<system.webServer>
    <security>
      <authentication>
        <anonymousAuthentication enabled="true" />
        <windowsAuthentication enabled="true" />
      </authentication>
    </security>
  </system.webServer>

{
  "iisSettings": {
    "windowsAuthentication": true,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:3381/",
      "sslPort": 0
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <handlers>
      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified"/>
    </handlers>
    <aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" 
            stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" 
            forwardWindowsAuthToken="true"/>
  </system.webServer>
</configuration>

namespace ASPNETCore2WindowsAuthentication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                                     .UseKestrel()
                                     .UseContentRoot(Directory.GetCurrentDirectory())
                                     .UseStartup<Startup>()
                                     .UseHttpSys(options => // Just for local tests without IIS, Or self-hosted scenarios on Windows ...
                                     {
                                         options.Authentication.Schemes =
                                              AuthenticationSchemes.Negotiate | AuthenticationSchemes.NTLM;
                                         options.Authentication.AllowAnonymous = true;
                                         //options.UrlPrefixes.Add("http://+:80/");
                                     })
                                     .Build();
            host.Run();
        }
    }
}

namespace ASPNETCore2WindowsAuthentication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                                     .UseKestrel()
                                     .UseContentRoot(Directory.GetCurrentDirectory())
                                     .UseIISIntegration()
                                     .UseDefaultServiceProvider((context, options) =>
                                     {
                                         options.ValidateScopes = context.HostingEnvironment.IsDevelopment();
                                     })
                                     .UseStartup<Startup>()
                                     .Build();
            host.Run();
        }
    }
}

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();

            services.Configure<IISOptions>(options =>
            {
                // Sets the HttpContext.User
                // Note: Windows Authentication must also be enabled in IIS for this to work.
                options.AutomaticAuthentication = true;
                options.ForwardClientCertificate = true;
            });
            
            services.AddAuthentication(options =>
            {
                // for both windows and anonymous authentication
                options.DefaultChallengeScheme = IISDefaults.AuthenticationScheme;
            });
        }

        private string authInfo()
        {
            var claims = new StringBuilder();
            if (User.Identity is ClaimsIdentity claimsIdentity)
            {
                claims.Append("Your claims: \n");
                foreach (var claim in claimsIdentity.Claims)
                {
                    claims.Append(claim.Type + ", ");
                    claims.Append(claim.Value + "\n");
                }
            }

            return $"IsAuthenticated: {User.Identity.IsAuthenticated}; Identity.Name: {User.Identity.Name}; WindowsPrincipal: {(User is WindowsPrincipal)}\n{claims}";
        }

namespace ASPNETCore2WindowsAuthentication.Controllers
{
    public class HomeController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }

        [Authorize]
        public IActionResult Windows()
        {
            return Content(authInfo());
        }

        private string authInfo()
        {
            var claims = new StringBuilder();
            if (User.Identity is ClaimsIdentity claimsIdentity)
            {
                claims.Append("Your claims: \n");
                foreach (var claim in claimsIdentity.Claims)
                {
                    claims.Append(claim.Type + ", ");
                    claims.Append(claim.Value + "\n");
                }
            }

            return $"IsAuthenticated: {User.Identity.IsAuthenticated}; Identity.Name: {User.Identity.Name}; WindowsPrincipal: {(User is WindowsPrincipal)}\n{claims}";
        }

        [AllowAnonymous]
        public IActionResult Anonymous()
        {
            return Content(authInfo());
        }

        [Authorize(Roles = "Domain Admins")]
        public IActionResult ForAdmins()
        {
            return Content(authInfo());
        }

        [Authorize(Roles = "Domain Users")]
        public IActionResult ForUsers()
        {
            return Content(authInfo());
        }
    }
}

 dotnet publish

[Authorize(Roles = @"<domain>\<group>")]
//or
[Authorize(Roles = @"<domain>\<group1>,<domain>\<group2>")]

services.AddAuthorization(options =>
{
   options.AddPolicy("RequireWindowsGroupMembership", policy =>
   {
     policy.RequireAuthenticatedUser();
     policy.RequireRole(@"<domain>\<group>"));  
   }
});

