[37108] in Kerberos
Re: multihomed IP address
daemon@ATHENA.MIT.EDU (Greg Hudson)
Mon Jun 22 12:44:12 2015
Message-ID: <55883B4B.3080806@mit.edu>
Date: Mon, 22 Jun 2015 12:43:55 -0400
From: Greg Hudson <ghudson@mit.edu>
MIME-Version: 1.0
To: Gsandtner Michael <michael.gsandtner@wien.gv.at>,
"'kerberos@mit.edu'" <kerberos@mit.edu>
In-Reply-To: <CDB785DEF421B94BA51F34F0FA19D7BD53BAF00F@ntex2010a.host.magwien.gv.at>
Cc: Weber Sylvia <sylvia.weber@wien.gv.at>
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Errors-To: kerberos-bounces@mit.edu
On 06/22/2015 06:53 AM, Gsandtner Michael wrote:
> We want to connect with ssh via kerberos. The host's name resolves to one IP address, but the IP address resolves to two names (this is a required DNS configuration):
> # nslookup vmlxsuche1test
> Name: vmlxsuche1test.host.magwien.gv.at
> Address: 10.153.92.100
>
> # nslookup 10.153.92.100
> 100.92.153.10.in-addr.arpa name = vmlxsuche1test.host.magwien.gv.at.
> 100.92.153.10.in-addr.arpa name = zktest.host.magwien.gv.at.
>
> ssh sometimes work, sometimes does not (falls back to authentication method: password).
> In both cases the credential cache on the client looks equal (got a TGS for both names):
ssh GSSAPI krb5 userauth does not work well when there are multiple
possible results for hostname canonicalization. For unfortunate
historical reasons, MIT krb5 defaults to reverse-resolving the IP
address when canonicalizing hostnames.
For this situation, I believe adding "rdns = false" to the [libdefaults]
section in krb5.conf should resolve the issue.
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