function listen-port ($port) { 
   $endpoint = new-object System.Net.IPEndPoint ([system.net.ipaddress]::any, $port) 
   $listener = new-object System.Net.Sockets.TcpListener $endpoint 
   $listener.start() 
   $listener.AcceptTcpClient()  # will block here until connection 
   $listener.stop() 
}