01: import java.net.*;
02: import java.io.*;
03:
04: public class LocalPortScanner {
05:
06: public static void main(String[] args) {
07:
08: for (int port = 1; port <= 65535; port++) {
09:
10: try {
11: // the next line will fail and drop into the catch block if
12: // there is already a server running on the port
13: // make sure your firewalls are turned off as otherwise
14: // you will get an error and it looks as if a port is active
15: ServerSocket server = new ServerSocket(port);
16: }
17: catch (IOException e) {
18: System.out.println("There is a server on port " + port + ".");
19: } // end try
20:
21: } // end for
22:
23: }
24:
25: }