允许从不同的计算机ping

Question

我创建了2个java程序，客户端ping服务器，服务器回复客户端。我遇到的问题是，当我尝试在同一台机器上运行客户端和服务器时，程序运行正常。但是当我试图单独运行客户端和服务器（即虚拟机中另一台机器上的客户端和服务器）时，我没有得到服务器的响应。有什么帮助吗？

客户端发送ping请求的功能

 public static void ping(String serverIP, int numberOfPacketToSend,int setTimeOut,int sendDa){
       int lossPacket = 0;

    try {
      String serverHostname = new String (serverIP);
      BufferedReader inFromUser = 
        new BufferedReader(new InputStreamReader(System.in)); 

      DatagramSocket clientSocket = new DatagramSocket(); 

      InetAddress IPAddress = InetAddress.getByName(serverHostname); 
      System.out.println ("connecting to " + IPAddress+"...");

      byte[] sendData = new byte[sendDa]; 
      byte[] receiveData = new byte[sendDa]; 


      for(int i = 0;i<numberOfPacketToSend;i++){

      String sentence = "Pinging "+serverIP; 
      //sendData = sentence.getBytes();         

//      System.out.println ("Sending data to " + sendData.length + 
//                          " bytes to server.");
      DatagramPacket sendPacket = 
         new DatagramPacket(sendData, sendData.length, IPAddress, 9876); 
          //System.out.println("data being send to server "+sendData.length);
      clientSocket.send(sendPacket); 

      DatagramPacket receivePacket = 
         new DatagramPacket(receiveData, receiveData.length); 

//      System.out.println ("Waiting for return packet");

      clientSocket.setSoTimeout(setTimeOut);

      try {
           clientSocket.receive(receivePacket); 
           String modifiedSentence = 
               new String(receivePacket.getData()); 

           InetAddress returnIPAddress = receivePacket.getAddress();

           int port = receivePacket.getPort();

//           System.out.println ("From server at: " + returnIPAddress + 
//                               ":" + port);
           System.out.println("Reply from "+serverIP+" bytes="+sendData.length); 

          }
      catch (SocketTimeoutException ste)
          {
           System.out.println ("Timeout Occurred: Packet assumed lost");
           lossPacket ++;
      }}

      clientSocket.close(); 
     }
   catch (UnknownHostException ex) { 
     System.err.println(ex);
    }
   catch (IOException ex) {
     System.err.println(ex);
    }
        System.out.println("Total loss packet = "+lossPacket);
        System.out.println("Number of packet send ="+numberOfPacketToSend);
        try{
        System.out.println("Percentage packet loss ="+((numberOfPacketToSend/lossPacket)*100)+"%");
        }catch(ArithmeticException e){System.out.println("Percentage packet loss = 0%");}
    }

}

服务器等待任何连接的功能

 public static void waitForConnection(int portNumber, String ServerAddress) throws IOException{
                try
     { 
      InetAddress addr = InetAddress.getByName("5.5.5.5");


        DatagramSocket serverSocket = new DatagramSocket(null);
        InetSocketAddress address = new InetSocketAddress(ServerAddress, portNumber);
        serverSocket.bind(address);



      byte[] receiveData = new byte[1024]; 
      byte[] sendData  = new byte[1024]; 

      while(true) 
        { 

          receiveData = new byte[1024]; 

          DatagramPacket receivePacket = 
             new DatagramPacket(receiveData, receiveData.length); 

          System.out.println ("Server up and running on port "+portNumber);

          serverSocket.receive(receivePacket); 

          String sentence = new String(receivePacket.getData()); 

          InetAddress IPAddress = receivePacket.getAddress(); 

          int port = receivePacket.getPort(); 

          System.out.println ("From: " + IPAddress + ":" + port);
          System.out.println ("Message: " + sentence);

          String capitalizedSentence = sentence.toUpperCase(); 

          sendData = capitalizedSentence.getBytes(); 

          DatagramPacket sendPacket = 
             new DatagramPacket(sendData, sendData.length, IPAddress, 
                               port); 

          serverSocket.send(sendPacket); 



        } 

     }
      catch (SocketException ex) {
        System.out.println("UDP Port 9876 is occupied.");
        System.exit(1);
      }
    }