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

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

[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

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.

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.



-- 
--
Groeten,
natxo
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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?

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?

And lastly - there's '--source agent' which is most likely to return
useful information, but that requires guest agent running inside.

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 ?

Michal