Usando uma ponte, um contêiner LXC não pode executar ping no roteador, mas o sistema operacional host pode

Question

Tenho uma máquina virtual em execução no VirtualBox e, nessa máquina virtual, tenho um contêiner LXC que estou tentando fazer a ponte para a interface NAT do VirtualBox:

-------------      -----------      -----------      ----------      ----------
| LXC       | ---> | Host OS | ---> | Virtual | ---> | Laptop | ---> | Router |
| Container |      | Linxu   |      | Box     |      |        |      |        |
-------------      -----------      -----------      ----------      ----------
eth0 10.1.0.35     br0 <-> eth0     NAT GW:          192.168.1.33    GW:
gw 10.1.0.2        br0 10.1.0.5      10.1.0.2/16                      192.168.1.1
                   gw 10.1.0.2

Ping 10.1.0.2      ping 10.1.0.2
 FAIL               OK

Eu não consigo pingar do contêiner LXC para o gateway do VirtualBox, mas posso a partir do sistema operacional host.

Nota: executando tcpdump no sistema operacional host, posso cantar pings sendo enviados do contêiner para o roteador e a resposta do roteador para o contêiner, mas tcpdump no contêiner não mostra tráfego.

LXC eth0

eth0      Link encap:Ethernet  HWaddr 00:16:3e:ed:82:b8
          inet addr:10.1.0.35  Bcast:10.1.255.255  Mask:255.255.0.0
          inet6 addr: fe80::216:3eff:feed:82b8/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:585 errors:0 dropped:0 overruns:0 frame:0
          TX packets:588 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:58003 (58.0 KB)  TX bytes:56447 (56.4 KB)

SO do host:

root@ubuntuserver:/# ifconfig
br0       Link encap:Ethernet  HWaddr 08:00:27:ca:5f:7a
          inet addr:10.1.0.5  Bcast:10.1.255.255  Mask:255.255.0.0
          inet6 addr: fe80::a00:27ff:feca:5f7a/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:2012 errors:0 dropped:0 overruns:0 frame:0
          TX packets:882 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:158794 (158.7 KB)  TX bytes:139083 (139.0 KB)

eth0      Link encap:Ethernet  HWaddr 08:00:27:ca:5f:7a
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:2968 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2404 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:281188 (281.1 KB)  TX bytes:312109 (312.1 KB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:180 errors:0 dropped:0 overruns:0 frame:0
          TX packets:180 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:14376 (14.3 KB)  TX bytes:14376 (14.3 KB)

vethStvXMU Link encap:Ethernet  HWaddr fe:9a:36:3a:84:1c
          inet6 addr: fe80::fc9a:36ff:fe3a:841c/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:557 errors:0 dropped:0 overruns:0 frame:0
          TX packets:554 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:53465 (53.4 KB)  TX bytes:55003 (55.0 KB)


root@ubuntuserver:/# brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.080027ca5f7a       no              eth0
                                                        vethStvXMU