How to determine which process or application is using excessive data My 2015 MacBook Pro uses wifi from a 4G dongle. Some process or application is regularly making large download requests, which are very expensive over 4G - it recently used $60 of data in a single day, for an unknown purpose.

How can I detect (and disable) these processes?

To demonstrate, I rebooted and immediately opened Activity Monitor (so I'd have an accurate measure of the network activity), then used the laptop for an hour or so (but without constantly monitoring the activity).

The total Data Received is 428Mb (confirmed on the wifi dongle), but the cumulative network traffic of the processes listed is far less than this:



I assume that one or more processes is running, requesting data, then closing, and that after this they're no longer individually listed in the Activity Monitor, so it's not possible to determine which processes are implicated.

How can I debug which application or process is causing this? Activity Monitor doesn't seem to be precise enough, so is there a better option?

PS I have disabled:


App Store "check for updates" and "automatically download"
DropBox
Google Drive
iCloud Drive
and I haven't opened iTunes.
You can monitor the traffic with numerous applications and tools. One that is already installed is 

/usr/bin/nettop


To block this unwanted traffic the easiest you also have numerous options:

– block the destinations via /etc/hosts

– block the ports used by those unruly programs using your builtin pf firewall 

– use one of the application level firewalls like
–– RadioSilence
–– LittleSnitch
–– HandsOff
–– Vallum
–– TripMode

Most important and practical is of course to just uninstall the offenders if posssible.