This gist uses the idf-release/v4.2 release of arduino-esp32, can be found here: https://github.com/espressif/arduino-esp32/tree/idf-release/v4.2
Ntop-ng Install on Ubuntu Server 18.04
Instructions are written for Raspberry Pi but can be used on any other platforms.
As there is no pre-built packages for ARM platforms I've found some packages but you might have no other choices than do the compilation yourself...
I've finally been able to get the hand on their pre-built packages... I've just read too fast their documentation... :face_palm:
You could find their packages here: http://packages.ntop.org/