Posted 24 May 2011 - 05:59 AM
With Linux/Unix a program should not have the ability to run with out you giving it permission to first.
Now, of course it doesn't matter what OS you are running. Whether it's Linux, Windows, or Mac, a virus/malicious program can be written for it.
But, because of the permissions on a Linux/Unix machine it should be very difficult for a program to get on your system and run with out you being the one downloading and running it.
Now, that isn't to say that you couldn't download and install a malicious program from the internet thinking that it is a program you want. But, that is where package managers and repositories come in. Unless you are an advanced user who knows what they are doing, there is no good reason not to use the repositories. Even as an advanced user there is little need to. If you are using a good distro, that is well maintained it's should have everything you need and be secure.
There is no 100% guarantee you will never get a virus on a Linux Machine, but the chances are very slim if you follow some basic rules. If a malicious package is going to get through all the developers, repository maintainers, and testing before it makes it to the stable repose chances are an anti-virus program will miss it too.
In closing, Anti-Virus is only good on un-secure machines. And if you system is not secure, you need to stop and ask yourself why.