实体框架连接字符串使能连接到DB服务器

Question

I'm using the entity framework in a winforms application.

When i set scsb.DataSource ="localhost" every thing works fine but when i try to connect to onother DB server i got an exception:

" The underlying provider failed on Open ."

public DistributionSSEntities1 Connection()
{
    var scsb = new SqlConnectionStringBuilder();
    scsb.DataSource = "192.168.1.100";
    scsb.InitialCatalog = "DistributionSS";
    scsb.IntegratedSecurity = true;
    //------------------------
    EntityConnectionStringBuilder builder = new EntityConnectionStringBuilder();
    builder.Metadata ="res://*/Model.Model.csdl|res://*/Model.Model.ssdl|res://*/Model.Model.msl";
    builder.Provider = "System.Data.SqlClient";
    builder.ProviderConnectionString = scsb.ConnectionString;
    DistributionSSEntities1 db = new DistributionSSEntities1(builder.ToString());
    return db;
}

Answer 1

Has the remote Sql been setup to allow remote connections? Has the remote Sql been allowed access through the windows firewall... there's so many reasons why it wouldn't connect.

You're using Integrated Security - which may work great for a local Sql; but the network user that your WinForm app is running under must have the correct rights to access the remote box.

I'd suggest to start eliminating possibilities do the following:

1. Check the Sql logs on the target server. That always has the exact reason why an attemp failed - not the watered down version you get through the exception. (eg. C:\\Program Files\\Microsoft SQL Server\\MSSQL11.SQLEXPRESS\\MSSQL\\Log)

2. Connect to it using a sql username password - not integrated security to make sure it's not that

3. Firewall

EDIT

It's important to remember that the error messages return to the client regarding login attempt failures are purposefully obscure or without information - to limit an attacker gaining enough information to improve the attack (see the technet article for proof). So checking the Sql Server logs is a necessity - if your login/connection attempt actually made it to the server.

From Article:

To increase security, the error message that is returned to the client deliberately hides the nature of the authentication error. However, in the SQL Server error log, a corresponding error contains an error state that maps to an authentication failure condition. Compare the error state to the following list to determine the reason for the login failure.

Answer 2

 public DistributionSSEntities Connection()
    {
        string ConString = "SERVER=192.168.1.100;DATABASE=DistributionSS;UID=sa;PASSWORD=125;";
        SqlConnectionStringBuilder SCB= new SqlConnectionStringBuilder(ConString);
        //------------------------
        EntityConnectionStringBuilder builder = new EntityConnectionStringBuilder();
        builder.Metadata = "res://*/Model.Model.csdl|res://*/Model.Model.ssdl|res://*/Model.Model.msl";
        builder.Provider = "System.Data.SqlClient";
        builder.ProviderConnectionString = SCB.ConnectionString;
        DistributionSSEntities db = new DistributionSSEntities(builder.ToString());
        return db;
    }