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<p class="MsoNormal">Hi all!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Consider the following dual stack network: <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">IPv4:<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">192.168.1.1/24<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">DHCP on 192.168.1.1 with DNSMASQ<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">DNS on 192.168.1.10 (pi-hole, docker)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">DNSMASQ has dhcp-option=6,192.168.1.10, so clients query the DNS directly. This allows pi-hole query DNSMASQ for the names of those clients.<o:p></o:p></li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">IPv6:<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Changing prefix when the router/cable modem reboots, so I cannot hardcode the prefix.
<o:p></o:p></li><ul style="margin-top:0in" type="circle">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level2 lfo1">Even tried locking down the DUID. Doesn’t work.<o:p></o:p></li></ul>
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">DNSMASQ has dhcp-range=::,constructor:br0,ra-only,12h. (ra-only to my understanding here is the same as SLAAC)<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">I did NOT set the dhcp-option=option6:23,[::]<o:p></o:p></li></ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Now the problem is that DNSMASQ still send the link-local address of br0 being the RDNS server as part of the RA.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The only way I found to disable this was to set the nameserver port to 0, essentially disabling the DNS component of DNSMASQ.
<o:p></o:p></p>
<p class="MsoNormal">This however breaks the lookups that pi-hole does against DNSMASQ.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is there another switch that I’m not seeing?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Other solutions I have considered:<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Set the dhcp-option=option6:23 to the link-local address of pi-hole. Working on that, but Docker and IPv6 aren’t the best friends when it comes to changing prefixes.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">ULA on the network, DD-WRT doesn’t support that.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Make pi-hole the DHCP server for IPv4, so it has the client names, deferring to DNSMASQ only for IPv6. Actual viable solution.<o:p></o:p></li></ul>
<p class="MsoNormal" style="background:white"><span lang="NL-BE" style="color:black;background:white">--</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span lang="NL-BE" style="color:black">Kristof</span><span style="color:black"><o:p></o:p></span></p>
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