Closing Open Doors
Alas, Microsoft Windows (in all of its recent incarnations) suffers from a sufficiently optimistic view of security that some form of protection for Internet links comes strongly recommended. Even other systemssuch as Macintosh and Linuxwill benefit from applying the general principles we describe here (though details will vary from system to system).
In general, there are two kinds of approaches involved in closing open doors to the Internet: one requires that you make certain configuration changes to your systems and perhaps add some additional software to help protect your Internet connection; the other relies on the use of special-purpose devices (often called "Internet appliances" or cable/DSL modems, even though they provide considerably more functions than linking one or more computers to the Internet).