On Fri, Sep 05, 2014 at 09:05:33AM +1000, Mark Andrews wrote:
> > Yes, in fact between posting and reading your answer, I went off
> > and did some reading. The problem as I now understand it seems to
> > be that:
> >
> > 1. *.clarion-hotels.cz IN CNAME exists.
> > 2. mail2.clarion-hotels.cz exists.
> > 3. _tcp.mail2.clarion-hotels.cz does not exist.
> >
> > and finally, the nameservers for clarion-hotels.cz incorrectly
> > apply the wildcard CNAME to a child of an existing sibling node
> > (mail2). This is detected as an error by various validating
> > resolvers.
> >
> > Is this right?
>
> Yes.
Thanks. I wrote to the operators of the DNS servers, and they are
planning to fix the bug, but implemented a short-term work-around,
where the wildcard CNAME was replaced by wildcard A record. However
the work-around is not working to the satisfaction of my resolver,
any idea why?
$ dig +dnssec +norecur -t tlsa _25._tcp.mail2.clarion-hotels.cz
@ns.forpsi.net
; <<>> DiG 9.8.3-P1 <<>> +dnssec +norecur -t tlsa
_25._tcp.mail2.clarion-hotels.cz @ns.forpsi.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 31810
;; flags: qr aa; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;_25._tcp.mail2.clarion-hotels.cz. IN TLSA
;; AUTHORITY SECTION:
clarion-hotels.cz. 3600 IN SOA ns.forpsi.net.
admin.forpsi.com. 2014090502 3600 1800 2592000 3600
clarion-hotels.cz. 3600 IN RRSIG SOA 5 2 3600 20141005113302
20140905113302 13077 clarion-hotels.cz.
Y4JCzy6U/fMI2tz+pLfQ1mFD2h1jxRMJ7nUwXS0cxlE9xcN8QFibwC75
BBivVbf3Xb2oPXJTRTvkkUAXR1wziOCy/qvK4LyNFX2ENn2aKGn3i93H
LrHM/5u1IoeG4niXbS22Tue3FEgYKcSX7UA5PDDQAQs2o+jX9IbwYawC teM=
*.clarion-hotels.cz. 3600 IN NSEC mail.clarion-hotels.cz. A
RRSIG NSEC
*.clarion-hotels.cz. 3600 IN RRSIG NSEC 5 2 3600
20141005113302 20140905113302 13077 clarion-hotels.cz.
lSf+ySQxo+sXxtuEZEIy7YghFeQnFlDd7vkZA8XO/ahgAzgxHZkAsQXk
RjoJVCLd3E3FgX55Pu0RA6IQVn1ynZFYp3l1P24bC93+l3vszNsnMKnD
qqjNIIzeYanNfkI34kdPpj5C1HhtrC1ZUhRwryphsKXX9KYFB/B4i+47 U2E=
mail2.clarion-hotels.cz. 3600 IN NSEC clarion-hotels.cz. A RRSIG
NSEC
mail2.clarion-hotels.cz. 3600 IN RRSIG NSEC 5 3 3600
20141005113302 20140905113302 13077 clarion-hotels.cz.
lX8m4n9dL8/055WYsv5LW/D9L7257lzOv9QAynpBlJiShQkYRFsAc9rT
ZFdrCeahWXg01/jGVrUNoxwJUUxUobt8GFcTiXHvI/w5ej6rsc80tUVT
BCnW9WsJBNiz7hDN8Ac3V8gKE77Td2TZxJpPtRdAOTW4mc6E04XsLIL7 XmQ=
;; Query time: 130 msec
;; SERVER: 81.2.194.130#53(81.2.194.130)
;; WHEN: Fri Sep 5 11:04:38 2014
;; MSG SIZE rcvd: 742
This time there is no erroneous wildcard CNAME response, just
ANSWER:0, and some NSEC records in the authority section. In
particular there is an NSEC record that should prove absense of
anything after "mail2", thus denying "_tcp.mail2"...
What's wrong now? Oddly enough when I ask for "mail3.<etc> IN TLSA
?" the resolver is happy with a "NODATA" response, containing
exactly the same records. So these records constitute proof that
"mail3" does not exist, but somehow fail to prove that "_tcp.mail2"
does not?
--
Viktor.
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