The keys have been in my truck's ignition ever since I bought it. In fact, as far back as I can remember, I've left my keys in the ignition of every vehicle I've ever owned. This lack of security works fairly well for me, because I live in a very rural area and drive fairly undesirable vehicles. Does that make me an idiot? Well, I agree I'm a bit naïve, and possibly foolish, but considering how often I lose things, it's a risk I'm willing to take.

My servers, however, don't have the luxury of a rural environment. The Internet knows no backwater, and anything plugged in to the Net is vulnerable, regardless of location. We've dedicated this issue to security. As Linux users, we may brag about how secure our systems are, but a system is only as secure as you make it, so it's important to read this issue and make sure you're doing your part to keep your system clean.

Our resident security whiz, Mick Bauer, gets us started by explaining DNS cache poisoning. If you use DNS (and if you use the Internet, you do), it's important to learn how to keep your system safe from getting hijacked. Kyle Rankin also helps us with our servers, but in his column, he explains how to install a blog. Sure, you can host your blog elsewhere, but if you want to control every aspect of it, you'll want to install it on your own server. Kyle shows how.

Everyone knows the first line of defense when it comes to a network is the firewall. This month, we look at two different methods to set up your own. I review Untangle, which is a Linux-based firewall solution designed to be a one-stop shop for all your firewalling and filtering needs. Untangle is a complete distro, and it comes with both free and commercial modules. Whether you want to set up a simple firewall or provide Web filtering, load balancing, virus scanning and so forth, Untangle is a simple product for very complicated tasks. If you prefer to set up your own firewall server, however, Mike Horn shows how to use Firewall Builder to create a custom, highly available firewall on your own box. There even are GUI tools, which I always appreciate.

Preparing for attack is a great idea, but sometimes it's good practice to attack your own servers, just to make sure they're secure. Raphael Mudge teaches how to shoot our servers in the foot using Armitage and Metasploit. They may sound like comic-book antagonists, but these two software packages really can reveal weak points in your security. Knowledge is power, and with security, the more you know the better.

Jeramiah Bowling takes us into the world of virtual servers this month, for some unique vulnerabilities to watch for when using a virtual environment. For the most part, virtual servers behave just like their steel and silicon counterparts, but they offer one more layer of vulnerability, so we should be careful how we secure them. Aleksey Tsalolikhin provides a different take on a well-known product this month as well, as he demonstrates Cfengine's ability to assist in securing computers. Anyone who manages configurations for multiple computers is familiar with Cfengine, but Aleksey describes some features we may not have considered before.

If all this talk of security is making you paranoid, don't worry. In this issue of Linux Journal, we still have the reviews, product announcements, and columns you're used to. Whether it's Reuven M. Lerner's column on Node.JS, Dave Taylor's continuation of the Mad Libs game he started last month, or Kyle Rankin and Bill Childer's new column Tales from the Server Room, this issue should entertain and educate, even if you're not a security nut.

Remember, just because I'm foolish with my car keys doesn't mean you need to be foolish with computer security. I always can offset my bad key habits with GPS tracking and hidden security cameras. If you put your password on a Post-It note stuck to your monitor, this issue won't help you. There's not a firewall in the world that can fix lazy!