Detect server IP address

Question

I have a client server architecture in Java where a server listens using a fixed port. The client can connect using the server ip address but I would like to scan the network using the port so that user don't have to deal with server's ip address. Currently I achieve this by looking at client's ip and looping into each possible address using client's ip (192.168.1.0 - I loop through 1-255 for the last part). This method works but is there a better way to do this in java?

  for (int a = 0; a < 256; a++) {
       try {
          String ServerIp = clientIpLast3Parts + "." + a;
          InetAddress IPAddress = InetAddress.getByName(ServerIp);
          DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, PORT);
          clientSocket.send(sendPacket);
          DatagramPacket receivePacket = new DatagramPacket(
                                    receiveData, receiveData.length);
          clientSocket.receive(receivePacket);
          InetAddress ServerIp = receivePacket.getAddress();
          String modifiedSentence = new String(receivePacket.getData());
          ip = ServerIp.getHostAddress().toString();

          if (modifiedSentence != null) {
              //Got it
              break;
           }

        } catch (Exception e1) {
   }

Answer 1

If you need automatically re-configurable topology, I'd recommend to use multicast notification. Server sends a periodical multicast packet with its unicast IP and port specified. Any client listens to that multicast group when starting until a packet with server IP/port received. Or use DNS :)