Easysoft Blog

Mon, 07 Jan 2019

Connecting Oracle to SQL Server over a Secure Connection

The SQL Server ODBC driver enables you to connect Oracle on Linux and UNIX platforms to SQL Server or SQL Azure. If you decide to encrypt the network connection from your client applications to SQL Server, or you are using SQL Azure, you need to use the TLS version of the driver, which is included in the SQL Server ODBC driver distribution.

If you do not use the TLS version of the SQL Server ODBC driver to connect to a SQL Server instance that has been configured to request an encrypted connection, you will get this error:

Client unable to establish connection: SSL requested but not supported

If you are already using the Easysoft SQL Server ODBC driver with Oracle:

  1. In the SQL Server data source pointed to by HS_FDS_CONNECT_INFO in your initSID.ora, make the following alterations:
    1. Alter the Driver from:
      Driver = Easysoft ODBC-SQL Server


      Driver = Easysoft ODBC-SQL Server SSL
    2. Add these lines:
      Encrypt = Yes
      TrustServerCertificate = Yes
  2. If you point to the driver library rather than the Driver Manager library in initSID.ora, alter the HS_FDS_SHAREABLE_NAME value to:
  3. Restart the Oracle listener.

If you are a new user:

  1. Install and license the SQL Server ODBC driver on the machine where Oracle is installed.

    For installation instructions, see the ODBC driver documentation.

    Note You need the unixODBC Driver Manager installed on your machine. The Easysoft distribution includes a version of the unixODBC Driver Manager that the Easysoft SQL Server ODBC driver has been tested with. The Easysoft driver setup program gives you the option to install unixODBC.

  2. Create an ODBC data source in /etc/odbc.ini that connects to the SQL Server database you want to access from Oracle®. For example:
    Driver                 = Easysoft ODBC-SQL Server SSL
    Server                 = my_machine\SQLEXPRESS
    User                   = my_domain\my_user
    Password               = my_password
    # If the database you want to connect to is the default
    # for the SQL Server login, omit this attribute
    Database               = Northwind
    Encrypt                = Yes
    TrustServerCertificate = Yes
  3. Use isql to test the new data source. For example:
    cd /usr/local/easysoft/unixODBC/bin
    ./isql.sh -v SQLSERVER_SAMPLE

    At the prompt, type "help" to display a list of tables. To exit, press return in an empty prompt line.

    If you are unable to connect, refer to this article for assistance.

  4. Create a DG4ODBC init file. To do this, change to the hs/admin subdirectory. For example:
    cd $ORACLE_HOME/product/11.2.0/xe/hs/admin

    Create a copy of the file initdg4odbc.ora. Name the new file initmssql.ora.

  5. Ensure these parameters and values are present in your init file:
    HS_FDS_CONNECT_INFO = var>my_mssql_odbc_dsn

    Replace my_mssql_odbc_dsn with the name of a SQL Server ODBC driver data source that connects to the target SQL Server instance. For example

  6. Comment out the line that enables DG4ODBC tracing. For example:
    #HS_FDS_TRACE_LEVEL = <trace_level>
  7. Add an entry to listener.ora that creates a SID_NAME for DG4ODBC. For example:
     (SID_LIST =
  8. Add a DG4ODBC entry to tnsnames.ora that specifies the SID_NAME created in the previous step. For example:
    MSSQL =
        (ADDRESS = (PROTOCOL = TCP)(HOST = oracle_host)(PORT = 1521))
        (CONNECT_DATA =
          (SID = mssql)
        (HS = OK)

    Replace oracle_host with the host name of your Oracle® machine.

  9. Start (or restart) the Oracle® Listener. For example:
    lsnrctl stop
    lsnrctl start
  10. Connect to your Oracle® database in SQL*Plus.
  11. In SQL*Plus, create a database link for the target SQL Server instance. For example:
    "my_sqlserver_user" IDENTIFIED by "my_password" USING 'mssql';
    SELECT * from suppliers@mssqllink

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