[Bug 1633479] Re: dhclient does not wait for ipv6 dad (duplicate address detection)

[Scott Moser]

I've verified that this fixes issue on yakkety.

## Set up a network in lxc that listens to dhcp ipv4 and ipv6

$ netname="v4and6"
$ profname="$netname-profile"
$ cnamepre="v4v6-"
$ lxc network create $netname
Network v4and6 created

$ lxc network set $netname ipv6.dhcp.stateful true
$ lxc profile create $profname
$ lxc profile device add $profname eth0 nic nictype=bridged parent=$netnam
Device eth0 added to v4and6-profile

$ lxc network show $netname
name: v4and6
config:
  ipv4.address: 10.152.128.1/24
  ipv4.nat: "true"
  ipv6.address: fd42:198e:d2a5:1d10::1/64
  ipv6.dhcp.stateful: "true"
  ipv6.nat: "true"
managed: true
type: bridge
usedby: []

$ lxc profile show $profname
name: v4and6-profile
config: {}
description: ""
devices:
  eth0:
    nictype: bridged
    parent: v4and6
    type: nic
usedby: []


## Now launch a container to verify
$ rel=yakkety
$ cname=v5v6-$rel
$ lxc launch ubuntu-daily:$rel --profile=$profname $cname
$ sleep 20; # give it time to come up
% lxc exec $cname /bin/bash

## inside
$ dev=eth0;
$ ifdown $dev; ip link set down dev $dev; killall dhclient;
Killed old client process
$ dhclient -6 -1 -v $dev
...
Can't bind to dhcp address: Cannot assign requested address
Please make sure there is no other dhcp server
...
$ echo $?
1

## That verified busted. now fix.
$ ifup eth0  # brings up ipv4 dhcp properly
$ m=http://archive.ubuntu.com/ubuntu
$ echo "deb $m $(lsb_release -sc)-proposed main" | sudo tee /etc/apt/sources.list.d/proposed.list

$ sudo apt-get install isc-dhcp-client
$ dpkg-query --show isc-dhcp-client
isc-dhcp-client   4.3.3-5ubuntu15.1

$ ifdown $dev; ip link set down dev $dev; killall dhclient;
$ dhclient -6 -1 -v $dev 
...
message status code Success: "success"
PRC: Bound to lease 00:01:00:01:1f:c5:e1:fb:b8:ae:ed:75:5f:9a.

$ echo $?
0


** Tags added: verification-done-yakkety

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https://bugs.launchpad.net/bugs/1633479

Title:
  dhclient does not wait for ipv6 dad (duplicate address detection)

Status in isc-dhcp package in Ubuntu:
  Fix Released
Status in isc-dhcp source package in Precise:
  Fix Committed
Status in isc-dhcp source package in Trusty:
  Fix Committed
Status in isc-dhcp source package in Xenial:
  Fix Released
Status in isc-dhcp source package in Yakkety:
  Fix Committed

Bug description:
  dhclient -6 does not wait for an interface go through duplicate address detection.
  As a result the following will almost always fail:

   $ dev=eth0
   $ ip link set down dev $dev
   $ dhclient -6 -1 -v eth0
   Internet Systems Consortium DHCP Client 4.3.3
   Copyright 2004-2015 Internet Systems Consortium.
   All rights reserved.
   For info, please visit https://www.isc.org/software/dhcp/

   Can't bind to dhcp address: Cannot assign requested address
   Please make sure there is no other dhcp server
   running and that there's no entry for dhcp or
   bootp in /etc/inetd.conf.   Also make sure you
   are not running HP JetAdmin software, which
   includes a bootp server.

   If you think you have received this message due to a bug rather
   than a configuration issue please read the section on submitting
   bugs on either our web page at www.isc.org or in the README file
   before submitting a bug.  These pages explain the proper
   process and the information we find helpful for debugging..
   $ echo $?
   1

  Related bugs:
   * bug 1447715: dhclient -6: Can't bind to dhcp address: Cannot assign requested address
   * bug 1633562: 'dhclient -6 -S' does not bring interface up 

  ProblemType: Bug
  DistroRelease: Ubuntu 16.10
  Package: isc-dhcp-client 4.3.3-5ubuntu15
  ProcVersionSignature: Ubuntu 4.8.0-22.24-generic 4.8.0
  Uname: Linux 4.8.0-22-generic x86_64
  NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
  ApportVersion: 2.20.3-0ubuntu8
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Fri Oct 14 09:18:52 2016
  EcryptfsInUse: Yes
  InstallationDate: Installed on 2015-07-23 (449 days ago)
  InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150722.1)
  SourcePackage: isc-dhcp
  UpgradeStatus: No upgrade log present (probably fresh install)

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