Microsoft's SQL UDP Info Query

It is possible to determine remote SQL server version Description : Microsoft SQL server has a function wherein remote users can query the database server for the version that is being run. The query takes place over the same UDP port which handles the mapping of multiple SQL server instances on the same machine. CAVEAT: It is important to note that, after Version 8.00.194, Microsoft decided not to update this function. This means that the data returned by the SQL ping is inaccurate for newer releases of SQL Server.
filter incoming traffic to this port