Comment 4 for bug 44170

Ooo, thanks for posting this hack ("pre-down false"); it's much smaller than mine (rewriting init scripts).

I'd add that ideally you should remove the -i option to halt in /etc/init.d/halt - at the moment there is apparently a bug that stops halt -i working on ubuntu, but it's supposed to shutdown all network interfaces (see #127010).

For sleep/hibernate, you also need to stop it unloading network modules in /etc/acpi/suspend.d/70-modules-unload.sh

hibernate + wake-on-lan + ssh + screen = teh win.