One of the big advantages of using Linux is that its security tends to be so much better than that of the competing alternatives. That's due in large part to the way Linux assigns permissions, but it's also certainly true that the open source operating system is targeted by malware writers far less frequently than Windows is, in particular, simply because it's less widely used and so much more diverse.
The fact remains, however, that no operating system is perfectly secure. For business users, in particular, a little extra security assurance is always a good idea, at the very least for your own peace of mind.

Here, then, are a few of the best free tools you can use to help keep your Linux systems secure.