Ben Stienstra

Keep track of ethernet/ip address pairings. It syslogs activity and reports certain changes via email.

• Install Raspbian, connect the Pi to your network, the broadcast domain (subnet) you want to monitor.
• Configure the Pi as you would normally.
  • Disable HDMI, WLAN, Bluetooth
  • Configure firewall
  • Remove pi user
  • enable ipv6 privacy addressing
  • Disable unnecessary services

• Configure outgoing mail. For example with a simple to use tool like ssmtp.

  apt install ssmtp mailtutils

• Test outgoing mail.

• Install arpwatch

  apt install arpwatch
  systemctl stop arpwatch
  rm /var/lib/arpwatch/*     # remove already found hosts

• Update the ethercodes

  cd /usr/share/arpwatch/
  mv ethercodes.dat ethercodes.old
  curl -O https://linuxnet.ca/ieee/oui/ethercodes.dat

• Script / crontab to update the file every month or so.
• Configure arpwatch /etc/arpwatch.conf

  eth0    -m <mail recipient>

• Enable and start arpwatch

  systemctl enable arpwatch
  systemctl start arpwatch