What is a Network Firewall
Network firewalls got their name from physical firewalls, used to prevent actual fires from spreading from one section of a building to another. A network firewall does the same thing – it restricts the flow of data and program instructions in and out of the system.
There are two types of firewalls that can be used on a network – hardware and software. This can be slightly misleading, as hardware cannot really work on its own without software to tell it what to do. And in turn, the software cannot do much without hardware, since the software must be stored and executed somewhere.A firewall is most often used between two networks. For example, a corporate network may have a firewall between it and the Internet. The Internet is merely a large set of networks that can talk to each other and the firewall restricts incoming traffic to certain areas or computers within the corporate network. An internal firewall can help keep resources restricted to certain groups, but it can also prevent viruses from being spread from group to group.
Personal firewalls are also known as software firewalls. These are used primarily on personal computers that connect to the Internet. They are slower than hardware firewalls and use the resources of the individual computer.
Firewalls help keep unwanted hackers and viruses from accessing your personal computer. It controls the traffic – both inbound and outbound – by a set of policies. Policies come with the firewall but these can be configured to the user’s specifications later. These policies decide which programs can access the Internet and exactly what type of traffic is allowed.
In order to use a web browser and some programs such as antivirus software, you need network access. You can set up the firewall to allow desired traffic while restricting other types of traffic. Your firewall can also “learn” what programs are to be allowed to access the Internet freely. You are usually notified the first time the program tries to access the Internet after the firewall is installed. You have the option then to allow or deny access. A good rule to follow is that if you don’t recognize the program or know what it does, don’t allow it to access the Internet.
Unbeknownst to many people, their computer may have open ports, which would allow hackers to gain access to their computer. Hackers know that some people are not aware of this and look for these easy access computers. Using a firewall can close off these ports and protect you and your computer from hackers. In fact, extremely good firewalls not only close the ports you are not using, they hide them from hackers completely. So if a hacker is scanning for open ports, it won’t receive a reply so your system is virtually invisible.
As great as that sounds, you cannot assume that personal firewalls are fail proof. Because a personal firewall is a software program, it is susceptible to virus attacks and there are viruses that specifically target firewall software. Such viruses can modify your policies without your knowledge, making you think your computer is safe when it actually isn’t.
But, firewalls can and should be used on all personal computers that connect to the Internet. While they cannot guarantee 100% safety, having a firewall installed provides you with much more protection that not having one at all.