Use Entity Framework with Web Proxy

Question

I have a project that uses Entity Framework Model First. The data source is in the internet, and I need it work using a network/web proxy for it. I had google it but I can't find any useful result, because all results are about EF's Entities Proxies. Some helpful code:

The connection string:

<add name="ConnectionName" connectionString="metadata=res://*/Latin.csdl|res://*/Latin.ssdl|res://*/Latin.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=mssqlserver.server.com;initial catalog=DatabaseName;user id=admin;password=adminPass;MultipleActiveResultSets=True;App=EntityFramework&quot;" providerName="System.Data.EntityClient" />

The usage:

static void Main(string[] args)
    {

        //set the proxy
        var proxy = new WebProxy("109.32.24.24", 808);
        proxy.Credentials = new NetworkCredential("", "");
        WebRequest.DefaultWebProxy = proxy;

        var db = new ContextName();

        if (db.QNames.First().Name == "Testing")
        {
            Console.WriteLine("Success Connection!");
            Console.ReadKey();
        }

    }

This raises a network connection error.

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EDIT

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The proxy that the network have is running over http protocol. I know that http is the protocol you normally use to browse the web with, you do not usually connect to databases with it but it is the only available and this question is about it. You can use web proxies for several .net connections, even Web Services, and my question is about using it with EF, I could't make this working. One last solution could be to use a program like Proxifier and redirect all computer's connections to the specified web proxy, but the idea is making it a bit more configurable.

Answer 1

this application may be running in a internetless network, that the only way for getting internet is using an HTTP proxy

Then you cannot do this, or at least not easily.

When a network is configured such that only HTTP traffic may leave the network, then you are restricted to ... only making HTTP calls. SQL Server's wire protocol is a custom, proprietary binary protocol, that does not resemble HTTP in any way. Hence you cannot connect to a remote instance of SQL Server through an HTTP proxy, if HTTP is your only way out. That's why I asked what kind of proxy you're talking about, because for example a SOCKS proxy does allow arbitrary TCP connections to run through it, and Windows supports it natively.

You can however set up an HTTP tunnel through the proxy. See Tunnel any kind of TCP traffic through HTTP/s. This assumes you control both sides of the connection, and can run or install arbitrary software (namely the tunneling software) next to your application software.

This also may or may not work depending on the configuration of the client's proxy server.

However, this looks like an XY problem. Depending on the actual problem, there are various approaches.

You do not want to expose, nor connect to SQL Server over the internet anyway.

Perhaps you could write a webservice instead, that your application then consumes. The web service talks HTTP, so it can be connected to through the HTTP proxy without any additional configuration or software. The webservice runs on, or nearby the SQL Server and you can expose your business logic through the service - without having to expose your SQL Server.

Another alternative would be a VPN connection, but again, all that depends on the actual problem and which sides of the connection you can control.