tcpipSocket/Echo/Server/Server.cs

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

namespace Server;

internal class Server
{
	static void Main(string[] args)
	{
		using (Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
		{
			IPEndPoint endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 20000);
			serverSocket.Bind(endPoint);
			serverSocket.Listen(20);

			using (Socket clientSocket = serverSocket.Accept())
			{
				Console.WriteLine(clientSocket.RemoteEndPoint);

				while (true)
				{
					byte[] buffer = new byte[256];
					int totalBytes = clientSocket.Receive(buffer);
					if (totalBytes < 1)
					{
						Console.WriteLine("Disconnecting client...");
						return;
					}

					string str = Encoding.UTF8.GetString(buffer);
					Console.WriteLine(str);

					clientSocket.Send(buffer);
				}
			}
		}
	}
}