 [Authorize(Policy = "RequireWindowsGroupMembership")]

[HttpGet("[action]")]
public IActionResult SomeValue()
{
    if (!User.IsInRole(@"Domain\Group")) return StatusCode(403);
    return Ok("Some Value");
}

    public class ApplicationClaimsTransformation : IClaimsTransformation
    {
        private readonly ILogger<ApplicationClaimsTransformation> _logger;

        public ApplicationClaimsTransformation(ILogger<ApplicationClaimsTransformation> logger)
        {
            _logger = logger;
        }

        public Task<ClaimsPrincipal> TransformAsync(ClaimsPrincipal principal)
        {
            if (!(principal.Identity is ClaimsIdentity identity))
            {
                return Task.FromResult(principal);
            }

            var claims = addExistingUserClaims(identity);
            identity.AddClaims(claims);

            return Task.FromResult(principal);
        }

        private IEnumerable<Claim> addExistingUserClaims(IIdentity identity)
        {
            var claims = new List<Claim>();
            var user = @"VahidPC\Vahid";
            if (identity.Name != user)
            {
                _logger.LogError($"Couldn't find {identity.Name}.");
                return claims;
            }

            claims.Add(new Claim(ClaimTypes.GivenName, user));
            return claims;
        }
    }

            services.AddScoped<IClaimsTransformation, ApplicationClaimsTransformation>();
            services.AddAuthentication(options =>
            {
                // for both windows and anonymous authentication
                options.DefaultChallengeScheme = IISDefaults.AuthenticationScheme;
            });

var userId = User.FindFirstValue(ClaimTypes.NameIdentifier);
var userName = User.FindFirstValue(ClaimTypes.Name);
var userName = User.FindFirstValue(ClaimTypes.GivenName);

public async Task<long> GetDirectorySize(string path, string searchPattern)
{
    if (!Directory.EnumerateFileSystemEntries(path, searchPattern).Any())
        return 0;
    else
        return await Task.Run<long>(() => Directory.GetFiles(path, searchPattern,
        SearchOption.AllDirectories).Sum(t => (new FileInfo(t).Length)));
}

 AsyncTaskMethodBuilder<long>.Create()

public async ValueTask<long> GetDirectorySize(string path, string searchPattern)
{
    if (!Directory.EnumerateFileSystemEntries(path, searchPattern).Any())
        return 0;
    else
        return await Task.Run<long>(() => Directory.GetFiles(path, searchPattern,
        SearchOption.AllDirectories).Sum(t => (new FileInfo(t).Length)));
}

 PM> install-package System.Threading.Tasks.Extensions

A few highlights for this release include:

• Support for 64-bit identity seed values
• Support for new BCL DateOnly and TimeOnly structs for SQLite
• Uniquify and validate check constraint names
• Pre-convention model configuration 

Preview 1 was the first-ever 64-bit Visual Studio, delivering improved scalability. Starting with Preview 2, we’re focusing on delivering new capabilities on the themes of personal and team productivity, modern development, and constant innovation. 

using(var client = new HttpClient())
{
   // do something with http client
}

 Unable to connect to the remote server
System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted.

using (var client = new HttpClient())
{
       var result = await client.GetAsync("http://example.com/");
}

for (int i = 0; i < 10; i++)
{
      using (var client = new HttpClient())
      {
            var result = await client.GetAsync("http://example.com/");
            Console.WriteLine(result.StatusCode);
      }
}

  TCP    192.168.1.6:13996      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:13997      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:13998      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:13999      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:14000      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:14001      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:14002      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:14003      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:14004      93.184.216.34:http     TIME_WAIT
  TCP    192.168.1.6:14005      93.184.216.34:http     TIME_WAIT

 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpTimedWaitDelay]

CancelPendingRequests
DeleteAsync
GetAsync
GetByteArrayAsync
GetStreamAsync
GetStringAsync
PostAsync
PutAsync
SendAsync

