<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 14 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
span.EmailStyle18
{mso-style-type:personal-reply;
color:black;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">As far as I know, the only “special” thing that BIND does consistently on a restart, that it doesn’t do on a regular basis in normal operation, is a “priming”
query to whatever is configured as root nameservers. I suppose it’s _<i>possible</i>_ that there is something about priming queries, particularly, that exercises a codepath in the router, with a horrible bug in it. This is – as Mark speculated – much more
likely if the router is trying to do something “smart” with your DNS, e.g. intrusion detection/prevention, reputation-based blacklisting, something like that. I’d look at the router config and see if you can turn any feature(s) like that *<b>off</b>*.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Failing that, if priming queries are the culprit, it should be fairly easy to reproduce the scenario, since one can issue identical-looking queries to the same
root-nameserver destinations (the main difference between these and other command-line-generated queries would consist of making them non-recursive). If you can reproduce the issue at will, maybe the router manufacturer would actually listen to your trouble
report.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Putting on my InfoSec paranoia hat for a second, if it’s the *<b>responses</b>* to the priming queries that are causing the router to go belly-up, then this is
a scary prospect indeed, since it raises the possibility that evildoers could send *<b>spoofed</b>* responses like that, to routers of that make/model, and this would be a powerful Denial of Service attack.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">
- Kevin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> bind-users [mailto:bind-users-bounces@lists.isc.org]
<b>On Behalf Of </b>Chris Serella<br>
<b>Sent:</b> Thursday, May 25, 2017 10:24 AM<br>
<b>To:</b> bind-users@lists.isc.org<br>
<b>Subject:</b> Weird issue with bind & router<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div id="divtagdefaultwrapper">
<p><span style="font-family:"Calibri","sans-serif";color:black">I run a small dev system on my home network, housing dns etc all under the one server.<br>
<br>
System: ubuntu16.04 server, ispconfig etc etc etc, you get the idea.<br>
<br>
Anyway, the problem i am having comes down to the router rebooting (is it crashing? I cant tell) every time bind starts/restarts. This ordinarily wouldnt be an issue, DNS rarely changes so the service does not need restarting but the problem occurs on system
boot too.<br>
<br>
The router in question is a Plusnet Hub One which I believe is actually a repackaged BT Hub 5. The "server" is an ACER AX3300 desktop with ubuntu server installed.<br>
<br>
Troubleshooting was difficult as i couldnt isolate what it was until i went over to ISPConfig for assistance, they informed me that a DNS reload on their software simply saves data to files and initiates a service restart.<br>
<br>
With this information to hand I made no changes to the DNS in ISPConfig, instead i opened a terminal and tunnels into the server and issued a bind9 restart from there.<br>
<br>
Sure enough the problem reared its ugly little head, The ssh session dropped out and looking over to the router i could see it was going through its power cycle. To be sure this wasn't some freakishly well timed coincidence, I completed the steps several times
more (3) all with the same result.<o:p></o:p></span></p>
</div>
</div>
</body>
</html>