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What is a Firewall?

Posted on May 10, 2011
Are you wondering if a firewall program is necessary to protect a computer? Do you think an antivirus program is enough to protect a PC from Internet worms? Are basic Mac OS X and Windows firewall applications enough? Can you depend on an ISP firewall?

Tags: firewall
Firewalls offer protection against hackers, worms and viruses by shielding the computer or network from unnecessary or malicious Internet connections. Firewall software controls Internet connections on a computer by using rules or policies that control incoming and outgoing Internet traffic. Basically, any program on a computer would not be able to make an inbound or outbound Internet connection unless the firewall software allows it.

A malicious or unnecessary communication by a program will trigger an alert from a firewall, prompting the user to decide whether to allow or block the connection. If there is a computer or network attack, such as port scanning or an Internet worm caused by a vulnerability in the operating system, a good firewall program will protect you from the threat.

Firewalls vs. Antivirus Software

If you want to fully protect your computer, using an antivirus product alone isn't enough. Antivirus software applications cannot block intruders or hackers because they are not designed to shield a PC or network from such attacks. Only a standalone firewall program can block malicious or unnecessary communications.

An antivirus program can identify and block threats such as viruses, Trojans, worms, spyware, adware, potentially unwanted software and other types of malware. However, the antivirus software can only block the threats if there is a virus signature that identifies files or processes as viruses or malware. Antivirus programs cannot block or prevent an application or file that is unknown. Even if your antivirus software has not identified an application as dangerous, a firewall program will still prevent the malicious application from sending or receiving data to and from your computer.

Built-In Firewall Protection in an Operating System

It's very important to keep firewall protection enabled. Windows XP SP2, Vista, Windows 7 and Mac OS X all include built-in firewalls which are enabled by default. This firewall protection is very basic, but good enough to protect your computer and network against many intrusions. However, most built-in firewalls do not include advanced controls, better features and additional protection, which is why it's a good idea to install and use third-party software.

Internet Service Provider (ISP) Firewalls

Most ISPs use a firewall, but this service is not really a good thing to depend on for personal firewall protection. The ISP firewall is used only to block or allow port numbers that a network or customers can use, in addition to shielding their servers or network against Internet worms or intrusions. Here are some examples of why an ISP uses a firewall on its network:

·    When an ISP wants to block certain ports - For example, the SMTP port number 25 may be blocked to cut down the amount of SPAM that is sent from the network. Another example is blocking ports used by sharing or P2P applications.
·    Protection against intruders and hackers to the ISP network - An ISP firewall will only protect intrusions and hack attempts around its network, but not the intrusion threats to a customer's PC, home or office networks.
·    Prevention of Internet worms on the ISP network - If there is a widespread Internet worm attack that may affect not only the ISP network but also customer computers, the ISP firewall may block the ports in use by the worm. However, this will not protect your computer or home and office networks from infection if the worm has bypassed the ISP's firewall software or is already in the network.

Third-Party Firewall Software from ISP

Some ISPs have partnered with security software vendors by providing a free or discounted security program. These firewall and antivirus programs are powered by a security software provider such as McAfee, F-Secure, Symantec, etc. The software is generally customized by the security software vendor in partnership with the ISP. However, it's usually still best to purchase the retail firewall or antivirus software because there's a catch when using these customized applications.

The catch: Discounted firewall software offered by an ISP may not be updated as frequently, which means that the customer would be using an older version of the security program customized for the ISP. On the other hand, those who have purchased firewall or antivirus software directly from the vendor or approved affiliates are receiving product updates as soon as they are available. Without these updates, a new vulnerability could take advantage of your system by attacking older versions of protection tools and put you at risk.

On the positive side, firewall software is generally very inexpensive, especially when bundled with other protection programs in an Internet security suite. If you're shopping for new antivirus software, look for deals that include a firewall. Or, if you already have a basic antivirus program, you may be able to upgrade to a more comprehensive version of the product that includes a firewall and other additional tools for just a few dollars more. In this day and age, those few extra dollars will be definitely well spent.

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