In this scenario, I have a machine that boots its root volume off of iSCSI, and it only has a single network interface. If network configuration is done the normal way, then taking the interface down to add it to the bridge would kill the connection, and the machine would hang since it would lose access to its root device.

Setting up the bridge in the initramfs pre-boot environment would seem like the right approach here....

Recent versions of CentOS/Redhat support this in dracut with the "bridge" kernel parameter, but I am unable to find the equivalent way to do this for Ubuntu Server.

Ubuntu's default busybox-initramfs package does not include brctl, so it looks like everything would need to be set up manually....

2 Answers 2


Looks like you get to do everything yourself; Ubuntu doesn't seem to have any support for this scenario. I suggest opening a feature request on Launchpad.

  • A small boot script doing the bridge creation and configuration, running in the init-premount stage solved my need. Having it create the bridge and run configure_networking then allows for it to be configured using the ip kernel parameter. Feb 22, 2013 at 5:01

The connection need not be killed. Have a look at this question (and my answer):

Bridge to a used eth1 card without losing connection via that card

In your case you need to copy the needed commands (including libs) to tmpfs before, of course, and probably have to execute them in a chroot environment.

  • Thank you for your suggestion. I tried it, and it did work, but I still think that doing the configuration pre-boot, rather than hot-swapping the address post-boot is the better way to go. Feb 22, 2013 at 4:33

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