ifup, ifdown no centos 6.3 convidado no virtualbox

Question

Em um Mac OSX, estou executando o VirtualBox 4.2.16 com um convidado centos 6.3. No convidado centos quando eu emito ifdown eth0 ou ifup eth0 eu recebo:

usage: ifdown <device name>

Mesma coisa com eth1. O que estou fazendo errado aqui?

A rede funciona - posso acessar sites - mas quero rejeitá-la. ifconfig mostra:

eth0      Link encap:Ethernet  HWaddr 08:00:27:9A:3D:5F  
          inet addr:10.0.2.15  Bcast:10.0.2.255  Mask:255.255.255.0
          inet6 addr: fe80::a00:27ff:fe9a:3d5f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11479 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10264 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2734159 (2.6 MiB)  TX bytes:824710 (805.3 KiB)

eth1      Link encap:Ethernet  HWaddr 08:00:27:2C:14:E3  
          inet addr:192.168.0.103  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::a00:27ff:fe2c:14e3/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:59800 errors:0 dropped:0 overruns:0 frame:0
          TX packets:60410 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:8133761 (7.7 MiB)  TX bytes:12307987 (11.7 MiB)

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:99713 errors:0 dropped:0 overruns:0 frame:0
          TX packets:99713 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:11816688 (11.2 MiB)  TX bytes:11816688 (11.2 MiB)

Obrigado!