Re: [libvirt PATCH v2 2/3] conf: add an attribute to turn on NAT for IPv6 virtual networks

On 6/9/20 12:17 PM, Daniel P. Berrangé wrote: > Historically IPv6 did not support NAT, so when IPv6 was added to > libvirt's virtual networks, when requesting <forward mode="nat"/> > libvirt will NOT apply NAT to IPv6 traffic, only IPv4 traffic. > > This is an annoying historical design decision as it means we > cannot enable IPv6 automatically. We thus need to introduce a > new attribute > > <forward mode="nat"> > <nat ipv6="yes"/> > </forward> > > The new attribute is a tri-state, so it leaves open the possibility of > us intentionally changing the default behaviour in future to honour > NAT for IPv6. Any network defined with an older libvirt, and even newly defined networks that don't have ipv6 set explicitly in the input XML, won't have an explicit value saved in the config. So if we change the default, those existing networks will have different behavior. I don't see how we could change the default without those existing networks getting automatically changed to ipv6='yes'.