SQL Server 2012: Add a linked server to PostgreSQL

Question

I try to connect a PostgreSQL to SQL Server 2012 server as linked server

I found some advices on different forum and follow it. But I'm stuck with an authentication problem.

I explain:

On the SQL Server, I have install the ODBC driver for PostgreSQL (psqlodbc_09_02_0100-x64). I created a system DSN to a specific database on the PostgreSQL. This DSN work correctly.

Using SSMS, I run this command to add the linked server:

EXEC master.dbo.sp_addlinkedserver 
@server = N'lnk_test', 
@srvproduct=N'PostgreSQL Unicode(x64)', 
@provider=N'MSDASQL', 
@provstr=N'Driver=PostgreSQL Unicode(x64);uid=postgres;Server=test1;database=accueil;pwd=MyPassword;SSLmode=disable;PORT=5432'

EXEC master.dbo.sp_addlinkedsrvlogin 
@rmtsrvname=N'lnk_test',
@useself=N'True',
@locallogin=NULL,
@rmtuser=NULL,
@rmtpassword=NULL

After running, I have a new Linked Server called "lnk_test". When I receive the following error message:

Cannot initialize the data source object of OLE DB provider "MSDASQL" for linked server "pgTest1_accueil".
OLE DB provider "MSDASQL" for linked server "pgTest1_accueil" returned message "[Microsoft][ODBC Driver Manager] Driver's SQLSetConnectAttr failed".
OLE DB provider "MSDASQL" for linked server "pgTest1_accueil" returned message "FATAL: authentification par mot de passe échouée pour l'utilisateur  « postgres »". (Microsoft SQL Server, Error: 7303)

The error message is in french, the traduction is: "authentication by password failed for user "postgres". I find the same error message in the log of the PostgreSQL server.

Is someone have an idea for resolving this problem?

Thanks in advance.

Jerome

[Update 2/08/2013] I complete this post with the result of a test I realize today.

WHen using a packet sniffer, I check the packets sended when testing the connection through the ODBS Data Source Administrator (64-bit) and through the Linked Server under SSMS.

The data are the same between the 2 system for:

• Opening the connection to the PostgreSQL

• Sending the connection string (all parameters are the same)

• the response of PostgreSQL asking for password (only different is the salt value, but it's normal)

• the password are sended in the same way (crypted with MD5)

But after, the response of the server differ:

For the ODBC Data Source, all works correctly. I receive the authentication and can send test query.

For SSMS, I receive an error message (as describe upper).

Answer 1

Ok, I found the solution.

In the pg_hba.conf file, I change the method for sending passwords from MD5 to trust. After reloading the server, my linked server connection works.

the entry is now:

Type Database User Address   Method

host all      all  x.x.x.x/x trust

In hope that help others peoples.