[dnsdist] dnstap shows UDP for a DoH-query

Remi Gacogne remi.gacogne at powerdns.com
Mon Jun 14 14:09:21 UTC 2021

Hi Tom,

On 6/14/21 2:41 PM, Tom via dnsdist wrote:
> Why do I see the protocol "UDP" in the fstrm-log for a DoH request, 
> although I am sure (tcpdump) that this request was made with tcp? Maybe 
> because dnsdist queries the backend server with UDP for the DoH request?

Yes, it looks like a bug. It is likely that there was indeed some 
confusion between the protocol the query was received on and the one 
used to contact the backend.
I know I had to clean that up in [1], because it introduces the ability 
to forward UDP queries over TCP/TLS, for example, so it made things even 
more complicated. So I know this will be fixed in 1.7.0, but we should 
fix that in 1.6.x as well. Would you mind opening a bug report in GitHub 
[2]? Otherwise I'll do so we remember to look into it.

[1]: https://github.com/PowerDNS/pdns/pull/10338
[2]: https://github.com/PowerDNS/pdns/issues/new/choose

Remi Gacogne
PowerDNS.COM BV - https://www.powerdns.com/

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