10:50 a.m.
hi,
On Tue, Mar 21, 2023 at 3:40 PM Michal Prívozník <mprivozn(a)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@lenovo ~]# virsh domifaddr --domain wec --source lease
> Name MAC address Protocol Address
>
-------------------------------------------------------------------------------
>
> [root@lenovo ~]# virsh domifaddr --domain wec --source arp
> Name MAC address Protocol Address
>
-------------------------------------------------------------------------------
>
> When using a ipv4 network, this works:
>
> root@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@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