There are several schools of thought about installing antivirus software for Ubuntu®, one of the most popular Linux operating system installations available as of 2011. There are viruses, spyware and malware on the Internet that will function and potentially compromise an Ubuntu® installation if the proper security precautions are not taken. Primarily, there are two types of antivirus software available for the operating system. One prevents the initial infection, while the second removes already installed software. Using both types in tandem can help to increase the already strong security that Linux software enjoys.
The Linux operating system has long had a reputation for being very secure. This is partly because of a practice of requiring proper system permissions to execute programs or access information. For a very long time, there was not antivirus software for Ubuntu® because it was thought it was not needed. It was believed the operating system permissions would prevent malicious software from being run. Web browsers then became more complex, and it became more probable that a hacker could write a program in a web application language that would find a way to execute itself on an Ubuntu® system and compromise security.
One of the main types of antivirus software for Ubuntu® is a download scanner or file scanner. This is a piece of software that either looks at a file being viewed online before it is loaded into the web browser or other program, or looks at a file that has been downloaded but not extracted. This works by attempting to identify the signature of a computer virus. The signature is a distinct piece of computer code, like a fingerprint, showing that a virus has been embedded inside of a file. More advanced antivirus software might have a library inside that can extract the harmful virus and repair the original file, making it safe for use.
The other type of antivirus software for Ubuntu® is intended to scan hidden or less-than-obvious areas within the file system to find viruses that have already been implanted on the host system. This can sometimes be very difficult to remove, because so many security features will either have been bypassed or overrun, possibly by tricking a user into granting high-level permissions to the malicious software. The antivirus software for Ubuntu® can scan through the directory structure of the file system looking for known files or traces of files that might indicate a virus is present or has been attached to existing files. In most cases, it can be removed, but there are certain types of computer viruses that can prevent other software from removing infected files.