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[Bug 1696415] Re: NetworkManager does not update IPv4 address lifetime even though DHCP lease was successfully renewed

 

This bug was fixed in the package network-manager -
1.2.6-0ubuntu0.16.04.2

---------------
network-manager (1.2.6-0ubuntu0.16.04.2) xenial; urgency=medium

  * Fix nm-dhcp-helper DBus Event/Notify race condition (LP: #1696415)

 -- Ray Link <rlink+launchpad@xxxxxxxxxx>  Thu, 19 Oct 2017 13:53:52
-0400

** Changed in: network-manager (Ubuntu Xenial)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1696415

Title:
  NetworkManager does not update IPv4 address lifetime even though DHCP
  lease was successfully renewed

Status in NetworkManager:
  Confirmed
Status in network-manager package in Ubuntu:
  Fix Released
Status in network-manager source package in Xenial:
  Fix Released

Bug description:
  SRU REQUEST:

  Debdiff (nm-dhcp-helper.debdiff) attached.

  Fixed in current Ubuntu zesty and newer: Bionic uses NM 1.8.x. This
  bug was fixed upstream in 1.4.

  [Impact]

   * nm-dhcp-helper sometimes fails to notify NetworkManager of a DHCP
     lease renewal due to a DBus race condition.

   * Upstream NetworkManager 1.4 fixes the race condition by changing
     nm-dhcp-helper's DBus notification from signal "Event" to method
     "Notify".

   * Original bug submitter backported NM 1.4's nm-dhcp-helper notification fix to NM 1.2. This SRU request applies that backported patch to Xenial's
     NM 1.2.x.

  [Test Case]

   * Not reliably reproducible. Out of hundreds of machines, only a
     dozen or so fail to notify NetworkManager of a DHCP lease
     renewal about 30-50% of the time. (i.e. It's always the same
     handful of machines that fail.)

   * All such machines with the patched packages have been fine for weeks,
     over many dozens of lease renewals.

  [Regression Potential]

  * The patch changes both nm-dhcp-helper and NetworkManager itself. As
  soon as the new packages are unpacked, the new nm-dhcp-helper will be
  used on DHCP lease renewals, with the new Notify mechanism. Since the
  running, old NetworkManager is still expecting Event notifications,
  the patched nm-dhcp-helper has fallback capability to Event.

  * Once NetworkManager is restarted and is running the patched version,
  it will have the new Notify support.

  [Other Info]

   * Upstream bug w/ patch:
  https://bugzilla.gnome.org/show_bug.cgi?id=784636

   * RHEL bug with links to the 1.4 commits from which the patch was
     derived: https://bugzilla.redhat.com/show_bug.cgi?id=1373276

   * NOTE:  The final comment on the upstream GNOME bug claims that the
  fix is incomplete.  However, it is possible that the running
  NetworkManager was not restarted (see Regression Potential notes
  above), which is why nm-dhcp-helper is falling back to Event.  The
  remainder of the log messages in that final comment are from a custom
  wrapper the submitter was running around nm-dhcp-helper.  I have
  deployed the exact same patch (without said wrapper) to real-world
  systems and tested extensively, and see nothing but successful DHCP
  lease renewal notifications using D-Bus Notify, not D-Bus Event.


  ----
  I've found an issue on some of our Xenial office machines, causing NetworkManager to drop its IP address lease in some cases when it shouldn't. I'm not sure if the actual bug is in NetworkManager or perhaps dbus or dhclient, but I'll do my best to help to figure out where it is.

  What appears to happen:
  * NetworkManager is informed of a new IPv4 lease.
  * During the lease, dhclient keeps it fresh by renewing it using DHCPREQUESTs regularly.
  * In spite of this, NetworkManager drops the IP address from the interface when the last reported lease time expires.

  This happens on various machines, once every few days. We are using a
  failover DHCP configuration using two machines (192.168.0.3 'bonaire'
  and 192.168.0.4 'curacao').

  The machine where I've done the debugging is called 'pampus'
  (192.168.0.166). As you can see in the logs, at 01:21:06
  NetworkManager reports a new lease with lease time 7200.

  jun 07 01:21:06 pampus dhclient[1532]: DHCPREQUEST of 192.168.0.166 on eth0 to 192.168.0.4 port 67 (xid=0x3295b440)
  jun 07 01:21:06 pampus dhclient[1532]: DHCPACK of 192.168.0.166 from 192.168.0.4
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   address 192.168.0.166
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   plen 24 (255.255.255.0)
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   gateway 192.168.0.5
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   server identifier 192.168.0.4
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   lease time 7200
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   nameserver '192.168.0.3'
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   nameserver '192.168.0.4'
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9530]   domain name 'office.screenpointmed.com'
  jun 07 01:21:06 pampus NetworkManager[1161]: <info>  [1496791266.9531] dhcp4 (eth0): state changed bound -> bound

