[libvirt] libvirt plans: dns support for IPv6?

Gene Czarcinski gene at czarc.net
Sat Sep 15 20:07:15 UTC 2012


On 09/14/2012 06:08 AM, Daniel P. Berrange wrote:
> FYI, already libvirt aims to work with old dnsmasq, in general there is
> no problem with using features from new dnsmasq. If the host has an old
> dnsmasq, they simply won't be able to take advantage of new features
> libvirt might support. The key is simply that if the host has the old
> dnsmasq, we should be careful not to invoke it in the wrong way for
> existing features.
I am not sure I understand the reasoning for continuing support of old 
versions of dnsmasq ... but so be it.  How is the version of dnsmasq 
being determined ... at [ugly] runtime or during configuration/compilation?

Adding IPv6 dns capability to libvirt is turning out to be a little more 
involve that I thought it would be.

Right now you can define a IPv6 network manually, define static IPv6 
addresses in the guests, and add the definitions to the host's 
/etc/hosts file.  That works.

The current dnsmasq 2.63 has a number of options for IPv6 and (to me) 
appears to duplicate some/all of the functionality of radvd.  It is not 
clear to me that all of these need to be supported.  However, there is 
one mode which uses "slaac" IPv6 addresses on a network running both 
IPv4 and IPv6 stacks.  It then does a "little dance" and will add the 
IPv6 address to cache under the guest system's FQDN.  But this is not 
dhcp support.

I am doing some testing but I believe that NetworkManager is not doing 
"the right thing" for stateful IPv6 addressing ... it is not sending the 
FQDN (not the host name like in IPv4 but the FQDN).  I am trying not to 
dig into the NetworkManager code and am doing some testing to prove that 
this is the problem.

Assuming that both of these approaches to IPv6 addressing and a dns 
service are desirable, this means adding some kind of network definition 
parameters so that libvirt knows what dnsmasq parameters to use.

Any comments appreciated.

Gene




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