Our PC also can become hijacked and used as a zombie computer to launch attacks against other computers, or to spew out spam.
Hardware, software free or buy firewalls are critical to protect our computer privacy and security -- for more information on the Critical, Advisory and Personal levels of computer protection, it's all there in The Three Levels Of Internet Risk Protection.
In short, a firewall is necessary for our Internet survival.
What Does A Firewall Do?
Computer firewalls prevent unwanted intrusions into our PC. These intrusions occur when someone exploits a combination of our PC's unique IP (Internet Protocol) address and one or more of the thousands of TCP (Transmission Control Protocol) and UDP (Universal Datagram Protocol) ports.
Whenever we use our browser, e-mail program, or other software to retrieve information from a Web site, ISP (Internet Service Provider) for our email, or remote server, the data is transmitted through one or more of these ports.
Why are these ports so important?
Well, whether it's a malicious hacker (cracker) trying to access our PC, spyware attempting to transmit to a remote server, or a spam pop-up, they have the same objective... to find an open port on our PC, or to trick our system into opening one.
When our computer is connected to the Internet, there's constant traffic through these ports. Ports are like doors and our computer has thousands of them. A firewall monitors these ports, shutting and hiding the doors so that our computer is made invisible to would-be Internet intruders.
Without the protection of hardware, software free or buy firewalls, we leave ourselves open to a range of malicious traffic entering our PCs... and this is what can happen:
We can prevent the above consequences by using a firewall. The choice of using software-based (free or buy firewalls) or hardware-based firewalls is a personal one, depending on what we want the firewall to do. Let's take a look at each type...
Here are some key points to help in your evaluation...
Built-In And Free Firewalls
Many newer operating systems, such as Windows XP, come with entry-level software firewalls and often, users don't realize they can be a security risk. If you're using Windows XP firewall, it will be worth reading The Risks Of The Windows Firewall.
Some free solutions provide basic protection only and are not to be confused with the best-of-breed, buy firewalls. For instance, a basic free firewall download won't normally stop the data on our hard drive being transmitted.
Contrast that with buy firewalls that vet both network traffic, applications, and detect and trace intrusions...
They allow us to analyze who's knocking on our computer's door, when and how the knock occurred and where it came from. Most importantly, only trusted network traffic enters and exits our system. Those kinds of features aren't included in the majority of free alternatives.
A free firewall download can offer reasonable protection from general computer intruders.
However, if you're using a computer for business, or to protect confidential records, then one of the buy firewalls offers more options than the free alternatives.
They can also be customized, and are regularly updated as new threats emerge. The buy firewalls also offer technical support, which can be important... especially if you're new to computers.
That doesn't mean to say that you shouldn't use a free firewall download. If you are a home user who just wants a basic, free firewall that protects you from intruders, then there are two that I'd recommend. Take a read of Free And Buy Firewalls Reviewed, to see the details.
If, like me, you have a home or small business network, you can protect the network with a hardware firewall.
What's a network? When two or more computers are connected together so they can communicate with each other, the computers are networked.
The hardware firewall is an external devices positioned between our computer or network and our cable or DSL modem connection. They can be difficult to configure and are much more expensive than software-based firewalls.
For maximum security, the most reliable way to protect a network is to purchase a router with firewall capabilities. These routers do more than act as a firewall...
Wireless routers are less secure than wired versions -- it's necessary to use the encryption software (for example, WEP and WAP) that accompanies them.
Hardware firewalls do keep incoming attacks off our local network, and they can shield our PC's IP address from the outside world, further protecting us from external attacks.
Because these hardware firewalls are external to the computer system, they can't monitor which applications are opening outbound connections -- we still need a software firewall installed on our PC to ensure malware, like spyware or Trojans, is not transmitting out our personal information.
So, with a network, for maximum protection, we require both a hardware and software firewall to be installed.
Remember, also... if one of our network computers is a laptop and it's used to connect to the Internet from other locations, then one of the buy firewalls is a necessity. Without the hardware firewall at home or the office, there is no screening protection at all, causing us to be at high risk from inbound attack and unknown outbound transmissions.
It will protect our system from many dangers, but not the malware we allow on to our PCs. Of course, we don't know we're allowing these programs in to our PCs.
Then, there's those free programs that we download off the Internet. Freeware is a rich source of spyware! Even just surfing the Net allows us to pick up tracking cookies or a drive-by download from the Web sites we may be visiting.
In other words, just giving permission to our firewall to allow port connections to the Internet exposes us to danger.
So, we have other software protection on our PCs to detect and remove this malware, such as antivirus and spyware blockers. For a summary of what these risks are and how to combat them, go to the article, Know These Computer Security Threats For Internet Protection.