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<div class="moz-cite-prefix">On 30/10/2019 02:33, Aaron D. Gifford
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAGDxMR5s-Z81k9Bg5BBTnhfE2Zs_+3LGoBPsQ6P4OJDJFLrsdg@mail.gmail.com">On
a FreeBSD system running PowerDNS authoritative server 4.2.0, I
noticed this:<br>
<div>
<div><br>
</div>
<div># sockstat -4<br>
USER COMMAND PID FD PROTO LOCAL ADDRESS
FOREIGN ADDRESS <br>
root pdns_serve 40055 4 udp4 <a
href="http://192.168.50.12:53" moz-do-not-send="true">192.168.50.12:53</a>
*:*<br>
root pdns_serve 40055 6 tcp4 <a
href="http://192.168.50.12:53" moz-do-not-send="true">192.168.50.12:53</a>
*:*<br>
root pdns_serve 40055 8 tcp4 <a
href="http://192.168.50.12:55401" moz-do-not-send="true">192.168.50.12:55401</a>
<a href="http://127.0.0.1:3306" moz-do-not-send="true">127.0.0.1:3306</a><br>
root pdns_serve 40055 9 tcp4 <a
href="http://192.168.50.12:54277" moz-do-not-send="true">192.168.50.12:54277</a>
<a href="http://127.0.0.1:3306" moz-do-not-send="true">127.0.0.1:3306</a><br>
root pdns_serve 40055 16 udp4 <a
href="http://192.168.50.12:19413" moz-do-not-send="true">192.168.50.12:19413</a>
*:*<br>
...<br>
<br>
</div>
<div>Why is it listening on UDP port 19413? I thought I'd
disabled various subsystems that might want to listen on a TCP
or UDP port.</div>
</div>
</blockquote>
<p>If you restart pdns I think you'll find it binds to a different
random port, which almost certainly means it's a socket which has
been created for the purpose of sending *outbound* UDP packets. I
see the same here:</p>
<p><tt>$ sudo netstat -naup | grep pdns</tt><tt><br>
</tt><tt>udp 0 0 0.0.0.0:53
0.0.0.0:* 17497/pdns_server</tt><tt><br>
</tt><tt>udp 0 0 0.0.0.0:12579
0.0.0.0:* 17497/pdns_server</tt><tt><br>
</tt><tt>udp6 0 0 :::53
:::* 17497/pdns_server</tt><tt><br>
</tt><tt>udp6 0 0 :::11846
:::* 17497/pdns_server</tt></p>
<p><tt>$ sudo systemctl restart pdns</tt><tt><br>
</tt></p>
<p><tt>$ sudo netstat -naup | grep pdns</tt><tt><br>
</tt><tt>udp 0 0 0.0.0.0:53
0.0.0.0:* 12560/pdns_server</tt><tt><br>
</tt><tt>udp 0 0 0.0.0.0:17662
0.0.0.0:* 12560/pdns_server</tt><tt><br>
</tt><tt>udp6 0 0 :::53
:::* 12560/pdns_server</tt><tt><br>
</tt><tt>udp6 0 0 :::16544
:::* 12560/pdns_server</tt></p>
<p>Although pdns auth no longer has a recursor option, and I have
expand-alias turned off, I suspect it is for sending NOTIFY
packets.</p>
<p>Anyway, it's not a listening port, so you don't need to worry
about it.<br>
</p>
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