Glossary

Note: these aren't the definitions you'd find in a book. If that's what you want, then go look in a book. These are they way I would explain the terms to someone. I'd appreciate it if you'd let me know of anything that's misleading or just plain wrong, but I'm not trying to be too strict. Life is tough enough. Sometimes, I may show some sarcasm, though.

Firewall

A way to block unwanted traffic from a company's internal network. It can be as simple as a router that simply prohibits TCP/IP packets of a certain type from crossing the boundary between the company's LAN and the Internet. In a complex system, it will allow traffic only from certain IP addresses, or only certain kinds of traffic, or only traffic that has been authenticated somehow.