无法在Linux上使用SQLConnection与Azure SQL连接

Question

I'm currently developing an ASP.NET Core WebApi that uses an Azure SQL Db for data persistence. I use Linux Mint 19 as a development environment. Unfortunately when dbConnection.Open() is called I keep getting SQLException:

Exception has occurred: CLR/System.Data.SqlClient.SqlException
An exception of type 'System.Data.SqlClient.SqlException' occurred in 
System.Data.SqlClient.dll but was not handled in user code: 'A 
network-related or instance-specific error occurred while establishing 
a connection to SQL Server. The server was not found or was not 
accessible. Verify that the instance name is correct and that SQL 
Server is configured to allow remote connections. (provider: TCP 
Provider, error: 40 - Could not open a connection to SQL Server)'

Here's my code:

 private const string connectionString = "Server=tcp:{myserver}.database.windows.net,1433;Initial Catalog={mydb};Persist Security Info=False;User ID={user};Password={pass};MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;";

 SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
        builder.DataSource = "my_server.database.windows.net";
        builder.UserID = "my_user";
        builder.Password = "my_pass";
        builder.InitialCatalog = "my_db";

        using(IDbConnection dbConnection = new SqlConnection(builder.ConnectionString)){
            dbConnection.Open();
            var result = dbConnection.Query<Task>("SELECT * FROM Tasks");

            if (dbConnection.State == ConnectionState.Open)
            {
            dbConnection.Close();

            }
        }

I've tried both using SQLConnectionStringBuilder and passing connectionString with my credentials. None of it worked.

I've opened port 1433 using the command:

sudo ufw allow 1433

but it didn't help, still getting the same exception.

Any help would be much appreciated.

Thanks.

UPDATE

I managed to connect with Azure SQL. It looks like my ISP blocks connection. I was able to connect using my smartphone WiFi hotspot.

Answer 1

First, make sure you have created appropriate firewall rule to allow traffic from your network to reach Azure SQL Database. Learn here how to do it.

Please try to ping your SQL Azure server. The ping should fail but it should return the current IP Address of the Azure SQL Database logical server. If you cannot see that IP returned then the issue is a DNS issue.

With the IP address returned on the previous step, try to telnet that IP address on port 1433.

telnet 181.37.11.112 1433

If you cannot connect using telnet, use traceroute command to diagnose when locate where data loss occurs.