Web客户端例外：基础连接已关闭：无法为SSL / TLS安全通道建立信任关系

时间：2012-09-27 15:24:56

标签： c# .net ssl

我有一个简单的应用程序，它使用C＃Web Client类下载网站HTML。这是我正在使用的代码的精简样本：

WebClient wc = new WebClient();
wc.Headers.Add("user-agent",
    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
htmlCode = wc.DownloadString("https://www.oig.hhs.gov/exclusions/exclusions_list.asp");

网站证书似乎存在问题，因为我遇到了这个例外：

The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel." "The remote certificate is invalid according to the validation procedure.

如果您将链接复制并粘贴到浏览器中，则需要您在允许您查看网站之前同意风险。它是一个政府网站，所以我不担心任何病毒或任何东西。有没有告诉网络客户端绕过这个问题，并继续访问该网站？

5 个答案:

答案 0 :(得分：42)

据我所知，这是因为他们使用的是无效或过期的SSL证书。您可以使用：

绕过（忽略）它 
ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;

修改2015 ：

这篇文章得到了很多赞成，但我对我的回答感到遗憾。它可能会删除您的错误，但它无法解决问题。接受任何SSL证书会使你在中间攻击中容易受到攻击，所以这通常是一个非常糟糕的主意。我将留下这个答案以供将来参考，但请注意，您应该尝试在根目录解决问题，即确保SSL证书有效。

答案 1 :(得分：14)

试试这个：
您希望将证书安装到本地计算机上。

如果代码中不的过程将执行以下操作：

  1. 以管理员模式（不是Chrome）打开Internet Explorer。
  2. 转到网站
  3. 选择继续
  4. 单击证书上的titelbar / url栏以查看证书。
  5. 点击安装证书。

    6. 因此，您可以尝试查看这些其他问题，看看它们是否对您有所帮助：

    尝试安装证书，如果要求继续，请查看是否再次访问该网址。

    ****编辑**：
    我阅读了网站证书，这是因为证书与网站的网址不匹配。

    一个简单的改变就是：

    htmlCode = wc.DownloadString("https://oig.hhs.gov/exclusions/exclusions_list.asp");

    只需删除www。

    即可

答案 2 :(得分：2)

进一步建立Leon Cullens＆＃39;回答我想出了以下内容。就像他在回答中说的那样，这不应该是你作为永久解决方案所做的事情，但如果你故意得到这个错误，这可能会帮助你。这应该为您没有选择并且只需要它工作的情况增加一点安全性。

我目前的情况是在开发目的期间我需要使用自签名证书而不是真正的签名证书。这当然会导致以下错误...

  

＆＃34;底层连接已关闭：无法建立信任   SSL / TLS安全通道的关系。＆＃34;

这是我尝试做的事情，让它更加安全，并尽量避免中间人攻击＆＃34;。我试图让它尽可能短而简单，但我想确保我画出整个图片以便于理解。

using System;
using System.Text;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Threading;

namespace TestSecurity
{
    class TestDownload
    {
        private void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            //Progress in the download
        }

        private void client_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e)
        {
            //Download has completed
        }

