[squid-users] Kerberos Authentication Failing for Windows 7+ with BH gss_accept_sec_context() failed

Paul Freeman paul.freeman at emlchem.com.au
Mon Oct 27 21:12:50 UTC 2014 

Pedro,

This sounds similar to a problem I had a couple of years ago when using Kerberos authentication with Squid (3.1.x) on Ubuntu (10.04 at that stage). (see RE: [squid-users] Re: Authentication using squid_kerb_auth with Internet Explorer 8 on Windows Server 2008 R2, squid-users group Nov 3 2010)



What I discovered after debugging the Kerberos authentication process with gdb was the MIT Kerberos version distributed with that version of Ubuntu did not support one of the encryption types requested by the newer versions of Windows (7, 2008).  This was a reported issue with the version of Kerberos used in Ubuntu.  I ended up patching the Ubuntu MIT Kerberos source (a trivial patch) and compiling the packages manually.  This corrected the problem.



I am unsure whether this is the root cause of your issue though but thought it might be worth mentioning.  I have not kept up with the MIT Kerberos packages included with Ubuntu 12.04 and 14.04 to know whether the patch is included in the later versions.



Regards



Paul



From: squid-users [mailto:squid-users-bounces at lists.squid-cache.org] On Behalf Of Pedro Lobo
Sent: Tuesday, 28 October 2014 7:26 AM
To: Markus Moeller
Cc: squid-users at squid-cache.org
Subject: Re: [squid-users] Kerberos Authentication Failing for Windows 7+ with BH gss_accept_sec_context() failed



Hi Markus Moeller,


Hi Markus,

Yeah, I'm currently using that option and permissions are correct too.


On 27 Oct 2014 19:47, Markus Moeller wrote:

   Hi Pedro,



     Did you try the –s GSS_C_NO_NAME option ?



   Markus



   "Pedro Lobo" <palobo at gmail.com<mailto:palobo at gmail.com>> wrote in message news:94F74226-F24B-4910-95B7-B86ACE815995 at gmail.com...

   Hey Everybody,

   Seems as though I celebrated too soon on Saturday. Today things are back to not working for Windows 7+ machines and XP/2003 machines are working just fine.

   I've also checked the permissions on the keytab file and they haven't changed since Saturday, so it's not that... ARGH!!!!

   Craving ideas and solutions right now... Pilot users are less than satisfied ;)

   Cheers,
   Pedro

   On 25 Oct 2014, at 14:13, Markus Moeller wrote:

      Hi Pedro,

      I wonder if he upper case in the name is a problem. Can you try

      auth_param negotiate program /usr/lib/squid3/negotiate_kerberos_auth -d -r -s GSS_C_NO_NAME

      instead of

      auth_param negotiate program /usr/lib/squid3/negotiate_kerberos_auth -d -r -s HTTP/proxy01tst.fake.net

      Markus

      "Pedro Lobo" palobo at gmail.com<mailto:palobo at gmail.com> wrote in message news:FD6832B9-3F1F-48C6-A76F-47A224F1697B at gmail.com...
      Hi Markus,

      I used msktutil to create the keytab.

      msktutil -c -s HTTP/proxy01tst.fake.net -h proxy01tst.fake.net -k /etc/squid3/PROXY.keytab --computer-name proxy01-tst --upn HTTP/proxy01tst.fake.net --server srv01.fake.net --verbose
      Output of klist -ekt:

      2 10/24/2014 22:59:50 proxy01-tst$@FAKE.NET<mailto:proxy01-tst$@FAKE.NET> (arcfour-hmac)
      2 10/24/2014 22:59:50 proxy01-tst$@FAKE.NET<mailto:proxy01-tst$@FAKE.NET> (aes128-cts-hmac-sha1-96)
      2 10/24/2014 22:59:50 proxy01-tst$@FAKE.NET<mailto:proxy01-tst$@FAKE.NET> (aes256-cts-hmac-sha1-96)
      2 10/24/2014 22:59:50 HTTP/proxy01tst.FAKE.net at FAKE.NET<mailto:proxy01tst.FAKE.net at FAKE.NET> (arcfour-hmac)
      2 10/24/2014 22:59:50 HTTP/proxy01tst.FAKE.net at FAKE.NET<mailto:proxy01tst.FAKE.net at FAKE.NET> (aes128-cts-hmac-sha1-96)
      2 10/24/2014 22:59:50 HTTP/proxy01tst.FAKE.net at FAKE.NET<mailto:proxy01tst.FAKE.net at FAKE.NET> (aes256-cts-hmac-sha1-96)
      2 10/24/2014 22:59:50 host/proxy01tst.FAKE.net at FAKE.NET<mailto:proxy01tst.FAKE.net at FAKE.NET> (arcfour-hmac)
      2 10/24/2014 22:59:50 host/proxy01tst.FAKE.net at FAKE.NET<mailto:proxy01tst.FAKE.net at FAKE.NET> (aes128-cts-hmac-sha1-96)
      2 10/24/2014 22:59:50 host/proxy01tst.FAKE.net at FAKE.NET<mailto:proxy01tst.FAKE.net at FAKE.NET> (aes256-cts-hmac-sha1-96)
      Yep, using MIT Kerberos

      Thanks in advance for any help.

