чатик на C#

[nwhta]

Всем привет! вот решил написать чатик с помощью протокола UDP
не я конечно писал а в инете искал коды подходящие ибо сам не знал с чего начать, хочу сервер поставить на ай пи, вставляю свой ай пи, и ошибка в строке multicastaddress = IPAddress.Parse("мой айпишник");
помогите разобраться пожалуйста, заранее спасибо!



сама форма

using System;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
using System.IO;
using System.Text;
using System.Threading;
namespace chat
{
    public partial class Form1 : Form
    {
        public static string Ip;


        public Form1()
        {
            InitializeComponent();
        }

        private void textBoxSendMessage_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                UdpChat chat = new UdpChat();
                Thread ListenThread = new Thread(new ThreadStart(chat.Listen));
                ListenThread.Start();
                string data = textBoxSendMessage.Text;
                chat.SendMessage(data);
            }
        }
}

класс UdpChat

using System;
using System.Net.Sockets;
using System.Net;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace chat
{
    class UdpChat
    {
        private UdpClient udpclient;
        private IPAddress multicastaddress;
        private IPEndPoint remoteep;
        public UdpChat()
        {
            multicastaddress = IPAddress.Parse("239.0.0.222");
            udpclient = new UdpClient();
            udpclient.JoinMulticastGroup(multicastaddress);
            remoteep = new IPEndPoint(multicastaddress, 2222);

        }
        public void SendMessage(string data)
        {
            Byte[] buffer = Encoding.UTF8.GetBytes(data);

            Byte[] encrypted = Encrypt(data);

            udpclient.Send(encrypted, encrypted.Length, remoteep);
        }

        public void Listen()
        {
            UdpClient client = new UdpClient();

            client.ExclusiveAddressUse = false;
            IPEndPoint localEp = new IPEndPoint(IPAddress.Any, 2222);

            client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            client.ExclusiveAddressUse = false;

            client.Client.Bind(localEp);

            client.JoinMulticastGroup(multicastaddress);

            string formatted_data;

            while (true)
            {
                Byte[] data = client.Receive(ref localEp);

                formatted_data = Decrypt(data);

                Console.WriteLine(formatted_data);
            }
        }
        private byte[] Encrypt(string clearText, string EncryptionKey = "123")
        {

            byte[] clearBytes = Encoding.UTF8.GetBytes(clearText);
            byte[] encrypted;
            using (Aes encryptor = Aes.Create())
            {
                Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
                encryptor.Key = pdb.GetBytes(32);
                encryptor.IV = pdb.GetBytes(16);
                using (MemoryStream ms = new MemoryStream())
                {
                    using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(clearBytes, 0, clearBytes.Length);
                        cs.Close();
                    }
                    encrypted = ms.ToArray();
                }
            }
            return encrypted;
        }

        private string Decrypt(byte[] cipherBytes, string EncryptionKey = "123")
        {
            string cipherText = "";
            using (Aes encryptor = Aes.Create())
            {
                Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
                encryptor.Key = pdb.GetBytes(32);
                encryptor.IV = pdb.GetBytes(16);
                using (MemoryStream ms = new MemoryStream())
                {
                    using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(cipherBytes, 0, cipherBytes.Length);
                        cs.Close();
                    }
                    cipherText = Encoding.UTF8.GetString(ms.ToArray());
                }
            }
            return cipherText;
        }
    }
}