A personal firewall is a security program that oversees all of your
computer's connections to the Internet. It may be included as part of an
Internet security suite, or it may be a free-standing program. Most
personal firewalls will deny Internet access to any program, or a new
version of any program, unless you have specifically allowed access.
This article will help you find information about configuring your
firewall to work with Firefox.
Note: In some cases, disabling an
Internet security program or firewall does not stop all of its parts
from being active. A program that reports that it is disabled may still
be able to block Firefox.