If you haven’t heard of the utility, it is called arpwatch. Arpwatch as the name implies, watches the MAC to IP pairings of devices on the network. If these change, then arpwatch will log and send an email to alert. In addition to changes, it will alert with new MAC to IP pairings. So the beauty of this for home, you can have it proactively alert you when devices become active on your LAN/WLAN networks, which is super handy and from a security posture, greatly diminishes your response time if an intruder or rogue device is able to connect to your network.