Question

Is there any way to connect to an MS SQL Server database with python on linux using Windows Domain Credentials?

I can connect perfectly fine from my windows machine using Windows Credentials, but attempting to do the same from a linux python with pyodbs + freetds + unixodbc

>>import pyodbc
>>conn = pyodbc.connect("DRIVER={FreeTDS};SERVER=servername;UID=username;PWD=password;DATABASE=dbname")

results in this error:

class 'pyodbc.Error'>: ('28000', '[28000] [unixODBC][FreeTDS][SQL Server]Login incorrect. (20014) (SQLDriverConnectW)')

I’m sure the password is written correctly, but I’ve tried many different combinations of username:

DOMAIN\username
DOMAIN\\username

or even

UID=username;DOMAIN=domain

to no avail. Any ideas?

Answer 1

As pointed out in one of the comments, this answer is quite stale by now. I regularly and routinely use GSSAPI to authenticate from Linux to SQL Server 2008 R2 but mostly with the EasySoft ODBC manager and the (commercial) EasySoft ODBC SQL Server driver.

In early 2009, a colleague and I managed to connect to a SQL Server 2005 instance from Solaris 10 using GSSAPI (Kerberos credentials) using DBB::Perl over a FreeTDS build linked against a particular version of the MIT kerberos libraries. The trick was — and this is a little bit difficult to believe but I have verified it by looking through the FreeTDS source code — to specify a zero-length user_name. If the length of the user_name string is 0 then the FreeTDS code will attempt to use GSSAPI (if that support has been compiled in). I have not been able to do this via Python and pyodbc as I could not figure out a way of getting ODBC to pass down a zero-length user_name.

Here in the perl code .. there are multiple opportunities for breakage wrt configuration files such as .freetds.conf etc. I seem to recall that the principal had to be in uppercase but my notes seem to be in disagreement with that.

$serverprincipal = 'MSSQLSvc/foo.bar.yourdomain.com:[e-mail]';
$dbh = DBI->connect("dbi:Sybase:server=THESERVERNAME;kerberos=$serverprincipal", '', '');

You will have to know how to use the setspn utility in order to get the SQL Server server to use the appropriate security principal name.

I do not have any knowledge of the kerberos side of things because our environment was set up by an out and out Kerberos guru and has fancy stuff like mutual trust set up between the AD domain that the SQL Server is running in and the Kerberos domain that my client was running in.

There is some code http://code.google.com/p/libsqljdbc-auth/ which does GSSAPI authentication from Linux to SQL Server but it is Java only. The author (who seems to know his stuff) also has contributed a similar patch to the jTDS project which works with more recent versions of Java that have GSSAPI built in.

So the pieces are all there, it is just a big tangled mess trying to get them all to work together. I found the pyodbc to unixODBC to FreeTDS odbc to TDS integration pretty hard to trace/debug. The perl stuff because it was a pretty thin wrapper on top to CT-Lib was much easier to get going.