Can anyone suggest a, preferably free, piece of internet security software for Ubunutu 12.10 64-bit version. Something that has built in real-time protection for malware/spyware/viruses/zero-day infections, firewall, etc. Features found in Norton 360 Premier, basically (minus the backup component).
Truth is, as long as you're not stupid enough to run your web browser under Root you'll be totally fine. Linux doesn't need security in the same way as Windows does (even still, I don't run anything on my windows laptop)
You have a firewall, it's called iptables and normally when you install Ubuntu Desktop it's all set up with a default set of rules.
Spyware? Malware? Practically forget about these on any Linux distro... The main thing that could "infect" your computer is running a rogue destructive command under root.
Echo the above. I've been 100% linux for over three years and never suffered for the absence of additional fw/av programmes.
Linux is a new way of thinking for windows users and the first thing to appreciate about it IMO is that you are not running day-to-day in a user profile that has full admin access to the entire system. FWIW, even when I was on windows I would start a fresh install by creating a day-to-day user profile which did not have superadmin privs. If you only switch to root user momentarily to manage system level stuff you should be AOK.
Except that root isn't where the juicy stuff is for normal desktop usage. Obligatory XKCD
Most of the malware I am seeing for Windows at the moment just runs under the user context and does not gain elevation, instead it does everything it wants under the user profile because in most cases that is where the stuff it is targetting lives. While at the moment there aren't many things in the wild which do similar things on a Linux desktop, one day they will come and it is best to be prepared before hand.
I've been running a Windows desktop for roughly six years now without any security software at all. You really just need some common sense and to make use of ad/script blocking plugins. At the end of the day 99% of web pages load fine (faster in many cases) and you can rest assured that almost every type of web based attack cannot touch you.