This connection method gives the best performance, but is the most intrusive.

• Method 3: Connect the DSS Hub to an DSS Agent installed on a separate machine using DSS's protocol on a special TCP/IP port number. Then connect the DSS Agent directly to the SQL Server database (available on a different machine) using the SQL Server protocol - TDS. This connection method involves three separate machines - one with the DSS Hub, another with the DSS Agent, and finally the machine containing the SQL Server database.

On Windows, the special TCP/IP port is serviced by a Windows service called DSS Agent Listener.

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To use this connection method, the Microsoft ODBC Driver for SQL Server must be installed on the machine from which the DSS Agent will connect to the SQL Server database. For information about the supported ODBC driver versions, refer to the DSS release notes (dss.rel) available in the DSS_HOME directory or the download page.

This connection method is useful when connecting from a Linux hub to avoid an (intrusive) installation of DSS on the machine containing the SQL Server database.

Connecting to Amazon RDS for SQL Server

DSS supports using Amazon RDS for SQL Server as a target, a hub, or for refresh-only workflows. DSS does not support log-based capture from Amazon RDS for SQL Server.

To enable the DSS process to connect to Amazon RDS for SQL Server, you must allow inbound traffic on the database listener port to the system running the DSS process.

• If an DSS Agent is in place, communication must be enabled for the system where the DSS Agent is running.
• When directly connected from an DSS Hub Server, the connection must be allowed for the DSS Hub Server.

If the DSS system connecting to Amazon RDS for SQL Server runs in the same VPC as Amazon RDS for SQL Server, you can use the internal rather than public IP address for the service to allow access. It is recommended to restrict access to only the DSS system that requires access, rather than allowing broader or public access.

The default database listener port that must be opened for a TCP/IP connection is 1433.

SQL Server on Linux

DSS supports SQL Server on Linux as source and as target. The following are required for using DSS with SQL Server running on Linux:

• Microsoft ODBC Driver for SQL Server. For information about the supported ODBC driver versions, refer to the DSS release notes (dss.rel) available in the DSS_HOME directory or the download page.

  ODBC Driver Configuration

Since v6.1.5/8, skip step 2 (create symbolic link) and step 3 (verify dynamic dependencies).

1.  Download and install the latest Microsoft ODBC Driver for SQL Server on Linux. For more information, refer to the Microsoft documentation - [Install the Microsoft ODBC driver for SQL Server (Linux)](https://docs.microsoft.com/en-us/sql/connect/odbc/linux-mac/installing-the-microsoft-odbc-driver-for-sql-server).

2.  Create a symbolic link (symlink) for the ODBC driver. Following is an example for Microsoft ODBC Driver for SQL Server **libmsodbcsql-17.5.so.1.1**:

    ```plaintext
    ln -s  /opt/microsoft/msodbcsql17/lib64/libmsodbcsql-17.5.so.1.1  $DSS_HOME/lib/libmsodbcsql-17.so
    ```

3.  After installing the Microsoft ODBC Driver for SQL Server, it is recommended to verify the dynamic dependencies. For example:

    ```plaintext
    ldd $DSS_HOME/lib/dss_ms17.so
    ```

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• The DSS database User (username for connecting DSS to SQL Server) should have read access to the .mdf and .ldf files. For this, the User should typically be added to the operating system user group mssql.

Related Articles

• SQL Server as Source
  • Capture from SQL Server using Direct Transaction Log Access
  • Capture from SQL Server using Archive Only
  • Capture from SQL Server using SQL Access
  • Capture from SQL Server using Database Triggers
• SQL Server as Target
• Location Connection for SQL Server