>On a Windows Server 2008, where the security is at a much higher level, the Web site responds for images, the Web site responds for .aspx pages that are not using a connection with SQL Server but the Web site does not respond for all pages that have a need to establish a connection with SQL Server.
>
>The Event View has this in Security log:
>
>"The Windows Filtering Platform has blocked a connection."
>
>This is the detail:
>
>Application Information:
> Process ID: 4
> Application Name: System
>
>Network Information:
> Direction: Outbound
> Source Address: AddressOfTheWebServer
> Source Port: 53802
> Destination Address: AddressOfTheSQLServer
> Destination Port: 139
> Protocol: 6
>
>Filter Information:
> Filter Run-Time ID: 0
> Layer Name: Connect
> Layer Run-Time ID: 48
>
>I sent this to security and they said that only port 1433 has to be opened from a Web server who wishes to communicate with SQL Server. Why am I still having this error then?

If the SQL Server is ready to accept connections on port 1433, why is the above connection request trying to go to 139? That port is typically blocked on servers that aren't running a file or printer sharing role.

For testing purposes it can be helpful to replace the server name with its IP address. This can eliminate a possible network lookup to resolve a name to an IP address.

You may also be able to specify the port explicitly e.g. http://www.connectionstrings.com/sqlconnection/connect-via-an-ip-address/