RPi Zero mesh network setup - overthesun/simoc-sam GitHub Wiki

Create OS image

To flash the SD card with the OS image:

• Download, install, and launch the latest version of the Raspberry Pi Imager
• Select the following options and press next:
  • Raspberry Pi Device: RASPBERRY PI ZERO
  • Operating System: RASPBERRY PI OS (LEGACY, 32 BIT) (recommended)
    • If you already have an image, select Use custom instead
  • Storage: select the SD card
• Would you like to apply OS customization settings?
  • Select EDIT SETTINGS
• In the GENERAL tab set:
  • hostname: samrpi1/2/3/N
  • Username: pi
  • Password: ...
  • Configure wireless LAN (optional)
  • Set locale settings (optional)
• In the SERVICES tab set:
  • Enable SSH
  • Use password authentication
  • Click on SAVE
• Would you like to apply OS customization settings?
  • Select YES
• Are you sure you want to continue?
  • Select YES
• When it's done click on CONTINUE and remove the SD card

Connect to the RPi Zero

• Attach the RPi Zero to the RPi 3 extension (a USB hub with Ethernet should work too)
• Insert the SD card and connect the Ethernet cable
• Boot the RPi and find its IP address from the router interface or with a ping sweep, e.g.:

  nmap -sn 192.168.0.0/24
  

• SSH into the device with ssh [email protected] or ssh [email protected]

Setting up Batman on the RPi Zero

• Install batctl with

  sudo apt-get install -y batctl
  

• Create the file ~/start-batman-adv.sh with the following content:

  #!/bin/bash
  # Tell batman-adv which interface to use
  sudo batctl if add wlan0
  # Activates the interfaces for batman-adv
  sudo ifconfig wlan0 up
  sudo ifconfig bat0 up # bat0 is created via the first command
  

• Make it executable

  chmod +x ~/start-batman-adv.sh
  

• Create the file /etc/network/interfaces.d/wlan0 with the following content (use sudo):

  auto wlan0
  iface wlan0 inet manual
  	wireless-channel 1
  	wireless-essid sam-mesh
   	wireless-mode ad-hoc
  	wireless-ap e4:5f:01:a1:93:90
  

  You might see a warning that says "bat0: The MTU of interface wlan0 is too small (1500) to handle the transport of batman-adv packets.". This can be fixed by adding mtu 1532 above (above wireless-channel 1, however on the RPi Zero it gives the error "Error: mtu greater than device maximum.". Everything still works with an mtu of 1500.
• Create the file /etc/network/interfaces.d/bat0 with the following content:

   auto bat0
   iface bat0 inet static
  	address 172.27.0.250
  	netmask 255.255.0.0
  	pre-up /usr/sbin/batctl if add wlan0 
  

• Change the IP address in the file above so that the last digit corresponds to the hostname (e.g. samrpi4 -> 172.27.0.4)
• Ensure that the batman-adv kernel module is loaded at boot time:

  echo 'batman-adv' | sudo tee --append /etc/modules
  

• Stop the DHCP process from trying to manage the wireless lan interface:

  echo 'denyinterfaces wlan0' | sudo tee --append /etc/dhcpcd.conf
  

• Make sure the IPs in bat0 are updated and the startup script called by adding the following to /etc/rc.local (use sudo):

  # check/update bat0 IP
  python3 /home/pi/simoc-sam/simoc-sam.py fix-ip
  
  /home/pi/start-batman-adv.sh &
  

• Reboot

Setting up wlan1 on an RPi 4

On an RPi 4, it is possible to connect a WiFi dongle to have an additional network interface (wlan1). With this configuration, wlan0 will still be used for the mesh network, whereas wlan1 can be used to connect to a router and get internet access.

• Insert the WiFi dongle (TP-Link TL-WN823N)
• Follow the procedure above
• Add the following lines at the end of ~/start-batman-adv.py:

  # Startup the wifi dongle (wlan1)
  sudo ifdown wlan1
  sudo ifup wlan1
  

• Create the file /etc/network/interfaces.d/wlan1 with the following content:

  auto wlan1
  iface wlan1 inet dhcp
  wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
  

• Edit the file /etc/wpa_supplicant/wpa_supplicant.conf with the following content:

  ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
  update_config=1
  
  network={
     ssid="NETWORKSSID"
     scan_ssid=1
     key_mgmt=WPA-PSK
     psk="THEVERYSECRETPASSWORD"
  }
  

Troubleshooting

To check the connections:

ifconfig bat0
ifconfig wlan0
iwconfig

sudo batctl n
sudo batctl o
sudo batctl ping

To trace the route to another device:

sudo batctl traceroute 172.27.0.2

Other standard commands work, e.g.:

ping 172.27.0.2
ssh [email protected]

Note that attempting to ping a hostname directly doesn't work, unless you add the .local suffix:

ping samrpi1.local
sudo batctl ping samrpi1.local

In case you get problems like: SIOCSIFFLAGS: Operation not possible due to RF-kill it can be solved by a: sudo rfkill unblock all