C# Socket: connect to server through proxy server

Question

VS 2008

I am using the code below to detect if the client can connect to our SIP server. This was working fine. However, the client has changed there network and now my application has to connect to the SIP server from behind a proxy server.

The error I get is the:

"A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond xxx.xxx.xx.xx:xx"

This code was working ok, until I have to connect from behind a proxy server.

I could not see any properties there I can add the proxy address to the socket.

Am I missing something?

Many thanks for any suggestions,

public bool IsSIPServerAvailable()
{
    bool isAvailable = true;
    Socket sock = new Socket(AddressFamily.InterNetwork,
                             SocketType.Stream,
                             ProtocolType.Tcp);

    try
    {
        sock.Connect("xxx.xxx.xx.xx", xx);
    }
    catch (SocketException ex)
    {
        Console.WriteLine(ex.Message);
        isAvailable = false;
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
        isAvailable = false;
    }
    finally
    {
        if (sock.Connected)
        {
            sock.Close();
        }
    }

    return isAvailable;
}

Community · Accepted Answer · 2017-05-23 12:32:13Z

3

See my answer here, maybe it will be helpful. The general idea is to first establish connection to a proxy, and then use HTTP CONNECT command to open another TCP connection to a given host and port.

edited May 23, 2017 at 12:32

CommunityBot

11 silver badge

answered Jun 27, 2010 at 12:21

Haspemulator

11.4k9 gold badges55 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Community · Accepted Answer · 2017-05-23 12:02:00Z

1

This is very similar to this question. I don't think it is possible to create a socket connection through a proxy server. You would need some kind of a protocol and more over, usually administrators set up proxy servers to refuse connections from ports other than standard HTTP, HTTPS.

One solution would be to use tunneling over HTTP.

edited May 23, 2017 at 12:02

CommunityBot

11 silver badge

answered May 4, 2009 at 6:10

kgiannakakis

104k28 gold badges163 silver badges197 bronze badges

Comments

weismat · Accepted Answer · 2009-05-04 06:11:49Z

1

The whole idea of a proxy is to change the network topology without changing the applications. Thus there is no need to change the app, but a change is required in the proxy configuration/setup.

To check the proxy config independently of your application, you can use Telnet Host Port and see if you get the same timeout/error message or if you get disconnected after entering a few characters.

answered May 4, 2009 at 6:11

weismat

7,4716 gold badges45 silver badges59 bronze badges

Collectives™ on Stack Overflow

C# Socket: connect to server through proxy server

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related