All organizations connected to the Internet should use a firewall. Internet-borne attacks, ranging from direct intruder attacks to indirect attacks in the form of malicious active content in email or from Web sites, are sufficiently prevalent that operating without firewall protection would be very dangerous. An increasingly important aspect of modern firewalls is their ability to filter on e-mail and Web content for viruses and malicious active content. Viruses are rampant. Recent years have seen many outbreaks of viruses and worms that have caused major damage and losses to productivity.
Securing personal computers at home or remote locations is now as important as securing them at the office; many people telecommute or work at home and operate on organization or agency proprietary data. Home users dialing an Internet Service Provider (ISP) may have little firewall protection available to them, because the ISP has to accommodate potentially many different security policies. Therefore, personal firewalls have been developed to provide protection for remote systems and to perform many of the same functions as larger firewalls.