INTERNET APPLICATION DEVELOPMENT
MID MARKET ERP DEVELOPMENT
By Derek Du
When dealing with firewalls, you must have a clear understanding of which port your application is using.
Today I took it for granted that a SQL Server named instance such as \SQLEXPRESS is sharing the same 1433 port with the default SQL Server instance. Later after I found out it didn’t work, it finally occurred to me that two processes cannot listen to the same port.
Anyways, I found out that named instances are using a dynamic port by default, which is assigned by SQL Browser who is listening to 1434. You can also view the assigned dynamic port via SQL Server Configuration Manager -> Select your instance -> Double click on TCP/IP -> Click on IP Addresses tab, at the bottom of the page you will see a dynamic port. And below it you can assign a static port, which I did and it solved my problem.
Port number of SQL Server
This blog post originally appeared in Derek's blog.