We previously assumed that Qubes would always give clients IP addresses
on a particular network. However, it is not required to do this and in
fact uses a different network for disposable VMs.
With this change:
- We no longer reject clients with unknown IP addresses
- The `Unknown_client` classification is gone; we have no way to tell
the difference between a client that isn't connected and an external
address.
- We now consider every client to be on a point-to-point link and do not
answer ARP requests on behalf of other clients. Clients should assume
their netmask is 255.255.255.255 (and ignore /qubes-netmask).
This is a partial fix for #9. It allows disposable VMs to connect to the
firewall but for some reason they don't process any frames we send them
(we get their ARP requests but they don't get our replies). Taking eth0
down in the disp VM, then bringing it back up (and re-adding the routes)
allows it to work.