      Cheers,
      Pedro

      On 25 Oct 2014, at 1:26, Markus Moeller wrote:

      Hi Pedro,

      How did you create your keytab ? What does klist –ekt <squid.keytab> show ( I assume you use MIT Kerberos) ?

      Markus

      "Pedro Lobo" palobo at gmail.com<mailto:palobo at gmail.com> wrote in message news:40E1E0E7-50C6-4117-94AA-50B06573430A at gmail.com...
      Hi Squid Gurus,

      I'm at my wit's end and in dire need of some squid expertise.

      We've got a production environment with a couple of squid 2.7 servers using NTLM and basic authentication. Recently though, we decided to upgrade and I'm now setting up squid 3.3 with Kerberos and NTLM Fallback. I've followed just about every guide I could find and in my testing environment, things were working great. Now that I've hooked it up to the main domain, things are awry.

      If I use a machine that's not part of the domain, NTLM kicks in and I can surf the web fine. If I use a Windows XP or Windows Server 2003, kerberos works just fine, however, if I use a machine Windows 7, 8 or 2008 server, I keep getting a popup asking me to authenticate and even then, it's and endless loop until it fails. My cache.log is littered with:

      negotiate_kerberos_auth.cc(200): pid=1607 :2014/10/24 23:03:01| negotiate_kerberos_auth: ERROR: gss_accept_sec_context() failed: Unspecified GSS failure. Minor code may provide more information.
      2014/10/24 23:03:01| ERROR: Negotiate Authentication validating user. Error returned 'BH gss_accept_sec_context() failed: Unspecified GSS failure. Minor code may provide more information. '
      The odd thing, is that this has worked before. Help me Obi Wan... You're my only hope! :)

      Current Setup
      Squid 3.3 running on Ubuntu 14.04 server. It's connected to a 2003 server with function level 2000 (I know, we're trying to fase out the older servers).

      krb5.conf

      [libdefaults]
      default_realm = FAKE.NET
      dns_lookup_kdc = yes
      dns_lookup_realm = yes
      ticket_lifetime = 24h
      default_keytab_name = /etc/squid3/PROXY.keytab

      ; for Windows 2003
      default_tgs_enctypes = rc4-hmac des-cbc-crc des-cbc-md5
      default_tkt_enctypes = rc4-hmac des-cbc-crc des-cbc-md5
      permitted_enctypes = rc4-hmac des-cbc-crc des-cbc-md5

      [realms]
      FAKE.NET = {
      kdc = srv01.fake.net
      kdc = srv02.fake.net
      kdc = srv03.fake.net
      admin_server = srv01.fake.net
      default_domain = fake.net
      }

      [domain_realm]
      .fake.net = FAKE.NET
      fake.net = FAKE.NET

      [logging]
      kdc = FILE:/var/log/kdc.log
      admin_server = FILE:/var/log/kadmin.log
      default = FILE:/var/log/krb5lib.log
      squid.conf

      auth_param negotiate program /usr/lib/squid3/negotiate_kerberos_auth -d -r -s HTTP/proxy01tst.fake.net
      auth_param negotiate children 20 startup=0 idle=1
      auth_param negotiate keep_alive off

      auth_param ntlm program /usr/bin/ntlm_auth --diagnostics --helper-protocol=squid-2.5-ntlmssp --domain=FAKE.NET
      auth_param ntlm children 10
      auth_param ntlm keep_alive off
      Cheers,
      Pedro

      Cumprimentos
      Pedro Lobo
      Solutions Architect | System Engineer

      pedro.lobo at pt.clara.net<mailto:pedro.lobo at pt.clara.net>
      Tlm.: +351 939 528 827 | Tel.: +351 214 127 314

      Claranet Portugal
      Ed. Parque Expo
      Av. D. João II, 1.07-2.1, 4º Piso
      1998-014 Lisboa
      www.claranet.pt<http://www.claranet.pt>

      Empresa certificada ISO 9001, ISO 20000 e ISO 27001


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      http://lists.squid-cache.org/listinfo/squid-users


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      squid-users mailing list
      squid-users at lists.squid-cache.org<mailto:squid-users at lists.squid-cache.org>
      http://lists.squid-cache.org/listinfo/squid-users

      Cumprimentos
      Pedro Lobo
      Solutions Architect | System Engineer

      pedro.lobo at pt.clara.net<mailto:pedro.lobo at pt.clara.net>
      Tlm.: +351 939 528 827 | Tel.: +351 214 127 314

      Claranet Portugal
      Ed. Parque Expo
      Av. D. João II, 1.07-2.1, 4º Piso
      1998-014 Lisboa
      www.claranet.pt<http://www.claranet.pt>

      Empresa certificada ISO 9001, ISO 20000 e ISO 27001


        _____


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      squid-users mailing list
      squid-users at lists.squid-cache.org<mailto:squid-users at lists.squid-cache.org>
      http://lists.squid-cache.org/listinfo/squid-users


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