Html – Need help with setting up SSL

As stated above, 1) SSL can be set at the server, side, or virtual directory.

2) If the server/site/vdir is configured using the "Require Secure Channel" setting, the response from the server will be a "403.4 Forbidden: SSL is required to view this resource." error or a "403.5 Forbidden: SSL 128 is required to view this resource.".

You can actually customize the 403.4 or 403.5 error to redirect back to HTTPS. Create a VDIR under your site with NO SSL Requirement (**This is Important) - I use "CustomError". Create an ASP File inside this directory called 403_4_Error.asp containing the following:

<%@ LANGUAGE="VBScript" %> 
<%
if Request.ServerVariables("HTTPS") <> "on" then
    sServer = Request.ServerVariables("SERVER_NAME")
    sScript = Request.ServerVariables("SCRIPT_NAME")
    sQuery  = Request.ServerVariables("QUERY_STRING")
    Response.Write("https://" & sServer & sScript & "?" & sQuery)
end if
%>

Edit the server/site/vdir's Custom Error property for 403.4/403.5 and set the MessageType to URL and the URL to "/CustomError/403_4_Error.asp".

Note that ASP is used, you could easily use ASP.net or any other scripting language.

As a workaround you could add a handler to the ServicePointManager's ServerCertificateValidationCallback on the client side:

System.Net.ServicePointManager.ServerCertificateValidationCallback +=
    (se, cert, chain, sslerror) =>
        {
            return true;
        };

but be aware that this is not a good practice as it completely ignores the server certificate and tells the service point manager that whatever certificate is fine which can seriously compromise client security. You could refine this and do some custom checking (for certificate name, hash etc). at least you can circumvent problems during development when using test certificates.