Networking problem with firewall and KVM

[Serge Hallyn]

Quoting Lorenzo Milesi (maxxer at ufficyo.com):
> > So you bring up the host, all is well, you start up the kvm guest and
> > boom you lose access to the wan?
> 
> sadly the guest allows me to access the wan, so I cannot test it without.
> but I tested another distro as VM guest and with that one I can access internet from the host. I thought it was a pfsense fault, but with that distro I still have other issue in accessing the host. i.e. when I'm in VPN I can ping it but not ssh.
> I strongly believe there's something wrong on the host.
> 
> Here attached output of the requested commands (a little mixed up, sry :) ) with the guest running. Sadly cannot provide the same with stopped firewall because I'm away now.

Ok, br1 has no ip address.  Your /etc/network/interfaces entry for
br1 showed it as manual, not dhcp, without an address - I assumed
the address lines either were cut out or you manually set it later.

So I guess your guest works because its tap0, bridged into br1,
gets an address from the WAN's dhcp server.  br1 itself doesn't
get an address nor does eth2, so host can't directly access the
WAN.

That's my guess.

-serge