A hacker is simply an online vandal, if you think about it. What do vandals do but damage things that don't belong to them, for no good reason other than to do it. A hacker wants to worm his way into a network of his choosing to do serious (or not-so-serious) damage, such as stealing email addresses or your personal data.
Hacking is mostly focused on causing trouble for big companies and government agencies. But anything is fair game, and that's why some junior hackers will stoop so low as to hack the IP addresses of our computers, just to mess things up for a bit.
Your network identifier: an IP address.
As you likely know, every computer that is connected to a network or the Internet has its own IP address. Everyone on the Internet has to have an IP address to send emails, look up information or buy online. It's as simple as this: When you're connected, you have an actively working IP address. And depending on where you are, your IP address can change.
A lot of Internet chatter that says our IP addresses can reveal our identities is not accurate. As experts have pointed out, if our IP addresses were truly the gateway to all of our personal and private information, then the entire Internet would be one big mess. But fortunately, our IP addresses alone do not make us easy targets.
Unfortunately, that doesn't mean hackers will leave IP addresses alone. Remember—hackers simply like to mess things up, so they'll still see what disruption they might be able to cause.
But just how would the hacker get into your computer anyway?
Ports: like doors to your home.
In the world of TCP/IP, the interface between the networks and your programs occurs through a system of electronic channels called ports. Each of these ports has a unique number that identifies it. So, in a sense, the ports are pipelines in the computer through which data can flow to and from a particular application and the network protocol software.
Each IP address has ports associated with it. Those ports are an important part of your computer system: Several programs (applications) might be running on the same computer, and the built-in network software on your computer needs to have a way of knowing what incoming packet of data is intended for what application. It needs to know, for example, how to send incoming emails to your email program.
That's how that happens.
A building with rooms.
So we have IP addresses, ports and programs. Think of them as an address on your computer, a doorway into a room, and a room itself. With this picture in mind, look at your port as a back door that allows entry into your house...your computer. Completing the analogy, the room is a single application (program) you're running.
If you're connected to the Internet and running a program, a related port (identified by a number) will be open. That's good for you, but it could allow someone who knows your IP address (an outsider, a hacker) access into your connection, with some ability to engage or affect the program you're running.
Behind the door.
Fortunately, each room/program is somewhat self-contained and doesn't have connecting doors to the other "rooms" in your computer. So, even if a hacker gets your IP address, sneaks into your port through the big back door and gets into your program, that's as far as they can go.
Is there a way to block the door? Yes. That's where a firewall comes into the picture. It essentially blocks intruder activity from getting through the ports.
Making your IP address invisible.
One way to keep hackers at bay is to hide your true IP address. One way to do this is to set up a personal Virtual Private Network (VPN). With a VPN, your online requests are routed through a vast network of computers, and you use a temporary VPN to communicate online. A hacker would not see your true IP address and wouldn't be able to connect to your computer.