Maintained by: NLnet Labs

[Unbound-users] Forwarding fails with DNSSEC validation

Hauke Lampe
Sun Jun 14 17:34:21 CEST 2009


Hello.

Forwarding without DNSSEC validation works fine. However, forwarding
with DNSSEC validation fails for insecure zones (and sometimes secured,
too), unless I set "harden-dnssec-stripped: no".

Forwarder is BIND 9.6.1rc1 and so far I had not much trouble with
validating (BIND) resolvers behind it.

Where should I look for the cause of this problem?
Or is "harden-dnssec-stripped" supposed to be disabled in a forwarding
setup?


A failing query for an insecure zone typically looks like this:

> info: resolving <www.example.com. A IN>
> info: response for <www.example.com. A IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: resolving <www.example.com.dlv.isc.org. DLV IN>
> info: response for <www.example.com.dlv.isc.org. DLV IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: resolving <com.dlv.isc.org. DS IN>
> info: response for <com.dlv.isc.org. DS IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: NSEC RRset for the referral did not prove no DS.
> info: Could not establish validation of INSECURE status of unsigned response.

The forwarder returns the correct response, as far as I can see:

> hauke at pope:~$ dig +dnssec com.dlv.isc.org. DS  @10.42.23.3
[...]
> ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 1
[...]
> ;; AUTHORITY SECTION:
> dlv.isc.org.		3600	IN	SOA	ns-int.isc.org. hostmaster.isc.org. 2009061202 7200 3600 2419200 3600
> dlv.isc.org.		3600	IN	RRSIG	SOA 5 3 3600 20090712140015 20090612140015 64263 dlv.isc.org. BVoz6eKZVJL4Fqd3sxuxringDn3823lWmmw7r+wnQAeAfEZalql2srh/ vUhIWqxF2LZWDgAgg3Wgzaq9XHtUX4h9gmtxjA80vTbOaO7TAoUGPSz7 A6KYL3epOuiTNW5zV0JWoo3JRUXn5baCCcc8HZnh+Zinl8CmLEmRo0yr yk8=
> seatex.com.cn.dlv.isc.org. 3600	IN	RRSIG	NSEC 5 6 3600 20090712140015 20090612140015 64263 dlv.isc.org. e629+1zdL6GKD9Ti6q96UjXldZio7SXgqNIYOGem2iFgFrwEBhNnHPHm Zpg/5LPh1FgPjPsdYcphBCOTiUnZ1pcZ8LfMHtPM57hB7VF7eoExkIXU cJCGndG0+vBaZ8Yf7HXeOESoWDNdX0GPTspld68rgLY5UfSQdIbzI2xS Chk=
> seatex.com.cn.dlv.isc.org. 3600	IN	NSEC	absolight.com.dlv.isc.org. RRSIG NSEC DLV

Curious thing: Even though tcpdump shows no difference in both query and
response packets, the response to Unbound's query is not cached.
Querying with dig forces the forwarder to retrieve the record again and
cache it. Is this normal?

Queries for secure zones succeed most of the time:

> info: resolving <www.hauke-lampe.de. A IN>
> info: response for <www.hauke-lampe.de. A IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: resolving <hauke-lampe.de.dlv.isc.org. DLV IN>
> info: response for <hauke-lampe.de.dlv.isc.org. DLV IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: validate(positive): sec_status_secure
> info: validation success <hauke-lampe.de.dlv.isc.org. DLV IN>
> info: resolving <hauke-lampe.de. DNSKEY IN>
> info: response for <hauke-lampe.de. DNSKEY IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: validated DNSKEY <hauke-lampe.de. DNSKEY IN>
> info: validate(positive): sec_status_secure
> info: validation success <www.hauke-lampe.de. A IN>

but sometimes they fail:

> info: resolving <www.hauke-lampe.de. A IN>
> info: response for <www.hauke-lampe.de. A IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: resolving <hauke-lampe.de.dlv.isc.org. DLV IN>
> info: response for <hauke-lampe.de.dlv.isc.org. DLV IN>
> info: reply from <.> 10.42.23.3#53
> info: query response was ANSWER
> info: Validate: message contains bad rrsets

What bad rresets could Unbound mean? Again, the response from the
forwarder looks good to me:

> hauke at pope:~$ dig +dnssec hauke-lampe.de.dlv.isc.org. DLV IN @10.42.23.3
[...]
> ;; ANSWER SECTION:
> hauke-lampe.de.dlv.isc.org. 3600 IN	DLV	56203 5 2 0DDE2A17776A0ED199F95AF248674711F2476A451CC816CB68B2FD55 55AC7CC7
> hauke-lampe.de.dlv.isc.org. 3600 IN	DLV	56203 5 1 A663185665B4D3B4B3999ADCD320F4387E016322
> hauke-lampe.de.dlv.isc.org. 3600 IN	RRSIG	DLV 5 5 3600 20090712140015 20090612140015 64263 dlv.isc.org. VRVFXaeQqywauBSAVYdFwYuqui6OnfW76E0Jdui+ebIJeIKIZddSCzET 7OLeGKd6ls5wHw/UGXFbBLHCBL97QJgoQbMSLspn9HDE3HzXfXP0eDqF Pcl0Lcxk5xW9dspYEduluFAsDbNu95kzOOXaYyE9dOCqP7gSXhqoMZyj dXY=

Hauke.


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