I am able to get a UDP reply from the socket using nc. TCP requests are handled fine. No UDP requests show up in the log. UDP request to the upstream DNS server are answered fine when queried directly. Is there anything that can cause UDP requests to be blocked other than a firewall? The router isn't blocking UDP. This seems to be only dnsmasq.<br>
<br>Output from Dig:<br><br>[ ~]$ dig <a href="http://debian.org">debian.org</a> @<a href="http://192.168.1.115">192.168.1.115</a><br><br>; <<>> DiG 9.7.3-P3-RedHat-9.7.3-8.P3.el6 <<>> <a href="http://debian.org">debian.org</a> @<a href="http://192.168.1.115">192.168.1.115</a><br>
;; global options: +cmd<br>;; connection timed out; no servers could be reached<br>[ ~]$ dig +tcp <a href="http://debian.org">debian.org</a> @<a href="http://192.168.1.115">192.168.1.115</a><br><br>; <<>> DiG 9.7.3-P3-RedHat-9.7.3-8.P3.el6 <<>> +tcp <a href="http://debian.org">debian.org</a> @<a href="http://192.168.1.115">192.168.1.115</a><br>
;; global options: +cmd<br>;; Got answer:<br>;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34510<br>;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0<br><br>;; QUESTION SECTION:<br>;<a href="http://debian.org">debian.org</a>. IN A<br>
<br>;; ANSWER SECTION:<br><a href="http://debian.org">debian.org</a>. 1992 IN A 206.12.19.7<br><a href="http://debian.org">debian.org</a>. 1992 IN A 128.31.0.51<br><br>;; Query time: 56 msec<br>
;; SERVER: 192.168.1.115#53(192.168.1.115)<br>;; WHEN: Wed Jan 11 17:47:47 2012<br>;; MSG SIZE rcvd: 60<br><br><br>Corresponding log entries:<br><br>Jan 11 18:16:36 dnsmasq[6821]: started, version 2.57 cachesize 150<br>
Jan 11 18:16:36 dnsmasq[6821]: compile time options: IPv6 GNU-getopt DBus I18N DHCP TFTP IDN<br>
Jan 11 18:16:36 dnsmasq[6821]: warning: ignoring resolv-file flag because no-resolv is set<br>Jan 11 18:16:36 dnsmasq-dhcp[6821]: DHCP, IP range 192.168.1.2 -- 192.168.1.99, lease time 12h<br>Jan 11 18:16:36 dnsmasq[6821]: using nameserver 192.168.1.100#53<br>
Jan 11 18:16:36 dnsmasq[6821]: read /etc/hosts - 7 addresses<br>Jan 11 18:17:07 dnsmasq[6840]: query[A] <a href="http://debian.org">debian.org</a> from 192.168.1.102<br>Jan 11 18:17:07 dnsmasq[6840]: forwarded <a href="http://debian.org">debian.org</a> to 192.168.1.100<br>
Jan 11 18:17:07 dnsmasq[6840]: reply <a href="http://debian.org">debian.org</a> is 206.12.19.7<br>Jan 11 18:17:07 dnsmasq[6840]: reply <a href="http://debian.org">debian.org</a> is 128.31.0.51<br><br>Nothing from the UDP request.<br>
<br><br><br><div class="gmail_quote">On Wed, Jan 11, 2012 at 2:24 PM, <span dir="ltr"><<a href="mailto:dnsmasq-discuss-request@lists.thekelleys.org.uk">dnsmasq-discuss-request@lists.thekelleys.org.uk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Message: 4<br>
Date: Wed, 11 Jan 2012 18:02:35 +0000<br>
From: Simon Kelley <<a href="mailto:simon@thekelleys.org.uk">simon@thekelleys.org.uk</a>><br>
To: <a href="mailto:dnsmasq-discuss@lists.thekelleys.org.uk">dnsmasq-discuss@lists.thekelleys.org.uk</a><br>
Subject: Re: [Dnsmasq-discuss] UDP DNS Requests<br>
Message-ID: <<a href="mailto:4F0DCEBB.7010407@thekelleys.org.uk">4F0DCEBB.7010407@thekelleys.org.uk</a>><br>
Content-Type: text/plain; charset=UTF-8; format=flowed<br>
<br>
On 11/01/12 17:47, Mike Owens wrote:<br>
> I was hoping for some more ideas on why DNS won't respond to UDP<br>
> requests but responds just fine to TCP requests. I've trimmed down the<br>
> dnsmasq.conf file to the minimum for what I need. The conf is in my last<br>
> message. I've commented out all unnecessary enties in the host file.<br>
> I've disabled access to the resolv.conf file. I am explicitly<br>
> referencing one and only one DNS server for forwarding. The referenced<br>
> DNS server responds to UDP requests just fine. I've disabled and removed<br>
> the firewall on the dnsmasq machine. What are the other possible causes<br>
> of not receiving responses from UDP requests?<br>
><br>
<br>
Broadly, there's several places that the query could get lost, either<br>
it's not getting to dnsmasq, or dnsmasq isn't forwarding it, or dnsmasq<br>
is forwading it and it's not getting upstream or it's getting upstream<br>
and the reply is getting lost.<br>
<br>
Setting<br>
<br>
log-queries<br>
<br>
and examining the log should tell you which of these is true, but I<br>
don't think we've seen any logs posted for UDP queries.<br>
<br>
<br>
Can you dig <domain> @<a href="http://127.0.0.1" target="_blank">127.0.0.1</a> on the machine running dnsmasq?<br>
<br>
Cheers,<br>
<br>
Simon.<br>
<br>
<br>
<br></blockquote></div>