On Debian 64bit, I configured a lxc like this :

host ip : vm guest on this host :

I've done the bridge on my host

auto eth0 
iface eth0 inet manual
        up ifconfig eth0 up
        down ifconfig eth0 down

auto br0 
iface br0 inet static
        bridge_ports eth0
        bridge_fd       0

On guest side, I changed the config with

lxc.utsname = myGuest
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = br0
lxc.network.name = eth0
lxc.network.hwaddr = 00:FF:12:34:56:78
lxc.network.ipv4 =

When I run the VM : my host ( and my guest ( can ping each other But now, other physical machines on the same network ( cannot see my guest.

Same issue from my guest that can only see the IP of its host !

In fact I would like to get the same behaviour than a bridge network on VmWare Workstation. What kind of routage VmWare does to be seen "everywhere" on the network ?

(By the way, my host is already on a ESX server, but I think it is not relevant at this level)

  • You should set tcpdump and see what's going on when requests are being made. At this point, I would suspect arp requests not being relayed from host to guests. At least, a layer 2 problem, as there should not be routing issue (same subnet). Is your guest able to ping hosts outside its own host? Is there any firewalling issue? – philippe Jan 29 '13 at 13:06

Your host is virtualized with VMware, then it is plugged to the virtual switch which does not expect any more mac-addresses to be shown than those of VMware virtualized servers (so not lxc inside the VMware guest). So this is definitely a layer 2 issue: VMWare (at least VSwitch) received paquets with a mac-address different than the host mac-address and drop them. So there would be no way for the guest to reach outside its host, as it should go through the Vswitch to do that.

A workaround is to enabled different mac-addresses on the Vswitch. It is performed by editing settings on the Vswitch (on the VMware host, configuration, networking, select the vswitch your lxc-host is connected to, properties, Edit, security, MAC address changes -> Accept).

  • Great post Philippe, But The "Accept" flag is already on... – Stef Jan 29 '13 at 13:39
  • mmmh thanks! but I don't see any accept flag anywhere, or do I have missed it? ;) – philippe Jan 29 '13 at 13:42
  • Ok sorry, the "MAC address changes" of the vswitch0 is already checked with "Accept" value – Stef Jan 29 '13 at 13:53
  • Sorry! I may not have told you the appropriate flag to set on; It may be Promiscuous mode (the Vswitch then acts like a dummy network hub - be careful to security issue then, VMware guests would be able to get the traffic of the whole subnet); I am not quite sure about which of these options have to be set up :/ Hope it will help you finding a solution! – philippe Jan 29 '13 at 14:02
  • Ok, cool advice. At the end, What you said is if I do all the "stuff" on "physical machine" I will not have the problem don't you ? – Stef Jan 29 '13 at 14:07

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