A response to this post:
How do you get down off an elephant?
Specifically, I disagree with this assertion from the article:
"A virus is simply a Windows program, so it doesn't run in Linux."
That's an inaccurate definition of the term "virus" which seems to suggest there are no virii for any operating systems other than Windows.
Also malware includes not just virii, but worms, trojans and root-kits. These known and widely available tools are not the only options available to intruders either.
GNU/Linux users should not have any false sense of security just based on the fact that viruses designed for exclusively for windows won't run on GNU/Linux.
Here is a list of "Linux computer viruses" according to a page on wikipedia.org.
The following excerpt lists various kinds of malware, not just virii:
The following is a partial list of known Linux malware: Trojans * Kaiten - Linux.Backdoor.Kaiten trojan horse * Rexob - Linux.Backdoor.Rexob trojan Viruses * Alaeda - Virus.Linux.Alaeda * Bad Bunny - Perl.Badbunny * Binom - Linux/Binom * Bliss * Brundle * Bukowski * Diesel - Virus.Linux.Diesel.962 * Kagob a - Virus.Linux.Kagob.a * Kagob b - Virus.Linux.Kagob.b * MetaPHOR (also known as Simile) * Nuxbee - Virus.Linux.Nuxbee.1403 * OSF.8759 * Podloso - Linux.Podloso (The iPod virus) * Rike - Virus.Linux.Rike.1627 * RST - Virus.Linux.RST.a * Satyr - Virus.Linux.Satyr.a * Staog * Vit - Virus.Linux.Vit.4096 * Winter - Virus.Linux.Winter.341 * Winux (also known as Lindose and PEElf * ZipWorm - Virus.Linux.ZipWorm Worms * Adm - Net-Worm.Linux.Adm * Adore * Cheese - Net-Worm.Linux.Cheese * Devnull * Kork * Linux/Lion (also known as Ramen) * Mighty - Net-Worm.Linux.Mighty * Millen - Linux.Millen.Worm * Slapper * SSH Bruteforce
We're all still responsible as individuals for our own information security. It's not good to have a false sense of security just because windows malware doesn't run on GNU/Linux systems.
Should we scan our GNU/Linux system for malware or hostile network activity? I wouldn't recommend against the idea. Neither would I suggest people buy any proprietary software to handle the task. Using proprietary software for your security is ironic, since using proprietary software compromises your privacy, autonomy and security by default.
Getting familiar with Nmap, Snort, Firestarter, Squid, Tor, GPG, and ClamAV would be a good start for those who choose to remain responsible for their own security. One might also try auditing their wireless network with air-crack.
Better to be aware of your vulnerabilities (however few or many they may be) instead of putting absolute confidence in the security of pre-configured software downloaded from repositories.