[c#] Could not establish trust relationship for SSL/TLS secure channel -- SOAP

I have a simple web service call, generated by a .NET (C#) 2.0 windows app, via the web service proxy generated by Visual Studio, for a web service also written in C# (2.0). This has worked for several years, and continues to do so at the dozen or so places where it is running.

A new installation at a new site is running into a problem. When attempting to invoke the web service, it fails with the message saying:

Could not establish a trust relationship for the SSL/TLS secure channel

The URL of the web service uses SSL (https://) -- but this has been working for a long time (and continues to do so) from many other locations.

Where do I look? Could this be a security issue between Windows and .NET that is unique to this install? If so, where do I set up trust relationships? I'm lost!

The very simple "catch all" solution is this:

System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

The solution from sebastian-castaldi is a bit more detailed.

A variation I've been using for a while it if helps anyone.

The caller has to explicitly request that untrusted certifications are required and places the callback back into it's default state upon completion.

    /// <summary>
    /// Helper method for returning the content of an external webpage
    /// </summary>
    /// <param name="url">URL to get</param>
    /// <param name="allowUntrustedCertificates">Flags whether to trust untrusted or self-signed certificates</param>
    /// <returns>HTML of the webpage</returns>
    public static string HttpGet(string url, bool allowUntrustedCertificates = false) {
        var oldCallback = ServicePointManager.ServerCertificateValidationCallback;
        string webPage = "";
        try {
            WebRequest req = WebRequest.Create(url);

            if (allowUntrustedCertificates) {
                // so we can query self-signed certificates
                ServicePointManager.ServerCertificateValidationCallback = 
                    ((sender, certification, chain, sslPolicyErrors) => true);
            }

            WebResponse resp = req.GetResponse();
        
            using (StreamReader sr = new StreamReader(resp.GetResponseStream())) {
                webPage = sr.ReadToEnd().Trim();
                sr.Close();
            }
            return webPage;
        }
        catch {
            // if the remote site fails to response (or we have no connection)
            return null;
        }
        finally {
            ServicePointManager.ServerCertificateValidationCallback = oldCallback;
        }
    }

My solution (VB.Net, the "staging" (UAT) version of this application needs to work with the "staging" certificate but not affect requests once they are on the live site):

    ...
        Dim url As String = ConfigurationManager.AppSettings("APIURL") & "token"
        If url.ToLower().Contains("staging") Then
           System.Net.ServicePointManager.ServerCertificateValidationCallback = AddressOf AcceptAllCertifications
        End If
    ...

    Private  Function AcceptAllCertifications(ByVal sender As Object, ByVal certification As System.Security.Cryptography.X509Certificates.X509Certificate, ByVal chain As System.Security.Cryptography.X509Certificates.X509Chain, ByVal sslPolicyErrors As System.Net.Security.SslPolicyErrors) As Boolean
        Return True
    End Function

I had a similar problem in .NET app in Internet Explorer.

I solved the problem adding the certificate (VeriSign Class 3 certificate in my case) to trusted editors certificates.

Go to Internet Options-> Content -> Publishers and import it

You can get the certificate if you export it from:

Internet Options-> Content -> Certificates -> Intermediate Certification Authorities -> VeriSign Class 3 Public Primary Certification Authority - G5

thanks

If you are using Windows 2003, you can try this:

Open Microsoft Management Console (Start --> Run --> mmc.exe);

Choose File --> Add/Remove Snap-in;

In the Standalone tab, choose Add;

Choose the Certificates snap-in, and click Add;

In the wizard, choose the Computer Account, and then choose Local Computer. Press Finish to end the wizard;

Close the Add/Remove Snap-in dialog;

Navigate to Certificates (Local Computer) and choose a store to import:

If you have the Root CA certificate for the company that issued the certificate, choose Trusted Root Certification Authorities;

If you have the certificate for the server itself, choose Other People

Right-click the store and choose All Tasks --> Import

Follow the wizard and provide the certificate file you have;

After that, simply restart IIS and try calling the web service again.

Reference: http://www.outsystems.com/NetworkForums/ViewTopic.aspx?Topic=Web-Services:-Could-not-establish-trust-relationship-for-the-SSL/TLS-...

Microsoft's SSL Diagnostics Tool may be able to help identify the issue.

UPDATE the link has been fixed now.

I just encountered this issue. My resolution was to update the system time by manually syncing to the time servers. To do this you can:

• Right-click the clock in the task bar
• Select Adjust Date/Time
• Select the Internet Time tab
• Click Change Settings
• Select Update Now

In my case this was syncing incorrectly so I had to click it several times before it updated correctly. If it continues to update incorrectly you can even try using a different time server from the server drop-down.

The following snippets will fix the case where there is something wrong with the SSL certificate on the server you are calling. For example, it may be self-signed or the host name between the certificate and the server may not match.

This is dangerous if you are calling a server outside of your direct control, since you can no longer be as sure that you are talking to the server you think you're connected to. However, if you are dealing with internal servers and getting a "correct" certificate is not practical, use the following to tell the web service to ignore the certificate problems and bravely soldier on.

