Safe Places Outside of Your Neighborhood (Network)

Safe Places Outside of Your Neighborhood (Network)

It could be that you live near a park, and most parents in the neighborhood let their kids hang out at the park. It's a public place, so it's not as safe as being at home, but it might be safe enough.

Likewise, many networks create the equivalent of a safe public park with their firewalls. Firewalls act like routers in that they forward packets based on the destination IP address. Like routers, a firewall typically has at least two physical interfaces, and like a router, a firewall can have more than two interfaces. Outside interfaces connect to the Internet, which is considered relatively unsafe. The inside interface connects to the internal network, which is relatively safe. In firewall lingo, a third interface might be connected to another LAN, called a demilitarized zone (DMZ), which is somewhere between the inside and outside interfaces in terms of safety. Figure 18-8 shows the general idea.