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Not to cache TXT records in general sounds sort of detrimental to
the concept of a caching resolver. And apparently none of the
resolvers does evaluate which TXT records are legitimate and which
are useless/nefarious - as in being attempts of DNS tunnelling.<br>
<br>
TXT records might be required for SPF/DKIM/DMARC.<br>
<br>
NULL records on the other hand should perhaps not be cached, or even
permitted for queries, considering
<a class="moz-txt-link-freetext" href="https://tools.ietf.org/html/rfc1035">https://tools.ietf.org/html/rfc1035</a><br>
<br>
<blockquote type="cite">
<pre class="newpage">NULLs are used as placeholders in some experimental extensions of the DNS</pre>
</blockquote>
<br>
As far as I have read and understood the best protection against DNS
Tunnelling is traffic analysis, e.g. firewall with deep packet
inspection, and/or tools for <br>
payload analysis.<br>
<br>
<div class="moz-cite-prefix">On 22.11.2018 11:35, Unbound-users
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CABPjrMUD4vw5zXcWh62hXCFG8dPV-6j0tGNz79Ufr5YWVgk4bQ@mail.gmail.com">
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<div dir="auto">Hello,</div>
<div dir="auto"><br>
</div>
<div dir="auto">First of all : great project and product, thanks
a lot for that:)</div>
<div dir="auto"><br>
</div>
<div dir="auto">I would appreciate if you could give me some
hint...</div>
<div dir="auto"><br>
</div>
<div dir="auto">Since I am observing a lot of DNS Tunnel “users”
, the cache started to store totally useless records of type
TXT and NULL. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Of course, never ending struggle called blocking
DNS Tunnel domains helps, but from time to time appears sth
new, that makes mess.</div>
<div dir="auto"><br>
</div>
<div dir="auto"> </div>
<div dir="auto">Can we configure unbound to not to store TXT
& NULL records? Or if you think this idea is silly, please
let me know😊</div>
<div dir="auto"><br>
</div>
<div dir="auto"><br>
</div>
<div dir="auto">Thanks a lot</div>
<div dir="auto"><br>
</div>
<div dir="auto">Maciej</div>
</div>
</blockquote>
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