Opening Ports in the Firewall
Firewall systems help prevent unauthorized access to computer resources. To enhance security, Windows XP Professional Service Pack 2 (SP2) turns on Windows Firewall. To connect to SQL Server from another computer, you must open a port in the firewall.
Opening ports in your firewall can leave your server exposed to malicious attacks. Be sure to understand firewall systems before opening ports. For more information, see Security Considerations for a SQL Server Installation.
After you configure the Database Engine to use a fixed port, follow the following instructions to open that port in your Windows Firewall. (You do not have to configure a fixed port for the default instance, because it is already fixed on port 1433.)
For more information about the default Windows firewall settings, and a description of the TCP ports that affect the Database Engine, Analysis Services, Reporting Services, and Integration Services, see Configuring the Windows Firewall to Allow SQL Server Access.
To open a port in Windows Firewall
On the Start menu, click Control Panel.
In Control Panel, click Network and Internet Connections, and then open Windows Firewall.
In Windows Firewall, click the Exceptions tab, and then click Add Port.
In the Add a Port dialog box, in the Name box, type SQL Server<instanceName>.
In the Port number box, type the port number of the Database Engine instance. Use 1433 for the default instance. Type 49172 if you are configuring a named instance and configured a fixed port in the previous task. Verify that TCP is selected, and then click OK.