Requesting html over https with c# Webclient

Question

I am attempting various html resources via c# WebClient class from a site I have no control over. When I attempt to access urls such as \"https://archive.org/details/OTRR_

Answer 1

I tried this example and received the error "The request was aborted: Could not create SSL/TLS secure channel"

To fix this problem it's possible to change the SecurityProtocol in my case Tls12 and it's working good.

Answer 2

Have a read of this: http://support.microsoft.com/kb/915599

The server you are accessing doesn't support TLS so you will need to force it to use SSL3.

Add the following line to your call:

ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;

Here's a fully working example:

using System;
using System.IO;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

class Program
{
    static void Main(string[] args)
    {
        Uri address = new Uri("https://archive.org/details/OTRR_In_The_Name_Of_The_Law_Singles");

        ServicePointManager.ServerCertificateValidationCallback += ValidateRemoteCertificate;
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 ;

        using (WebClient webClient = new WebClient())
        {
            var stream = webClient.OpenRead(address);
            using (StreamReader sr =new StreamReader(stream))
            {
                var page = sr.ReadToEnd();
            }
        }
    }

    /// <summary>
    /// Certificate validation callback.
    /// </summary>
    private static bool ValidateRemoteCertificate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors error)
    {
        // If the certificate is a valid, signed certificate, return true.
        if (error == System.Net.Security.SslPolicyErrors.None)
        {
            return true;
        }

        Console.WriteLine("X509Certificate [{0}] Policy Error: '{1}'",
            cert.Subject,
            error.ToString());

        return false;
    }

Answer 3

Just add this line before var stream = webClient.OpenRead(address);

System.Net.ServicePointManager.ServerCertificateValidationCallback += (send, certificate, chain, sslPolicyErrors) => { return true; };

That should sort out the SSL/TLS error

Answer 4

in .net Framework 4.0 add

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; //TLS 1.2