By default when you install a SQL Server Express, it is configured to be only accessible from the local machine.
Here are the steps required to make your SQL Server Express database available from the outside:
- Run SQL Server Configuration Manager.
- Go to SQL Server Network Configuration > Protocols for SQLEXPRESS.
- Enable TCP/IP.
- In the SQL Server Configuration Manager also verify that SQL Server Browser is running.
Now before you continue you have to know if you want to use a dynamic port range for SQLExpress or not. If you want to use a dynamic port range, you can immediately jump to the firewall configuration, otherwise you’ll have to do some extra configuration first:
- Right-click on TCP/IP and select Properties.
- Scroll down to IPAll.
- Make the TCP Dynamic Ports empty
- Set the TCP Port value to 1433.
Last step is to configure the firewall and add an exception that allows SQL Server traffic:
- If you are using the dynamic ports, choose Add a program on the Exceptions tab of the Windows Firewall item.
- Browse to the location of the instance of SQL Server that you want to allow through the firewall, for example C:\Program Files\Microsoft SQL Server\MSSQL11.<instance_name>\MSSQL\Binn, select sqlservr.exe, and then click Open.
- If you are using a specific port, add a new inbound rule for TCP traffic on port 1433.
More information here: http://technet.microsoft.com/en-us/library/cc646023.aspx