On Fri, Aug 19, 2022 at 4:33 PM François Patte <francois.patte@mi.parisdescartes.fr> wrote:
Bonjour,

This morning, logwatch reported this in the iptables section:

Logged 99 packets on interface enp3s0
.........
 From 10.91.96.218 - 6 packets to udp(54366)

How, this IP address could be logged on my private network (which is
192.168.1.0)?

I miss something....

Thank you for clarification.

You could try running the command:
$ arp -e
This will show a list of devices your computer recently communicated with and their hardware addresses.  If you see 10.91.96.218 in the list, copy the HWaddress column and paste it into https://maclookup.app to see the manufacturer.  That could help narrow it down. 
 
--
Charlie Murff