[Dnsmasq-discuss] Authoritative and recursive service from the same interface

[Eric Luehrsen]

On 09/28/2018 06:46 PM, Simon Kelley wrote:
> On 28/09/18 23:07, Marc Heckmann wrote:
>> Very nice, I will test this.
>>
>> I am curious though: what will be used for the NS record if the
>> auth-server configuration is omitted?
> 
> 
> It appears to return an NS record of "." ie the DNS root. Which is not
> particularly sensible. This may need some more thought....
> 
> Simon.
> 
>>
>> -m
>>
>>
>> On Fri, Sep 28, 2018 at 4:42 PM Simon Kelley <simon at thekelleys.org.uk
>> <mailto:simon at thekelleys.org.uk>> wrote:
>>
>>      On 28/09/18 02:33, Marc Heckmann wrote:
>>      > Hello,
>>      >
>>      > I'm currently running dnsmasq in a Docker container and have setup a
>>      > domain for which dnsmasq is to be authoritative for. This is to do
>>      > subdomain delegation to the dnsmasq server. I am using the
>>      auth-server &
>>      > auth-zone configuration options for this. This works as expected
>>      and is
>>      > verifiable using dig with the "+norecurse" option to query for the NS
>>      > and SOA records. However, as it's a Docker container, I only have and
>>      > actually need a single interface (eth0) and when I specify eth0 in the
>>      > "auth-server" option, i.e "auth-server=<glue_record>,eth0", I noticed
>>      > that it stops answering recursive queries for names that it is not
>>      > authoritative for.
>>      >
>>      > I worked around this by replacing "eth0" with an IP that is not
>>      present
>>      > in the container's network namespace and dnsmasq now does what I want
>>      > which is to answer to both non-recursive and recursive queries
>>      from the
>>      > same interface.
>>      >
>>      > My question is the following: Are there any side effects to this hack?
>>      > Is there any reason why dnsmasq should not be able to provide
>>      recursive
>>      > and authoritative service from the same interface? I can
>>      understand the
>>      > security reasons for wanting to prevent this on an Internet exposed
>>      > interface, but why not at allow for an option to officially support
>>      > providing both kinds of service on the same interface?
>>      >
>>      > Thanks.
>>      >
>>      > -m
>>      >
>>      >
>>
>>
>>      This patch, in the pending 2.80 release, addresses this, is allows you
>>      to omit the auth-server configuration and get both recursive and
>>      authoritative answers on the interface(s) that dnsmasq is listening on.
>>
>>      http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=397c0502e255ea0a470982666dea93e0b2f52043

In other software something like the following makes a reasonable 
non-functioning default, when things go wrong. It terminates locally 
instead of whatever root-as-NS will cause.
7200 IN SOA localhost. nobody.invalid. 1 3600 1200 9600 300
7200 IN NS localhost.