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+launch...@cs.cmu.edu> 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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