What is a firewall?

A firewall helps protect you against unwanted outside connections to your computer. Everyone on the Internet should use a firewall in addition to anti-virus and spyware removal software.

Why do I need a firewall?

A firewall helps you block unwanted connections to open network ports on your computer. You might open a port on purpose, but a port can also be opened by a virus or worm, without your knowledge. Once a port is opened, a stranger may be able to take control of your computer, or your computer may be used to spread viruses and other malware.

Will a firewall get in my way?

  • We recommend the built-in Windows firewall for all Windows systems, and the OS X firewall for OS X Macs. Most everyday services such as printing, email, connecting to acs.bu.edu or using a web browser will work fine without adjusting these firewalls.
  • If you choose instead to use a third-party firewall, such as Norton Personal Firewall or ZoneAlarm, you may find it more restrictive and/or intrusive.

Where do I get a firewall?

WINDOWS 2007 and WINDOWS VISTA

If you are running Windows 2007 or Windows Vista, then the built-in firewall is turned on by default.

firewall To check your Firewall settings in Vista, go to the Start menu, click Control Panel, and click Security.
Now click Windows Firewall.

WINDOWS XP

If you are running Windows XP SP2 (released August 2004), then the built-in firewall is turned on by default.

To check your Firewall settings in Windows XP SP2, go to the Start menu, click Control Panel, and click Security Center.
Now click Windows Firewall.

WINDOWS 2000 OR EARLIER

Windows 2000 does not have a built-in firewall, but commercial, free and shareware products might still be available — see www.shareware.com or a general Internet search for examples.

MAC OS X

Mac OS X has a firewall which should be turned on by default.

  1. Open System Preferences and click Sharing.
  2. Click the Firewall tab and make sure the window says Firewall On. If it is not on, click Start to turn it on.
  3. Optional: you may want to click on the Advanced button and turn on Enable Firewall Logging if you think you might ever want to check back and see what your firewall has blocked. Click OK to close this window.
  4. You can now close the Sharing window.