Online book on software security tips.

A guide to installing and transitioning to the Linux operating system. Topics include getting and installation, system administration, the XWindows system, and networking.

HOWTOs describe in detail a certain aspect of configuring or using Linux. Site has information about the HOWTOs and using them, and an annotated index.

Security issues that face the administrator, security philosophy, examples of how to secure the system from intruders.

Describes how to obtain, install and configure the enhanced IP firewalling chains software for Linux, and how they might be used, by Paul Russell.

Teaches the basics of firewall systems and give you some detail on setting up both a filtering and proxy firewall on a Linux based PC, by Mark Grennan.

Explains how to set up secure POP connections using ssh, by Manish Singh.

A tutorial on how to setup a bridge and a firewall with Linux, by Peter Breuer.

Tutorial on using ppp over telnet to do network stuff transparently through an Internet firewall. (Francois-Rene Rideau)

Linux PPP HOWTO at Linux DOC.