Re: [Samba] Samba, Solaris, Windows 2008 - Kerberos Guess Realm Wrong?

On Wed, 12 Nov 2008, Paul Sobey wrote:

> On Wed, 5 Nov 2008, Paul Sobey wrote:
>
>> I've just built Samba 3.2.4 on Solaris 10, with ADS support. Domain join to
>> a Windows 2008 domain works perfectly, having pre-created the servername in
>> the appropriate OU.
>>
>> In my winbind logs, I see the following (domain name obfuscated):
>> [2008/11/05 11:28:06, 2]
>> libsmb/cliconnect.c:cli_session_setup_kerberos(619)
>> Doing kerberos session setup
>>
>> [2008/11/05 11:28:06, 1] libsmb/clikrb5.c:ads_krb5_mk_req(680)
>> ads_krb5_mk_req: krb5_get_credentials failed for server$@FOO (Cannot
>> resolve network address for KDC in requested realm)
>>
>> [2008/11/05 11:28:06, 1]
>> libsmb/cliconnect.c:cli_session_setup_kerberos(626)
>> cli_session_setup_kerberos: spnego_gen_negTokenTarg failed: Cannot resolve
>> network address for KDC in requested realm
>>
>> The realm is guessed wrongly - only the short name of the domain, rather
>> than the fully qualified realm name, as specified in krb5.conf.
>>
>> My AD full name is foo.bar.com, short name FOO. My question is - when
>> guessing the principal for the target DC, why does Samba guess 'FOO',
>> rather than 'FOO.BAR.COM'? I have a Linux machine joined to the same domain
>> running 3.0.28 which correctly guesses the realm.
>
> Not sure whether this helps diagnose, but I just upgraded my Linux desktop to
> Samba 3.2.4 and now get exactly the same error - winbind is refusing to
> authenticate me at all. In my pam.conf I have krb5_auth set to try and make
> winbind authenticate my via kerberos.
>
> How can I troubleshoot this? It seems Samba 3.2.4 gets the Kerberos realm
> wrong when authenticating against Windows 2008. I thought it was a Solaris
> issue before but it seems to be OS independent. Is anybody else seeing it?

Not sure whether this helps anybody, but by patching the source of
libsmb/cliconnect.c with the following, ie hard coding the proper name of
the Kerberos realm, the error goes away.

893a894
> DEBUG(3,("cli_session_setup_spnego:
dest_realm is %s\n", dest_realm));
895a897,900
> DEBUG(3,("cli_session_setup_spnego:
hacking realm!\n", dest_realm));
> realm = SMB_STRDUP("FOO.BAR.COM");
> strupper_m(realm);
> DEBUG(3,("cli_session_setup_spnego: realm
is now %s\n", realm));
896a902
> DEBUG(3,("cli_session_setup_spnego:
getting realm from cache\n", realm));

To reiterate - under 3.2.4 code, 'realm' gets set to 'FOO', rather than
'FOO.BAR.COM'.

Difference in winbind logs:

Bad version:

[2008/11/12 15:49:17, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(839)
got principal=not_defined_in_RFC4178@please_ignore

[2008/11/12 15:49:17, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(880)
cli_session_setup_spnego: got a bad server principal, trying to guess
....

[2008/11/12 15:49:17, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(908)
cli_session_setup_spnego: guessed server
principal=domaincontroller$@FOO

[2008/11/12 15:49:17, 2]
libsmb/cliconnect.c:cli_session_setup_kerberos(619)
Doing kerberos session setup

[2008/11/12 15:49:17, 1] libsmb/clikrb5.c:ads_krb5_mk_req(680)
ads_krb5_mk_req: krb5_get_credentials failed for domaincontroller$@FOO
(Cannot resolve network address for KDC in requested realm)

[2008/11/12 15:49:17, 1] libsmb/cliconnect.c:cli_session_setup_kerberos(626)
cli_session_setup_kerberos: spnego_gen_negTokenTarg failed: Cannot
resolve network address for KDC in requested realm

[2008/11/12 15:49:17, 4] winbindd/winbindd_cm.c:cm_prepare_connection(843)
failed kerberos session setup with Cannot resolve network address for
KDC in requested realm

[2008/11/12 15:49:17, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(804)
Doing spnego session setup (blob length=124)

Hacked version:

[2008/11/12 18:23:55, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(839)
got principal=not_defined_in_RFC4178@please_ignore
[2008/11/12 18:23:55, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(880)
cli_session_setup_spnego: got a bad server principal, trying to guess
....
[2008/11/12 18:23:55, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(894)
cli_session_setup_spnego: dest_realm is FOO
[2008/11/12 18:23:55, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(897)
cli_session_setup_spnego: hacking realm!
[2008/11/12 18:23:55, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(900)
cli_session_setup_spnego: realm is now FOO.BAR.COM
[2008/11/12 18:23:55, 3]
libsmb/cliconnect.c:cli_session_setup_spnego(914)
cli_session_setup_spnego: guessed server
principal=domaincontroller$@FOO.BAR.COM
[2008/11/12 18:23:55, 2]
libsmb/cliconnect.c:cli_session_setup_kerberos(619)
Doing kerberos session setup
[2008/11/12 18:23:55, 3] libsmb/clikrb5.c:ads_cleanup_expired_creds(604)
ads_cleanup_expired_creds: Ticket in ccache[MEMORY:cliconnect]
expiration Thu, 13 Nov 2008 04:23:55 GMT
[2008/11/12 18:23:55, 3] libsmb/clikrb5.c:ads_krb5_mk_req(713)
ads_krb5_mk_req: server marked as OK to delegate to, building
forwardable TGT
[2008/11/12 18:23:55, 5]
libsmb/smb_signing.c:set_smb_signing_real_common(144)
SMB signing enabled!


Hope this is useful for somebody.

Paul

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