FreeBSD6 Unleashed

Using a Firewall

It’s undeniable that firewalls (machines that operate as routers with filters) are almost indispensable to Internet server maintenance. Bored “script kiddies” with nothing better to do than to try to break into systems with easily accessible hacking tools make it imperative that you protect your system. Most administrators need protection that goes beyond simply electing not to run certain services and keeping on top of security bulletins. You need a generalized shield at the kernel level that prevents your system from being accessed at all on certain ports, from certain hosts, or over certain protocols. Firewalls, particularly the IPFW firewall that comes with FreeBSD, provide an answer to this need.

A firewall can prevent the ...