[Dnsmasq-discuss] Dnsmaq giving default gateway address as dns server on DHCP offer

richardvoigt at gmail.com richardvoigt at gmail.com
Sun Aug 6 20:16:51 BST 2017


If it doesn't work when started at boot, but does if you started it
manually, the most likely reason is that the boot scripts are passing
command-line options such as a different config file.  If you edited the
default config file, when you start dnsmasq by hand, that's the one it
finds.

The command line arguments of the auto-launched dnsmasq instance should
give further information (the 'ps' command should show the command lines of
running processes)

On Sun, Aug 6, 2017 at 1:07 PM, Anoop Ravi <anoopravik at gmail.com> wrote:

> That seems to be correct. That may be the reason why it is working
> when i give dhcp-option 6.
>
> Do you have any guess what could be going wrong? Is there any flag
> which I need to enable to make dnsmasq work as dns server as well?
>
> I have seen a strage behavior as well. Resolution wont work on bootup.
> But when I restart dnsmasq(killing PID and starting commandline) it
> works. Do you have any clue?
>
> Any help is much appreciated.
>
> Thanks,
> Anoop
>
> On 8/6/17, richardvoigt at gmail.com <richardvoigt at gmail.com> wrote:
> > One clear difference is that the query that succeeded is for a different
> > name than the one that failed.
> >
> > But the bigger problem is that the reply is somehow going straight to the
> > client.  When dnsmasq is acting as a caching proxy, these steps happen:
> >
> > 1. the client sends a query to dnsmasq
> > 2. dnsmasq checks its cache and doesn't find a match
> > 3. dnsmasq sends a query to the upstream server
> > 4. the upstream server sends a reply to dnsmasq
> > 5. dnsmasq adds the information to its cache
> > 6. dnsmasq sends a reply to the client
> >
> > In your capture, #4 isn't happening -- the reply destination address is
> > wrong.
> >
> >
> >
> > On Sun, Aug 6, 2017 at 12:47 PM, Anoop Ravi <anoopravik at gmail.com>
> wrote:
> >
> >> Hi Richard,
> >>
> >> I dont want to use dhcp-option 6 to override nameservers. I took a
> >> packet capture on both local lan interface and the interface which
> >> talks to outside world. I could see that in both scenarios (working
> >> and nonworking), names are getting resolved at the outer interface.
> >> But somehow query is getting refused at the local interface. Do you
> >> have any clue why this is happening?
> >>
> >> Attaching screenshot of comparison on local interface packet capture.
> >>
> >> Thanks,
> >> Anoop
> >>
> >
>
>
> --
> Anoop.
>
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