What Is A Firewall?

A firewall is a system that controls access between two networks. Using pre-defined rules, it either permits or denies access between the system it is designed to protect and any other networks attempting to communicate with that system. A firewall can protect your computer by denying access to hackers trying to access your computer over the Internet. It can log attempts to enter your system and activate alarms when unauthorized entry is detected. The term comes from the fact that firewalls, like fire doors, can limit the damage between one area (a private network like your computer) and another (a public network such as the Internet).

For home users, a firewall can be a hardware device with configured security software, a software program running on an individual computer, or a combination of both. Either option allows you to define access policies for anyone attempting to access your computer. Some also regulate outbound traffic, determining what services, or ports, your computer can access on the Internet. Most firewalls intended for home use come with settings that allow the user to operate on the Internet without much intervention.

Firewall Benefits
 
Prevent unauthorized access. A firewall can block unauthorized login attempts on your computer. This can be a very effective safeguard against hackers and intrusion attempts. The firewall acts as a chokepoint between your computer and the Internet, assuring that all traffic passes through one regulated area.

Screen outbound traffic. A firewall can regulate the information that flows from your computer to the Internet. This means that if a hacker gains access to your computer (through a Trojan horse program, for example) it can help ensure your computer doesn't send out information without your knowledge.

Restrict services. A firewall can be set to block services that are known to be problems. It can regulate which applications are entitled to send or to receive information from external sources. Using these controls, users can limit their security risk by granting permissions only to essential services.

Log activity. A firewall can generate log reports showing every attempt to access your computer. This log information can provide vital information about vulnerabilities and threats.

Hide multiple computers. Through Network Address Translation (NAT), a simple router can assign the IP addresses of computers on your home network, making it appear as if there is only one computer (or IP address).

Protect your privacy. Some commercial firewall packages offer additional security and privacy options that protect against malicious code in Web pages, submission of cookies, and secure information encryption.

A firewall won't protect you from unauthorized access of your computer in your home. Use the login and password features of your operating system if you suspect your computer's information may be compromised at home.

Viruses. Most firewalls are not configured with up-to-date virus definitions, so a firewall alone usually won't protect you from virus threats. For this reason, each computer on your home network should have a current version of antivirus software.

User error. It's common for hackers to trick computer users into compromising their computer security. Some send phony e-mails to users, posing as ISP administrators to try to solicit passwords from users. In these cases, where permission is granted to strangers, a firewall may not be able to prevent any resulting damage.

Software bugs. While a good firewall can regulate access to specific applications on your computer, it's not a catch-all solution for software that isn't up-to-date. Most product documentation offers a method to get updates and patches, and most vendor Web sites contain current updates. Product registration often entitles you to receive notification whenever the software is updated.

Every hacking attempt. A good firewall offers protection against the majority of intrusion attempts, but no security system is 100% impenetrable. This doesn't mean defense is futile -- a relatively simple set-up provides you with a level of security that should help deter hackers.