using System;
using System.Net;
using System.Net.NetworkInformation;
using System.Text;

namespace icmp_client
{
    public class IcmpClient
    {
        // args[0] can be an IPaddress or host name.
        // args[1] message for send
        public static void Main (string[] args)
        {
            Ping pingSender = new Ping ();
            PingOptions options = new PingOptions ();

            // Use the default Ttl value which is 128,
            // but change the fragmentation behavior.
            options.DontFragment = true;

            // Create a buffer of 32 bytes of data to be transmitted.
            string data = args[1];
            byte[] buffer = Encoding.ASCII.GetBytes(data);

            int timeout = 120;
            PingReply reply = pingSender.Send(args[0], timeout, buffer, options);
            if (reply.Status == IPStatus.Success)
            {
                Console.WriteLine("Address: {0}", reply.Address.ToString ());
                Console.WriteLine("Message: {0}", data);
                Console.WriteLine("Buffer size: {0}", reply.Buffer.Length);
            }
        }
    }
}

1. IP-адресс или имя получателя сообщения
   
2. Текст сообщения
   

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

namespace icmp_server
{
    public class IcmpServer
    {
        private const int ICMP_TYPE_OFFSET = 20;
        private const int ICMP_TYPE_ECHO_REQUEST = 8;
        private const int PAYLOAD_OFFSET = 28;
        
        public static void Main(string[] args)
        {            
            IPAddress ipAddr = IPAddress.Parse(args[0]);
            IPEndPoint ipMyEndPoint = new IPEndPoint(ipAddr, 0);
            EndPoint myEndPoint = (ipMyEndPoint);
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp);
            socket.Bind(myEndPoint);
            socket.IOControl(IOControlCode.ReceiveAll, BitConverter.GetBytes(1), null); 
            while (true)
            {
                Byte[] ReceiveBuffer = new Byte[socket.ReceiveBufferSize];
                var nBytes = socket.ReceiveFrom(ReceiveBuffer, ReceiveBuffer.Length, SocketFlags.None, ref myEndPoint);
                var icmpType = ReceiveBuffer[ICMP_TYPE_OFFSET];
                if (icmpType == ICMP_TYPE_ECHO_REQUEST)
                {
                    Console.WriteLine("Echo Request received");
                    Console.WriteLine("Received: {0} bytes", nBytes);
                    if(nBytes > PAYLOAD_OFFSET)
                    { 
                      var payLoadSize = nBytes - PAYLOAD_OFFSET;
                      byte[] payLoad = new byte[payLoadSize];
                      Array.Copy(ReceiveBuffer, PAYLOAD_OFFSET, payLoad, 0, payLoadSize);
                      string msg = Encoding.ASCII.GetString(payLoad);
                      Console.WriteLine("Data hex: {0}", BitConverter.ToString(payLoad));
                      Console.WriteLine("Data text: {0}", msg);
                    }
                    Console.WriteLine("---------------");
                }
            }

        }
    }
}

1. IP-адресс интерфейса получения сообщений
   

• https://ru.wikipedia.org/wiki/IPv4
  
• https://ru.wikipedia.org/wiki/ICMP
  
• https://docs.microsoft.com/ru-ru/dotnet/api/system...