“I use a neat little device called a Netwinder from Rebel.com.
The Netwinder is a Linux appliance; it runs a customized
distribution of Red Hat Linux 6.1 on its StrongARM RISC chip, and
has a pretty useful Web-based administration GUI that, among other
things, lets you configure the firewall ruleset. The Netwinder
uses the ipchains firewall software that has become very popular in
the Linux world, and also does IP masquerading, which lets me hide
multiple machines behind a single IP address from my ISP. Because
my internal network uses a non-routable address system, even if
someone was to break into my Netwinder the intrusion would stop
there.”
“The rebel.com Netwinder is definitely Good Enough, and is
highly recommended. We’ve recently upgraded to the rack-mounted
version, but our original Netwinder was also Good Enough; and for
most small offices, using a Netwinder as your means of
communication with the outside world may be the best way to
go.”
“I have my Netwinder’s filtering rules set up to basically let
anything that originates from my private network reach the outside
world, but to severely restrict inbound connections. Be advised:
setting up any firewall’s filtering rules is a non-trivial
exercise, even with a GUI; you really need to do some reading and
ask some questions. If possible, have a knowledgeable friend help
you the first time or three that you set one up.”