I played around several of the networking, security & firewall issues of linux systems for a company which I was working for. We had done a linux based satellite broadband access gateway aimed at SOHO and corporate IS departments. As a part of the setup done for enabling virtual private networks and interactive video-conferencing, I prepared this document (first version) for our internal use. I later thought of giving this out for public usage. Hope you appreciate the document.
Copyright © 2001 Ramesh Panuganty. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license can be found at the Free Software Foundation.
The author does not accept any responsibility of any consequences that may result of the instructions in this document, in any manner. Use the examples and the other content at your risk. The author is also not responsible for any system outages or security issues that you may come across with your setup. Proceed with caution.