How to change the default host/port in .NET Core applications

Introduction

In the rapidly evolving landscape of web development,.NET Core stands out with its ability to efficiently build modern, cross-platform applications. A key aspect of deploying these applications is configuring the server settings, specifically the default host and port. This comprehensive guide delves into various methods for customizing these settings, ensuring that your.NET Core applications run exactly where and how you want them.

Understand the basics

.NET applications, by default, are configured to run on a default port and local IP address. While suitable for early development, different production scenarios may require specific configurations for reasons ranging from security protocols to compliance requirements.

Changing the host and port

You can use one of the 4 methods below to change the default host and port in a.NET core application:

Method 1: Using the launchSettings.json file

The launchSettings.json file is the reference point for development environment configurations. Located within the Properties folder, it allows environment-specific settings, such as Development, Staging, and Production.

{
 "iisSettings": {
 "windowsAuthentication": false,
 "anonymousAuthentication": true,
 "iisExpress": {
 "applicationUrl": "http://localhost:54321/",
 "sslPort": 0
 }
 },
 "profiles": {
 "IIS Express": {
 "commandName": "IISExpress",
 "launchBrowser": true,
 "launchUrl": "weatherforecast",
 "environmentVariables": {
 "ASPNETCORE_ENVIRONMENT": "Development"
 }
 },
 "YourProjectName": {
 "commandName": "Project",
 "dotnetRunMessages": true,
 "launchBrowser": true,
 "applicationUrl": "https://localhost:5001;http://localhost:5000",
 "environmentVariables": {
 "ASPNETCORE_ENVIRONMENT": "Development"
 }
 }
 }
 }

By changing the applicationUrl property in your project profile, you can set custom URLs.

Method 2: Programmatic configuration

For more control, especially in production, configure the host and port it directly into the Program.cs or Startup.cs file, depending on your project configuration.

.NET 5 or later:.NET 5 and later introduced a WebApplicationBuilder, altering the way applications are configured.

var builder = WebApplication.CreateBuilder(args);

 builder.WebHost.ConfigureKestrel(serverOptions =>
 {
 serverOptions.Listen(System.Net.IPAddress.Any, 5000); //Listen on all network interfaces on port 5000
 });

 var app = builder.Build();
 app.MapGet("/", () => "Hello World!");
 app.Run();

.NET Core 3.1 or earlier:

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
 WebHost.CreateDefaultBuilder(args).UseStartup().UseUrls("http://0.0.0.0:5000"); //Set custom host and port

Method 3: Environment Variables

Setting the ASPNETCORE_URLS environment variable is an effective way to define URLs, especially useful in dockerized environments.

export ASPNETCORE_URLS="http://*:5000"

This configuration tells the application to listen on port 5000 on all IP addresses.

Method 4: Using appsettings.json

For a more permanent solution that doesn't require changing code or environment variables, consider using the appsettings.json file. This method allows you to set URLs directly in your application's configuration file.

{
 "Kestrel": {
 "Endpoints": {
 "Http": {
 "Url": "http://0.0.0.0:8000"
 },
 "Https": {
 "Url": "https://0.0.0.0:8001"
 }
 }
 }
 }

In this configuration, the Kestrel server is explicitly asked to listen on both HTTP and HTTPS protocols, with customizable ports and IP addresses. This approach offers flexibility for defining different endpoints and is easily adjusted without changing the application source code.

Conclusion

The ability to customize default host and port settings in.NET Core applications gives developers the flexibility to meet the specific requirements of their deployment environments. Whether via launchSettings.json for development, direct programmatic configuration, environment variables, or the appsettings.json file for broader application settings,.NET Core offers a range of options to ensure your applications are accessible and secure, meeting your specific operational needs.