Although this is wishlist, it would make a big difference in the useablity of
the package for non-gurus like myself.

It would be very helpful if README.Debian, or perhaps customized man page or
documentation, explained how to setup networking to work with the the ifup
script you have provided.

I think just an example of a stanza for /etc/network/interfaces would suffice,
along with the options to use for kvm.

I have looked around  the net, esp starting from https://wiki.debian.org/KVM,
but nothing seems exactly right.  For example, many instructions say to do
things that the ifup script is doing automatically.  And a lot of the
information looks old.

Among other things I'm having trouble figuring out the difference between
bridging and tap/tun.  Do I need to set up a bridge for tap to work?  Should I
use -net bridge or -net tap?

For the record, I copied this from https://wiki.debian.org/QEMU#Host_and_guests_on_same_network
into my interfaces file:

auto br0
iface br0 inet dhcp
   pre-up ip tuntap add dev tap0 mode tap user root
   pre-up ip link set tap0 up
   bridge_ports all tap0
   bridge_stp off
   bridge_maxwait 0
   bridge_fd      0
   post-down ip link set tap0 down
   post-down ip tuntap del dev tap0 mode tap

(except the original had user <username>, did ifup br0,
and it seems to work.

The ifup seems to have brought down my network connections temporarily
as it came up; e.g., an ssh session was lost.  I used -net tap.

Still not understanding what's going on...

Ross