IPFire can be configured using a serial console - which is a common way to configure network hardware like switches and firewalls. For that, a serial cable ( null modem ) is required. Since modern computers no longer come with a serial port, a USB-to-serial adapter can be used as well.
Connect your firewall with the serial cable and your computer first and then power it on.
Linux
On any Linux-based computer, you can use screen to connect to the serial console. The command is:
sudo screen /dev/ttyUSB0 115200
115200 is the default baud rate for IPFire. /dev/ttyUSB0 is most likely the device node for a USB-to-serial adapter. If you are using an actual serial port on your computer, this would be /dev/ttyS0.
You can leave screen by typing Ctrl-A K.
Windows
PuTTY is a great tool for connecting to a serial console. Start it, select "Serial" as connection type, and enter your serial interface as well as the baud rate of 115200. Most likely your serial interface will be called COM3.
You need to set the parameters to 8 Data bits, 1 Stop bit, and no parity, no flow control. (8N1)
MacOS
The Mac has similar tools as a Linux-based computer and you can use screen to connect to the serial console. The command is:
sudo screen /dev/ttyABC 115200
115200 is the default baud rate for IPFire. /dev/ttyABC is an example device node for a USB-to-serial adapter. To search for the USB-to-serial adapter enter ls -al /dev/tty.* or maybe ls -al /dev/tty*.
Exit screen by typing Ctrl-A K. Yes, memorize this key sequence!
Depending on the USB-to-serial adapter, a driver may need to be installed on the Mac. Information about the adapter should include a reference to the needed driver.