Paranoid Penguin - Seven Top Security Tools
This article is by no means a comprehensive list of the many, many excellent security tools available for Linux. I would have loved to devote blurbs to Tripwire, AIDE, Nikto, GnuPG, FreeS/WAN, Snort, PSAD, Stunnel, OpenSSL and a score of other worthy tools. But I've had fun showing off some of my favorite tools, and I hope you've found it useful. Remember, many of these tools bestow awesome powers upon their bearer: use them responsibly, ethically and carefully. But so long as you do, have fun.
Mick Bauer, CISSP, is Linux Journal's security editor and an IS security consultant in Minneapolis, Minnesota. He's the author of Building Secure Servers With Linux (O'Reilly & Associates, 2002).