I am trying to run an asp.net core 3.1 mvc web app that is running on a debian 10 container hosted on RHEL 7. The app is authenticating through Azure Ad OIDC SSO. the app must connect to Azure AD through a corporate proxy. I am trying to set up the proxy in asp.net core so that only the authentication traffic is going through the proxy. My startup file looks as follows:
using AutoMapper;
using CMM_MVP.Factories;
using CMM_MVP.Models;
using CMM_MVP.Services;
using CMM_MVP.Utils;
using Microsoft.AspNetCore.Authentication.OpenIdConnect;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.DataProtection;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc.Authorization;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Identity.Web;
using Microsoft.Identity.Web.UI;
using Microsoft.IdentityModel.Logging;
using System;
using System.Data;
using System.Data.SqlClient;
using System.Net;
using System.Net.Http;
namespace CMM_MVP
{
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.
// For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
public void ConfigureServices(IServiceCollection services)
{
services.AddAutoMapper(typeof(Startup));
services.AddCors();
services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
.AddMicrosoftIdentityWebApp(Configuration.GetSection("AzureAd"));
IdentityModelEventSource.ShowPII = true;
services.AddControllersWithViews(options =>
{
var policy = new AuthorizationPolicyBuilder()
.RequireAuthenticatedUser()
.Build();
options.Filters.Add(new AuthorizeFilter(policy));
});
services.AddRazorPages().AddMicrosoftIdentityUI();
//allow the HTTP Context object to be passed as a service to the controllers.
services.AddHttpContextAccessor();
services.AddSingleton<ISqlServerConnectionUtil, SqlServerConnectionUtil>();
services.AddSingleton<IRepository<CustomerModel>, MockCustomersRepository>();
services.AddScoped<ICustomerService, CustomerService>();
services.AddSingleton<IUserService, UserService>();
services.AddScoped<ICaseService, CaseService>();
services.AddScoped<IViewCaseService, ViewCaseService>();
services.AddScoped(typeof(IModelFactory<>), typeof(ModelFactory<>));
services.AddDataProtection()
.SetApplicationName("xxx")
.PersistKeysToFileSystem(new System.IO.DirectoryInfo(@"/var/dpkeys/"));
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
IdentityModelEventSource.ShowPII = true;
}
else {
app.UseHsts();
}
// Add support for sessions before using routing
//app.UseSession();
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseCors(builder =>
{
builder
.AllowAnyOrigin()
.AllowAnyMethod()
.AllowAnyHeader();
});
app.UseAuthentication();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}");
});
}
}
}
I have seen that other threads exist using OpenIDConnect : Authenticate with Azure AD using .Net Core 3.00 from behind Corporate Proxy However since then Microsoft has introduced and recommended Microsoft.Identity.Web for Azure AD OIDC authentication which I am using instead. I have found another colleague that used the successfully working following setup (starts after .AddMicrosoftIdentityWebApp(Configuration.GetSection("AzureAd")); ):
var aadProxy = new WebProxy()
{
Address = new Uri("http://address:port"),
UseDefaultCredentials = true
};
IdentityModelEventSource.ShowPII = true;
services.AddHttpClient("proxiedClient")
.ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler()
{
UseProxy = true,
Proxy = aadProxy,
PreAuthenticate = true
});
services.Configure<AadIssuerValidatorOptions>(options => { options.HttpClientName = "proxiedClient"; });
He also uses the following code, which does not apply to me as I am not setting up JwtTokens:
services.Configure<JwtBearerOptions>(JwtBearerDefaults.AuthenticationScheme, options =>
{
options.TokenValidationParameters.RoleClaimType = "roles";
options.BackchannelHttpHandler = new HttpClientHandler()
{
UseProxy = true,
Proxy = aadProxy,
PreAuthenticate = true,
};
});
I understood that the "BackchannelHttpHandler" is what handles the metadta from Azure AD. I have searched for ways to set the BackchannelHttpHandler for my use-case but could not find any.
It looks to me that setting up the BackchannelHttpHandler is the only thing i am missing atm but I do not know for sure?
Also I do not know how to configure it?
I have got this working now for few days without any probs. To answer my 2 questions:
Answer: BackchannelHttpHandler was indeed the only thing I was missing.
Answer: using the options pattern: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/options?view=aspnetcore-3.1 the BackchannelHttpHandler property can be configured : https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.authentication.openidconnect.openidconnectoptions?view=aspnetcore-3.1 right after the line : services.Configure(options => { options.HttpClientName = "proxiedClient"; });
in the question. the code that needs to be added after the line above to configure the BackchannelHttpHandler property in OpenIDConnect options is as follows:
services.Configure<OpenIdConnectOptions>(OpenIdConnectDefaults.AuthenticationScheme,
options =>
{
options.BackchannelHttpHandler = new HttpClientHandler()
{
UseProxy = true,
Proxy = aadProxy,
PreAuthenticate = true,
};
});
That's all. SSO through Azure AD OpenID Connect is working successfully now.