libvirt users - Mar 2023 - virsh domifaddr --domain domname --source {lease, arp} not showing results with ipv6

hi,

On Tue, Mar 21, 2023 at 3:40?PM Michal Pr?vozn?k <mprivozn at redhat.com>
wrote:
> On 3/19/23 20:21, Natxo Asenjo wrote:
> > hi,
> >
> > I have configured a routed network on my laptop with a ipv6 subnet and
> > dnsmasq is handing out ipv6 addresses to my vms and it works really
wel,
> > but finding out which ips have been used is not as easy as with ipv4.
> >
> > [root at lenovo ~]# virsh domifaddr --domain wec --source lease
> >  Name       MAC address          Protocol     Address
> >
>
-------------------------------------------------------------------------------
> >
> > [root at lenovo ~]# virsh domifaddr --domain wec --source arp
> >  Name       MAC address          Protocol     Address
> >
>
-------------------------------------------------------------------------------
> >
> > When using a ipv4 network, this works:
> >
> > root at lenovo ~]# virsh domifaddr --domain evenng --source arp
> >  Name       MAC address          Protocol     Address
> >
>
-------------------------------------------------------------------------------
> >  vnet2      52:54:00:4c:83:98    ipv4         192.168.122.229/0
> > <http://192.168.122.229/0>
> >
> > [root at lenovo ~]# virsh domifaddr --domain evenng --source lease
> >  Name       MAC address          Protocol     Address
> >
>
-------------------------------------------------------------------------------
> >  vnet2      52:54:00:4c:83:98    ipv4         192.168.122.229/24
> > <http://192.168.122.229/24>
> >
> > I can obviously look into the leases file and find out the address,
but
> > it would be nice to be able to use the virt tooling.
>
> Looks like you won't find any info for IPv6 there, because that's
> exactly what '--source lease' is doing. Are you sure that your IPv6
> address is not autoconfigured and it indeed is libvirt spawned dnsmasq
> that's assigning the IPv6 address?
>
this is the xml:

# cat networks/ipv6.xml
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made
using:
  virsh net-edit ipv6
or other application using the libvirt API.
-->

<network>
  <name>ipv6</name>
  <uuid>49957183-e4e4-4541-8746-11be67f0a511</uuid>
  <forward mode='open'/>
  <bridge name='virbr1' stp='on' delay='0'/>
  <mac address='52:54:00:09:8e:66'/>
  <domain name='ipv6'/>
  <ip family='ipv6' address='2a02:xxx:xx:7::1'
prefix='64'>
    <dhcp>
      <range start='2a02:xxx:xx:7::100'
end='2a02:xxx:xx:7::1ff'/>
    </dhcp>
  </ip>
</network>

so it looks like a dhcp server to me ;-)

I just found out about virsh net-dhcp-leases and that one lists the leases:

# virsh net-dhcp-leases --network ipv6
 Expiry Time           MAC address         Protocol   IP address
     Hostname          Client ID or DUID
---------------------------------------------------------------------------------------------------------------------------------------------
 2023-03-22 16:35:44   52:54:00:0e:ee:da   ipv6       2a02:xxx:xx:7::1ba/64
  WIN-C0HD8RH61MI   00:01:00:01:2b:a7:05:c5:52:54:00:0e:ee:da

> For the '--source arp' case - libvirt reads the arp table
(effectively
> the same info is exposed under /proc/net/arp file) and finds a matching
> entry there, based on the MAC address. Can you see whether there's a
match?
>
No, that only entry right now there is my router:

]# cat /proc/net/arp
IP address       HW type     Flags       HW address            Mask
Device
xx.x.x.1         0x1         0x2         cafebabecafe     *        wifi0

>
> And lastly - there's '--source agent' which is most likely to
return
> useful information, but that requires guest agent running inside.
>
Indeed, no agent running on the vm, could add it.
>
> Michal
>
> >
> > This is on a fedora 37 running qemu-kvm-7.0.0-14.fc37.x86_64 and
> > dnsmasq-2.89-1.fc37.x86_64, everything intalled from the fedora
> > repositories.
>
>
> So is it safe to assume that libvirt (which is where you're reporting
> the issue) is: libvirt-8.6.0-5.fc37 ?
>
yes: libvirt-8.6.0-5.fc37.x86_64

>
> Michal
>
>
So dumping the net-dhcp-leases works also for me, it's just not consequent
with the ipv4 behaviour, that's all.

