Security in Linux is extremely important to consider in every scenario, even in the home. Linux by itself is generally secure, but the more services you run that are world-exposed, the more vulnerability potentials you have open to the world as well. Some primary examples of how important security is, what potential issues could become of an insecure system could result in, and various security models, from basic to advanced methods of security will be provided within this section of this site.
Security Risks
First of all, potential security risks are when you run any kind of service that is exposed directly to the internet. Most people, today, have their internet routed through a desktop network router which by default takes all the front-end traffic and only forwards specific traffic based on port-forward rules setup, or by UPnP temporarily requested port forward rules. Some people directly connect to the internet straight from their desktop or laptop, which is the most dangerous.
Some potential risks do exist for either, of course. If you're directly connected to the internet without any router/firewall sitting in front of your desktop, this opens up the entire world to your computer. Many desktop related apps already open up ports, intended for local use, but publicly bound most of the time include such things as Xorg, your graphical environment, ssh servers, cups - the printing service, avahi - used to advertise your system to others locally, also many X applications do as well, such as Skype and Dropbox. All these applications are potential security exploits waiting to happen to get remote access into your system to cause harm to you, your computer, or to others.
Harmful Information
Some of the potential security issues could result in personal information of you being stolen. Your identity, your phone number, address, even potentially your financial information. I'm sure none of this you would want to expose to any random stranger from anywhere in the entire world with internet access, I sure wouldn't!
Damages to Your Data
Exploiters may just be simply destructive, wanting to take you out, for reason none-other than simply because they can. This could include deleting everything your user account owns to potentially everything on your computer itself, possibly even other connected computers in your network.
Damage to Others
Many vulnerabilities exist and try to spread themselves into insecure system. Often times, these types of exploits can either attempt to gather information about you continuously, be used to damage your data, or worse, effect others as well. Imagine if a worm got into your system and embedded itself into a way that it was remotely accessible, or polls an external resource, to make your system become a turret to attack other peoples, or to attempt to spread itself to others like it did to you. These kind of security exploits are m ore common than you think and also very dangerous to you as an individual. Imagine if you were infected as a turret for a mass DoS(Denial of Service) and at some point the target became the FBI website and thus your system starts sending massive amounts of traffic to their website. It would almost be guaranteed that in a few hours later you would have a knock on your door, or have it busted down, and you would be taken off to jail without even knowing why.
Security is Needed
As you can see from the above examples, your security is not only important to you and your data, but to others as well, and that some issues could impact your life more than you may have realized. It's always recommended that everyone always try to do even the least amount needed to reasonably secure your computer to prevent these kinds of situations ever causing you problems.
This security section will help you do exactly that. Setting up a firewall is always the first and most important step of security. Expose only what you need open, and handle traffic as securely as possible, even while allowing what you want to come in for your everyday internet use. Further security hardening techniques are included to truly lock your computer down as tightly as possible but maintaining full functionality as it would normally.