[ Thanks to Jermey for this link.
]
“Most people are familiar with the term firewall and realize
that it is a device or system that keeps unwanted people and data
out of computer systems or networks. However, the word means
slightly different things to different people. This can lead to
difficulty when discussing the concept. If you ask home users
whether they have a firewall, they will probably think first of a
software program installed on their home computers, like BlackICE
Defender or ZoneAlarm, referred to as personal firewalls. At most
they might have a Linksys dedicated router/firewall. These
utilities range in price from $50 to 100. Ask a small office
network administrator about firewall, and the person will probably
think of something like the NETGEAR or NetScreen router/firewall,
or a stronger, dedicated router/firewall system running software
like SmoothWall or Astaro Linux. These are often referred to as
small office/home office (SOHO) firewalls and cost anywhere from
$100 to a few hundred dollars. Meanwhile, if an enterprise security
specialist is asked what firewall means, he or she will think more
of the heavy-duty enterprise network firewall systems such as a
Cisco PIX, Check Point, or SunScreen, costing hundreds to thousands
of dollars…”