Re: [vserver] /proc/net/dev missing when networknamespaces are active

From: Herbert Poetzl <>
Date: Wed 27 Jun 2012 - 03:25:07 BST
Message-ID: <>

On Mon, Jun 25, 2012 at 09:12:58AM +1000, Steve Kieu wrote:
>> I investigated this a bit further.
>> - The simple trick of bind-mounting a suitable directory
>> on /proc/net works in a very limited way as /proc/net is a
>> symlink to /proc/self/net

> I think you should never try that.

> When mount bind you effectively use the deferent network
> namespace for the new namespace in teh vserver.

you cannot bind mount across namespaces (atm)

> Looks like it works in someway but it will mess up your
> host network.

it is very unlikely that a bind mount will mess up the
(host) networking

> Use unshare as you already noted below then you have completely
> new ns

unshare will allow you to create new namespaces, but
you have to tell the kernel what namespaces you want
to unshare

>> Atm I assume there is a bug in util-vserver and if it is only
>> using an old/obsolete approach to enable the namespaces or a
>> collision between /proc/self/net-hiding and namespaces.

there is no old/obsolete approach to enabling namespaces
and I'm pretty confident util-vserver does nothing wrong

> As I said before - it is not the network namespace in the
> kernel but it is vserver utils tool.

util-vserver does not unshare network namespaces unless
you tell it to, by default, util-vserver (and Linux-VServer)
use network isolation not network namespaces.

> The thing is, if the vserver folks think layer 2 networking
> virtualization *is* important or not. then they can actively
> fix the bug (or not to).

not sure what 'the bug' actually is ...

> I encountered a strange problem with vserver networking before
> and really not happy with the way it is. The problem that when
> vserver share a bridge with the host (use bridge because I want
> that network to be used for kvm as well) and when a kvm machine
> using same bridge be turned off - Or some vserver use the
> bridge got turned off - the whole bridge lose their connection
> - sometimes it is recovered by itself but most of the time not.

I'm happily using Linux-VServer together with kvm on a
routed as well as bridged setup and never encountered
any issues (why would there be any? Linux-VServer does
not mess with layer 2)

> I have to login to the host (in different interface) and do
> arpping to manually update mac addr with IP to get it up. not
> sure why -

I presume your problem is related to a primary IP
disappearing and the 'promote secondaries' feature
being disabled (note that this is not even Linux-VServer
related, it's a mainline networking 'feature')

> The problem is gone away currently with my LXC containers setup.

> I do hope that the vserver devs fix the bug so I can use
> network ns again with vserver.

please elaborate what 'the bug' is in your opinion and
describe the setup where 'you used network namespaces with


> Thanks,

>> Regards,
>> Adrian
>> --
>> LiHAS - Adrian Reyer - Hessenwiesenstraße 10 - D-70565 Stuttgart
>> Fon: +49 (7 11) 78 28 50 90 - Fax: +49 (7 11) 78 28 50 91
>> Mail: - Web:
>> Linux, Netzwerke, Consulting & Support - USt-ID: DE 227 816 626 Stuttgart

> --
> Steve Kieu
Received on Wed Jun 27 03:25:20 2012

[Next/Previous Months] [Main vserver Project Homepage] [Howto Subscribe/Unsubscribe] [Paul Sladen's vserver stuff]
Generated on Wed 27 Jun 2012 - 03:25:20 BST by hypermail 2.1.8