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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1332420

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

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

** Tags added: trusty

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https://bugs.launchpad.net/bugs/1332420

Title:
  IPv6 multicast broken in kernel

Status in “linux” package in Ubuntu:
  Incomplete

Bug description:
  Dear all,

  a regression has been introduced in Linux Kernels by patch
  https://github.com/torvalds/linux/commit/efe4208f47f907

  The regression behaves in a way that when there are multiple IPv6
  sockets created with multicast/link-local addresses on the same
  interface, handling of the packets is broken. (Reported e. g. on
  http://www.spinics.net/lists/netdev/msg286344.html)

  This can be reproduced by
  1. installing Ubuntu 14.04 with default kernel
  2. installing dibbler-server and configuring with basic dhcpv6 settings (hand out one subnet), for example:
  /etc/dibbler/server.conf:
  log-level 8
  preference 0
  iface <IFACE> {
   t1 1800-2000
   t2 2700-3000
   prefered-lifetime 3600
   valid-lifetime 7200
   subnet 2001:db8:abcd::/64
   class {
      pool 2001:db8:abcd::1000-2001:db8:abcd::1fff
   }
   ta-class {
      pool 2001:db8:abcd::2000-2001:db8:abcd::2fff
   }
   option dns-server 2001:db8:abcd::1
  }

  3. get a DHCPv6 client and request addresses from the server
  4. view the packets on the interface affected, use e.g.: tcpdump -i <IFACE> '(udp port 546)||(udp port 547)' -n
  There will be multicast DHCPv6 solicits, however no DHCPv6 responses, as Dibbler creates two  sockets on the same interface (multicast socket first, link-local socket next).

  There is a patch available in the upstream, that will be probably
  merged to 3.15.2 kernel (it is not present in current 3.15.1 vanilla
  kernel) - http://patchwork.ozlabs.org/patch/352246/

  When applying this patch to trusty-proposed linux-
  image-3.13.0-30-generic_3.13.0-30.54 from Git repositories at git
  clone git://kernel.ubuntu.com/ubuntu/ubuntu-trusty.git and recompiling
  the kernel, everything starts to work as expected.

  Please apply this patch ASAP to fix IPv6 multicast, there is more and
  more IPv6 in the wild and this bug is a serious one.

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