[Bug 1886809] Re: Pulse connect VPN exists because unwanted avahi network starts

[Trent Lloyd]

I'm not sure it makes sense to just universally skip "tun*" interfaces
(at least yet) but we may need to review the scenarios in which
/etc/network/if-up.d/avahi-autoipd is executing.

Helio: Can you provider a reproducer scenario? e.g. is this ubuntu
server, ubuntu desktop, what is the contents of:
/etc/network/interfaces, /etc/network/interfaces.d/*, /etc/netplan/* and
whether network manager is in use or not. And lastly exactly how pulse
VPN is installed and configured, and how that interface is
started/connected?

Additionally you may find this issue goes away with netplan versus the
older-style interfaces files. In any case with as much info as possible
for a reproducer I can check your exact scenario.

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https://bugs.launchpad.net/bugs/1886809

Title:
  Pulse connect VPN exists because unwanted avahi network starts

Status in avahi package in Ubuntu:
  New

Bug description:
  Pulse VPNs exists very often because avahi enforces network
  192.250.0.0/0 over tun0 interface.  The message error is:

  rmon.error Unauthorized new route to 169.254.0.0/0.0.0.0 has been
  added (conflicts with our route to 0.0.0.0), disconnecting
  (routemon.cpp:598)

  No matter the options to skip avahi on /etc/default/avahi-daemon, it
  always calls /etc/network/if-up.d/avahi-autoipd and raises this
  discovery network.

  A fix can be done patching /etc/network/if-up.d/avahi-autoipd to skip
  any tunnel interface.

  --- /etc/network/if-up.d/avahi-autoipd.dpkg-old 2020-07-08 13:25:41.834569800 +0200
  +++ /etc/network/if-up.d/avahi-autoipd  2020-07-07 10:07:37.611118581 +0200
  @@ -11,6 +11,10 @@
   
   [ -x /usr/sbin/avahi-autoipd ] || exit 0
   
  +case "$IFACE" in
  +       tun*) exit 0 ;;
  +esac
  +
   [ "$IFACE" != "lo" ] || exit 0
   case "$ADDRFAM" in
          inet) ;;

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