... How NetFilter Works NetFilter, or more commonly known by the name of the manipulation utility, iptables, works, on the surface, similarly to the ipchains ... chains in NetFilter and ipchains is that in ipchains all packets going from one network interface to another traverse all three of the main chains (INPUT, FORWARD, and OUTPUT). In NetFilter, however, ... certain environments).Figure 7-3. NetFilter OUTPUT Chain Processing [View full size image] One of the key features that NetFilter has over ipchains is that NetFilter is a stateful packet...