[Dnsmasq-discuss] domain-needed is ignored

Spon Spon spon901 at yahoo.com
Thu Jun 21 10:34:54 BST 2018


The lookup is forwarded to upstream DNS server.  This can be seen in log and also through tcpdump. So even domain-needed is used the lookup leaks to upstream server, and as per this settings it should not.


      From: Geert Stappers <stappers at stappers.nl>
 To: dnsmasq-discuss at lists.thekelleys.org.uk 
 Sent: Thursday, June 21, 2018 11:20 AM
 Subject: Re: [Dnsmasq-discuss] domain-needed is ignored
   
On Thu, Jun 21, 2018 at 06:15:30AM +0000, Spon Spon wrote:
> Hi,
> I have following configuration of dnsmasq:
    ...
> domain-needed
    ...
> 
> Because of domain-needed option I expected that host only lookup,
> without domain part will not forwarded to upstream servers (in my case
> 192.168.2.1, but this seems it is not the case.

Please elaborate "seems"
Is it being polite or only having "forwarded" in logging and no further proof?


> The dnsmasq run on an EdgeRouter and has following version:
> root at bucuresti:/etc# /usr/sbin/dnsmasq --version
> Dnsmasq version 2.78-20-geaeda96  Copyright (c) 2000-2017 Simon Kelley
> Compile time options: IPv6 GNU-getopt DBus i18n IDN DHCP DHCPv6 no-Lua TFTP conntrack ipset auth DNSSEC loop-detect inotify
> 
> This software comes with ABSOLUTELY NO WARRANTY.
> Dnsmasq is free software, and you are welcome to redistribute it
> under the terms of the GNU General Public License, version 2 or 3.
> 
> If I lookup a host with local domain, then the request is not going
> to upstream server. Please see below the logged queries:
> 
> Jun 21 09:13:31 dnsmasq[21398]: query[A] rrr from 127.0.0.1
> Jun 21 09:13:31 dnsmasq[21398]: config rrr is NODATA-IPv4
> Jun 21 09:13:31 dnsmasq[21398]: query[AAAA] rrr from 127.0.0.1
> Jun 21 09:13:31 dnsmasq[21398]: config rrr is NODATA-IPv6
> Jun 21 09:13:31 dnsmasq[21398]: query[MX] rrr from 127.0.0.1
> Jun 21 09:13:31 dnsmasq[21398]: forwarded rrr to 192.168.2.1
> Jun 21 09:13:38 dnsmasq[21398]: query[A] rrr.b from 127.0.0.1
> Jun 21 09:13:38 dnsmasq[21398]: config rrr.b is NXDOMAIN
> Jun 21 09:13:38 dnsmasq[21398]: query[A] rrr.b from 127.0.0.1
> Jun 21 09:13:38 dnsmasq[21398]: config rrr.b is NXDOMAIN
> 
> Is this a bug? Is there any configuration missing? I expected that
> rrr lookup wil not be forwarded to upstream server (192.168.2.1)
> 

Dnsmasq manual pages says

  -D, --domain-needed
      Tells dnsmasq to never forward A or AAAA queries for plain names,
      without dots or domain  parts,  to upstream  nameservers. If
      the name is not known from /etc/hosts or DHCP then a "not found"
      answer is returned.

So it would prevent the cost of a dail-out connection.


  .....  local testing .....


Jun 21 09:41:14 weiss dnsmasq[24942]: query[MX] inertia from 172.24.0.36
Jun 21 09:41:14 weiss dnsmasq[24942]: forwarded inertia to 172.24.0.10

That un-expected, due 'domain-needed', forward is visible with tcpdump
at my upstream DNS    :-(


Groeten
Geert Stappers
-- 
Leven en laten leven

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