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I am running an Ubuntu server(9.04) virtual machine(virtualbox) on my computer at work and one night Win 7 rebooted after some security updates. After bringing the VM back up again the network didn't work.

The only thing I can see in the dmesg log is:

[] eth0: registered as PCnet/FAST III 79c973
[] udev: renamed network interface eth0 to eth1

My /etc/network/interfaces looks like:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

The iconfig shows only lo interface.

If I try:

sudo ifup eth0 
SIOCSIFADDR: No such device
eth0: ERROR while getting interface flags: No such device
...............

sudo ifup eth1
Ignoring unknown interface eth1=eth1

I am not a ubuntu geek, just use it as a git repository, any help to bring the network up again will be appreciated.

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can you run mii-tool on your ubuntu and post the output ? . mii-tool can show you the state of your physical network interfaces (in your case, the simulated interface) –  Andrew Keith Oct 24 '09 at 20:59
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migrated from stackoverflow.com Oct 25 '09 at 1:50

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5 Answers

Perhaps mac address or driver has changed for the network card.

Remove /etc/udev/rules.d/*-persistent-net.rules and reboot vm.

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Edit "/etc/udev/rules.d/70-persistent-net.rules".

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Seems like there is a hardware change in your virtual machine. Changing the "eth0"s to "eth1"s in the /etc/network/interfaces file might help. After this, you should at least restart your networking service by typing "sudo service networking restart" in the console but a full restart is better in this situation.

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All the above are correct. Udev has mapped eth0 to a MAC address that, for some reason has disappeared. Looks like the reboot caused your VM to assign a new MAC address to the VM's NIC. You can either:

  • edit /etc/udev/rules.d/70-persistent-net.rules and correct the eth0 to MAC address mapping, or
  • edit /etc/network/interfaces and change eth0 to eth1
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The ifup and ifdown commands look inside of /etc/network/interfaces to find the configuration for an interface. If you don't have it declared there, it won't be found. Try this instead to bring up the interface:

sudo ifconfig eth1 up
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