#пора_граммировать [7] ... авторизация на сайте МосБиржи #headers

using System;
using System.Net;
using System.Text;

namespace AuthMoexSmpl
{
    class Program
    {
        static void Main(string[] args)
        { 
            string authLink = "https://passport.moex.com/authenticate";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(authLink);
            request.ContentType = "text/plain; charset=utf-8";
            request.Headers["Authorization"] = "Basic " + Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes("login:password")); //свои данные
            request.PreAuthenticate = true;
            request.CookieContainer = new CookieContainer();                 
            HttpWebResponse response = request.GetResponse() as HttpWebResponse;            
            for(int i=0; i < response.Headers.Count; ++i)  
	                Console.WriteLine("\nHeader Name:{0}, Value :{1}",response.Headers.Keys[i],response.Headers[i]);
        }
    }
}

D:\devel\net\AuthMoexSmpl>dotnet run

Header Name:Cache-Control, Value :no-store, must-revalidate, no-cache, ma

Header Name:Connection, Value :close

Header Name:Date, Value :Fri, 10 Nov 2017 19:53:12 GMT

Header Name:Pragma, Value :no-cache

Header Name:ETag, Value :"xxxxxx"

Header Name:Server, Value :nginx

Header Name:Set-Cookie, Value :MicexPassportCert=xxxxxxx; domain=.moex.com; path=/, _passport_se
m xxxxx; path=/; HttpOnly

Header Name:Status, Value :200 OK

Header Name:X-Runtime, Value :713

Header Name:X-Moex-Passport-Certificate, Value :xxxxxx

Header Name:X-Powered-By, Value :Phusion Passenger 4.0.57

Header Name:Access-Control-Allow-Credentials, Value :true

Header Name:Access-Control-Expose-Headers, Value :X-MicexPassport-Marker