According to the FBI, cybercrime complaints rose 20 percent in 2009, and victims lost $559 million, more than double the year before. With online crime on the rise, it's more important than ever to protect your systems. But you don't have to pay a lot of money for security. The open source community continues to produce (and maintain) excellent tools that fulfill a wide variety of security needs.
This year, we've once again updated our list of top open source security apps. While the list isn't exhaustive by any means, we tried to include many of the best tools in a variety of categories. We dropped a few projects from last year's list that have gone inactive or closed source, and we've added a few newcomers that are worth your consideration. Anti-Virus/Anti-Malware

1. ClamAV

Probably the best-known and most popular open-source anti-virus engine, ClamAV powers numerous commercial and open-source security apps. The version here runs on Linux/Unix, but it's also available with a variety of front-ends for other operating systems (see below). Operating System: Linux.

2. ClamWin Free Antivirus

As you might expect from the name, this app lets you use ClamAV with Windows. The latest version supports Windows 7, and offers improved speed over earlier releases. Operating System: Windows.

3. ClamTk

Like ClamWin, ClamTK provides a front end for the ClamAV engine, this time for the Linux OS. It allows you to schedule system scans, but it does not provide real-time scanning for incoming files. Operating System: Linux.

4. Rootkit Hunter

This no-frills tool scans for rootkits and other malware on Linux system. While it does not provide live or scheduled scanning, the Web site explains how to set up your system to scan daily. Operating System: Linux, Unix.

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