A Firewall Software, in the simplest terms can be described as a network security system, (software-based in this case), that is able to control all the incoming and outgoing network traffic based on a set of well defined rules by experts.
This Firewall Software helps to prevent hackers or malicious software (such as worms and Trojans) from gaining access to your computer via a network or the Internet. It can also help in stopping your computer from sending malicious software to other computers.
The main role played by a Firewall Software is to distinctively separate a secure area from a less secure area and to control communications between the two areas. Firewall Software can also assume a variety of other important functions, but are chiefly responsible for controlling incoming and outgoing communications on anything from a single machine to an entire network.
A Firewall Software, which others may refer to as software firewall, are tailored to run on a single computer. These are mostly home or small office computers that have broadband access, which tend to be left unattended to most of the time.
Computers are able to communicate over many different recognized ports, and the Firewall Software will tend to permit these without prompting or alerting the user. For instance, computers access Web pages over port 80 and use port 443 for secure Web communications. A home computer would expect to receive data over these ports. However, a software firewall may actually block any access from the Internet over port 421, over which it does not expect to receive any data.
A Firewall Software also allows certain programs on the user’s personal computer to access the Internet, often by automatic permission of the user. Windows Update, antivirus software, and Microsoft Word are some programs that a user may legitimately expect to access the Internet. However, a program like gator.exe that is attempting to access the Internet when it shouldn’t be running might be a red alert. Hence the user could decline access for this program. This is a handy feature when spyware, adware or any other type of malware is suspected.
Some Firewall Software will also allow for configuration of trusted zones. These grant unlimited communication over a wide variety of ports. This type of access may be necessary when a user starts a VPN client to reach a corporate intranet.
Firewall Software also depend heavily on the user’s ability to make the right decisions. Suppose someone using a Firewall Software mistakenly gives a Trojan permission to access the Internet, security on that machine is really compromised even though there is nothing wrong with the Firewall Software itself.
In additional, Firewall Software helps to prevent outside computers from accessing computers inside the network. On the outbound side, firewalls can also be configured such that it prevents mischievous employees from sending certain types of emails or transmitting sensitive data outside of the network. Firewalls can be additionally programmed to prevent access to certain websites (like social networking sites) where they are not deemed useful.