Azure SQL - port 13399

Copper Contributor

We have found an azure data studio connection on prem being dropped to an azure sql database because port 13399 was not being allowed.

Whilst I'm aware of this:


I have not seen this before and indeed not had the issue with any other asql database.

any thoughts?

3 Replies

@barry960 It’s unusual to encounter issues with port 13399 specifically for Azure Data Studio connections to an Azure SQL Database. The port is associated with the Dedicated Administrator Connection (DAC), a special connection used for administrative tasks. It’s essential for troubleshooting and maintenance. 


Kindly ensure that port 13399 is open and accessible between your on-premises environment and the Azure SQL Database server. Verify that the necessary firewall rules are in place. You mentioned opening TCP ports 1434 and 14000-14999, but don’t forget also to allow outbound connections on port 1433.


Note: Azure Data Studio connections to Azure SQL Database work seamlessly without additional adjustments. However, ensure you use the correct server name, authentication method, and database credentials. 


Check the logs and diagnostics in Azure Data Studio for potential error messages or warnings related to the failed connection. Further, investigate any specific features or options that might affect the connection.


You can read more about Azure Data Studio troubleshooting.

And also Troubleshooting connectivity issues and other errors with Azure SQL Database and Azure SQL Managed I... 


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Hi thanks for the response.

where does it say 13399 is associated with DAC? I cannot find any reference to the port at all.


@barry960 the documentation does not explicitly mention the association between port 13399 and the DAC in the context of SQL Server listens, but it is a special connection used for administrative tasks. 


DAC operates on port 1434 or dynamically assigns to another TCP port during the Database Engine startup.  Kindly check the error log for the port number on which the DAC is listening. 

Note: These are essential administrative tasks and troubleshooting.