BaseAddress
DefaultRequestHeaders
MaxResponseContentBufferSize
Timeout

var sp = ServicePointManager.FindServicePoint(new Uri("http://thisisasample.com"));
sp.ConnectionLeaseTimeout = 60*1000; //In milliseconds

using System;
using System.Collections.Generic;
using System.Net.Http;

namespace HttpClientTips
{
    public interface IHttpClientFactory : IDisposable
    {
        HttpClient GetOrCreate(
            Uri baseAddress,
            IDictionary<string, string> defaultRequestHeaders = null,
            TimeSpan? timeout = null,
            long? maxResponseContentBufferSize = null,
            HttpMessageHandler handler = null);
    }
}

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Net;
using System.Net.Http;
using System.Threading;

namespace HttpClientTips
{
    /// <summary>
    /// Lifetime of this class should be set to `Singleton`.
    /// </summary>
    public class HttpClientFactory : IHttpClientFactory
    {
        // 'GetOrAdd' call on the dictionary is not thread safe and we might end up creating the HttpClient more than
        // once. To prevent this Lazy<> is used. In the worst case multiple Lazy<> objects are created for multiple
        // threads but only one of the objects succeeds in creating the HttpClient.
        private readonly ConcurrentDictionary<Uri, Lazy<HttpClient>> _httpClients =
                         new ConcurrentDictionary<Uri, Lazy<HttpClient>>();
        private const int ConnectionLeaseTimeout = 60 * 1000; // 1 minute

        public HttpClientFactory()
        {
            // Default is 2 minutes: https://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.dnsrefreshtimeout(v=vs.110).aspx
            ServicePointManager.DnsRefreshTimeout = (int)TimeSpan.FromMinutes(1).TotalMilliseconds;
            // Increases the concurrent outbound connections
            ServicePointManager.DefaultConnectionLimit = 1024;
        }

        public HttpClient GetOrCreate(
           Uri baseAddress,
           IDictionary<string, string> defaultRequestHeaders = null,
           TimeSpan? timeout = null,
           long? maxResponseContentBufferSize = null,
           HttpMessageHandler handler = null)
        {
            return _httpClients.GetOrAdd(baseAddress,
                             uri => new Lazy<HttpClient>(() =>
                             {
                                 // Reusing a single HttpClient instance across a multi-threaded application means
                                 // you can't change the values of the stateful properties (which are not thread safe),
                                 // like BaseAddress, DefaultRequestHeaders, MaxResponseContentBufferSize and Timeout.
                                 // So you can only use them if they are constant across your application and need their own instance if being varied.
                                 var client = handler == null ? new HttpClient { BaseAddress = baseAddress } :
                                               new HttpClient(handler, disposeHandler: false) { BaseAddress = baseAddress };
                                 setRequestTimeout(timeout, client);
                                 setMaxResponseBufferSize(maxResponseContentBufferSize, client);
                                 setDefaultHeaders(defaultRequestHeaders, client);
                                 setConnectionLeaseTimeout(baseAddress, client);
                                 return client;
                             },
                             LazyThreadSafetyMode.ExecutionAndPublication)).Value;
        }

        public void Dispose()
        {
            foreach (var httpClient in _httpClients.Values)
            {
                httpClient.Value.Dispose();
            }
        }

        private static void setConnectionLeaseTimeout(Uri baseAddress, HttpClient client)
        {
            // This ensures connections are used efficiently but not indefinitely.
            client.DefaultRequestHeaders.ConnectionClose = false; // keeps the connection open -> more efficient use of the client
            ServicePointManager.FindServicePoint(baseAddress).ConnectionLeaseTimeout = ConnectionLeaseTimeout; // ensures connections are not used indefinitely.
        }

        private static void setDefaultHeaders(IDictionary<string, string> defaultRequestHeaders, HttpClient client)
        {
            if (defaultRequestHeaders == null)
            {
                return;
            }
            foreach (var item in defaultRequestHeaders)
            {
                client.DefaultRequestHeaders.Add(item.Key, item.Value);
            }
        }

        private static void setMaxResponseBufferSize(long? maxResponseContentBufferSize, HttpClient client)
        {
            if (maxResponseContentBufferSize.HasValue)
            {
                client.MaxResponseContentBufferSize = maxResponseContentBufferSize.Value;
            }
        }

