<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div><span></span></div> <div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4054">Hi Simon,</div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4057" dir="ltr"> I am definitely not a DHCP expert and I don't want either to become a pain. Yet...</div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4055" dir="ltr"> I<font id="yui_3_16_0_ym19_1_1538994195320_5208" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif"> can<font id="yui_3_16_0_ym19_1_1538994195320_4931"> </font><font id="yui_3_16_0_ym19_1_1538994195320_4908"><font id="yui_3_16_0_ym19_1_1538994195320_4798">read that not only </font></font><font id="yui_3_16_0_ym19_1_1538994195320_4908"><font id="yui_3_16_0_ym19_1_1538994195320_4798">the</font> </font>beha</font>vior is not inline with RFC, but it even contradicts the RFC:</div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4056" dir="ltr"><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4022" dir="ltr">"3.2 Client-server interaction - reusing a previously allocated network address
</div><pre id="yui_3_16_0_ym19_1_1538994195320_4073" style="color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; overflow-wrap: break-word; white-space: pre-wrap;"> If a client remembers and wishes to reuse a previously allocated
network address, a client may choose to omit some of the steps
described in the previous section. The timeline diagram in figure 4
shows the timing relationships in a typical client-server interaction
for a client reusing a previously allocated network address."
<font id="yui_3_16_0_ym19_1_1538994195320_4722" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">=> So My iPhone is legit.</font>
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"Servers with knowledge of the client's configuration parameters
<pre id="yui_3_16_0_ym19_1_1538994195320_4147" style="color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; overflow-wrap: break-word; white-space: pre-wrap;"> respond with a DHCPACK message to the client. Servers SHOULD NOT
check that the client's network address is already in use; the
client may respond to ICMP Echo Request messages at this point."
</pre><font id="yui_3_16_0_ym19_1_1538994195320_5051" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">=> Invalidates the fix you did in 2017:</font>
"<table width="100%" id="yui_3_16_0_ym19_1_1538994195320_4223" style="font-family: Arial, sans-serif; font-size: 1em; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(245, 245, 245); text-decoration-style: initial; text-decoration-color: initial; color: black; line-height: 1.4em !important;" border="1" cellspacing="0" cellpadding="0"><tbody id="yui_3_16_0_ym19_1_1538994195320_4224"><tr id="yui_3_16_0_ym19_1_1538994195320_4225"><td id="yui_3_16_0_ym19_1_1538994195320_4226" style="padding: 0em; vertical-align: top; line-height: 1.4em !important;"><pre id="yui_3_16_0_ym19_1_1538994195320_4227" style="margin: 10px 10px 0px; padding: 0px; font-size: 1em; width: auto;"><span id="yui_3_16_0_ym19_1_1538994195320_4228" style='color: black; font-family: Consolas, "Bitstream Vera Sans Mono", "Courier New", Courier, monospace !important;'>commit 5ce3e76fbf89e942e8c54ef3e3389facf0d9067a</span></pre></td></tr><tr id="yui_3_16_0_ym19_1_1538994195320_4229"><td id="yui_3_16_0_ym19_1_1538994195320_4230" style="padding: 0em; vertical-align: top; line-height: 1.4em !important;"><pre id="yui_3_16_0_ym19_1_1538994195320_4231" style="margin: 0px 10px; padding: 0px; font-size: 1em; width: auto;"><span id="yui_3_16_0_ym19_1_1538994195320_4232" style='color: black; font-family: Consolas, "Bitstream Vera Sans Mono", "Courier New", Courier, monospace !important;'>Author: Simon Kelley <simon@thekelleys.org.uk></span></pre></td></tr><tr id="yui_3_16_0_ym19_1_1538994195320_4233"><td id="yui_3_16_0_ym19_1_1538994195320_4234" style="padding: 0em; vertical-align: top; line-height: 1.4em !important;"><pre id="yui_3_16_0_ym19_1_1538994195320_4235" style="margin: 0px 10px; padding: 0px; font-size: 1em; width: auto;"><span id="yui_3_16_0_ym19_1_1538994195320_4236" style='color: black; font-family: Consolas, "Bitstream Vera Sans Mono", "Courier New", Courier, monospace !important;'>Date: Fri Apr 28 22:14:20 2017 +0100</span></pre></td></tr><tr id="yui_3_16_0_ym19_1_1538994195320_4237"><td id="yui_3_16_0_ym19_1_1538994195320_4238" style="padding: 0em; vertical-align: top; line-height: 1.4em !important;"><pre id="yui_3_16_0_ym19_1_1538994195320_4239" style="margin: 0px 10px; padding: 0px; font-size: 1em; width: auto;"> </pre></td></tr><tr id="yui_3_16_0_ym19_1_1538994195320_4240"><td id="yui_3_16_0_ym19_1_1538994195320_4241" style="padding: 0em; vertical-align: top; line-height: 1.4em !important;"><pre id="yui_3_16_0_ym19_1_1538994195320_4242" style="margin: 0px 10px 10px; padding: 0px; font-size: 1em; width: auto;"><span id="yui_3_16_0_ym19_1_1538994195320_4243" style='color: black; font-family: Consolas, "Bitstream Vera Sans Mono", "Courier New", Courier, monospace !important;'> DHCPv4: do ICMP-ping check in all cases other that current lease.</span></pre></td></tr></tbody></table>"
<font id="yui_3_16_0_ym19_1_1538994195320_5050" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">=> This is a real Bug affecting the current behavior. I would really appreciate that you unlink the authoritative link to always breaking this statement:</font>
"Servers SHOULD NOT respond if their information is not
<pre id="yui_3_16_0_ym19_1_1538994195320_4342" style="color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; overflow-wrap: break-word; white-space: pre-wrap;"> _guaranteed_ to be accurate. For example, a server that identifies a
request for an expired binding that is owned by another server SHOULD
NOT respond with a DHCPNAK unless the servers are using an explicit
mechanism to maintain coherency among the servers."
<font id="yui_3_16_0_ym19_1_1538994195320_5045" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">I agree that the example exposes a philosophy similar to what you implemented, in the sense that being an authoritative server somehow fulfils the second part of the example, but the example is just an example. IMHO not having a trace of the lease in combination with being authoritative should/could be interpreted as a potential Rogue client attempting a MIM attack which is actually an accurate info to be used to NAK the request, or arguably not answer at all. Could you at least make this behavior configurable? Thanks a lot!!!</font>
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<font id="yui_3_16_0_ym19_1_1538994195320_5049" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">I am not sure I understand what the implications might be that you fear in NAK-ing the request.</font>
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<font face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">Thanks a lot!</font>
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<font face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">Regards,</font>
<font id="yui_3_16_0_ym19_1_1538994195320_5047" face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif">Bernard
</font></pre></pre><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4068" dir="ltr"><font face="HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif"></font><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4069" dir="ltr"> </div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1538994195320_4357"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1538994195320_3882" style="display: block;"> <div id="yui_3_16_0_ym19_1_1538994195320_3881" style="font-family: Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_ym19_1_1538994195320_3880" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, Sans-Serif; font-size: 16px;"> <div id="yui_3_16_0_ym19_1_1538994195320_3934" dir="ltr"><br></div> </div> </div> </div></div></body></html>