The first two use lambda expressions, the third uses regular code. The first accepts any certificate. The last two at least check that the host name in the certificate is the one you expect.
... hope you find it helpful

//Trust all certificates
System.Net.ServicePointManager.ServerCertificateValidationCallback =
    ((sender, certificate, chain, sslPolicyErrors) => true);

// trust sender
System.Net.ServicePointManager.ServerCertificateValidationCallback
                = ((sender, cert, chain, errors) => cert.Subject.Contains("YourServerName"));

// validate cert by calling a function
ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(ValidateRemoteCertificate);

// callback used to validate the certificate in an SSL conversation
private static bool ValidateRemoteCertificate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors policyErrors)
{
    bool result = cert.Subject.Contains("YourServerName");
    return result;
}

If not work bad sertificate, when ServerCertificateValidationCallback return true; My ServerCertificateValidationCallback code:

ServicePointManager.ServerCertificateValidationCallback += delegate
{
    LogWriter.LogInfo("???????? ??????????? ?????????, ?? ?????? ServerCertificateValidationCallback");
    return true;
};

My code which the prevented execute ServerCertificateValidationCallback:

     if (!(ServicePointManager.CertificatePolicy is CertificateValidation))
    {
        CertificateValidation certValidate = new CertificateValidation();
        certValidate.ValidatingError += new CertificateValidation.ValidateCertificateEventHandler(this.OnValidateCertificateError);
        ServicePointManager.CertificatePolicy = certValidate;
    }

OnValidateCertificateError function:

private void OnValidateCertificateError(object sender, CertificateValidationEventArgs e)
{
    string msg = string.Format(Strings.OnValidateCertificateError, e.Request.RequestUri, e.Certificate.GetName(), e.Problem, new Win32Exception(e.Problem).Message);
    LogWriter.LogError(msg);
    //Message.ShowError(msg);
}

I disabled CertificateValidation code and ServerCertificateValidationCallback running very well

Try this:

System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

Notice that you have to work at least with 4.5 .NET framework

I personally like the following solution the most:

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

... then before you do request getting the error, do the following

System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };

Found this after consulting Luke's Solution

I had this error running against a webserver with url like:

a.b.domain.com

but there was no certificate for it, so I got a DNS called

a_b.domain.com

Just putting hint to this solution here since this came up top in google.

In my case I was trying to test SSL in my Visual Studio environment using IIS 7.

This is what I ended up doing to get it to work:

• Under my site in the 'Bindings...' section on the right in IIS, I had to add the 'https' binding to port 443 and select "IIS Express Developement Certificate".

• Under my site in the 'Advanced Settings...' section on the right I had to change the 'Enabled Protocols' from "http" to "https".

• Under the 'SSL Settings' icon I selected 'Accept' for client certificates.

• Then I had to recycle the app pool.

• I also had to import the local host certificate into my personal store using mmc.exe.

My web.config file was already configured correctly, so after I got all the above sorted out, I was able to continue my testing.

Luke wrote a pretty good article about this .. pretty straight forward .. give this a try

Luke's Solution

Reason (quote from his article (minus cursing)) ".. The problem with the code above is that it doesn’t work if your certificate is not valid. Why would I be posting to a web page with and invalid SSL certificate? Because I’m cheap and I didn’t feel like paying Verisign or one of the other **-*s for a cert to my test box so I self signed it. When I sent the request I got a lovely exception thrown at me:

System.Net.WebException The underlying connection was closed. Could not establish trust relationship with remote server.

I don’t know about you, but to me that exception looked like something that would be caused by a silly mistake in my code that was causing the POST to fail. So I kept searching, and tweaking and doing all kinds of weird things. Only after I googled the ***n thing I found out that the default behavior after encountering an invalid SSL cert is to throw this very exception. .."

add this:

 ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;}

right before the line that you're calling the service

If you do not wan't to blindly trust everybody and make a trust exception only for certain hosts the following solution is more appropriate.

public static class Ssl
{
    private static readonly string[] TrustedHosts = new[] {
      "host1.domain.com", 
      "host2.domain.com"
    };

    public static void EnableTrustedHosts()
    {
      ServicePointManager.ServerCertificateValidationCallback = 
      (sender, certificate, chain, errors) =>
      {
        if (errors == SslPolicyErrors.None)
        {
          return true;
        }

        var request = sender as HttpWebRequest;
        if (request != null)
        {
          return TrustedHosts.Contains(request.RequestUri.Host);
        }

        return false;
      };
    }
}

Then just call Ssl.EnableTrustedHosts when your app starts.

For those who are having this issue through a VS client side once successfully added a service reference and trying to execute the first call got this exception: “The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel” If you are using (like my case) an endpoint URL with the IP address and got this exception, then you should probably need to re-add the service reference doing this steps:

• Open the endpoint URL on Internet Explorer.
• Click on the certificate error (red icon in address bar)
• Click on View certificates.
• Grab the issued to: "name" and replace the IP address or whatever name we were using and getting the error for this "name".

Try again :). Thanks