Why there are 3 different ports for the .net core 2.1 SPA?

Question

I'm learning dotnet core 2.1 SPA, and when I run the donet core 2.1 SPA Angular with dotnet run, I noticed that there are 3 differnt ports:

1. https:localhost:5001
2. http:localhost:5000
3. http:localhost:34941

When I use the second url, it just automatically redirect to the first url, and I got security error. For the 3rd url, it works. I think because it's for the client, where 1st and 2nd url would be used for APIs calls with authentications? What would happen in a live environment?

The configuration in Program.cs file

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
}

Answer 1

5000 and 5001: Kestrel HTTP and HTTPS Defaults

5000 is for HTTP and 5001 is for HTTPS. Those are defaults in the ASP.NET Core Kestrel Server. 5000 redirects to 5001 because of app.UseHttpsRedirection() in your Startup class.

34941: Any available port for the NG Live Development Server

This is an arbitrary, available port that Microsoft.AspNetCore.SpaServices uses to start the NG Live Development Server. The spa.UseAngularCliServer(npmScript: "start") method in your Startup class calls the the start script from your package.json file like this:

ng serve --extract-css "--port" "50415"`

The port that it passes is any currently available port that the SpaServices find.

See also

• https://github.com/aspnet/JavaScriptServices
• https://github.com/aspnet/KestrelHttpServer