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.