Get data from udp client and write to file in c#

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C#3.0

C#

sockets

I am newbie in dot net architecture or c# and I want to develop c# application in which udp socket will receive data from other client & store data in file at starting of application and same process should follow same task on button click event in same application!!
Please give any idea for implementing such scenario.
I write below code on formLoad event of application

public void Form1_Load(object sender, EventArgs e)
        {
            IPNetworking getip = new IPNetworking();
            
            try
            {
                CheckForIllegalCrossThreadCalls = false;
                serverSocket = new Socket(AddressFamily.InterNetwork,
                            SocketType.Dgram,ProtocolType.Udp);

                string ipaddr = getip.GetIP4Address();

                IPEndPoint endpt = new IPEndPoint(IPAddress.Parse(ipaddr), 21845);
                
                serverSocket.Bind(endpt);
               

                IPEndPoint ipesender = new IPEndPoint(IPAddress.Parse(ipaddr),0);
                EndPoint epsender = (EndPoint)ipesender;
                serverSocket.BeginReceiveFrom(byteData,0,byteData.Length,SocketFlags.None,
                                                ref epsender, new AsyncCallback(OnReceive),epsender);

                   File.WriteAllBytes("data.txt", byteData);
               
            }
            catch (Exception exce)
            {
                MessageBox.Show(exce.Message, "Server UDP", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }