Usage

Firewall Punch Demo

Copyright (c) 2011 Sean Fisk

Licensed under the terms of the MIT/X11 license.

Description

Firewall Punch Demo is a proof-of-concept Java client and server to illustrate the UDP firewall punching technique used by Skype and similar programs.

It was inspired by an article on The H Security blog, The Hole Trick : How Skype & Co. Get Round Firewalls (www.h-online.com).

How to Use

Server

  1. Download the Server JAR file.
  2. Open a terminal in the download directory.
  3. Run the server with
    java -jar fp_server.jar PORT

Client

  1. Download the Client JAR file.
  2. Open a terminal in the download directory.
  3. Run the client with
    java -jar fp_client.jar HOST PORT

Running a server and two clients on the same machine

NOTE: This does not really demonstrate the real use of the program.

  1. Open three terminals.

  2. Start the server in the first terminal.

    java -jar fp_server.jar 5000

  3. Start a client each in the remaining terminals.

    java -jar fp_client.jar localhost 5000

  4. Once they are connected, kill the server with Ctrl-C.

  5. Continue communication between the clients!
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