[lxc-users] Default container IPv6 autoconfiguration settings

[Bostjan Skufca]

Hi all,

I was just debugging some IPv6 connectivity problems and realised that
container interfaces do not inherit host's default settings about IPv6
autoconfiguration.

More precisely I am talking about these two parameters:
- /proc/sys/net/ipv6/conf/*/accept_ra
- /proc/sys/net/ipv6/conf/*/autoconf


### Conditions:
- host has these two parameters set to value 0 for all following
"interfaces":
---> physical
---> bridged
---> /all/... and /default/.., which seem most important when creating new
interfaces which is done when container starts.


### Expected result:
One would assume that interface visible inside the container would copy
host's values from from /default/* location.


### Actual result:
Container interface has these two settings set to 1, causing additional IP
addresses to spuriously appear on container interfaces (depending on timing
of RA broadcasts.
This is especially annoying when using bridged interface inside container
and IPv6 address appears on "physical" interface when it should only be
configured on the bridge that contains given interface.


### Proposed solutions:
It is of course possible to configure these settings from inside container,
as I am currently doing to work around this problem.

But I propose and put forward for discussion two non-excluding possible
solutions:
1. Copy settings from /proc/sys/net/ipv6/conf/default/*
2. Allow these settings to be set with lxc.net.ipv6.* settings in container
configuration file.


Looking forward to read your opinions,
b.
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