[Pdns-users] RE ignoring non-query opcode 6
b.candler at pobox.com
Wed Feb 7 08:59:23 UTC 2018
On 07/02/2018 08:41, bert hubert wrote:
> no one knows why the A-10 is
> sending queries with this opcode
A quick Google search found this:
The *default* healthcheck is to send garbage UDP packets (p553):
"Layer 4 UDP – Every 5 seconds, the ACOS device sends a packet with a
valid UDP header and a garbage payload to the UDP port. The port passes
the health check if it either does not reply, or replies with any type
of packet except an ICMP Error message. "
But if you configure it to use the DNS healthcheck, it should send a
valid query (p558):
"ACOS device sends a lookup request for the specified domain name or
server IP address. By default, recursion is allowed. ... Optionally, you
can disable recursion."
This should clearly be opcode 0.
I think the OP should take a tcpdump of the healthcheck packets. If they
have configured DNS healthchecking, with a domain name to query, then
they can submit the tcpdump as evidence of a bug. If they are relying
on the default UDP healthchecking then it won't be a valid DNS packet in
the first place.
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