Install IPFire on a Raspberry Pi CM4 on DFRobot Carrier Board over Serial Console

This tutorial covers how to install a IPFire Firewall on to a Raspberry Pi Compute Module 4 that is carried on DFRobot's Router Carrier Board Mini using a serial console.

Disclaimer: all provided links in this article aren't sponsored!

Tutorial tested against a Raspberry Pi Compute Module 4 (4GB, rev. 1.2) and IPFire Core Update 179. During the setup a second Raspberry Pi 4 with local attached keyboard and monitor was used. → IPFire's wiki can be found here.

→ And the DFRobot's wiki here.

Preparation / Requirements

SD-Card (32 GB) + SD-Card-Reader

Raspberry Pi Compute Module 4 (4GB RAM recommended)

Jumper Wires (Female to Female)

Official Raspberry Pi USB-C Powersupply (CM4 requires 5V 3A!)

Configured and running Raspberry Pi (either with SSH-access or working display output)

Depending on your Setup:

HDMI-Cable

Keyboard

Download and flash the Image to the SD-Card

Download the aarch64 Flash Image from IPFire's webpage: ipfire.org/download. Then flash the Image on another computer to the SD-Card. Therefore you can use Win32DiskImager (Windows), the official Raspberry Pi Imager (Linux, Windows and MacOS) or BalenaEtcher (Web, Linux and Windows).

The compressed IMG is required, the ISO image will not work!

If experiencing boot issues when using newer hardware revisions have a look at the official IPFire wiki: wiki.ipfire.org!

Before ejecting the SD-Card perform the following changes:

→ Enable the serial console: add (if not present) enable_uart=1 to config.txt.

→ Check if SERIAL-CONSOLE in uENV.txt is SERIAL-CONSOLE=ON.

Connect both Pi's with jumper cables

Now connect the following pins on your carrier board's GPIO and your second Pi's GPIO with three jumper wires (female to female):

Carrier Board (CM4)	2nd Raspberry Pi	Use
6	6	Ground
10	8	Receive and send
8	10	Send and receive

When connected properly you can power up the carrier board.

(It is recommended to first power up the second Pi and start the serial console before powering up the carrier board.)

Images sourced from siocours.lycees.nouvelle-aquitaine.pro and wiki.dfrobot.com - CM4 DFRobot Carrier Board

Open serial console using screen

Before you can open a serial connection: serial console must also be enabled on the Pi from which you wish to connect. Therefore check if your /boot/config.txt contains enable_uart=1. If not, add it at top (!) and reboot.

When using a Raspberry Pi 4B also add the following lines to your config.txt to get a human-readable console:

dtoverlay=pi3-disable-bt dtoverlay=pi3-miniuart-bt

In general there might be issues with newer versions of the Raspberry Pi, therefore consider using an older version as second device. Additionally do not dis- and reconnect to a running console session, otherwise your console might not be readable anymore for this session.

Then you can execute the follwing command from the second Pi to connect to your serial console. It doens't matter if you're using an attached keyboard and monitor or a SSH-connection.

screen /dev/ttyS0 115200

→ you might install screen befire by running the following command:

sudo apt install screen

Finally perform the setup of IPFire as usual!

With Ctrl+A and D you can quit the screen-session.

//Resources used: cyberciti.biz - linux serial console, scribles.net - uart communitation between to Raspberry Pis and wiki.ipfire.org - Raspberry Pi 4 Model B