libvirt users - May 2016 - Dump network traffic from each VM.

Hi guys,

Does anybody know how to dump the network trafic from each virtual
machine using libvirt?

Here, we usually use VPN softwares and other network tools inside
Virtual Machines (Windows and Linux). Sometimes, this applications
does not work properly, so we need to dump the network traffic of each
Virtual Machine to compare and debug.

How can I enable it using libvirt? I know that if you use a QEMU
instance, you can enable the dump using "-netdev dump,...".

Thanks! :-)

Julio Cesar Faracco

On Wed, May 04, 2016 at 12:37:14PM -0300, Julio Faracco
wrote:
> Hi guys,
> 
> Does anybody know how to dump the network trafic from each virtual
> machine using libvirt?
> 
> Here, we usually use VPN softwares and other network tools inside
> Virtual Machines (Windows and Linux). Sometimes, this applications
> does not work properly, so we need to dump the network traffic of each
> Virtual Machine to compare and debug.
> 
> How can I enable it using libvirt? I know that if you use a QEMU
> instance, you can enable the dump using "-netdev dump,...".
Libvirt does not support the QEMU netdev dump feature at this time.

Best bet is to just connect tcpdump to the TAP device associated
with the virtual machine in question. See the XML config for the
name of the currently assigned TAP device

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
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Hi Daniel,

I changed the libvirt code to support "-net dump" because it is
more comfortable to me and to users here.

I don't know if it is interesting to the community, but... most of the
code is ready if someone needs.

Julio Cesar Faracco

2016-05-05 10:34 GMT-03:00 Daniel P. Berrange
<berrange@redhat.com>:
> On Wed, May 04, 2016 at 12:37:14PM -0300, Julio Faracco wrote:
>> Hi guys,
>>
>> Does anybody know how to dump the network trafic from each virtual
>> machine using libvirt?
>>
>> Here, we usually use VPN softwares and other network tools inside
>> Virtual Machines (Windows and Linux). Sometimes, this applications
>> does not work properly, so we need to dump the network traffic of each
>> Virtual Machine to compare and debug.
>>
>> How can I enable it using libvirt? I know that if you use a QEMU
>> instance, you can enable the dump using "-netdev dump,...".
>
> Libvirt does not support the QEMU netdev dump feature at this time.
>
> Best bet is to just connect tcpdump to the TAP device associated
> with the virtual machine in question. See the XML config for the
> name of the currently assigned TAP device
>
> Regards,
> Daniel
> --
> |: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/
:|
> |: http://libvirt.org              -o-             http://virt-manager.org
:|
> |: http://autobuild.org       -o-         http://search.cpan.org/~danberr/
:|
> |: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc
:|