Health check fails from Linux machine, not from Windows machine


We’re implementing 2fa authentication with DUO for an application of ours we’re building. This works perfectly when we run the software locally (redict url via ngrok) or on a Windows server, but not on our production server: the health check (.DoHealthCheck()) always fails.

We use the C# client from github: GitHub - duosecurity/duo_universal_csharp: Duo two-factor authentication for .NET web applications

To extract the problem from our application itself we created a small console app app which does nothing else than create a Duo Universal client with our settings, and run the health check and outputs if it succeeded or not. This also only works on the Windows machines (outputs ‘True’) and not the Linux machines (outputs ‘False’).

I suspect it has something to do differences between the SSL version and/or protocol in both the linux and windows machines.

I changed the DoHealthCheck a bit to output the error, and that says:
System.Security.Authentication.AuthenticationException: The remote certificate was rejected by the provided RemoteCertificateValidationCallback

Anyone any ideas how to fix this?

Hi @DevElopment ,

Would you mind submitting this as an issue on the repo?

I posted in the repo.

Thanks! We’ll continue the conversation over there.