Earlier quoted context omitted.
It is true that there are not absolutely zero instances of telemetry or "phoning home" in Linux, but Desktop Linux is not a similar experience to Windows or macOS in this regard, and it isn't approaching that point, either. You can tcpdump a clean install of Debian or what-have-you and figure out all of what's going on with network traffic. Making it whisper quiet typically isn't a huge endeavor either, usually just…
Are there any tools that enable capturing traffic from outside the OS you’re monitoring, that still allow for process-level monitoring? Meaning, between the big vendors making the OS, and state-level actors making hardware, I wouldn’t necessarily trust Wireshark on machine A to provide the full picture of traffic from machine A. We might see this already with servers running out-of-band management like iDRAC (which i…
Still, if you were extra paranoid, it wouldn't be unreasonable or even difficult to check from an external vantage point.
> Are there any tools that enable capturing traffic from outside the OS you’re monitoring, that still allow for process-level monitoring?
Doing both of these things at once would be hard, though. You can't really trust the per-process tagging because that processing has to be done on the machine itself. I think it isn't entirely implausible (at the very least, you could probably devise a scheme to split the traffic for specific apps into different VLANs. For Linux I would try to do this using netns.)