On Sun, 2016-12-18 at 20:37 -0500, Laine Stump wrote: > On 12/16/2016 11:58 AM, Martin Wilck wrote: > > "Static" DHCP networks are those where no dynamic DHCP range is > > defined, only a list of host entries is used to serve permanent > > IP addresses. On such networks, we don't want dnsmasq to reply > > to other requests than those statically defined. But > > "dhcp-authoritative" will cause dnsmasq to do just that. > > Therefore we can't use "dhcp-authoritative" for static networks. > > Not surprising that this simple change would have unexpected > consequences - that seems to be a basic law of the universe :-) > > ACK to this, but it has me wondering 1) what is the range for which > it > returns a positive response? Is it for anything within the IP > address/netmask of the interface it's listening on? Or something > larger > than that? (Does it just blindly ACK any request it gets?) and 2) Do > we > know for certain that the same thing doesn't happen when there is > also a > dhcp range defined? I can't answer this for certain at the moment. I got a report from our cloud people and this patch fixed their configuration; I haven't seen it in my own environment. Wrt 2), I'd bet that the same thing will happen with a DHCP range defined. But would that be wrong? If dnsmasq is allowed to take IP addresses from a dynamic range, why shouldn't it do so (*)? Several DHCP servers in the same subnet are a strange configuration anyway. In the case of the "static" network it makes a certain amount of sense (in our case, the libvirt DHCP server was only used to serve the IP of a single static host, which was then used as DHCP server for all other hosts on the network), but if a "dynamic" dhcp service already exists, adding another one looks like begging for trouble to me. I can try to figure stuff out in more detail, but it'll take some time. Regards, Martin (*) I can see a corner case: when libvirt dnsmasq's dynamic range was depleted. Should it be allowed to respond to queries in that case? Sorry, I don't know. -- Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107 SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg) -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
