return 'Access denied!'                                                                                                                                     return '''                                                                          <form method="POST">                                                                <label for="password">Password:</label>                                         <input type="password" id="password" name="password">                           <input type="submit" value="Submit">                                        </form>                                                                     '''                                                                                                                                                                                                                                         if __name__ == '__main__':                                                          app.run()                                                                   admin@i-025ebc807a8b09af0:~$                                                    

admin@i-04a2ddcc84aaf3ca3:~$ ^C                                                 admin@i-04a2ddcc84aaf3ca3:~$ ^C                                                 admin@i-04a2ddcc84aaf3ca3:~$ ^C                                                 admin@i-04a2ddcc84aaf3ca3:~$ ^C                                                 admin@i-04a2ddcc84aaf3ca3:~$ ^C                                                 admin@i-04a2ddcc84aaf3ca3:~$ ^C                                                 admin@i-04a2ddcc84aaf3ca3:~$                                                    exit                                                                            admin@i-04a2ddcc84aaf3ca3:~$ ls -l /home/admin/kihei                            -rwxr-xr-x 1 admin root 2207109 Sep 17 17:28 /home/admin/kihei                  admin@i-04a2ddcc84aaf3ca3:~$ more /home/admin/kihei                                                                                                             ******** /home/admin/kihei: Not a text file ********                                                                                                            admin@i-04a2ddcc84aaf3ca3:~$                                                    

write(2, "main.main", 9main.main)                = 9                            write(2, "(", 1()                        = 1                                    write(2, ")\n", 2)                                                              )                      = 2                                                      write(2, "\t", 1        )                       = 1                             write(2, "./main.go", 9./main.go)                = 9                            write(2, ":", 1:)                        = 1                                    write(2, "64", 264)                       = 2                                   write(2, " +", 2 +)                       = 2                                   write(2, "0x47d", 50x47d)                    = 5                                write(2, "\n", 1                                                                )                       = 1                                                     exit_group(2)                           = ?                                     +++ exited with 2 +++                                                           admin@i-00c2fc1811a7c6c41:~$                                                    

                                                                                example:  knock myserver.example.com 123:tcp 456:udp 789:tcp                                                                                                    admin@i-080ac908debd2d3d7:~$ knock -v 127.0.0.1 80:tcp 1                        hitting tcp 127.0.0.1:80                                                        hitting tcp 127.0.0.1:1                                                         admin@i-080ac908debd2d3d7:~$ knock -v 127.0.0.1 80:tcp                          hitting tcp 127.0.0.1:80                                                        admin@i-080ac908debd2d3d7:~$ curl -D - -v localhost                             *   Trying 127.0.0.1:80...                                                      * connect to 127.0.0.1 port 80 failed: Connection refused                       * Failed to connect to localhost port 80: Connection refused                    * Closing connection 0                                                          curl: (7) Failed to connect to localhost port 80: Connection refused            admin@i-080ac908debd2d3d7:~$ nc -vv 12