Is there any antivirus or any sort of scanner available for Linux so that one can insure the security of system and is it so that Ubuntu is hack-proof?
If not than what are the basic steps which a new Ubuntu user keep in mind for security concern.
Setup a Virtual Machine using Virtualbox or VMWare and install Backtrack. Once Backtrack is setup and installed, configure Nessus. Once Nessus is installed access it via a browser and scan the Ubuntu system. Nessus will provide a report on any security vulnerabilities it finds. Keep in mind it won't find everything. I would also recommend consulting the CIS benchmarks for further securing your Ubuntu instances.