socket connect error "9" EBADF

[WalterK]

My client program connects to a server in the following manner in a procedure which is called upon user action (edit data, clicking a button):

  if (not Net_Init) then
      begin
      Sock := fpSocket(AF_INET,SOCK_STREAM,0);
      if (Sock = -1) then
         begin
         exit;
         end;
      Net_Init := true;
      end;

   if (not Connect(Sock,External_IP,Sin,Sout)) then
      begin
      exit;
      end;

-- send data & get results...

close Sin, Sout

This works the first time, then fails with error "9" - bad file number.

Should I do the Connect inside the initialization IF?  What if the connection times out while the user is editing his data?
Should I re-connect each time?  Doesn't this waste time/resources?
Other?  I see there are things like SO_KEEPALIVE = 9 and SO_LINGER = 13 but the fpc/rtl manual doesn't describe them.

I can hack up something that works, but I'm hoping for a tried and true solution.

Thanks.