This means, that using just ESP board, without additional modules, it isn’t possible to immediately notify user during the attack, only after it ends. However, it could be possible with additional modules, such as:

Bluetooth (local, not very practical)
GSM (send SMS)
SD card (create logs when attack started, afterwards send notification)

Since I don’t have any of these modules, I decided to accomplish it with a different approach, which is to receive notification right after attack ends, to at least be aware of it.

The obvious solution would be an Ethernet port, possibly through a USB dongle