[Bug 1828749] Re: ifconfig dummy0 : Device not found

[Robie Basak]

I'll add an ifupdown bug task for you.

> If "auto dummy0" and "ifup dummy0" are not maintained then why
bother to have a dummy device at all?

We haven't discussed that, since that wasn't the failing use case you
presented in your original report! I appreciate that you narrowed down
the root cause to your reported change in behaviour in ifconfig, but for
judging importance and priority, it is the use case that matters.

Please could you provide full steps to reproduce your ifupdown use case
that works in Xenial but fails in Bionic? Including a sample
/etc/network/interfaces, details of why you're using dummy0, what
documentation directed you to do that, etc. Then we can refer to the
same understanding of your situation as a starting point.

** Also affects: ifupdown (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: ifupdown (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1828749

Title:
  ifconfig dummy0 : Device not found

Status in ifupdown package in Ubuntu:
  Incomplete
Status in net-tools package in Ubuntu:
  New

Bug description:
  Desired behavior:
    The ifconfig command should be able to deal with the
    dummy device.  This worked fine until recently.

  Observed behavior:
    :; ifconfig dummy0
    dummy0: error fetching interface information: Device not found

    This problem appeared when I upgraded to bionic.

  Highly informative workaround:
    :; ip link add dummy0 type dummy
    That command works, and makes the problem go away permanently.
    The ifconfig command works fine after that.
    The ifup and ifdown commands also work fine after that.

    For convenient debugging, you can use the command:
    :; ip link del dummy0 type dummy
    which makes the problem come back.
    You can also experiment with dummy1 et cetera.

  Package ownership issues:
    Compare: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=909204
    That report was filed against ippusbxd, which is almost certainly
    not the relevant package.

    For that matter, I have no idea whether the root cause is in the
    net-tools package or the kernel networking stack.  All I know is
    the ip command plays nicely with the kernel while the ifconfig
    command does not.

  
  Notes:
    The kernel module for the dummy interface is preloaded in
    all situations described here.  That's not the issue.

    An apport file is attached, to describe the environment.
    Also, since you asked:

    :; apt-cache policy net-tools
  net-tools:
    Installed: 1.60-26ubuntu1
    Candidate: 1.60-26ubuntu1
    Version table:
   *** 1.60-26ubuntu1 500
          500 http://ubuntu.cs.utah.edu/ubuntu xenial/main amd64 Packages
          100 /var/lib/dpkg/status

    :; lsb_release -rd
    Description:    Ubuntu 16.04.6 LTS
    Release:        16.04

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