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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have run into an issue described in a couple previous threads:<o:p></o:p></p>
<p class="MsoNormal"><a href="https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q4/015997.html">https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q4/015997.html</a><o:p></o:p></p>
<p class="MsoNormal"><a href="https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2022q3/016526.html">https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2022q3/016526.html</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">As a summary, if two clients get served the same IP from dnsmasq DHCP, dnsmasq will serve a NAK to the second client. Good client software should just retry on this condition, but unfortunately getting served a NAK causes bugs in some PXE
firmware.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve attached a patch to add a new option: `dhcp-hold-offered`, which creates a short (30s) lease on a DHCP offer. I don’t think it makes sense to change the behavior of dnsmasq unconditionally to get around this issue, as this is working
around a bug in external software. This is a small update allowing users to have a workaround for this issue.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here is some data of the lease file from testing (running `watch -n 1 cat /<b>var</b>/lib/misc/dnsmasq.leases`):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I see the initial short lease get created:<o:p></o:p></p>
<p class="MsoNormal">1790020329 {MAC1} {IP1} * *<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The lease is respected, and the second server is given the next IP in range:<o:p></o:p></p>
<p class="MsoNormal">1790020333 {MAC2} {IP2} * *<o:p></o:p></p>
<p class="MsoNormal">1790020329 {MAC1} {IP1} * *<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Both servers end up with their full lease (30m in this case):<o:p></o:p></p>
<p class="MsoNormal">1790022110 {MAC2} {IP2} * *<o:p></o:p></p>
<p class="MsoNormal">1790022110 {MAC1} {IP1} * *<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Let me know if you can look at the patch. Here is the source commit:<o:p></o:p></p>
<p class="MsoNormal"><a href="https://thekelleys.org.uk/gitweb-noai/?p=dnsmasq.git;a=commit;h=ad9208358eadcf747619511ec8b98134bf85a5f">https://thekelleys.org.uk/gitweb-noai/?p=dnsmasq.git;a=commit;h=ad9208358eadcf747619511ec8b98134bf85a5f</a>3<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Matt<o:p></o:p></p>
<p class="MsoNormal"><a href="mailto:Matthew.Harkness@spacex.com">Matthew.Harkness@spacex.com</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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