无法从ASP.NET应用程序访问SQL Server

Question

I have an ASP.NET page which has a small form to handle enrollment into his course.

Obviously the data from this form has to be inserted into a database.

My problem lies in the actual connection to the database server, I have it on my local PC, for testing purposes.

I can connect to the server just fine through my SQL Server Management Studio, however when I try to connect from my web application (uploaded it to a free host purely for testing), it gives me this error:

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: 0 - An attempt was made to access a socket in a way forbidden by its access permissions.)

After extensive Google'ing and rewriting the connection string in my web.config file, I still can't find what's going wrong exactly.

I know for a fact that the DNS I'm using works, as a friend of mine has already tested it several days ago by connecting through his own SQL Server Management Studio.

Here's my web.config : (blanked out the password in the constring, obviously)

<?xml version="1.0"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.5"/>
    <httpRuntime targetFramework="4.5"/>
    <customErrors mode="Off"/>
  </system.web>
  <appSettings>
      <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />
  </appSettings>
  <connectionStrings>
     <add name="SQLCS" 
          providerName="System.Data.SqlClient"   
          connectionString="Server=ydekempe.ddns.net,5555\Cocktails;Database=Website;Integrated Security=False;User ID=WebUser;Password=********;"/>
  </connectionStrings>
</configuration>

And just for being complete in providing you everything you may need, here's the code for the actual connection:

protected void Inschrijven(object sender, EventArgs e)
{
    int uid = 0;
    string conStr = ConfigurationManager.ConnectionStrings["SQLCS"].ConnectionString;

    try
    {
        using (SqlConnection conn = new SqlConnection(conStr))
        {
            using (SqlCommand cmd = new SqlCommand("Inschrijven", conn))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter())
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.Parameters.AddWithValue("@naam", txtNaam.Text.Trim());
                    cmd.Parameters.AddWithValue("@voornaam", txtVoorNaam.Text.Trim());
                    cmd.Parameters.AddWithValue("@Email", txtEmail.Text.Trim());
                    cmd.Connection = conn;
                    conn.Open();
                    uid = Convert.ToInt32(cmd.ExecuteScalar());
                    conn.Close();
                }
            }
        }
    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }
    string msg = "";
    switch (uid)
    {
        case 0:
            msg = "Er ging iets mis.\\nProbeer later opnieuw";
            break;
        case -1:
            msg = "Dit e-mail adres is al in gebruik.";
            break;
        default:
            msg = "Inschrijving verwerkt.";
            break;
    }
    ClientScript.RegisterStartupScript(GetType(), "Boodschap", "Boodschap: '" + msg + "');", true);
}

PS: The actual connection info is IP: ydekempe.ddns.net & Port: 5555 Just in case you were wondering.

Answer 1

The database server is your local, and where is the Web server hosted? You mentioned it is a free host and I am guessing it is not on your local machine. Make sure your machine is accessible from wherever the web application is hosted. For instance, If its is in AWS, you have to verify both Inbound and Outbound rules.

Answer 2

Turns out, it was the webhost blocking the outgoing port.

Reply from tech support at SmarterASP :

Dear Customer,

Sorry, for performance reasons, we don't allow our customer to connect to remote database server. We suggest you simply make a backup of your database and restore it to our server to test your application. You'll see a much faster performance and reliability using this method.

However, if you must connect to a remote database server, please consider upgrading to our Premium Plan or Semi Dedi Plan. Once you upgrade to these hosting plans, you can enable any ports your want in your Control Panel -> Security Manager -> Outgoing Port Manager.

And don't worry, we provide a 60 days FULL Money Back for all of our plans.

Thank you.