  After this, dhclient is supposed to keep the lease fresh, which it
  does. E.g. at 03:13:19 you can see a DHCPREQUEST and DHCPACK; I've
  seen this DHCPACK in a tcpdump and it contains a new lease time of
  7200 seconds.

  jun 07 03:13:19 pampus dhclient[1532]: DHCPREQUEST of 192.168.0.166 on eth0 to 192.168.0.4 port 67 (xid=0x3295b440)
  jun 07 03:13:19 pampus dhclient[1532]: DHCPACK of 192.168.0.166 from 192.168.0.4
  jun 07 03:13:19 pampus dhclient[1532]: bound to 192.168.0.166 -- renewal in 2708 seconds.

  However, at 03:21:07 (exactly 2 hours and 1 second after the last
  lease reported by NetworkManager) Avahi and NTP report that the IP
  address is gone:

  jun 07 03:21:07 pampus avahi-daemon[1167]: Withdrawing address record for 192.168.0.166 on eth0.
  jun 07 03:21:07 pampus avahi-daemon[1167]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.0.166.
  jun 07 03:21:07 pampus avahi-daemon[1167]: Interface eth0.IPv4 no longer relevant for mDNS.
  jun 07 03:21:08 pampus ntpd[18832]: Deleting interface #3 eth0, 192.168.0.166#123, interface stats: received=2512, sent=2549, dropped=0, active_time=111819 secs

  So I suspect NetworkManager dropped the IP address from the interface,
  because it wasn't informed by dhclient that the lease was renewed. The
  logs don't explicitly say this, so I may have to turn on more verbose
  debugging logs in NetworkManager or dhclient to verify this.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: network-manager 1.2.6-0ubuntu0.16.04.1
  ProcVersionSignature: Ubuntu 4.4.0-66.87-generic 4.4.44
  Uname: Linux 4.4.0-66-generic x86_64
  NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
  ApportVersion: 2.20.1-0ubuntu2.6
  Architecture: amd64
  Date: Wed Jun  7 14:48:59 2017
  IfupdownConfig:
   # interfaces(5) file used by ifup(8) and ifdown(8)
   auto lo
   iface lo inet loopback
  InstallationDate: Installed on 2016-11-04 (214 days ago)
  InstallationMedia: Ubuntu 14.04.5 LTS "Trusty Tahr" - Release amd64 (20160803)
  IpRoute:
   default via 192.168.0.5 dev eth0  proto static  metric 100
   192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.166
   192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.166  metric 100
  IwConfig:
   lo        no wireless extensions.

   eth1      no wireless extensions.

   eth0      no wireless extensions.
  NetworkManager.state:
   [main]
   NetworkingEnabled=true
   WirelessEnabled=true
   WWANEnabled=true
   WimaxEnabled=true
  RfKill:

  SourcePackage: network-manager
  UpgradeStatus: No upgrade log present (probably fresh install)
  nmcli-con:
   NAME                UUID                                  TYPE            TIMESTAMP   TIMESTAMP-REAL                AUTOCONNECT  AUTOCONNECT-PRIORITY  READONLY  DBUS-PATH                                   ACTIVE  DEVICE  STATE      ACTIVE-PATH
   Wired connection 1  37da1802-e1ce-3326-a6d0-f855cc32806d  802-3-ethernet  1496839466  wo 07 jun 2017 14:44:26 CEST  yes          4294966297            no        /org/freedesktop/NetworkManager/Settings/0  yes     eth0    activated  /org/freedesktop/NetworkManager/ActiveConnection/0
   Wired connection 2  a040d7fe-3c52-39ba-82b8-50fad0b602c1  802-3-ethernet  1496399665  vr 02 jun 2017 12:34:25 CEST  yes          4294966297            no        /org/freedesktop/NetworkManager/Settings/1  no      --      --         --
  nmcli-dev:
   DEVICE  TYPE      STATE        DBUS-PATH                                  CONNECTION          CON-UUID                              CON-PATH
   eth0    ethernet  connected    /org/freedesktop/NetworkManager/Devices/0  Wired connection 1  37da1802-e1ce-3326-a6d0-f855cc32806d  /org/freedesktop/NetworkManager/ActiveConnection/0
   eth1    ethernet  unavailable  /org/freedesktop/NetworkManager/Devices/2  --                  --                                    --
   lo      loopback  unmanaged    /org/freedesktop/NetworkManager/Devices/1  --                  --                                    --
  nmcli-nm:
   RUNNING  VERSION  STATE      STARTUP  CONNECTIVITY  NETWORKING  WIFI-HW  WIFI     WWAN-HW  WWAN
   running  1.2.6    connected  started  full          enabled     enabled  enabled  enabled  enabled

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