请求被中止无法在共享主机服务器C＃上创建ssl / tls安全通道

Question

We are not able to connect to https server using webrequest or htmlagilitypack It showing below error

The underlying connection was closed: An unexpected error occurred on a receive.System.Net.WebException: or could not create SSL/TLS secure channel on server

Our code works fine on localhost and we also added following portion in my code file but we aren't able to identify why it's happening only on the server.

ServicePointManager.Expect100Continue = true;

ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;

if anyone has any idea on this then please share with us.

Answer 1

Sometimes it is because the webrequest wont accept self signed certificates. I have this singleton class I usually use. It accepts all self signed certificates. It would be easier to determine if there is a simpler solution if if you shared the url you are trying to access.

public sealed class Certificates
{
    private static Certificates instance = null;
    private static readonly object padlock = new object();

    Certificates()
    {
    }

    public static Certificates Instance
    {
        get
        {
            lock (padlock)
            {
                if (instance == null)
                {
                    instance = new Certificates();
                }
                return instance;
            }
        }
    }
    public void GetCertificatesAutomatically()
    {
        ServicePointManager.ServerCertificateValidationCallback +=
            new RemoteCertificateValidationCallback((sender, certificate, chain, policyErrors)
                => { return true; });
    }

    private static bool RemoteCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
    {
        //Return true if the server certificate is ok
        if (sslPolicyErrors == SslPolicyErrors.None)
            return true;

        bool acceptCertificate = true;
        string msg = "The server could not be validated for the following reason(s):\r\n";

        //The server did not present a certificate
        if ((sslPolicyErrors &
            SslPolicyErrors.RemoteCertificateNotAvailable) == SslPolicyErrors.RemoteCertificateNotAvailable)
        {
            msg = msg + "\r\n    -The server did not present a certificate.\r\n";
            acceptCertificate = false;
        }
        else
        {
            //The certificate does not match the server name
            if ((sslPolicyErrors &
                SslPolicyErrors.RemoteCertificateNameMismatch) == SslPolicyErrors.RemoteCertificateNameMismatch)
            {
                msg = msg + "\r\n    -The certificate name does not match the authenticated name.\r\n";
                acceptCertificate = false;
            }

            //There is some other problem with the certificate
            if ((sslPolicyErrors &
                SslPolicyErrors.RemoteCertificateChainErrors) == SslPolicyErrors.RemoteCertificateChainErrors)
            {
                foreach (X509ChainStatus item in chain.ChainStatus)
                {
                    if (item.Status != X509ChainStatusFlags.RevocationStatusUnknown &&
                        item.Status != X509ChainStatusFlags.OfflineRevocation)
                        break;

                    if (item.Status != X509ChainStatusFlags.NoError)
                    {
                        msg = msg + "\r\n    -" + item.StatusInformation;
                        acceptCertificate = false;
                    }
                }
            }
        }

        //If Validation failed, present message box
        if (acceptCertificate == false)
        {
            msg = msg + "\r\nDo you wish to override the security check?";
            //          if (MessageBox.Show(msg, "Security Alert: Server could not be validated",
            //                       MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation, MessageBoxDefaultButton.Button1) == DialogResult.Yes)
            acceptCertificate = true;
        }

        return acceptCertificate;
    }

}

Just call the method before doing a web request like so.

Certificates.Instance.GetCertificatesAutomatically();

Also it would help diagnose the problem if we could see(the code) how you're making your webrequest.