MQTTStudy/MQTTSample/MqttBrokerApp/Program.cs

using MQTTnet;
using MQTTnet.Server;

namespace MqttBrokerApp
{
    internal class Program
    {
        private static readonly int PORT = 1883;

        static async Task Main(string[] args)
        {
            var mqttFactory = new MqttFactory();
            var mqttServerOption = new MqttServerOptionsBuilder()
                .WithDefaultEndpoint()
                .WithDefaultEndpointPort(PORT)
                .Build();

            var mqttServer = mqttFactory.CreateMqttServer(mqttServerOption);
            await mqttServer.StartAsync();

            Console.WriteLine("MQTT Broker started. Press any key to exit...");
            Console.ReadLine();

            await mqttServer.StopAsync();
        }
    }
}