Narrowing consideration to threats faced by small networks from external sources, Zeigler and his editors introduce security by delivering a prerequisite tutorials on packet architecture and normal network-based client / server-daemons for communication. Not threatening communications daemon-to-daemon is part of the routine operation of a network operating system POSIX-compliant (such as Linux or Windows NT), but the background chatter incessantly makes finding hostile intrusions looking sometimes subtle irregularities in throughput environment high. In fact, the bombing of the network with useless packets can create a diversion for a more damaging attack. Distinguishing the good packets from the packet potentially hostile or merely useless require a level of filtering that relies on specific criteria from the network environment. Zeigler sorts all these problems and outlines practical strategies for packet filtering network administration. Linux Firewalls is a how-to for Linux boxes home, including creating and debugging firewall rules for home LANs and network interfaces. For larger LAN users, Zeigler describes intrusion logging; configurations based on varying levels of trust, and how, why, and when reporting problems to the authority of the network. In the wrong hands, reports a good firewall sensationalism hyped-up cloak-and-dagger or monotonous treatises in bitwise accounting.