To allow virtual machines to access the internet, I have created a bridge on my host computer. For use by the host itself, the bridge is set up to have a private IPv4 address (which is converted to an external address via NAT in my home router), a static private IPv6 address for local communication and a dynamic IPv6 address obtained via SLAAC for internet access.
This setup has worked well with Fedora 26 and 27, but with Fedora 28 the bridge device does not get any IPv6 assigned, not even a link-local one:
$ ifconfig bridge0
bridge0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.11 netmask 255.255.255.0 broadcast 192.168.0.255
ether 00:25:22:06:b2:1c txqueuelen 1000 (Ethernet)
RX packets 4118 bytes 3503462 (3.3 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3613 bytes 448237 (437.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Contents of /etc/sysconfig/network-scripts/ifcfg-bridge0:
Static and link-local addresses are assigned correctly with IPV6_AUTOCONF=no, but then of course the dynamic address for internet access is missing.
The issue does not occur on simple Ethernet interfaces without bridge.
Created attachment 1433533 [details]
[PATCH] device: start IP configuration when master carrier goes up
(In reply to Beniamino Galvani from comment #1)
> Created attachment 1433533 [details]
> [PATCH] device: start IP configuration when master carrier goes up
Applied to master:
After upgrading NetworkManager from version 1.10.6 to 1.10.8 IPv6 addresses are assigned correctly to the bridge and output of "route -A inet6" also looks reasonable.
However since the upgrade done yesterday (from updates-testing) it happened several times that IPv6 did not work though, i.e. "ping -6 IPv6-capable-site" hangs forever and indicates 100% packet loss after ^C, while "ping -4 ..." works. It just came to my mind that this might be a firewall problem and indeed after "systemctl stop firewalld" IPv6 immediately started to work and continued to work after "systemctl start firewalld".
Normally I use a custom firewall configuration but the issue also has occured with default settings.
(In reply to Norbert Jurkeit from comment #4)
> After upgrading NetworkManager from version 1.10.6 to 1.10.8 IPv6 addresses
> are assigned correctly to the bridge and output of "route -A inet6" also
> looks reasonable.
Yes, the fix is included in NetworkManager-1.10.8-1.fc28.
> However since the upgrade done yesterday (from updates-testing) it happened
> several times that IPv6 did not work though, i.e. "ping -6
> IPv6-capable-site" hangs forever and indicates 100% packet loss after ^C,
> while "ping -4 ..." works. It just came to my mind that this might be a
> firewall problem and indeed after "systemctl stop firewalld" IPv6
> immediately started to work and continued to work after "systemctl start
This is probably the same issue of bug 1575431.
Thanks for the hint! I just changed IPv6_rpfilter to "no" in /etc/firewalld/firewalld.conf as proposed in bug 1575431 and that seems to fix the issue also for me.
Additional info: I have 2 other Fedora 28 computers in the same LAN, but with ordinary network configuration (because I don't run VMs on them) and haven't encountered any IPv6 connectivity issues there. So even if NetworkManager is not the root cause the bridge configuration seems to induce the issue.
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