[Pdns-users] Strange problem with powerdns and keepalived

Marc Haber mh+pdns-users at zugschlus.de
Wed Jan 25 20:38:08 UTC 2012

On Tue, Jan 24, 2012 at 06:22:22AM -0800, Rory Toma wrote:
> On 1/24/2012 12:42 AM, Marc Haber wrote:
> >On Mon, Jan 23, 2012 at 05:42:16PM -0800, Rory Toma wrote:
> >>I'm not sure that this is a powerdns problem, per se, but it seems
> >>to only affect powerdns.
> >>
> >>I have a keepalived setup using a /16 network. When pdns binds to
> >>the keepalived port, udp queries work just fine, but tcp queries
> >>fail with a "tcp port domain unreachable".
> >Can PowerDNS cope with an IP address being configured after PowerDNS
> >was started? What does netstat say wrt listening ports?
> Yes, my keepalived and powerdns startup scripts add the IP address
> in for listening.

So you restart PowerDNS whenever keepalived changes IP addresses.

>  Both UDP and TCP port 53 show up in netstat.

So we don't have an issue here. Can you run tcpdump on a client while
you try to telnet to your server's TCP port 53? I'd like to see
whether it is your server itself or some other system sending the
"unreachable", and whether it is a TCP RST or an ICMP unreachable.

If the TCP RST or the IMCP unreachable actually comes from your
server's IP, please tcpdump on the server the traffic from and to your
client's IP, to find out whether we are actually talking with your
PowerDNS host.

I am debugging in the dark at the moment, but these tests may bring
more insight.

> >>Is there some obscure setting I'm missing? I'm running pdns
> >>(I can't upgrade to newer because I rely on a specific behavior in
> >>this version)
> >Just out of curiosity: Which specific behavior?
> I need it to forward queries, even queries where power dns is SOA,
> to another name server.

Sounds like a bug in PowerDNS 2.9.22 ;)


Marc Haber         | "I don't trust Computers. They | Mailadresse im Header
Mannheim, Germany  |  lose things."    Winona Ryder | Fon: *49 621 31958061
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