        private bool client_RemoteCertificateValidation(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
            if (sslPolicyErrors == SslPolicyErrors.RemoteCertificateChainErrors)
            {
                //Check to make sure the domain is correct
                X509Certificate2 certificate_details = (X509Certificate2)certificate;
                if (certificate_details.Thumbprint == "91A92CA60555DB51BEDDFE1AE4ECE54C8EBEBA97")
                {
                    #region Fingerprint for certificate
                    string storedFingerprint = "" +
                    "42048c788db687ed84407da10f78182e3487d1fc31c07ee131151f4e19b360ad2a8c452c2e7d614a5691d5479787fe70dabd" +
                    "64617465732e626c75656172726f77646576656c6f706d656e742e636f6d3110300e06035504080c0747656f72676961311f" +
                    "301d060355040a0c16426c7565204172726f7720446576656c6f706d656e74310b3009060355040613025553312f302d0609" +
                    "2a864886f70d0109011620737570706f727440626c75656172726f77646576656c6f706d656e742e636f6d31123010060355" +
                    "04070c09436c6576656c616e64301e170d3136303232393231313733335a170d3137303232383231313733335a3081b03129" +
                    "302706035504030c20757064617465732e626c75656172726f77646576656c6f706d656e742e636f6d3110300e0603550408" +
                    "42048c788db687ed84407da10f78182e3487d1fc31c07ee131151f4e19b360ad2a8c452c2e7d614a5691d5479787fe70dabd" +
                    "0613025553312f302d06092a864886f70d0109011620737570706f727440626c75656172726f77646576656c6f706d656e74" +
                    "2e636f6d3112301006035504070c09436c6576656c616e6430820122300d06092a864886f70d01010105000382010f003082" +
                    "010a0282010100a1cdf5af6f1bba5cc8495d8061895f39858fde814f5581266505bf4cbe0b26506278bc247963bb7c42f0b8" +
                    "b00638871932ed7d0a3c6562be8e5b513f24da2768051acde875b53bf94c8ea2cec397145db206b2524c42a2019a0bfa14e2" +
                    "a7ef0d311235e07b7e0363345fd7f397e365c0865b1b8fa8ad7eebdc1fcdce360db04f2822438621534ae10744155a710641" +
                    "9a69c16745974a37c5b06917036351b92c06540a6c70aa776c143eef6f7b8ec31c0c40a9eab8a399c9065bea688ea7bd1db2" +
                    "30af56d2ca0f8983f9e8dacb5613755fbcd8229d7042668a9130468a7480a2afde8c18bab895472ddf1ed2c49291c04e8cc2" +
                    "ff24db33d231b3a2498c03a5650203010001a34d304b301d0603551d0e0416041476b5c2c82ff138b87c0e2d6c046af4c634" +
                    "55040a0c16426c75652048c1f54dcb82e3487d1fc31c07ee1313fba9204c7b3232ba9204c7b323a021abcbda85bfca9c9931" +
                    "092a864886f70d01010b050003820101001ab0dfd318cc2e93a997445d0950ffcb63544c58fe1ded6e234aa7ccdcb5c890b1" +
                    "61b51ae08c1f54dcb3fbeca9c9932bde91d202b89c0b6f0af1a370017fa9f6a021abcbda85bfecebebc6d6067d4dc1e51ec5" +
                    "02cf95867516a84f01410cf80d7af4f0d3e9a86cf7b0323dba9204c7b3232c58b2289032a12aaa1ec4f64065da8bbde4fe47" +
                    "42048c788db687ed84407da10f78182e3487d1fc31c07ee131151f4e19b360ad2a8c452c2e7d614a5691d5479787fe70dabd" +
                    "de819522bb7ef870595d9738a6acdd39b7fcf6f36948ef2b404c2b6d7ebe577555148ad90013a5c2e812b2b907c808288040" +
                    "0db6702407585328f7e6c84b40451384391783001174d0";
                    #endregion

                    //Use the following to get the server's fingerprint to be saved and compared against
                    StringBuilder hex = new StringBuilder(certificate_details.RawData.Length * 2);
                    foreach (byte b in certificate_details.RawData)
                        hex.AppendFormat("{0:x2}", b);
                    string serverFingerprint = hex.ToString();

                    if (serverFingerprint == storedFingerprint) return true;
                    else return false;
                }
                else return false;
            }
            else if (sslPolicyErrors == SslPolicyErrors.None)
                return true;
            else
                return false;
        }

        public void TestDownload(Uri targetURL, bool useCredentials, string user, string pass)
        {
            WebClient client = new WebClient();
            bool taskCompleted = false;

            //Create the event handlers to monitor progress
            client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
            client.DownloadDataCompleted += new DownloadDataCompletedEventHandler(client_DownloadDataCompleted);
            ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(client_RemoteCertificateValidation);

            //Resolve the host
            IPHostEntry host = Dns.GetHostEntry(targetURL.Host);
            IPAddress ip = (host.AddressList.Length > 0 ? host.AddressList[0] : null);

            //Show the UI the resolved host

            //Account for credentials
            if (useCredentials)
            {
                NetworkCredential credentials = new NetworkCredential(
                    user,
                    pass);
                client.Credentials = credentials;
            }
            else client.Credentials = null;

            //Download file
            client.DownloadDataAsync(targetURL, taskCompleted);

            //Go to sleep until the file download has completed
            do { Thread.Sleep(500); } while (client.IsBusy);

            //File download complete

            //Destory the event handlers as they are no longer needed
            ServicePointManager.ServerCertificateValidationCallback -= client_RemoteCertificateValidation;
            client.DownloadProgressChanged -= client_DownloadProgressChanged;
            client.DownloadDataCompleted -= client_DownloadDataCompleted;
        }
    }
}

答案 3 :(得分：0)

我遇到了这个问题：

  

无法为SSL / TLS安全通道建立信任关系。

我使用.NET客户端连接到Apache服务器上的Web服务。 这就是纠正这个问题的原因。 

(proxy).UserAgent = "Apache-HttpClient/4.1.1 (java 1.5)";

答案 4 :(得分：0)

根据this Answer，在使用WebClient实例之前添加以下行：

 [{
"spotType": "Handicap",
"used": false,
"_id": ObjectId("5c0ea6a64d8e4667682dd889")
},
{
"spotType": "Handicap",
"used": false,
"_id": ObjectId("5c0ea6a64d8e4667682dd882")
},
{
"spotType": "Handicap",
"used": false,
"_id": ObjectId("5c0ea6a64d8e4667682dd881")
}]
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