        private static void setRequestTimeout(TimeSpan? timeout, HttpClient client)
        {
            if (timeout.HasValue)
            {
                client.Timeout = timeout.Value;
            }
        }
    }
}

namespace HttpClientTips.Web
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton<IHttpClientFactory, HttpClientFactory>();
            services.AddMvc();
        }

namespace HttpClientTips.Web.Controllers
{
    public class HomeController : Controller
    {
        private readonly IHttpClientFactory _httpClientFactory;
        public HomeController(IHttpClientFactory httpClientFactory)
        {
            _httpClientFactory = httpClientFactory;
        }

        public async Task<IActionResult> Index()
        {
            var host = new Uri("http://localhost:5000");
            var httpClient = _httpClientFactory.GetOrCreate(host);
            var responseMessage = await httpClient.GetAsync("home/about").ConfigureAwait(false);
            var responseContent = await responseMessage.Content.ReadAsStringAsync().ConfigureAwait(false);
            return Content(responseContent);
        }

Public Class MyResource
    Implements IDisposable
    Public Sub DoWork()
        Throw New ArgumentException("A")
    End Sub

    Public Overloads Sub Dispose() Implements System.IDisposable.Dispose
        Throw New ArgumentException("B")
    End Sub
End Class

Public NotInheritable Class TestClass
    Private Sub New()
    End Sub
    Public Shared Sub Test()
        Using r As New MyResource()
            Throw New ArgumentException("C")
            r.DoWork()
        End Using
    End Sub
End Class
Module Module1

    Sub Main()
        Try
            TestClass.Test()
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

End Module

private Tuple<string, string, int> GetPersonInfo()
{
     return new Tuple<string, string, int>("Steve", "Jobs", 56);
}

private IEnumerable<int> GetNumbers()
{
   var result = new List<int>();

   for (int i = 0; i <= 100; i++)
      result.Add(i);

   return result;
}

private IEnumerable<int> GetNumbers()
{
   for (int i = 0; i <= 100; i++)
   {
        yield return i;
   }
}

public interface ICar
{
   string GetName();
   string GetManufacturerCompany();
}

private class GenricClass<T> where T : ICar
{
}

public class Audi : ICar
{
   public string GetName()
   {
      throw new NotImplementedException();
   }

   public string GetManufacturerCompany()
   {
      throw new NotImplementedException();
   }
}

private static void Main(string[] args)
{
   var invalidTest = new GenricClass<int>();
   var validTest = new GenricClass<Audi>();
}

namespace System.Net.Http.Json {
    public static class HttpClientJsonExtensions {
        public static Task<object> GetFromJsonAsync(this HttpClient client, string requestUri, Type type, JsonSerializerOptions options, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<object> GetFromJsonAsync(this HttpClient client, string requestUri, Type type, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<object> GetFromJsonAsync(this HttpClient client, Uri requestUri, Type type, JsonSerializerOptions options, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<object> GetFromJsonAsync(this HttpClient client, Uri requestUri, Type type, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<TValue> GetFromJsonAsync<TValue>(this HttpClient client, string requestUri, JsonSerializerOptions options, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<TValue> GetFromJsonAsync<TValue>(this HttpClient client, string requestUri, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<TValue> GetFromJsonAsync<TValue>(this HttpClient client, Uri requestUri, JsonSerializerOptions options, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<TValue> GetFromJsonAsync<TValue>(this HttpClient client, Uri requestUri, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<HttpResponseMessage> PostAsJsonAsync<TValue>(this HttpClient client, string requestUri, TValue value, JsonSerializerOptions options = null, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<HttpResponseMessage> PostAsJsonAsync<TValue>(this HttpClient client, string requestUri, TValue value, CancellationToken cancellationToken);
        public static Task<HttpResponseMessage> PostAsJsonAsync<TValue>(this HttpClient client, Uri requestUri, TValue value, JsonSerializerOptions options = null, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<HttpResponseMessage> PostAsJsonAsync<TValue>(this HttpClient client, Uri requestUri, TValue value, CancellationToken cancellationToken);
        public static Task<HttpResponseMessage> PutAsJsonAsync<TValue>(this HttpClient client, string requestUri, TValue value, JsonSerializerOptions options = null, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<HttpResponseMessage> PutAsJsonAsync<TValue>(this HttpClient client, string requestUri, TValue value, CancellationToken cancellationToken);
        public static Task<HttpResponseMessage> PutAsJsonAsync<TValue>(this HttpClient client, Uri requestUri, TValue value, JsonSerializerOptions options = null, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<HttpResponseMessage> PutAsJsonAsync<TValue>(this HttpClient client, Uri requestUri, TValue value, CancellationToken cancellationToken);
    }

