Hello friends,
I don't know much about linux and its distributions. Please tell me does not linux need antivirus softwares? Why? Someone one on orkut.com told me once that there is no/less virus threats to linux as compared to Windows. Please discuss.
Regards.

Your question has been asked and answered about 37 billion times. A quick search on this (LQ) site will literally flood you with information. If that's not enough just google linux viruses and you'll get 83 kazillion hits.
Have fun.
jdk

And they would know, naturally.

If you check the AV software sites, you'll find they list only dozens of low-risk linux viruses/threats compared with millions of windows ones. This should give you a hint.

Also read:
Why GNU/Linux Viruses are Fairly Uncommon

Interestingly there is (right now) a zero-day exploit for 2.6.30 kernels
http://lwn.net/Articles/341773/

However, these things are pretty rare. Usually vulnerabilities get detected and patched before an active exploit exists. The exploits are usually so obscure that it takes an academic researcher to spot them. In this case, the [i]code] itself is fine, and it is optimisations in the compiler which introduce loophole making the exploit possible.

In almost all recent cases, you need to allow access for the exploit to work. If you do not allow remote logins you aught to be fine. In other words - AV software won't help.

I should point out that attacks tend not to be aimed at operating systemn these days - the OSs are pretty secure. They are much more likely to be application explaits - anyone can run a milicious javascript in their browser if that ability is switched on for eg. This is platform indipendant.

Usually, windows users like to claim that linux is just as vulnerable than windows - with the lack of actual malware being attributed to linuxes perceivel low market penetration. However, there is no increase in linux-targeted malware in those markets where linux does have high penitration - like web servers and search engines.

The real reason there is so little malware for linux is that, even if it works, it so hard to get it on to the machine, and so hard to do anything once it is installed.

The gripping hand, though, is that all systems are vulnerable to user stupidity. Running linux does not mean that you can browse with impunity. There is plenty of malware which can run in your browser.

The main concern is not so much that a bad guy can peek at the content of your HDD - it's more that they will attempt to harness your processing power and bandwidth to a botnet. Then they use your computer to go after a target they actually care about.


Windows itself has sometimes been mistaken for a virus however, if you follow a simple checklist it is easy to distinguish the difference:

Viruses
1. replicate quickly
2. use up excess system resourses, slowing the desired process as they do
3. usually carried, unknown to the user, along with valuable programs and systemsurces,
4. will occasionally make the user suspect their system is too slow (see 2) and the user will buy new hardware
5. are designed to work for the creator at the expense of the owner of the computer
6. are well supported by their authors
7. program code is fast, compact and efficient
8. tend to become more sophisticated as they mature.
9. are not advertised in glossy magazines
10. have a whole industry dedicated to their removal

So you see... windows is not a virus.

What else does vista do?

It was about viruses, not Microsoft Windows.

In any software there are potentially some things that can be misused. You can watch out for a million of things, and in the end it boils down to you having to decide which things are big enough threat that you can and should use time to stand guard for them. For Windows users computer viruses are quite a nuisance at the moment, for Linux users the biggest threat is more probably something else (I'd say human based). I'm fairly sure that some geek has made a virus scanner for her/his TI-85, but it's another thing if it's of any use then

Windows Vista is not a virus either. After all, viruses are released in a timely manner.

However, we are at risk of a hijack here.
mg15: does all this answer your question?

If you run a samba server on your linux computer, you may want to run an antivirus to prevent an infected Windows host from using your share to infect other Windows machines. The scanner may also check your configuration files for mistakes. This can be important if you are running as web server for example.

In Linux one worry is rootkits. If an attacker gets root access to your computer, he will install a root kit. It is a group of replacement programs and linux kernel modules, designed to become invisible.
There are two programs which look for rootkits. rkhunter and chkrootkit.
They also look for suspicious activity, such as programs that access the network interface in promiscuous mode.

There are programs such as AIDE that are used to monitor the filesystem for changes in files, and email reports to root. Don't be surprised if such a service is already running on your system. Look in your package manager.

Viruses are only part of the picture. Don't become complacent because you run Linux.

Windows is actually very robust and virus-resistant ... i-f you are running as a "limited user" (as you should be).

The proverbial Achilles Heel of Windows is really just "the way in which it is customarily used," which is "by all-powerful Administrators." (In fact, the "cheap Home versions" make it all but impossible to be anything but an all-powerful Administrator.) Windows is designed to respect such users as "He Who Must Be Obeyed," which is actually insane in this context.

Linux and OS/X ... "don't do that." Therefore, when a malevolent program says, "shoot yourself in the foot!" ... the gun merely goes "click."

It is a trivial matter to do the same with Windows ... in fact, to exercise far more precise control! ... but millions of Windows installations don't, and their owners have never even been informed of the issue.

Thank you Simon Bridge, b0uncer,jschiwal and sundialsvcs
We have got a very useful discussion here.
Thanks again.