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

[Wido den Hollander]

I just ran into the same issue on a 16.04 system in a IPv6-only network.

My network configuration looks like this:

auto eno1
iface eno1 inet6 dhcp


The fix posted by Graham works for me. After modifying that line I succesfully get DHCPv6 after a clean reboot.

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

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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:
  Confirmed

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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