“Security through obscurity” may be a catchy phrase, but it’s not the only thing that’s catching among Windows users. The expression is intended to suggest that proprietary software is more secure by virtue of its closed nature.

If hackers can’t see the code, then it’s harder for them to create exploits for it–or so the thinking goes. Unfortunately for Windows users, that’s just not true–as evidenced by the never-ending parade of patches coming out of Redmond.

In fact, one of Linux’s many advantages over Windows is that it is more secure–much more. For small businesses and other organizations without a dedicated staff of security experts, that benefit can be particularly critical.

Five key factors underlie Linux’s superior security:
1. Privileges Linux systems are by no means infallible, but one of their key advantages lies in the way account privileges are assigned. In Windows, users are generally given administrator access by default, which means they pretty much have access to everything on the system, even its most crucial parts. So, then, do viruses. It’s like giving terrorists high-level government positions. With Linux, on the other hand, users do not usually have such “root” privileges; rather, they’re typically given lower-level accounts. What that means is that even if a Linux system is compromised, the virus won’t have the root access it would need to do damage system wide; more likely, just the user’s local files and programs would be affected. That can make the difference between a minor annoyance and a major catastrophe in any business setting.

2. Social Engineering Viruses and worms often spread by convincing computer users to do something they shouldn’t, like open attachments that carry viruses and worms. This is called social engineering, and it’s all too easy on Windows systems. Just send out an e-mail with a malicious attachment and a subject line like, “Check out these adorable puppies!”–or the porn equivalent–and some proportion of users is bound to click without thinking. The result? An open door for the attached malware, with potentially disastrous consequences organizationwide. Thanks to the fact that most Linux users don’t have root access, however, it’s much harder to accomplish any real damage on a Linux system by getting them to do something foolish. Before any real damage could occur, a Linux user would have to read the e-mail, save the attachment, give it executable permissions and then run the executable. Not very likely, in other words.

3. The Monoculture Effect However you want to argue the exact numbers, there’s no doubt that Microsoft Windows still dominates most of the computing world. In the realm of e-mail, so too do Outlook and Outlook Express. And therein lies a problem: It’s essentially a monoculture, which is no better in technology than it is in the natural world. Just as genetic diversity is a good thing in the natural world because it minimizes the deleterious effects of a deadly virus, so a diversity of computing environments helps protect users. Fortunately, a diversity of environments is yet another benefit that Linux offers. There’s Ubuntu, there’s Debian, there’s Gentoo, and there are many other distributions. There are also many shells, many packaging systems, and many mail clients; Linux even runs on many architectures beyond just Intel. So, whereas a virus can be targeted squarely at Windows users, since they all use pretty much the same technology, reaching more than a small faction of Linux users is much more difficult. Who wouldn’t want to give their company that extra layer of assurance?

4. Audience Size Hand-in-hand with this monoculture effect comes the not particularly surprising fact that the majority of viruses target Windows, and the desktops in your organization are no exception. Millions of people all using the same software make an attractive target for malicious attacks.

5. How Many Eyeballs “Linus’ Law”–named for Linus Torvalds, the creator of Linux–holds that, “given enough eyeballs, all bugs are shallow.” What that means is that the larger the group of developers and testers working on a set of code, the more likely any flaws will be caught and fixed quickly. This, in other words, is essentially the polar opposite of the “security through obscurity” argument. With Windows, it’s a limited set of paid developers who are trying to find problems in the code.

They adhere to their own set timetables, and they don’t generally tell anyone about the problems until they’ve already created a solution, leaving the door open to exploits until that happens. Not a very comforting thought for the businesses that depend on that technology. In the Linux world, on the other hand, countless users can see the code at any time, making it more likely that someone will find a flaw sooner rather than later.

Not only that, but users can even fix problems themselves. Microsoft may tout its large team of paid developers, but it’s unlikely that team can compare with a global base of Linux user-developers around the globe. Security can only benefit through all those extra “eyeballs.”

Once again, none of this is to say that Linux is impervious; no operating system is. And there are definitely steps Linux users should take to make their systems as secure as possible, such as enabling a firewall, minimizing the use of root privileges, and keeping the system up to date. For extra peace of mind there are also virus scanners available for Linux, including ClamAV.

These are particularly good measures for small businesses, which likely have more at stake than individual users do. It’s also worth noting that security firm Secunia recently declared that Apple products have more security vulnerabilities than any others–including Microsoft’s. Either way, however, when it comes to security, there’s no doubt that Linux users have a lot less to worry about.