This tutorial covers the installation and use of hacker protection software such as Portsentry, tripwire, ssh. It also covers configuration and administration steps to make a Linux server secure against hackers.

Network Security Library has links to many UNIX (and, especially, Linux) security articles on host hardening, security admin guides, and special purpose hardening tips.

Brief introduction to the IP networking services, how to configure them, and how to set up a relatively secure Linux workstation. Published in ACM Crossroads, the ACM student magazine.

General overview of security issues that face the administrator of Linux systems. It covers general security philosophy and a number of specific examples of how to better secure your Linux system from intruders.

Setting up a secure Linux server using RedHat and the Linux From Scratch system.

A brief historical analysis of the management of cryptography.

Get the details of a secure Trustix 1.1 installation

How to achieve the goal of every system admin: boring, predictable computers

Provides a checklist on how to secure UNIX/Linux NIS (formerly YP) services in an intranet environment.

Netfilter project provides HOWTOs for packet filtering, NAT and netfilter code hacking for Linux.