--
regards,
natxo
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On 3/21/23 16:50, Natxo Asenjo wrote:
> hi,
> 
> On Tue, Mar 21, 2023 at 3:40?PM Michal Pr?vozn?k <mprivozn at redhat.com
> <mailto:mprivozn at redhat.com>> wrote:
> 
>     On 3/19/23 20:21, Natxo Asenjo wrote:
>     > hi,
>     >
>     > I have configured a routed network on my laptop with a ipv6 subnet
and
>     > dnsmasq is handing out ipv6 addresses to my vms and it works
>     really wel,
>     > but finding out which ips have been used is not as easy as with
ipv4.
>     >
>     > [root at lenovo ~]# virsh domifaddr --domain wec --source lease
>     > ?Name ? ? ? MAC address ? ? ? ? ?Protocol ? ? Address
>     >
>    
-------------------------------------------------------------------------------
>     >
>     > [root at lenovo ~]# virsh domifaddr --domain wec --source arp
>     > ?Name ? ? ? MAC address ? ? ? ? ?Protocol ? ? Address
>     >
>    
-------------------------------------------------------------------------------
>     >
>     > When using a ipv4 network, this works:
>     >
>     > root at lenovo ~]# virsh domifaddr --domain evenng --source arp
>     > ?Name ? ? ? MAC address ? ? ? ? ?Protocol ? ? Address
>     >
>    
-------------------------------------------------------------------------------
>     > ?vnet2 ? ? ?52:54:00:4c:83:98 ? ?ipv4 ? ? ? ? 192.168.122.229/0
>     <http://192.168.122.229/0>
>     > <http://192.168.122.229/0 <http://192.168.122.229/0>>
>     >
>     > [root at lenovo ~]# virsh domifaddr --domain evenng --source lease
>     > ?Name ? ? ? MAC address ? ? ? ? ?Protocol ? ? Address
>     >
>    
-------------------------------------------------------------------------------
>     > ?vnet2 ? ? ?52:54:00:4c:83:98 ? ?ipv4 ? ? ? ? 192.168.122.229/24
>     <http://192.168.122.229/24>
>     > <http://192.168.122.229/24
<http://192.168.122.229/24>>
>     >
>     > I can obviously look into the leases file and find out the
>     address, but
>     > it would be nice to be able to use the virt tooling.
> 
>     Looks like you won't find any info for IPv6 there, because
that's
>     exactly what '--source lease' is doing. Are you sure that your
IPv6
>     address is not autoconfigured and it indeed is libvirt spawned dnsmasq
>     that's assigning the IPv6 address?
> 
> 
> this is the xml:
> 
> # cat networks/ipv6.xml
> <!--
> WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
> OVERWRITTEN AND LOST. Changes to this xml configuration should be made
> using:
> ? virsh net-edit ipv6
> or other application using the libvirt API.
> -->
> 
> <network>
> ? <name>ipv6</name>
> ? <uuid>49957183-e4e4-4541-8746-11be67f0a511</uuid>
> ? <forward mode='open'/>
> ? <bridge name='virbr1' stp='on' delay='0'/>
> ? <mac address='52:54:00:09:8e:66'/>
> ? <domain name='ipv6'/>
> ? <ip family='ipv6' address='2a02:xxx:xx:7::1'
prefix='64'>
> ? ? <dhcp>
> ? ? ? <range start='2a02:xxx:xx:7::100'
end='2a02:xxx:xx:7::1ff'/>
> ? ? </dhcp>
> ? </ip>
> </network>
> 
> so it looks like a dhcp server to me ;-)
Yep. That's fine. The only thing missing now is how's the
<interface/>
configured in domain XML. Because '--source leases' is designed to work
only with <interface type='network'/>. Any other type (e.g.
type='bridge') is ignored.
> 
> I just found out about virsh net-dhcp-leases and that one lists the leases:
> 
> # virsh net-dhcp-leases --network ipv6
> ?Expiry Time ? ? ? ? ? MAC address ? ? ? ? Protocol ? IP address ? ? ? ?
> ? ? ? ?Hostname ? ? ? ? ?Client ID or DUID
>
---------------------------------------------------------------------------------------------------------------------------------------------
> ?2023-03-22 16:35:44 ? 52:54:00:0e:ee:da ? ipv6 ? ? ?
> 2a02:xxx:xx:7::1ba/64 ? WIN-C0HD8RH61MI ?
> 00:01:00:01:2b:a7:05:c5:52:54:00:0e:ee:da
And the fact that you can see some leases but virsh doesn't report any
suggests that you may be using type='bridge'.
> 
> 
>     For the '--source arp' case - libvirt reads the arp table
(effectively
>     the same info is exposed under /proc/net/arp file) and finds a matching
>     entry there, based on the MAC address. Can you see whether there's
a
>     match?
> 
> 
> No, that only entry right now there is my router:
> 
> ]# cat /proc/net/arp
> IP address ? ? ? HW type ? ? Flags ? ? ? HW address ? ? ? ? ? ?Mask ? ?
> Device
> xx.x.x.1 ? ? ? ? 0x1 ? ? ? ? 0x2 ? ? ? ? cafebabecafe ? ? * ? ? ?? wifi0
Yeah, this is why '--source arp' doesn't display anything. And I
just
realized that IPv6 doesn't use ARP, so that won't work :-)
>     And lastly - there's '--source agent' which is most likely
to return
>     useful information, but that requires guest agent running inside.
> 
> 
> Indeed, no agent running on the vm, could add it.
> 
> 
If you want to get most consistent answer then that's probably the way
to go.

Michal