Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Newtonsoft.Json.Serialization;
using System.Net;
using Owin;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication.WsFederation;

namespace Foo.Bar
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc().AddJsonOptions(o => o.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver());

            services.AddAuthentication(options =>
            {
                options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                options.DefaultSignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                options.DefaultChallengeScheme = WsFederationDefaults.AuthenticationScheme;
            })
            .AddWsFederation(options =>
            {
                options.Wtrealm = "https://localhost:44363/foobar";
                options.MetadataAddress = "https://win-9j9dv1tr92n/security/FederationMetadata/2007-06/FederationMetadata.ashx";
                options.Wreply = "https://localhost:44363/foobar";
            })
            .AddCookie();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseExceptionMiddleware();
                app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions
                {
                    HotModuleReplacement = true,
                    ReactHotModuleReplacement = true
                });
                /* This will cause all HTTPS certificates to be validated, regardless of if they're trusted or not. 
                 * It should NOT be used in production. */
                ServicePointManager.ServerCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true;
            }
            else
            {
                app.UseExceptionMiddleware();
                app.UseExceptionHandler();
            }

            app.UseAuthentication();
            app.UseStaticFiles();

            app.UseMvc(routes =>
            {

                routes.MapRoute(
                    name: "areaRoute",
                    template: "{area:exists}/{controller}/{action}");

                /*routes.MapSpaFallbackRoute(
                    name: "spa-fallback",
                    defaults: new { controller = "Home", action = "Index" }); */
            });
        }
    }
}