C#

<br />
private void AddLine(TextBox tb, string text)<br />
{<br />
if (tb.InvokeRequired)<br />
  {<br />
  AddLineDel d = new AddLineDel(AddLine);<br />
  this.Invoke(d, new object[] { tb, text });<br />
  }<br />
else<br />
  tb.Text += "\r\n" + text;<br />
}<br />
<br />
private void Listen_button_Click(object sender, EventArgs e)<br />
{<br />
Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);<br />
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, port);<br />
<br />
sock.Bind(ipep);<br />
sock.Listen(2);<br />
sock.BeginAccept(new AsyncCallback(AcceptConn), sock);<br />
}<br />
<br />
private void AcceptConn(IAsyncResult iar)<br />
{<br />
Socket oldserver = (Socket)iar.AsyncState;<br />
client = oldserver.EndAccept(iar);<br />
AddLine(textBox1, "Connection from:" + client.RemoteEndPoint.ToString());<br />
Thread receiver = new Thread(new ThreadStart(ReceiveData));<br />
receiver.IsBackground = true;<br />
receiver.Start();<br />
}<br />
<br />
private void ReceiveData()<br />
{<br />
int recv;<br />
string datastr = "";<br />
while (true)<br />
  {<br />
  if (client.Connected)<br />
    {<br />
    cleardata();<br />
    recv = client.Receive(data);<br />
    datastr = Encoding.ASCII.GetString(data);<br />
    if (datastr == "exit")<br />
      break;<br />
    AddLine(textBox1, datastr);<br />
    }<br />
  }<br />
  client.Close();<br />
  AddLine(textBox1, "Connection closed");<br />
  return;<br />
  }<br />
}<br />