Send a message on IP

public partial class Form1 : Form
    {
        // The TCP client will connect to the server using an IP and a port
        TcpClient tcpClient;
        // The file stream will read bytes from the local file you are sending
        FileStream fstFile;
        // The network stream will send bytes to the server application
        NetworkStream strRemote;

        public Form1()
        {
            InitializeComponent();
        }

        private void ConnectToServer(string ServerIP, int ServerPort)
        {
            // Create a new instance of a TCP client
            tcpClient = new TcpClient();
            try
            {
                // Connect the TCP client to the specified IP and port
                tcpClient.Connect(ServerIP, ServerPort);
                txtLog.Text += "Successfully connected to server\r\n";
            }
            catch (Exception exMessage)
            {
                // Display any possible error
                txtLog.Text += exMessage.Message;
            }
        }

        private void btnConnect_Click(object sender, EventArgs e)
        {
            // Call the ConnectToServer method and pass the parameters entered by the user
            ConnectToServer(txtServer.Text, Convert.ToInt32(txtPort.Text));
        }

        private void btnSend_Click(object sender, EventArgs e)
        {
            // If tclClient is not connected, try a connection
            if (tcpClient.Connected == false)
            {
                // Call the ConnectToServer method and pass the parameters entered by the user
                ConnectToServer(txtServer.Text, Convert.ToInt32(txtPort.Text));
            }

            // Prompt the user for opening a file
            if (openFile.ShowDialog() == DialogResult.OK)
            {
                txtLog.Text += "Sending file information\r\n";
                // Get a stream connected to the server
                strRemote = tcpClient.GetStream();
                byte[] byteSend = new byte[tcpClient.ReceiveBufferSize];
                // The file stream will read bytes from the file that the user has chosen
                fstFile = new FileStream(openFile.FileName, FileMode.Open, FileAccess.Read);
                // Read the file as binary
                BinaryReader binFile = new BinaryReader(fstFile);

                // Get information about the opened file
                FileInfo fInfo = new FileInfo(openFile.FileName);

                // Get and store the file name
                string FileName = fInfo.Name;
                // Store the file name as a sequence of bytes
                byte[] ByteFileName = new byte[2048];
                ByteFileName = System.Text.Encoding.ASCII.GetBytes(FileName.ToCharArray());
                // Write the sequence of bytes (the file name) to the network stream
                strRemote.Write(ByteFileName, 0, ByteFileName.Length);

                // Get and store the file size
                long FileSize = fInfo.Length;
                // Store the file size as a sequence of bytes
                byte[] ByteFileSize = new byte[2048];
                ByteFileSize = System.Text.Encoding.ASCII.GetBytes(FileSize.ToString().ToCharArray());
                // Write the sequence of bytes (the file size) to the network stream
                strRemote.Write(ByteFileSize, 0, ByteFileSize.Length);

                txtLog.Text += "Sending the file " + FileName + " (" + FileSize + " bytes)\r\n";

                // Reset the number of read bytes
                int bytesSize = 0;
                // Define the buffer size
                byte[] downBuffer = new byte[2048];

                // Loop through the file stream of the local file
                while ((bytesSize = fstFile.Read(downBuffer, 0, downBuffer.Length)) > 0)
                {
                    // Write the data that composes the file to the network stream
                    strRemote.Write(downBuffer, 0, bytesSize);
                }

                // Update the log textbox and close the connections and streams
                txtLog.Text += "File sent. Closing streams and connections.\r\n";
                tcpClient.Close();
                strRemote.Close();
                fstFile.Close();
                txtLog.Text += "Streams and connections are now closed.\r\n";
            }
        }

        private void btnDisconnect_Click(object sender, EventArgs e)
        {
            // Close connections and streams and update the log textbox
            tcpClient.Close();
            strRemote.Close();
            fstFile.Close();
            txtLog.Text += "Disconnected from server.\r\n";
        }
    }

public partial class Form1 : Form
    {
        // The thread in which the file will be received
        private Thread thrDownload;
        // The stream for writing the file to the hard-drive
        private Stream strLocal;
        // The network stream that receives the file
        private NetworkStream strRemote;
        // The TCP listener that will listen for connections
        private TcpListener tlsServer;
        // Delegate for updating the logging textbox
        private delegate void UpdateStatusCallback(string StatusMessage);
        // Delegate for updating the progressbar
        private delegate void UpdateProgressCallback(Int64 BytesRead, Int64 TotalBytes);
        // For storing the progress in percentages
        private static int PercentProgress;

        public Form1()
        {
            InitializeComponent();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            thrDownload = new Thread(StartReceiving);
            thrDownload.Start();
        }

        private void StartReceiving()
        {
            // There are many lines in here that can cause an exception
            try
            {
                // Get the hostname of the current computer (the server)
                string hstServer = Dns.GetHostName();
                // Get the IP of the first network device, however this can prove unreliable on certain configurations
                IPAddress ipaLocal = Dns.GetHostEntry(hstServer).AddressList[0];
                // If the TCP listener object was not created before, create it
                if (tlsServer == null)
                {
                    // Create the TCP listener object using the IP of the server and the specified port
                    tlsServer = new TcpListener(ipaLocal, Convert.ToInt32(txtPort.Text));
                }
                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "Starting the server...\r\n" });
                // Start the TCP listener and listen for connections
                tlsServer.Start();
                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "The server has started. Please connect the client to " + ipaLocal.ToString() + "\r\n" });
                // Accept a pending connection
                TcpClient tclServer = tlsServer.AcceptTcpClient();
                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "The server has accepted the client\r\n" });
                // Receive the stream and store it in a NetworkStream object
                strRemote = tclServer.GetStream();
                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "The server has received the stream\r\n" });

                // For holding the number of bytes we are reading at one time from the stream
                int bytesSize = 0;
                
                // The buffer that holds the data received from the client
                byte[] downBuffer = new byte[2048];
                // Read the first buffer (2048 bytes) from the stream - which represents the file name
                bytesSize = strRemote.Read(downBuffer, 0, 2048);
                // Convert the stream to string and store the file name
                string FileName = System.Text.Encoding.ASCII.GetString(downBuffer, 0, bytesSize);
                // Set the file stream to the path C:\ plus the name of the file that was on the sender's computer
                strLocal = new FileStream(@"C:\raj\" + FileName, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);

                // The buffer that holds the data received from the client
                downBuffer = new byte[2048];
                // Read the next buffer (2048 bytes) from the stream - which represents the file size
                bytesSize = strRemote.Read(downBuffer, 0, 2048);
                // Convert the file size from bytes to string and then to long (Int64)
                long FileSize = Convert.ToInt64(System.Text.Encoding.ASCII.GetString(downBuffer, 0, bytesSize));

                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "Receiving file " + FileName + " (" + FileSize + " bytes)\r\n" });

                // The buffer size for receiving the file
                downBuffer = new byte[2048];

                // From now on we read everything that's in the stream's buffer because the file content has started
                while ((bytesSize = strRemote.Read(downBuffer, 0, downBuffer.Length)) > 0)
                {
                    // Write the data to the local file stream
                    strLocal.Write(downBuffer, 0, bytesSize);
                    // Update the progressbar by passing the file size and how much we downloaded so far to UpdateProgress()
                    this.Invoke(new UpdateProgressCallback(this.UpdateProgress), new object[] { strLocal.Length, FileSize });
                }
                // When this point is reached, the file has been received and stored successfuly
            }
            finally
            {
                // This part of the method will fire no matter wether an error occured in the above code or not

                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "The file was received. Closing streams.\r\n" });

                // Close the streams
                strLocal.Close();
                strRemote.Close();

                // Write the status to the log textbox on the form (txtLog)
                this.Invoke(new UpdateStatusCallback(this.UpdateStatus), new object[] { "Streams are now closed.\r\n" });

                // Start the server (TCP listener) all over again
                StartReceiving();
            }
        }

        private void UpdateStatus(string StatusMessage)
        {
            // Append the status to the log textbox text 
            txtLog.Text += StatusMessage;
        }

        private void UpdateProgress(Int64 BytesRead, Int64 TotalBytes)
        {
            if (TotalBytes > 0)
            {
                // Calculate the download progress in percentages
                PercentProgress = Convert.ToInt32((BytesRead * 100) / TotalBytes);
                // Make progress on the progress bar
                prgDownload.Value = PercentProgress;
            }
        }


        private void btnStop_Click(object sender, EventArgs e)
        {
            strLocal.Close();
            strRemote.Close();
            txtLog.Text += "Streams are now closed.\r\n";
        }

        private void btnStop_Click_1(object sender, EventArgs e)
        {
           
        }
    }