Improper firewall settings are another system configuration
issue that can inhibit SQL Server connectivity across your network. Firewall
systems help prevent unauthorized access to computer resources and are usually
desirable,
but to access an instance of SQL Server through a firewall, you’ll
need to configure the firewall on the computer running SQL Server to allow
access. Many firewall systems are available, and you’ll need to check the
documentation for your system for the exact details of how to configure it. In
general, you’ll need to carry out the following steps:- Configure the SQL Server instance to use a specific TCP/IP port. Your default SQL Server uses port 1433 by default, but that can be changed. Named instances use dynamic ports by default, but that can also be changed using the SQL Server Configuration Manager.
- Configure your firewall to allow access to the specific port for authorized users or computers.
- As an alternative to configuring SQL Server to listen on a specific port and then opening that port, you can list the SQL Server executable (Sqlservr.exe) and the SQL Browser executable (Sqlbrowser.exe) when requiring a connection to named instances, as exceptions to the blocked programs. You can use this method when you want to continue to use dynamic ports.
