3.4 What are some cheap packet screening tools?
The Texas AMU security tools include software for implementing
screening routers. Karlbridge is a PC-based screening router kit
A version of the Digital Equipment Corporation ``screend'' kernel
screening software is available for BSD-derived operating systems.
There are numerous kernel-level packet screens, including
ipf, ipfw, and ipfwadm. Typically,
these are included in various free Unix implementations, such as
. You might also find
these tools available in your commercial Unix implementation.
If you're willing to get your hands a little dirty, it's completely
possible to build a secure and fully functional firewall for the price
of hardware and some of your time.