Changed security defaults for Samba 3.6 release notes

Andrew Bartlett abartlet at
Mon Dec 13 23:29:45 MST 2010

Some release note suggestions:

Changed security defaults

Samba 3.6 has adopted a number of improved security defaults that will
impact on existing users of Samba.  

 client ntlmv2 auth = yes
 client use spnego principal = no
 send spnego principal = no

The impact of 'client ntlmv2 auth = yes' is that by default we will not
use NTLM authentication as a client.  This applies to the Samba client
tools such as smbclient and winbind, but does not change the separately
released in-kernel CIFS client.  To re-enable the poorer NTLM encryption
set '--option=clientusentlmv2auth=no' on your smbclient command line, or
set 'client ntlmv2 auth = no' in your smb.conf

The impact of 'client use spnego principal = no' is that we may be able
to use Kerberos to communicate with a server less often in smbclient,
winbind and other Samba client tools.  We may fall back to NTLMSSP in
more situations where we would previously rely on the insecure
indication from the 'NegProt' CIFS packet.  This mostly occursed when
connecting to a name alias not recorded as a servicePrincipalName for
the server.  This indication is not available from Windows 2008 or later
in any case, and is not used by modern Windows clients, so this makes
Samba's behaviour consistent with other clients and against all servers.

The impact of 'send spnego principal = no' is to match Windows 2008 and
not to send this principal, making existing clients give more consistent
behaviour (more likely to fall back to NTLMSSP) between Samba and
Windows 2008, and between Windows versions that did and no longer use
this insecure hint.

I hope this helps.

Andrew Bartlett 
Andrew Bartlett                      
Authentication Developer, Samba Team 
Samba Developer, Cisco Inc.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 190 bytes
Desc: This is a digitally signed message part
URL: <>

More information about the samba-technical mailing list