Techniques to Detect Filtered Hosts and Bypass Firewalls

This paper will attempt to describe techniques used to discover heavily filtered and firewalled hosts, that will not answer to standard PING responses. It is assumed that the reader has a firm knowledge of the major internet protocols (TCP,IP,UDP,ICMP). . . . This paper will attempt to describe techniques used to discover heavily filtered and firewalled hosts, that will not answer to standard PING responses. It is assumed that the reader has a firm knowledge of the major internet protocols (TCP,IP,UDP,ICMP). Most other protocols will not be discussed but techniques described here can be applied to many protocols.

The link for this article located at Net-Security.org is no longer available.