public static string Login()
        {
            IPHostEntry hostEntry = Dns.GetHostEntry("сайт");
            IPAddress address = hostEntry.AddressList[0];
            IPEndPoint ipe = new IPEndPoint(address, 80);
            Socket socket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

            try
            {
                socket.Connect(ipe);
                if (socket.Connected)
                {
                    Console.WriteLine("Connected to " + ipe.ToString());
                }
                else
                {
                    Console.WriteLine("Can not connect...");
                }
            }
            catch (SocketException ex)
            {
                Console.WriteLine(ex.Message);
            }

            string request = 
                "POST сайт HTTP/1.1\r\n" +
                "Accept: text/html\r\n" +
                "Host: сайт\r\n" +
                "Cookie: income=1\r\n" +
                "Referer: сайт\r\n"+
                "Content-Length: " + "142" + "\r\n" + 
                "Content-Type: application/x-www-form-urlencoded\r\n\r\n"
                +"параметры";

            Byte[] bytesSent = Encoding.ASCII.GetBytes(request);
            Byte[] bytesReceived = new Byte[1024];
            socket.Send(bytesSent, bytesSent.Length, 0);
            string page = "";
            int bytes = 0;

            do
            {
                bytes = socket.Receive(bytesReceived, bytesReceived.Length, 0);
                page = page + Encoding.ASCII.GetString(bytesReceived, 0, bytes);
            }
            while (bytes > 0);

            return page;
        }

HTTP/1.1 302 Moved Temporarily
X-Powered-By: Servlet/2.5
Server: Sun Java System Application Server 9.1_02
Set-Cookie: JSESSIONID=ac85e657399e7058ae4fd3fe2505; Path=/
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Cache-Control: no-store
X-Powered-By: JSF/1.2
Location: сайт
Content-Type: text/html; charset=iso-8859-1
Content-Length: 0
Date: Wed, 18 Feb 2009 19:06:40 GMT
Connection: close