UDP Hole Punching.java

package com.company;
 
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class UDPHolePunchingServer {
 
    public static void main(String args[]) throws Exception {
 
        // Waiting for Connection of Client1 on Port 7070
        // ////////////////////////////////////////////////
 
        // open serverSocket on Port 7070
        DatagramSocket serverSocket1 = new DatagramSocket(1234);
 
        System.out.println("Waiting for Client 1 on Port " + serverSocket1.getLocalPort());
 
        // receive Data
        DatagramPacket receivePacket = new DatagramPacket(new byte[1024], 1024);
        serverSocket1.receive(receivePacket);
 
        // Get IP-Address and Port of Client1
        InetAddress IPAddress1 = receivePacket.getAddress();
        int port1 = receivePacket.getPort();
        String msgInfoOfClient1 = IPAddress1 + "-" + port1 + "-";
 
        System.out.println("Client1: " + msgInfoOfClient1);
 
        // Waiting for Connection of Client2 on Port 7071
        // ////////////////////////////////////////////////
 
        // open serverSocket on Port 7071
        DatagramSocket serverSocket2 = new DatagramSocket(1235);
 
        System.out.println("Waiting for Client 2 on Port " + serverSocket2.getLocalPort());
 
        // receive Data
        receivePacket = new DatagramPacket(new byte[1024], 1024);
        serverSocket2.receive(receivePacket);
 
        // GetIP-Address and Port of Client1
        InetAddress IPAddress2 = receivePacket.getAddress();
        int port2 = receivePacket.getPort();
        String msgInfoOfClient2 = IPAddress2 + "-" + port2 + "-";
 
        System.out.println("Client2:" + msgInfoOfClient2);
 
        // Send the Information to the other Client
        // /////////////////////////////////////////////////
 
        // Send Information of Client2 to Client1
        serverSocket1.send(new DatagramPacket(msgInfoOfClient2.getBytes(), msgInfoOfClient2.getBytes().length, IPAddress1, port1));
 
        // Send Infos of Client1 to Client2
        serverSocket2.send(new DatagramPacket(msgInfoOfClient1.getBytes(), msgInfoOfClient1.getBytes().length, IPAddress2, port2));
 
        //close Sockets
        serverSocket1.close();
        serverSocket2.close();
    }
}