On Thu, Jul 31, 2014 at 2:17 AM, Andras Horvath <m...@log69.com> wrote:
>
> I've run into a strange problem that I am not able to track down in the
last 3 days. Could someone kindly help and give directions?
>
> On my 6.5 x64 system my bridged KVM guests (several kind of Windows and
many kind of Linux guests) do not get the broadcast messages. Every network
packets reach them from the subnet except broadcast and multicast messages.
How can that be?
>
> In kernel the bridge filter by iptables is turned off - turning on STP
does not help - enabling promisc mode in interface does not help either.
>
> Running tcpdump on host shows that the broadcast reaches the interface
from a different computer on the subnet, but does not get in the guest. I
ran tcpdump on the Linux guests and wireshark on the Windows ones. Testing
the same with VirtualBox on a different computer, tcpdump and wireshark
shows the broadcast packets.
>
> What is weird that every network packets reach my guests in KVM except
the broadcast ones.
HOST GUEST
+-------------+ +-------------+
LAN ---+--- eth0 | | |
| | | |
| tapX ----+---+--- nicX |
| mactapX | | macnicX |
| | | |
| br0 | | |
+-------------+ +-------------+
Are all the mactapX and macnicX MAC addresses different from one another?
