[Pdns-users] RE ignoring non-query opcode 6

[bert hubert]

On Tue, Feb 06, 2018 at 07:37:16PM -0800, Jake Hansen wrote:
> Hello kind gents,

Hello Jake!  We have women here too, by the way!  I think so, at least.

> Someone turned me on to pdns_recursor and i'm trying to deploy it.  I have
> a pair of A-10 Load balancers front ending and now the logs are spamming
> 
> Ignoring non-query opcode 6 from xx.xx.xx.xx on server socket!

I checked, we indeed log this unconditionally, which is a bit sad.

> I was googling around and found that sometime ago, a patch was added to
> drop non zero opcodes.  I suspect that the opcodes are some sort of keep
> alive check by the load balancers.  Should I be worried about this?

Well, I think you should be worried that your A-10 is somehow sending
nonsense DNS packets to check liveness. Opcode 6 is not defined. 
https://www.iana.org/assignments/dns-parameters/dns-parameters.xml#dns-parameters-5

We'll make sure you can mute this warning with 'log-common-errors=no' in the
future.

For now, if this warning upsets you, you may want to ponder either putting
dnsdist in front of your recursor to filter out opcode=6 queries, or (and
this is likely better), replace the whole A-10 load balancer with dnsdist.

Sorry we can't be more helpful, I checked, no one knows why the A-10 is
sending queries with this opcode, or how you can stop it. Might want to ask
A-10.

        Bert