Program.cs

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            var s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            var e = new SocketAsyncEventArgs();
            s.SetSocketOption(SocketOptionLevel.Tcp, (SocketOptionName)15, 1);
            e.RemoteEndPoint = new IPEndPoint(IPAddress.Parse("localhost"), 8000);
            byte[] bytes = Encoding.ASCII.GetBytes("Aloha!");
            e.SetBuffer(bytes, 0, bytes.Length);
            e.Completed += (sender, arg) =>
            {
                if (e.SocketError == SocketError.Success)
                {
                    Console.WriteLine("OK.");
                }
                else
                {
                    Console.WriteLine("Error in Socket!");
                }
            };
            s.ConnectAsync(e);
            Thread.Sleep(2000);
        }
    }
}