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Re: Hostname does not match common name problem

--On Saturday, March 14, 2009 12:21 PM +0100 Michael StrÃder <michael@stroeder.com> wrote:

Sascha wrote:

I have a problem with an LDAP server that I need to connect to. I have the required certificate stored on the client but I am getting the following error message:

"TLS: hostname (A.xyz123.com) does not match common name in
certificate (*.xyz123.com)"

Personally I'm scared of accepting wildcard certs for security reasons.

As far as I understand it, RFC4514 section 3.1.3 allows wildcards
thus the connection should work, shouldn't it?

It's RFC 4513, section 3.1.3. And there it says:

   The server's identity may also be verified by comparing the reference
   identity to the Common Name (CN) [RFC4519] value in the leaf Relative
   Distinguished Name (RDN) of the subjectName field of the server's
   certificate.  This comparison is performed using the rules for
   comparison of DNS names in Section, below, with the exception
   that no wildcard matching is allowed.

So wildcard DNS names in CN is explicitly not allowed. You can try with
wildcard patterns in the subjectAltName cert extension.

Except that most cert vendors put the wildcard in CN and not subjectAltName. I note everything I ever tested with a wildcart cert accepted this *except* OpenLDAP. So I submitted an ITS somewhere back in OpenLDAP 2.2 land to allow this, and it has been in place ever since, and works to this day AFAIK.



Quanah Gibson-Mount
Principal Software Engineer
Zimbra, Inc
Zimbra ::  the leader in open source messaging and collaboration