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Ygor Thomaz

2016-Jul-13 17:35 UTC

[Samba] CentOS 6.8 + Samba4 + Kerberos: No credentials cache found

Hi everyone,

I am trying to release a server using ‍‍CentOS 6.8 + Samba4 (Winbind - LDAP
+ Kerberos) + NSS.

I was able to join the domain, but I still getting this warning/error
message:

[root at snfs2 ~]# net ads join -U myuser
Enter myuser's password:
***gss_init_sec_context failed with [Unspecified GSS failure.  Minor code
may provide more information: No credentials cache found]***
Using short domain name -- MYDOMAIN
Joined 'SNFS2' to dns domain 'MYDOMAIN.com'

Kerberos delivers the ticket normally:

[root at snfs2 ~]# kinit myuser
Password for myuser at DPPTORONTO.COM:
[root at snfs2 ~]# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: myuser at MYDOMAIN.COM

Valid starting     Expires            Service principal
07/13/16 12:44:49  07/13/16 22:44:51  krbtgt/MYDOMAIN.COM at MYDOMAIN.COM
    renew until 07/13/16 22:44:49

Below, you can find my configuration content:

[root at snfs2 ~]# cat /etc/samba/smb.conf

#####################
## GLOBAL SETTINGS ##
#####################
[global]
   workgroup = MYDOMAIN
   realm = MYDOMAIN.COM
   security = ads
   server string = snfs2.MYDOMAIN.com
   server max protocol = SMB3
   encrypt passwords = true
   unix extensions = false
   client use spnego = true

   ## winbind
   winbind use default domain = true
   winbind offline logon = false
   winbind cache time = 300
   winbind nested groups = true
   winbind enum users = true
   winbind enum groups = true
   winbind refresh tickets = true
   winbind nss info = rfc2307
   winbind rpc only = false

   idmap config * : range = 16777216-33554431
   ## idmap config MYDOMAIN ##
   idmap config MYDOMAIN : backend = nss
   idmap config MYDOMAIN : schema_mode = rfc2307
   idmap config MYDOMAIN : range = 1000-999999
   idmap config MYDOMAIN : readonly = true

   ## logging
   log file = /var/log/samba/log.%m
   max log size = 2000
   log level = 2
   syslog only = true

   ## printers
   load printers = no
   printcap = /dev/null
   disable spoolss = yes

[root at snfs2 ~]# net ads testjoin
gss_init_sec_context failed with [Unspecified GSS failure.  Minor code may
provide more information: No credentials cache found]
Join is OK

[root at snfs2 ~]# cat /etc/krb5.conf
[logging]
default = FILE:/var/log/krb5libs.log
kdc = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmind.log

[libdefaults]
default_realm = MYDOMAIN.COM
dns_lookup_realm = false
dns_lookup_kdc = false
ticket_lifetime = 24h
renew_lifetime = 7d
forwardable = true
# Note: Heimdal 1.3.1 deprecated DES encryption which is required for A`D
authentication before Windows Server 2008.
allow_weak_crypto = true

[realms]
MYDOMAIN.COM = {
kdc = MYDOMAIN1.MYDOMAIN.com:88
kdc = MYDOMAIN2.MYDOMAIN.com:88
admin_server = MYDOMAIN1.MYDOMAIN.com:749
}

[domain_realm]
MYDOMAIN.com = MYDOMAIN.COM
.MYDOMAIN.com = MYDOMAIN.COM

nsswitch.conf

passwd:     files ldap
shadow:     files ldap
group:      files ldap

Btw, I can access my samba share perfectly from my clients. I have exactly
the same configuration running normally at CentOS 7.2. No GSS msgs!

Does anyone have any idea what is causing this message?

Thank you!

--
Ygor Thomaz
Website: http://www.ygorthomaz.net/
"Be the change that you wish to see in the world." ― Mahatma Gandhi

Rowland penny

2016-Jul-13 18:22 UTC

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[Samba] CentOS 6.8 + Samba4 + Kerberos: No credentials cache found

On 13/07/16 18:35, Ygor Thomaz wrote:> Hi everyone,
>
> I am trying to release a server using ‍‍CentOS 6.8 + Samba4 (Winbind - LDAP
> + Kerberos) + NSS.
>
> I was able to join the domain, but I still getting this warning/error
> message:
>
> [root at snfs2 ~]# net ads join -U myuser
> Enter myuser's password:
> ***gss_init_sec_context failed with [Unspecified GSS failure.  Minor code
> may provide more information: No credentials cache found]***
> Using short domain name -- MYDOMAIN
> Joined 'SNFS2' to dns domain 'MYDOMAIN.com'
did you run 'kinit myuser' before trying to join to the domain?
> Kerberos delivers the ticket normally:
>
> [root at snfs2 ~]# kinit myuser
> Password for myuser at DPPTORONTO.COM:
> [root at snfs2 ~]# klist
> Ticket cache: FILE:/tmp/krb5cc_0
> Default principal: myuser at MYDOMAIN.COM
>
> Valid starting     Expires            Service principal
> 07/13/16 12:44:49  07/13/16 22:44:51  krbtgt/MYDOMAIN.COM at MYDOMAIN.COM
>      renew until 07/13/16 22:44:49
>
> Below, you can find my configuration content:
>
> [root at snfs2 ~]# cat /etc/samba/smb.conf
>
> #####################
> ## GLOBAL SETTINGS ##
> #####################
> [global]
>     workgroup = MYDOMAIN
>     realm = MYDOMAIN.COM
>     security = ads
>     server string = snfs2.MYDOMAIN.com
>     server max protocol = SMB3
>     encrypt passwords = true
>     unix extensions = false
>     client use spnego = true
>
>     ## winbind
>     winbind use default domain = true
>     winbind offline logon = false
>     winbind cache time = 300
>     winbind nested groups = true
>     winbind enum users = true
>     winbind enum groups = true
>     winbind refresh tickets = true
>     winbind nss info = rfc2307
>     winbind rpc only = false
>
>     idmap config * : range = 16777216-33554431
>     ## idmap config MYDOMAIN ##
>     idmap config MYDOMAIN : backend = nss
>     idmap config MYDOMAIN : schema_mode = rfc2307
>     idmap config MYDOMAIN : range = 1000-999999
>     idmap config MYDOMAIN : readonly = true
I not sure if you can use the 'nss' backend with AD and 'security =
ads'
says you are using AD. if you read the idmap_nss manpage, you will find 
this:

        The idmap_nss plugin provides a means to map Unix users and 
groups to
        Windows accounts and obsoletes the "winbind trusted domains
only"
        smb.conf option. This provides a simple means of ensuring that 
the SID
        for a Unix user named jsmith is reported as the one assigned to
        DOMAIN\jsmith which is necessary for reporting ACLs on files and
        printers stored on a Samba member server.

You cannot have a Unix user called 'jsmith' and a user called
'jsmith'
in AD, you can have one or the other, but not both.
You can however have a user called 'jsmith' in AD with the necessary 
rfc2307 attributes that will also make the user a Unix user. I suggest 
you see here:

https://wiki.samba.org/index.php/Setup_Samba_as_an_AD_Domain_Member

Rowland

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