[Bug 1543352] Re: inet6 dhcp doesn't wait for link-local address to leave tentative - dhclient fails to bind

[Ubuntu Foundations Team Bug Bot]

The attachment "ipv6-wait-properly-for-link-local-address-to-go-through-
dad.patch" seems to be a patch.  If it isn't, please remove the "patch"
flag from the attachment, remove the "patch" tag, and if you are a
member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by
~brian-murray, for any issues please contact him.]

** Tags added: patch

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https://bugs.launchpad.net/bugs/1543352

Title:
  inet6 dhcp doesn't wait for link-local address to leave tentative -
  dhclient fails to bind

Status in ifupdown package in Ubuntu:
  Triaged

Bug description:
  =
  Description:	Ubuntu Xenial Xerus (development branch)
  Release:	16.04

  ifupdown:
    Installed: 0.8.10ubuntu1
    Candidate: 0.8.10ubuntu1
  =

  With an /etc/network/interfaces file containing:

  auto eno16780032
  iface eno16780032 inet dhcp
  iface eno16780032 inet6 dhcp

  On boot, ifup starts 'dhclient -6' before the link local address has
  completed Duplicate Address Discovery (the address is marked
  'tentative').  In turn, dhclient reports 'Can't bind to dhcp address:
  Cannot assign requested address', and fails almost immediately.

  It would seem that either wait-for-ll6.sh should wait for the link
  local address to come up AND stop being tentative, or the dhcp method
  for inet6 should call settle-dad.sh after wait-for-ll6?

  This is partly a race condition, so on slower devices the dad may
  complete by the time dhclient has got started, however I can regularly
  reproduce this on a virtual machine.

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