Serversocket IP lock?

Question

I have developed a socket system in Delphi. It is possible to block an IP to not connect to my server?

Obs: The components were used: SERVERSOCKET and CLIENTSOCKET.

Answer 1

Yes, it is possible. You can intercept the client connection in the Serversocket Clientconnect event

procedure TForm1.ServerSocket1ClientConnect(Sender: TObject; Socket: TCustomWinSocket);
begin
  if not ValidaAcesso(Socket.RemoteAddress, Socket.RemotePort) then
    raise EConnException.Create('Endereço não autorizado!')
end;

Answer 2

I believe this is possible.

To block an address list (be in a Memo or in a StringList) you can use a function like this:

{ Verifica se uma lista contem determinada string(IP bloqueado) }
function IpIsBlocked(List: TStrings; const IPBlocked: string): Boolean;
Var
I: Integer;
begin
Result := False;
for i := 0 to List.Count -1 do
if List.Strings[I] = IPBlocked then
Result := True;
end;

Now just use the function Ipisblocked at the event OnClientConnect of Serversocket.

Example:

procedure TForm1.ServerSocket1ClientConnect(Sender: TObject; Socket: TCustomWinSocket);
begin
if IpIsBlocked(Memo1.Lines, 'XXX.XYX.XXX') then begin
ShowMessage(Format('O ip %s está bloqueado!', [socket.RemoteAddress]));
Socket.Close;
end;
end;

Well, basically this is it.