(obsolete, superseded by https://tollana.d-tor.org/notes-to-self/?p=585)
Well, another issue I just noticed after the recent reboot of valhalla. When bridging, do never, ever use IPv6 autoconfiguration on the actual ethernet interface or the bridge itself. That will totally screw up the routing!
Disable it by adding the following lines somewhere in /etc/sysctl.d:
net.ipv6.conf.wan.use_tempaddr = 0 net.ipv6.conf.wan.autoconf = 0 net.ipv6.conf.br0.use_tempaddr = 0 net.ipv6.conf.br0.autoconf = 0
You can change it directly by echoing the values to the respective proc files. Unfortunately, the changes only take effect after shutting down and taking the interface up again. So be really, really careful! Be warned: The interface won’t have an IPv6 address any more, so make sure that you have IPv4 connectivity!
You can do this with e.g. screen:
# screen # ip link set down wan ; sleep 1; ip link set up wan