c# socket listen on port
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
Socket listener = new Socket(ipAddress.AddressFamily,
SocketType.Stream, ProtocolType.Tcp);
listener.Bind(localEndPoint);
listener.Listen(100); // specifies how many pending connections to the
// Socket are allowed before a server busy error is returned to the connecting
//client.