I used to use `overlayroot-chroot` in Ubuntu:

<http://manpages.ubuntu.com/manpages/bionic/man8/overlayroot-chroot.8.html>

But now that I have changed to Debian it is not there, and `sudo apt install overlayroot-chroot` does not find it.

How does one get it for Debian?
['https://unix.stackexchange.com/questions/699971', 'https://unix.stackexchange.com', 'https://unix.stackexchange.com/users/358674/']
You say, "... on my network ..."

If you have access to the physical network layer, then yes, it is possible.

Some managed switches have the ability to copy traffic destined for port X to Port Y.

Another possibility, if the `tcpdump` host has multiple NICs, is to put the `tcpdump` host in between the other two hosts and let it bridge the traffic.
Solution found probably.
The syntax is correct, but modern switched networks (unlike the older with shared bus like the old good 10base2 or base5) don't send traffic out the switch port
not connected to the destination MAC address, so tcpdump will show packets only from host connected directly.