/usr/share/ntopng/scripts/callbacks/ is in ntopng-data 3.2+dfsg1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/ntopng/scripts/callbacks/interface/
/usr/share/ntopng/scripts/callbacks/interface/5min.lua
/usr/share/ntopng/scripts/callbacks/interface/daily.lua
/usr/share/ntopng/scripts/callbacks/interface/hourly.lua
/usr/share/ntopng/scripts/callbacks/interface/minute.lua
/usr/share/ntopng/scripts/callbacks/system/
/usr/share/ntopng/scripts/callbacks/system/5min.lua
/usr/share/ntopng/scripts/callbacks/system/boot.lua
/usr/share/ntopng/scripts/callbacks/system/daily.lua
/usr/share/ntopng/scripts/callbacks/system/discover.lua
/usr/share/ntopng/scripts/callbacks/system/housekeeping.lua
/usr/share/ntopng/scripts/callbacks/system/minute.lua
/usr/share/ntopng/scripts/callbacks/system/second.lua
/usr/share/ntopng/scripts/callbacks/system/shutdown.lua
/usr/share/ntopng/scripts/callbacks/system/startup.lua
/usr/share/ntopng/scripts/callbacks/user_scripts/
/usr/share/ntopng/scripts/callbacks/user_scripts/inline/
/usr/share/ntopng/scripts/callbacks/user_scripts/inline/default.lua
/usr/share/ntopng/scripts/callbacks/user_scripts/loader.lua
/usr/share/ntopng/scripts/callbacks/user_scripts/periodic/
/usr/share/ntopng/scripts/callbacks/user_scripts/periodic/default.lua