-module(simple_server).
  -compile(export_all).

  start() ->
      {ok, ListenSoc} = gen_tcp:listen(1084, [binary, {active, false}]),
      wait_accept(ListenSoc).

   wait_accept(ListenSoc) ->
      {ok, Socket} = gen_tcp:accept(ListenSoc),
      spawn(?MODULE, wait_accept, [ListenSoc]),
      send_resp(Socket).

  send_resp(Socket) ->
      gen_tcp:send(Socket, "Response from simple server...n"),
      ok = gen_tcp:close(Socket).

{{badmatch,{error,closed}},
 [{simple_server,wait_accept,1}]}

{ok, Socket} = gen_tcp:accept(ListenSock),

...
Pid = spawn(?MODULE, wait_accept, [ListenSoc]),
ok = gen_tcp:controlling_process(ListenSoc, Pid),
...