Re: mysterious/suspicious internet activity.

[home user]

(on Mon, 2020-11-30 at 23:56 +0000, Ed wrote)
> I thought you said your system was "quiet"?
>
> For your "network activity" issue the lines of interest are those
> which include "ESTABLISHED" as the state.
>
> It shows both "thunderbird" and "firefox" are both running and connected
> to hosts.  So, one would expect some network activity

When I opened the thread this morning (hours ago), my system was quiet.  
When, several minutes ago, I did the netstat -atuevp whose output I 
attached to my reply to you and Tim, yes, Thunderbird and Firefox were 
running.

Shall I reboot and re-do the netstat before launching Thunderbird and 
Firefox?

I will dig into the user-guide you referenced.  This will take time.