Samhain is free. People should check it out and run it daily at night. There's no reason not to. You'll never even notice it's there unless something happens.

There's also no reason to use it, unless you're running a server.

Malware is only a problem on servers?

But I guess I can accept the argument that it might be a little overkill.

I rarely if ever perform a regular scan of the whole system. I do monitor the logs and look for unusual activity. Otherwise, e-mails on the server are the only things that get scanned on a regular basis.

Hi,

rkhunter and chkrootkit on a daily base works okay for me. AV software running on my mailservers, but not locally on my workstation. Never found anything not intented by myself to be there.

I can't. I think you should run a HIDS on all of your boxes.

Could audio files (mp3, flac, etc) or video files (avi, mpg, mkv, etc) contain exploits or trojans?

My external backup drives contain mostly media files and ofcourse you cant do a reformat or you lose all your stuff.

What is the best practice for protecting external backup drives?

From my understanding, yes. I also believe jpg's or other image formats can as well. Though I am not sure how this is done or for that matter how likely, even if possible, it would be.

Unless I've missed something, unless your media files are executable (and I have no idea why someone would let data be executable), they can't do damage. Simply opening a media file in its appropriate viewer shouldn't allow any damage.

Given the fact that some OS installations are not that well-protected out of the box (Ubuntu's Remote Desktop comes to mind, see for instance the reports on Ubuntuforums), some users not knowing or caring for any security and the amount of hosts being compromised through the web stack still, I disagree.

They most certainly can. In fact, as pointed out by Amdx2_x64, even image files can contain exploits.

Image example: CVE-2010-1205; Audio example: CVE-2007-6279; Video example: CVE-2009-3389.

Next to whatever basic hardening / logging entails I use GNU/Tiger or LSAT, Auditd, Samhain (daemon: active) or Aide (cronjob: passive), Snort, a slightly modified Chkrootkit, Rootkit Hunter with add-ons and some home-brewn scripts. If I run AV SW it'll mostly be to help determine stuff sent to me or found elsewhere.

...and next to that PHP scripts are often uploaded with image type extensions to bypass crude filters.

It's easy to get way off base here. Install as much security as you can and then back off based on usability and cost limitations. Sometimes extra security does not return anything given what is being protected.

Sometimes "Fort Knox" style is the appropriate path if what you are protecting is worth the investment. I like to see costs (processing, I/O, admin time), barriers (knowledge, time, training, etc.) and investment (research, setup, etc.) be so low that people can't help but be secure and make good choices.

I think we are moving closer and closer to that with Linux and options we have today. This forum also contributes to that greater good.

Define "extra security"?