C# MySQL 无法连接到 ubuntu 服务器

Question

I'm currently developing ac# Login system, but the mysql part won't work.

already tried sudo ufw allow 3306/tcp, but still the error. Also tried with HeidiSql

"Can't connect to MySQL server on '5.230.22.130' (10061)

and yes, the user is %, not localhost!!

Error message:

"SocketException: Unable to connect because the destination computer refused to connect Server 5.230.22.130"

class DB
{

    private MySqlConnection connection =
        new MySqlConnection("Datasource=5.230.22.130;Port=3306;Database=***;uid=sqlAdmin;pwd=***;");
    public void openConnection()
    {
        if (connection.State == System.Data.ConnectionState.Closed)
        {
            connection.Open();
        }
    }

    public void closeConnection()
    {
        if (connection.State == System.Data.ConnectionState.Open)
        {
            connection.Close();
        }
    }

    public MySqlConnection getConnection()
    {
        return connection;
    }
}

Answer 1

Ubuntu per default has an active firewall and unless you have disabled it or opened the port already, connections will be blocked.

You can try to open the firewall for mysql server via console on the ubuntu machine (requires root)

sudo ufw allow 3306/tcp

also make sure the user account you want to connect with allows "%" connection and not only "localhost"