Linux Security: Craig Hunt Linux Library

This is the most complete, most advanced guide to Linux security you'll find anywhere. Written by a Linux security expert with over a decade of experience, Linux Security teaches you, step-by-step, all the standard and advanced techniques you need to know to keep your Linux environment safe from threats of all kinds. Hundreds of clear, consistent examples illustrate these techniques in detail†so you stay on track and accomplish all your goals. Coverage includes:
Understanding information and system security procedures
Developing a corporate security policy
Designing and deploying an effective system and network monitoring strategy
Managing the network services offered by Linux servers
Understanding Sendmail security, including authentication and privacy
Providing application-level mail security using PGP
Designing and deploying an Apache HTTP server, including SSL extensions
Securing your Samba server
Building a network layer firewall using IPtables and Linux kernel v.2.4
Using the NEC SOCKS5 transport layer firewall
Deploying the TIS firewall toolkit
Offering secure remote connectivity with IPsec and PPTP VPNs
Adding strong user authentication to Linux servers using Kerberos
Understanding the Linux Pluggable Authentication Modules (PAM)