[Bug 1800836] Re: systemd-networkd doesn't process IPv6 RA properly
Kjetil Torgrim Homme
1800836 at bugs.launchpad.net
Wed Sep 16 11:00:49 UTC 2020
This is still happening with 237-3ubuntu10.42 in Bionic. RA routes
announced with lifetime of 0s are not removed. It is the firewall which
used to be the default router which (continously) announce these 0s
lifetimes to make sure there are no issues with failover.
$ ip -6 route show default
default proto ra metric 100
nexthop via fe80::21b:21ff:febc:97e6 dev eth0 weight 1
nexthop via fe80::21b:21ff:febc:9416 dev eth0 weight 1
$ sudo rdisc6 eth0
Soliciting ff02::2 (ff02::2) on eth0...
Hop limit : 64 ( 0x40)
Stateful address conf. : No
Stateful other conf. : No
Mobile home agent : No
Router preference : medium
Neighbor discovery proxy : No
Router lifetime : 0 (0x00000000) seconds
Reachable time : unspecified (0x00000000)
Retransmit time : unspecified (0x00000000)
Recursive DNS server : 2a02:c0::1
DNS server lifetime : 2419200 (0x0024ea00) seconds
from fe80::21b:21ff:febc:9416
Hop limit : 64 ( 0x40)
Stateful address conf. : No
Stateful other conf. : No
Mobile home agent : No
Router preference : medium
Neighbor discovery proxy : No
Router lifetime : 0 (0x00000000) seconds
Reachable time : unspecified (0x00000000)
Retransmit time : unspecified (0x00000000)
Recursive DNS server : 2a02:c0::1
DNS server lifetime : 2419200 (0x0024ea00) seconds
from fe80::21b:21ff:febc:9416
Hop limit : 64 ( 0x40)
Stateful address conf. : No
Stateful other conf. : No
Mobile home agent : No
Router preference : medium
Neighbor discovery proxy : No
Router lifetime : 30 (0x0000001e) seconds
Reachable time : unspecified (0x00000000)
Retransmit time : unspecified (0x00000000)
Prefix : 2a02:c0:900:113::/64
On-link : Yes
Autonomous address conf.: Yes
Valid time : 86400 (0x00015180) seconds
Pref. time : 14400 (0x00003840) seconds
Recursive DNS server : 2a02:c0::1
DNS server lifetime : 2419200 (0x0024ea00) seconds
from fe80::21b:21ff:febc:97e6
Hop limit : 64 ( 0x40)
Stateful address conf. : No
Stateful other conf. : No
Mobile home agent : No
Router preference : medium
Neighbor discovery proxy : No
Router lifetime : 30 (0x0000001e) seconds
Reachable time : unspecified (0x00000000)
Retransmit time : unspecified (0x00000000)
Prefix : 2a02:c0:900:113::/64
On-link : Yes
Autonomous address conf.: Yes
Valid time : 86400 (0x00015180) seconds
Pref. time : 14400 (0x00003840) seconds
Recursive DNS server : 2a02:c0::1
DNS server lifetime : 2419200 (0x0024ea00) seconds
from fe80::21b:21ff:febc:97e6
** Changed in: systemd (Ubuntu)
Status: Expired => Confirmed
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https://bugs.launchpad.net/bugs/1800836
Title:
systemd-networkd doesn't process IPv6 RA properly
Status in systemd package in Ubuntu:
Confirmed
Bug description:
The gateways/firewalls in our DC are highly available and when there
is a failover their IPv6 VIP (fe80::1) moves from the master to the
backup one.
We found that only our Bionic VMs behind those gateways had issues
after a failover. Those Bionic VMs were all running systemd-networkd
(from netplan) and before the failover they had:
$ ip -6 route
...
default via fe80::1 dev eth0 proto ra metric 1024 pref medium
But after a failover:
$ ip -6 route
...
default proto ra metric 1024
nexthop via fe80::1 dev eth0 weight 1
nexthop via fe80::210:18ff:febe:6750 dev eth0 weight 1
And after another failover:
$ ip -6 route
...
default proto ra metric 1024
nexthop via fe80::1 dev eth0 weight 1
nexthop via fe80::210:18ff:febe:6750 dev eth0 weight 1
nexthop via fe80::210:18ff:fe77:b558 dev eth0 weight 1
This is problematic as those then use fe80::210:18ff:fe77:b558%$IFACE as their default gateway even when this gateway is unavailable:
$ ip -6 route get ::
:: from :: via fe80::210:18ff:fe77:b558 dev eth0 proto ra src fe80::a800:ff:fe51:8c37 metric 1024 pref medium
We concluded it was a systemd-networkd bug after checking that the following combinations were NOT affected:
1) Xenial+4.4 kernel
2) Xenial+4.15 kernel
3) Bionic+ifupdown
Additional information:
$ apt-cache policy systemd
systemd:
Installed: 237-3ubuntu10.3
Candidate: 237-3ubuntu10.3
Version table:
*** 237-3ubuntu10.3 500
500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
100 /var/lib/dpkg/status
237-3ubuntu10 500
500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
$ lsb_release -rd
Description: Ubuntu 18.04.1 LTS
Release: 18.04
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: systemd 237-3ubuntu10.3
ProcVersionSignature: Ubuntu 4.15.0-38.41-generic 4.15.18
Uname: Linux 4.15.0-38-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
Date: Wed Oct 31 08:47:28 2018
Lspci: Error: [Errno 2] No such file or directory: 'lspci': 'lspci'
Lsusb: Error: [Errno 2] No such file or directory: 'lsusb': 'lsusb'
MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-38-generic root=UUID=43b7ee2e-2ab1-4505-8e0b-d9fe0563a034 ro console=ttyS0 net.ifnames=0 vsyscall=none kaslr nmi_watchdog=0 possible_cpus=1
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: Ubuntu-1.8.2-1ubuntu1
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-xenial
dmi.modalias: dmi:bvnSeaBIOS:bvrUbuntu-1.8.2-1ubuntu1:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-xenial:cvnQEMU:ct1:cvrpc-i440fx-xenial:
dmi.product.name: Standard PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-xenial
dmi.sys.vendor: QEMU
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