dotnet add package RabbitMQ.Client

using RabbitMQ.Client;
using System.Text;

class Publisher
{
    public static void Main()
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using (var connection = factory.CreateConnection())
        {
            using (var channel = connection.CreateModel())
            {
                channel.ExchangeDeclare(exchange: "logs", type: "fanout");

                string message = "Hello World!";
                var body = Encoding.UTF8.GetBytes(message);

                channel.BasicPublish(exchange: "logs", routingKey: "",
                                     basicProperties: null, body: body);
                Console.WriteLine(" [x] Sent {0}", message);
            }
        }
    }
}

using RabbitMQ.Client;
using RabbitMQ.Client.Events;
using System;
using System.Text;

class Subscriber
{
    public static void Main()
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using (var connection = factory.CreateConnection())
        using (var channel = connection.CreateModel())
        {
            channel.ExchangeDeclare(exchange: "logs", type: "fanout");
            
            var queueName = channel.QueueDeclare().QueueName;
            channel.QueueBind(queue: queueName, exchange: "logs", routingKey: "");

            var consumer = new EventingBasicConsumer(channel);
            consumer.Received += (model, ea) =>
            {
                var body = ea.Body.ToArray();
                var message = Encoding.UTF8.GetString(body);
                Console.WriteLine(" [x] Received {0}", message);
            };
            channel.BasicConsume(queue: queueName, autoAck: true, consumer: consumer);

            Console.WriteLine(" Press [enter] to exit.");
            Console.ReadLine();
        }
    }
}