[Samba] Samba43 Kerberos issues

Juan Garcia juan at ish.com.au
Thu Jun 2 06:01:25 UTC 2016

> Hi Juan,
> I reply below but information requested by Rowland are still needed (or at
> least they will be helpful).

Hi Mathias,

Thanks for your reply, I've been busy working on other tasks but now 
this issue is my priority.

         default_realm = MY.DOMAIN.COM
         dns_lookup_realm = false
         dns_lookup_kdc = true

# Generated by resolvconf
domain my.domain.com
nameserver -> this is the ip address of my Firewall as I 
have all DNS requests go through the FW first and the firewall will talk 
to the SERVER1 for authentication.

  Global parameters
         interfaces = -> ip address of DC1
         bind interfaces only = yes
         workgroup = CW1
         realm = MY.DOMAIN.COM
         netbios name = SERVER1
         server role = active directory domain controller
         dns forwarder =
         printing = bsd
         server services = s3fs, rpc, wrepl, ldap, cldap, kdc, drepl, 
winbind, ntp_signd, kcc, dnsupdate, dns
         dcerpc endpoint servers = epmapper, wkssvc, rpcecho, samr, 
netlogon, lsarpc, spoolss, drsuapi, dssetup, unixinfo, browser, 
eventlog6, backupkey, dnsserver
         restrict anonymous = 1
         vfs objects = acl_xattr
         map acl inherit = Yes
         store dos attributes = yes
         unix extensions = no
         inherit acls = yes
         inherit permissions = yes
         ea support = no
         idmap_ldb:use rfc2307 = yes
         browseable= yes
         writable = yes
         read only= no
         create mask = 664
         force create mode = 664
         directory mask = 2777
         force directory mode = 2777
         kerberos method = system keytab
         client ldap sasl wrapping = sign
         allow dns updates = nonsecure and secure

I have also run the following tests on SERVER1:

# host -t A SERVER1.mydomain.com
SERVER1.mydomain.com has address

# klist -l
   Name                                    Cache name      Expires
administrator at MY.DOMAIN.COM   /tmp/krb5cc_0   >>> Expired <<<   *

> KDC is Key Distribution Center from Kerberos so I think as you: issue could
> come from there.
> You can force your client to use DC2 to verify the issue comes from DC1
> only. You will have to force in your krb5.conf usage of DC2 (no example
> from my side so you will need to look for an example by yourself :)

Ok, will do a research an try that

> As a useful information you could also tell us if you use internal DNS or
> Bind-DLZ DNS backend. That's important.
I use internal DNS, I've read that BIND sometimes could be a pain in the 

> About samba_dnsupdate:
> using --no-credentials:
> About DNS updates issue on _gc._tcp: no idea.
> About DNS updates issue on _msdcs zone: you must be authenticated to modify
> that zone.
> Using "testparm -v | grep nsupdate" you should see how is configured your
> samba server regarding how it sends DNS update.
> Using vi on samba_dnsupdate, commenting around line 408 (unlink(tmp) or
> something like that) you will find /tmp/tmp* files containing nsupdate
> commands. These files are generated by samba_dnsupdate and used by nsupdate.

I have commented the following line:

     except Exception, estr:
         if opts.fail_immediately:
         error_count = error_count + 1
         if opts.verbose:
             print("Failed nsupdate: %s : %s" % (str(d), estr))
     #os.unlink(tmpfile) => (this is commented) inside 

I have run testparm -v | grep nsupdate

# testparm -v | grep nsupdate
Load smb config files from /usr/local/etc/smb4.conf
Processing section "[Vol1]"
Processing section "[Vol2]"
Loaded services file OK.
WARNING: You have some share names that are longer than 12 characters.
These may not be accessible to some older clients.
(Eg. Windows9x, WindowsMe, and smbclient prior to Samba 3.0.)

Press enter to see a dump of your service definitions

	dns update command = /usr/local/sbin/samba_dnsupdate
	nsupdate command = /usr/bin/nsupdate -g
	server services = s3fs, rpc, wrepl, ldap, cldap, kdc, drepl, winbind, 
ntp_signd, kcc, dnsupdate, dns

Not sure where those definitions "nsupdate command" and "dns update 
command" are coming from as they are not in my smb4.conf

Thanks for looking into this.



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