以下是一个使用ASP.NET Core进行LDAP Active Directory身份验证的示例代码：

1. 首先，您需要在Startup.cs文件中配置LDAP身份验证服务。

using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication.OpenIdConnect;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace YourProjectNamespace
{
    public class Startup
    {
        private readonly IConfiguration _configuration;

        public Startup(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddAuthentication(options =>
                {
                    options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                    options.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
                })
                .AddCookie()
                .AddOpenIdConnect(options =>
                {
                    options.Authority = "https://your-ldap-server-url";
                    options.ClientId = "your-client-id";
                    options.ResponseType = "code";
                    options.CallbackPath = "/signin-oidc";
                    options.SignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                    options.UsePkce = false;
                    options.SaveTokens = true;
                    options.TokenValidationParameters.ValidateIssuer = false;
                    options.TokenValidationParameters.NameClaimType = "preferred_username";
                });

            services.AddControllersWithViews();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            // ...

            app.UseAuthentication();
            app.UseAuthorization();

            // ...
        }
    }
}

2. 接下来，您可以在Controller中使用[Authorize]属性来保护需要认证的操作。

using Microsoft.AspNetCore.Mvc;

namespace YourProjectNamespace.Controllers
{
    public class HomeController : Controller
    {
        [Authorize]
        public IActionResult Index()
        {
            // 这个操作需要认证
            return View();
        }

        // ...
    }
}

3. 最后，您可以在视图中使用标签来显示用户信息。

@using Microsoft.AspNetCore.Authentication

@if (User.Identity.IsAuthenticated)
{
    
Welcome, @User.Identity.Name!
    

        Logout
    
}
else
{
    
Anonymous
    Login
}

这是一个基本的示例，您可以根据自己的需求进行自定义和扩展。