The University of Texas at Austin

Security Awareness

Firewalls: What They Are, What They Can Do for You

Connecting to the Internet is safer when you install and use a firewall

One of the most important things you can do if you want to stay safe online is to protect where your computer connects to the Internet. Both incoming and outgoing Internet traffic can be exploited by cyber criminals to install malicious code, destroy files, cause malfunctions or even cause an online virus to proliferate. A correctly installed and configured firewall puts up a barrier between your private computer or network and a variety of these Internet threats.

A firewall is a piece of software or hardware that secures your computer by limiting who can send you information; some firewalls even help to prevent hackers from using your computer to launch attacks on other computers. While firewall protection is essential, it is also important to understand what a firewall can and cannot do so you can take the steps you need to be cyber secure.

Firewall Basics

When you access the Internet, information reaches your computer through various ports opened to receive specific types of data, such as from normal Web browsing, instant messaging or checking your e-mail. A firewall determines if a source address trying to connect to your computer through an open port is one you have decided to trust and denies access to any unauthorized traffic.

By dividing your communications into two distinct groups—incoming and outgoing—a firewall acts like a gatekeeper at a private club. Only those on the guest list can come into your computer and any abnormal behavior won’t be allowed to leave your computer and cause harm to others.

Using a firewall as part of your overall strategy for cyber security is important no matter how you connect to the Internet. While it won’t guarantee the safety of your computer, not having a firewall is taking a big risk. Sooner or later, there’s a good chance a hacker will discover an open port and gain access to all your information. Remember, too, that if the firewall on your computer is disabled, turned off, or has too many open ports, it can’t protect you at all.

Do’s and Don’ts

To help you determine the best overall approach to cyber security, consider what firewalls can and cannot do to protect you.

What Firewalls Do

Firewalls can protect your computer and your personal information from:

  1. Hackers breaking into your system
  2. Viruses and worms that spread across the Internet
  3. Outgoing traffic from your computer created by a virus infection

What Firewalls Don’t Do

Firewalls cannot provide protection:

  1. Against phishing scams and other fraudulent activity, spyware being installed on your computer, or viruses spread through e-mail
  2. From people who gain physical access to your computer or network
  3. For an unprotected wireless network (If you have installed a wireless network at home, be sure you also install a firewall!)
  4. After a network has been compromised
  5. Against Internet traffic that appears to be from a legitimate source

As part of an overall strategy for cyber security, firewalls play an important role in establishing the first line of defense against cyber threats. Combined with anti-spyware, anti-virus and anti-spam software, strong passwords and safe online practices, a firewall adds a layer of protection that increases your chance of staying safe online.