1import java.io.IOException;
2import java.net.Socket;
3
4public class App {
5 public static void main(String[] args) {
6 Socket tempSocket = new Socket(); // Initialize
7 boolean isOpened;
8
9 // Loop through all the 65536 ports
10 for (int port = 0; port < 65536; port++) {
11 // We will assume the current port is opened unless
12 // An exception occurs
13 isOpened = true;
14
15 try {
16 // Let's try connecting
17 tempSocket = new Socket("127.0.0.1", port);
18 }
19 catch (IOException e) {
20 // If an IOException occurs, then port is closed
21 isOpened = false;
22 }
23 finally {
24 // Close the socket to save resources
25 tempSocket.close();
26 }
27
28 // If port is opened print a message to the console
29 if (isOpened) {
30 String message = String.format("port %d is open", port);
31 System.out.println(message);
32 }
33 }
34 }
35}