless/WiFi from these instructions.
Scenario 2 - USB Ethernet (red) and on-board Ethernet (green)
This sub-section offers
In the IPFire setup Extended Network Menu the GREEN network is the on-board Ethernet port and is known as usb: Standard Microsystems Corp. SMSC9512/9514... The RED network is the USB Ethernet adapter and starts with usb:. e.g., my USB Ethernet adapter is known as usb: ASIX Electronics AX88179 Gigabit Ethernet.
USB-to-LAN adapters are listed here.