Re: problem resolving ardownload.adobe.com --enable-sit harmful?

2014-07-03 Thread Carl Byington
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I re-ran the dig to localhost (running bind 9.10.0-P2), and grabbed the
packets with tcpdump.

dig ardownload.adobe.com. @localhost

That sent a query to 192.150.19.247 with flags = 0, edns size = 512, and
got an NXDOMAIN answer. So I tried to reproduce that query with dig:

dig ardownload.wip4.adobe.com a @192.150.19.247 +dnssec +norecur
+noadflag +bufsize=512

According to tcpdump, that sent the same query, but it got the cname
answer.

The outgoing query from the local bind-9.10.0-P2 contains an extra 12
bytes of data in the OPT record, after the Z field containing the DO
bit. This version of bind was compiled with --enable-sit

It seems that the adobe servers choke on that.


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Re: problem resolving ardownload.adobe.com --enable-sit harmful?

2014-07-03 Thread Mark Andrews

I suggest that you log a complaint with Adobe requesting that they
contact their nameserver vendor for a fix.  This bug is similar in
nature to that of http://www.kb.cert.org/vuls/id/714121 (NXDOMAIN
incorrectly returned to a  query).  Unknown EDNS options are
supposed to be ignored by the nameserver, RFC 6891, though that
wasn't clear in RFC 2671.  NXDOMAIN however is a idiotic response
to a unknown EDNS option.

dig ardownload.wip4.adobe.com @da1gtm001.adobe.com +nsid

will also demonstate this bug and doesn't involve using experimental
EDNS opcodes that +sit does.

At least the server returns BADVERS to EDNS(1) queries.  

There are a number of nameservers that fail to respond correctly
to unknown EDNS options to EDNS(1) queries.  Dig can demonstrate the
server failing.

dig name @server +edns=1
dig name @server +nsid
dig name @server +sit (BIND 9.10.0 compiled with
 --enable-sit)
dig name @server +ednsopt=#[:payload] (BIND 9.11.0 or later)

Each domain I have seen failing has had different failure signatures.

It looks like nameserver vendors are not doing even rudimentry
checks like those above.  DiG has thos options so that we could
perform checks like these.

Until Adobe fix their broken servers you can use a server clause to
disable sending SIT requests to them.  Obviously this does not scale.

 server address { request-sit no; };

Mark

In message 1404418984.5134.52.ca...@ns.five-ten-sg.com, Carl Byington writes:
 I re-ran the dig to localhost (running bind 9.10.0-P2), and grabbed the
 packets with tcpdump.
 
 dig ardownload.adobe.com. @localhost
 
 That sent a query to 192.150.19.247 with flags = 0, edns size = 512, and
 got an NXDOMAIN answer. So I tried to reproduce that query with dig:
 
 dig ardownload.wip4.adobe.com a @192.150.19.247 +dnssec +norecur
 +noadflag +bufsize=512
 
 According to tcpdump, that sent the same query, but it got the cname
 answer.
 
 The outgoing query from the local bind-9.10.0-P2 contains an extra 12
 bytes of data in the OPT record, after the Z field containing the DO
 bit. This version of bind was compiled with --enable-sit
 
 It seems that the adobe servers choke on that.
 
 
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 938AmwcrygxiD7pZD3qYVtaL37idfHWp
 =Ah7c
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Mark Andrews, ISC
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PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
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Re: problem resolving ardownload.adobe.com --enable-sit harmful?

2014-07-03 Thread Carl Byington
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On Fri, 2014-07-04 at 09:41 +1000, Mark Andrews wrote:

 Until Adobe fix their broken servers you can use a server clause to
 disable sending SIT requests to them.  Obviously this does not scale.

  server address { request-sit no; };

Thanks. That works for now.


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