Mac® Security Bible

15.1. Understanding Gateways, Modems, and Routers

Gateways. Modems. Routers. Hubs. Switches. Access points. Firewalls. Base stations. All these terms and many more like them have been thrown around so carelessly for so long — especially by the companies that make Internet devices — that their meanings have become confused nearly to the point of irrelevancy. If you have a cable modem with a built-in Ethernet switch, does that make it a gateway? If it also has a Wi-Fi radio, does that mean it's an access point? If I have a router, do I also need a firewall? Questions like these can frustrate even the experts, partly because each company uses these terms in a slightly different way and partly because devices that combine multiple functions further blur the already fuzzy distinctions.

What I can do, however, is lay out a few basic concepts — and tell you how I use some of these terms in this book. I can't guarantee that this matches up with what's written on the box of the next gadget you buy, but it should at least give you a bit of direction.

15.1.1. Gateways

If the world were blanketed with Ethernet cabling the way it is with AC power lines (along with the switches, routers, and other doohickeys needed to make it all work), you could have a network connection run to your house or building and plug directly into it in much the same way that you plug in your toaster. But things don't work like that. For the most part, individuals who want to connect to the global Internet must do ...