    public static class HttpContentJsonExtensions {
        public static Task<object> ReadFromJsonAsync(this HttpContent content, Type type, JsonSerializerOptions options = null, CancellationToken cancellationToken = default(CancellationToken));
        public static Task<T> ReadFromJsonAsync<T>(this HttpContent content, JsonSerializerOptions options = null, CancellationToken cancellationToken = default(CancellationToken));
    }

    public sealed class JsonContent : HttpContent {
        public Type ObjectType { get; }
        public object Value { get; }
        public static JsonContent Create(object inputValue, Type inputType, MediaTypeHeaderValue mediaType = null, JsonSerializerOptions options = null);
        public static JsonContent Create<T>(T inputValue, MediaTypeHeaderValue mediaType = null, JsonSerializerOptions options = null);
        protected override void SerializeToStream(Stream stream, TransportContext context, CancellationToken cancellationToken);
        protected override Task SerializeToStreamAsync(Stream stream, TransportContext context);
        protected override Task SerializeToStreamAsync(Stream stream, TransportContext context, CancellationToken cancellationToken);
        protected override bool TryComputeLength(out long length);
    }
}

var httpClient = new HttpClient();
httpClient.BaseAddress = new Uri("https://localhost:5000");

var profiles = await httpClient.GetFromJsonAsync<Profile[]>("api/users/profiles");

var profile = new Profile { FirstName = "User 1", LastName = "Name 1", Age = 25 };
using var response1 = await httpClient.PostAsJsonAsync("api/users/profiles", profile);
response1.EnsureSuccessStatusCode();


var updatedProfile = new Profile { FirstName = "User 2", LastName = "Name 2", Age = 40 };
using var response2 = await httpClient.PutAsJsonAsync("api/users/profiles", profile);
response2.EnsureSuccessStatusCode();

var profile = new Profile { FirstName = "User 1", LastName = "Name 1", Age = 25 };
var json = JsonSerializer.Serialize(profile);
var stringContent = new StringContent(json, Encoding.UTF8, "application/json");
using var response4 = await httpClient.PostAsync("api/users/profiles", stringContent);
response4.EnsureSuccessStatusCode();

var httpClient = new HttpClient();
httpClient.BaseAddress = new Uri("https://localhost:5000");

var request = new HttpRequestMessage(HttpMethod.Get, "api/users/profiles");
using var response1 = await httpClient.SendAsync(request);
if (response1.IsSuccessStatusCode)
{
  var profiles = await response1.Content.ReadFromJsonAsync<Profile[]>();
}

var request = new HttpRequestMessage(HttpMethod.Get, "api/users/profiles");
using var response2 = await httpClient.SendAsync(request);
if (response2.IsSuccessStatusCode)
{
   using var streamResult = await response2.Content.ReadAsStreamAsync();
   var profiles = JsonSerializer.DeserializeAsync<Profile[]>(streamResult);
}

var httpClient = new HttpClient();
var uri = "https://localhost:5000";
httpClient.BaseAddress = new Uri(uri);

var requestMessage = new HttpRequestMessage(HttpMethod.Post, "https://localhost:5000")
{
   Content = JsonContent.Create(new Profile { FirstName = "User 1", LastName = "Name 1", Age = 25 })
};
using var reponse1 = await httpClient.SendAsync(requestMessage);
reponse1.EnsureSuccessStatusCode();