<!DOCTYPE html><html><head><title></title><style type="text/css">p.MsoNormal,p.MsoNoSpacing{margin:0}
p.MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div>There are much smarter people than me here, but if I might chime in:<br></div><div><br></div><div>Two basic assumptions in networking are that no two separate devices will<br></div><div>share the same MAC address, and a device's MAC address doesn't change after<br></div><div>it's manufactured. Obviously there are practical exceptions (spoofing, privacy<br></div><div>MAC addresses, etc.), but those are the assumptions we operate under (I think<br></div><div>this is the real takeaway from the discussion about VMs). Meanwhile, no such<br></div><div>assumptions can be made about hostnames.<br></div><div><br></div><div>So, from Dnsmasq's point of view, given conflicting configuration, it makes<br></div><div>sense to always prefer the MAC address over the hostname, since it's a stronger<br></div><div>identifier.<br></div><div><br></div><div>Accordingly, if the assumption about MAC address <=> machine doesn't hold true<br></div><div>in your environment, it seems to me the best option is probably to avoid using<br></div><div>MAC addresses as machine identifiers at all. Can you set DHCP client IDs? Or<br></div><div>use hostnames for the host machines' regular OSes as well?<br></div><div><br></div><div>Alternatively, can you set up the live USBs to use custom MAC addresses,<br></div><div>so the assumption does hold true?<br></div><div><br></div><div>Regards,<br></div><div>Nick<br></div><div><br></div><div>On Mon, Jun 21, 2021, at 12:09 PM, Jesus M Diaz wrote:<br></div><blockquote type="cite" id="qt" style=""><div dir="ltr"><div>I never talked of VM on purpose, because they are not VM (hence, no hypervisor or any other controller plane). Indeed I talked of live linux distributions running on USB that I only use for very specific tasks, and of course, I run them over physical machines, but these physical machines are usually running their own OS.<br></div><div><br></div><div>But all this, imho, is not relevant at all, it was explained just to express that *sometimes* it might happen that one DHCP request matches more than one dhcp-host entry in the dnsmasq.con file. That is the only relevant situation, and my question was: is there any way to set a precedence among the potentially matching dhcp-hosts entries?<br></div><div><br></div><div>I don't really understand why the philosophical discussion on what a computer is or is not.<br></div><div><br></div><div>Thanks anyway everybody for the comments.<br></div><div><br></div></div><div><br></div><div class="qt-gmail_quote"><div dir="ltr" class="qt-gmail_attr">On Mon, 21 Jun 2021 at 14:54, Alex Morris <<a href="mailto:dnsmasq-discuss@alexmorris.co.uk">dnsmasq-discuss@alexmorris.co.uk</a>> wrote:<br></div><blockquote class="qt-gmail_quote" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0.8ex;border-left-color:rgb(204, 204, 204);border-left-style:solid;border-left-width:1px;padding-left:1ex;"><div>On Mon, 21 Jun 2021, at 13:42, Jesus M Diaz wrote:<br></div><div>> <br></div><div>> so, if I have two virtual computers running over the same hardware, <br></div><div>> <br></div><div><br></div><div>...then your hypervisor ought to provide unique MAC addresses for each guest NIC.<br></div><div><br></div><div>> <br></div><div>> what should be used as identifier for dnsmasq?<br></div><div>> <br></div><div><br></div><div>The unique MAC address allocated by the hypervisor to the guest NIC.<br></div><div><br></div><div><br></div><div>-- <br></div><div>Alex<br></div><div><br></div><div>_______________________________________________<br></div><div>Dnsmasq-discuss mailing list<br></div><div><a href="mailto:Dnsmasq-discuss@lists.thekelleys.org.uk" target="_blank">Dnsmasq-discuss@lists.thekelleys.org.uk</a><br></div><div><a href="https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss" rel="noreferrer" target="_blank">https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss</a><br></div></blockquote></div><div>_______________________________________________<br></div><div>Dnsmasq-discuss mailing list<br></div><div><a href="mailto:Dnsmasq-discuss%40lists.thekelleys.org.uk">Dnsmasq-discuss@lists.thekelleys.org.uk</a><br></div><div><a href="https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss">https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss</a><br></div><div><br></div></blockquote><div><br></div></body></html>