Connecting to Microsoft SQL Server from Linux can be done through two different methods: ODBC and JDBC. Unfortunately, FreeTDS doesn’t connect to the newest versions of SQL Server unless you want to enable legacy connections.
The 
Microsoft JDBC Driver 4.0 for SQL Server, a Type 4 JDBC driver provides database connectivity through the standard JDBC application program interfaces (APIs) available in Java Platform, Enterprise Edition 5 and 6.
The Microsoft ODBC Driver (Linux) For SQL Server provides native connectivity from Windows to Microsoft SQL Server and Windows Azure SQL Database on Linux.