Using the dummy0 interface for a local-only service to be broadcasted by Avahi

Martin Pitt martin.pitt at
Thu Dec 29 11:42:37 UTC 2016

Hello Till,

Till Kamppeter [2016-12-19 13:00 -0200]:
> sudo modprobe dummy
> sudo ifconfig dummy0 netmask multicast
> sudo ifconfig dummy0 up multicast
> What I would like to do is to add the "dummy0" interface as a local-only,
> multicast interface to the distro, either as a default part like "lo" or
> initiated by the maintainer scripts of the ippusbxd Debian package (or the
> printing snap).

lxc/lxd used to hardcode an IP range like this, and it had to be dropped
because it caused conflicts on "real" existing networks. The range
is reserved and very actively being used for local networks, including
Canonical's own VPN, and thus prone to create conflicts. If you need to do
something like that, I don't see a way to get away with a static IPv4 address.
Maybe IPv6 has some clever address schema that makes conflicts improbable.
> Does it cause any problems using "dummy0" for a production purpose? Is there
> any better way? Perhaps even one which would allow me to work with
> localhost?

Making avahi work on 'lo' certainly sounds even nicer.

> How should I implement this? Simply run above commands from maintainer
> scripts of ippusbxd? Get them run when the first IPP-over-USB printer is
> detected via UDEV? Or implementation in network-manager or so?

Creating the interface in postinst is a no-go. It won't survive a reboot and it
can't/must not be done when installing into chroots. It could ship or generate
an ifupdown/netplan/systemd-networkd configuration file, though.


Martin Pitt                        |
Ubuntu Developer (  | Debian Developer  (

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