[lxc-devel] [Lxc-users] Request for inclusion into mainline LXC utils

[Michael H. Warfield]

On Mon, 2010-01-25 at 02:18 +0100, Michael Holzt wrote:

: - snip

> I haven't played with ipv6 for some years, but i'm sure that your 
> problems can be fixed without much work. For starters i would try
> something like this:

> interface foo inet6 manual
> 	pre-up ifconfig foo up

Well, it was a good shot.  But, unfortunately, all for naught.  It still
no workie.

The Debian container:

eth0      Link encap:Ethernet  HWaddr 00:04:08:01:02:40  
          inet addr:172.20.38.130  Bcast:172.20.38.255  Mask:255.255.255.0
          inet6 addr: fe80::204:8ff:fe01:240/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:246 errors:0 dropped:0 overruns:0 frame:0
          TX packets:186 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:21383 (21.3 KB)  TX bytes:23934 (23.9 KB)

The Fedora container:

eth0      Link encap:Ethernet  HWaddr 00:04:08:01:02:0A  
          inet addr:172.20.38.131  Bcast:172.20.38.255  Mask:255.255.255.0
          inet6 addr: 2001:4830:3000:8202:204:8ff:fe01:20a/64 Scope:Global
          inet6 addr: fe80::204:8ff:fe01:20a/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:127 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:12396 (12.1 KiB)  TX bytes:1008 (1008.0 b)

I DON'T understand this.  It makes NO sense to me.  At that point
EVERYTHING SHOULD BE under control of the kernel.  But...  Somehow the
Debian configuration fails, even if I restart the routing daemon and
re-advertise those routes.  At that point, everything should just
autoconf with no action from the user space at all.

There is one other very important weirdism.  IPv6 stateless autoconf, by
design and by intent, is disabled if IPv6 forwarding is enabled in the
kernel (remember too, this is a 2.6.30 kernel) and these containers are
residing on a machine acting as an IPv6 router (recurse back to my
earlier comments about very complex configurations and routing) although
they, themselves are not routers.  The host machine is running a routing
advertisement daemon (zebra) providing IPv6 routes.  That host routes to
and from REAL IPv6 networks as well as these virtual containers as well.

In the host sysctl.conf:

net.ipv6.conf.all.forwarding = 1

Confirmed by:

[root at complex ~]# cat /proc/sys/net/ipv6/conf/all/forwarding
1

In the Fedora container, I have not hat to set that to 0 but...

[root at alcove ~]# cat /proc/sys/net/ipv6/conf/all/forwarding
0

Like magic.  And there it works.

In the Debian container, it was NOT showing up as 1 but 0.  So I set it
in /etc/sysctl.conf.  Now...

root at ubuntu:~# cat /proc/sys/net/ipv6/conf/all/forwarding
0

And there it still doesn't work.  What is the difference?  Why doesn't
it work properly with Debian?  These containers are running side by side
in the same host environment (re-enforcing some relevance to the
lxc-devel topic).

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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